Radioisotopes such as cesium-137, iridium-192, and gold-198 have replaced radium in brachytherapy sources. Brachytherapy involves placing sealed radioactive sources close to or inside a tumor and can be delivered at low, medium, or high dose rates. Key factors in choosing radioisotopes include half-life, radiation output, specific activity, and photon energy. Proper selection of radioisotopes and dose rates optimizes treatment effectiveness while minimizing radiation exposure.
This document provides an overview of brachytherapy including its principles, methods, advantages, limitations, indications, classifications, and clinical applications. Brachytherapy involves placing radioactive sources close to or inside the tumor to deliver a high dose of radiation directly to the tumor with rapid dose fall-off sparing surrounding normal tissues. It discusses various brachytherapy techniques including interstitial, intracavitary, and surface applications for treating cancers of the breast, prostate, head and neck, and soft tissue sarcomas among others.
This document discusses planned and unplanned gaps in radiation therapy treatment schedules. Planned gaps are built into the schedule to account for tumor repopulation during weekends and holidays. Unplanned gaps negatively impact treatment outcomes by prolonging the overall time and allowing tumors to regrow. The effects of gaps depend on the prolongation length, tumor proliferation rate, and timing of the interruption. Corrections like increasing the dose or number of fractions are sometimes made to account for biological effects of treatment gaps.
The document summarizes recommendations from ICRU Report 38 regarding dose specification, reporting, and volumes for intracavitary brachytherapy for gynecological cancers. It discusses:
1. Historical dose reporting systems like milligram-hours and Point A/B and introduces the concept of a reference volume receiving 60Gy.
2. Factors to report like treatment technique, time-dose patterns, and doses to organs at risk.
3. Volumes for reporting like the treated volume, high-dose volume, irradiated volume, and Point A volume.
4. Recommendations for specifying and reporting doses in a standardized way to allow comparison between different brachytherapy procedures
This document discusses various time-dose models used in radiotherapy, including the Strandqvist, Cohen, NSD, and TDF models. It explains the need for these models to optimize treatment regimes for tumor control while sparing normal tissues. The document also covers gap correction factors used when treatment schedules are interrupted and the various factors that can affect tumor control outcomes due to gaps in treatment. Compensatory methods like accelerated scheduling and increased dosing are presented to account for treatment gaps.
2 d vs 3d planning in pelvic malignanciesAbhishek Soni
Three dimensional radiation treatment planning is superior to two dimensional planning for pelvic malignancies. 3D planning allows for a more accurate definition of the tumor and dose distribution, resulting in a more homogeneous dose to the target volume while better sparing nearby critical organs such as the bladder and rectum. Dose volume histograms based on 3D planning show improved target coverage and lower doses to organs at risk compared to 2D planning. Precise delineation of contours is important for effective 3D planning.
This is a made easy summary of ICRU 89 guidelines for gynecological brachytherapy. Extra practical questions for MD/DNB Radiotherapy exams are also attached.
SBRT is a precise form of radiation therapy that delivers very high ablative doses of radiation to tumors in a small number of fractions. It has become the standard of care for early stage non-small cell lung cancer (NSC LC) that is not surgically resectable. Key aspects of SBRT planning and delivery include delineating targets and organs at risk on imaging, determining appropriate dose and fractionation based on tumor location, using motion management strategies to account for tumor motion, precise daily image guidance, and ensuring dose constraints are met to minimize risks to critical structures like the spinal cord. SBRT provides superior local tumor control compared to conventional fractionation for early stage NSCLC with a favorable toxicity profile.
This document provides an overview of brachytherapy including its principles, methods, advantages, limitations, indications, classifications, and clinical applications. Brachytherapy involves placing radioactive sources close to or inside the tumor to deliver a high dose of radiation directly to the tumor with rapid dose fall-off sparing surrounding normal tissues. It discusses various brachytherapy techniques including interstitial, intracavitary, and surface applications for treating cancers of the breast, prostate, head and neck, and soft tissue sarcomas among others.
This document discusses planned and unplanned gaps in radiation therapy treatment schedules. Planned gaps are built into the schedule to account for tumor repopulation during weekends and holidays. Unplanned gaps negatively impact treatment outcomes by prolonging the overall time and allowing tumors to regrow. The effects of gaps depend on the prolongation length, tumor proliferation rate, and timing of the interruption. Corrections like increasing the dose or number of fractions are sometimes made to account for biological effects of treatment gaps.
The document summarizes recommendations from ICRU Report 38 regarding dose specification, reporting, and volumes for intracavitary brachytherapy for gynecological cancers. It discusses:
1. Historical dose reporting systems like milligram-hours and Point A/B and introduces the concept of a reference volume receiving 60Gy.
2. Factors to report like treatment technique, time-dose patterns, and doses to organs at risk.
3. Volumes for reporting like the treated volume, high-dose volume, irradiated volume, and Point A volume.
4. Recommendations for specifying and reporting doses in a standardized way to allow comparison between different brachytherapy procedures
This document discusses various time-dose models used in radiotherapy, including the Strandqvist, Cohen, NSD, and TDF models. It explains the need for these models to optimize treatment regimes for tumor control while sparing normal tissues. The document also covers gap correction factors used when treatment schedules are interrupted and the various factors that can affect tumor control outcomes due to gaps in treatment. Compensatory methods like accelerated scheduling and increased dosing are presented to account for treatment gaps.
2 d vs 3d planning in pelvic malignanciesAbhishek Soni
Three dimensional radiation treatment planning is superior to two dimensional planning for pelvic malignancies. 3D planning allows for a more accurate definition of the tumor and dose distribution, resulting in a more homogeneous dose to the target volume while better sparing nearby critical organs such as the bladder and rectum. Dose volume histograms based on 3D planning show improved target coverage and lower doses to organs at risk compared to 2D planning. Precise delineation of contours is important for effective 3D planning.
This is a made easy summary of ICRU 89 guidelines for gynecological brachytherapy. Extra practical questions for MD/DNB Radiotherapy exams are also attached.
SBRT is a precise form of radiation therapy that delivers very high ablative doses of radiation to tumors in a small number of fractions. It has become the standard of care for early stage non-small cell lung cancer (NSC LC) that is not surgically resectable. Key aspects of SBRT planning and delivery include delineating targets and organs at risk on imaging, determining appropriate dose and fractionation based on tumor location, using motion management strategies to account for tumor motion, precise daily image guidance, and ensuring dose constraints are met to minimize risks to critical structures like the spinal cord. SBRT provides superior local tumor control compared to conventional fractionation for early stage NSCLC with a favorable toxicity profile.
This document summarizes key considerations for intensity-modulated radiation therapy (IMRT) treatment planning and dosimetry. It discusses beam modeling, dose calculation, inverse planning, and quality assurance. Accurate modeling of beam penumbra, multileaf collimator characteristics, output factors for small fields, and dose calculation algorithms are essential for ensuring dosimetric accuracy. Proper target and organ-at-risk delineation and appropriate margins are also important for effective IMRT planning.
This document discusses various particle beams used in radiation therapy, including their properties and effectiveness. It states that proton beams have superior dose distribution compared to photon beams but lower LET. Neutron beams have high LET properties but poor dose distribution. Heavy charged particle beams like carbon ions have both superior distribution and high LET. BNCT uses boron compounds and neutrons to specifically target tumor cells but is limited by availability and cost. Overall, the document provides an overview of different particle therapies and their advantages over conventional photon radiation.
Proton beam therapy uses protons to treat cancer. It can reduce the dose to healthy tissues compared to photon therapy by depositing most of the energy at a specific depth. Proton therapy has potential applications in tumors near critical structures where dose escalation may improve outcomes. However, more evidence from controlled trials is still needed to demonstrate comparative effectiveness versus other radiation therapies.
This document discusses Intra-cavitary Brachytherapy (ICBT) for treating cervical cancer. It describes different historical ICBT systems like Paris, Stockholm, and Manchester systems. It also discusses modern techniques like remote afterloaders and recommendations for reporting absorbed doses and volumes in ICBT. Key points include different dose rates (LDR, MDR, HDR), advantages of remote afterloaders in maintaining geometry and dose distribution, and recommending specifying absorbed dose to the target volume rather than at a single point for ICBT.
This document provides information about brachytherapy dosimetry systems. It discusses different brachytherapy treatment techniques including intracavitary, interstitial, and permanent vs. temporary implants. Common radionuclides used in brachytherapy are described. Dosimetry systems for interstitial and intracavitary brachytherapy like Patterson-Parker, Quimby, Paris, Manchester, Stockholm, and ICRU systems are summarized. Key aspects of these systems including reference points, volumes, and dose specifications are highlighted.
The ICRU was conceived in 1925 to propose a unit for measuring radiation in medicine. It is now responsible for defining units of measure for radiation quantities and developing recommendations on their safe application. The ICRU works with committees to publish reports on topics like radiation therapy, dosimetry, and protection. Its goals are to evaluate data on ionizing radiation and maintain contacts to benefit radiation science.
This document discusses the history and techniques of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). It begins by outlining the early development of SRS by Lars Leksell in the 1950s. It then defines key terms like SRS, SBRT, and fractionated stereotactic radiosurgery. The document goes on to discuss the rationale and advantages of SRS/SBRT, including its ability to deliver high radiation doses with steep dose gradients using multiple beams and image guidance. It also covers topics like tumor oxygenation, cell kill mechanisms, and recent technological advances in the field like VMAT, flattening filter free beams, and 4D
This slide includes physical, biological properties of proton and its advantage over the photon. It also provides information from beam production to treatment planning system of proton therapy, its potential applications, cost effectiveness and demerits.
Future Developments In Radiation Therapy For Prostate Cancerfondas vakalis
This document discusses future developments in radiation therapy for prostate cancer. It summarizes that dose escalation improves disease control but can increase toxicity risks. Newer radiation techniques like IMRT, fiducial markers, on-board imaging, and protons may allow safer dose escalation by better sparing nearby organs. Further refinements include selective dose painting within the prostate using MRI/MRS imaging fusion to guide treatment. The document also reviews the history and ongoing improvements in brachytherapy techniques for localized prostate treatments.
A novel technique of radiation delivery with ultrahigh dose rate radiation therapy delivered in milisecond of time. Although, still in investigational phase
1. Re-irradiation involves delivering a second course of radiation to patients who develop recurrent or new primary tumors in an area previously treated with radiation. It requires careful patient selection and consideration of normal tissue tolerance to minimize toxicity risks.
2. A multidisciplinary evaluation is necessary to determine if re-irradiation provides a survival or palliative benefit over other treatment options like chemotherapy or surgery. Factors like tumor type, initial treatment details, disease control, and patient performance status must be considered.
3. Advanced radiation techniques like IMRT can help spare nearby organs-at-risk and lower toxicity when used for re-irradiation. Close monitoring during treatment is still needed to watch for normal tissue complications.
Isodose curves depict absorbed dose distributions and variations in volume and planes. They join points of equal dose. Isodose charts show the variation in dose as a function of depth and transverse distance from the central beam axis. Factors like beam energy, field size, and distance affect isodose curve shape through penumbra and dose deposition. Multiple beams are often needed to adequately treat tumors while sparing surrounding tissues. Beam arrangements, weights, and modifiers must be optimized for each plan.
Management of cacrinoma cervix: Techniques of radiotherapy (2D conventional, 3D Conformal radiotherapy (3DCRT) and IMRT with a review of various contouring guidelines.
Carcinoma cervix brachytherapy- dr upasnaUpasna Saxena
Dr. Upasna Saxena presented on brachytherapy. Brachytherapy involves placing radioactive sources close to or inside the tumor. It has advantages like high localized dose and sparing of surrounding tissues. Intracavitary brachytherapy is commonly used to treat cervical cancer using applicators like tandems and ovoids. Key planning points include Point A which is 2cm lateral and 2cm superior to the cervical os. Dose to organs at risk like bladder and rectum are also important. Proper placement and geometry of applicators is important for adequate dose coverage and sparing of organs at risk.
The vmat vs other recent radiotherapy techniquesM'dee Phechudi
VMAT is a new type of intensity-modulated radiation therapy (IMRT) treatment technique that uses the same hardware (i.e. a digital linear accelerator) as used for IMRT or conformal treatment, but delivers the radiotherapy treatment using a rotational or arc geometry rather than several static beams.
This technique uses continuous modulation (i.e. moving the collimator leaves) of the multileaf collimator (MLC) fields, continuous change of the fluence rate (the intensity of the X rays) and gantry rotation speed across a single or multiple 360 degree rotations
1. Isodose curves represent the dose distribution from radiation beams and are lines connecting points of equal percentage depth dose. They are used to depict the volumetric and planar variations in absorbed dose.
2. The parameters that affect the shape of isodose curves include beam quality, source size, SSD, SDD, field size, and beam modifiers like wedges and flattening filters. Lower beam energy results in greater lateral scatter and more bulging curves.
3. Multiple radiation fields can be combined using appropriate beam weights, sizes, angles and modifiers to deliver a more uniform dose to the tumor while sparing surrounding tissues. Parameters like setup accuracy and plan practicality are also considered.
Glimpse of clinical radiobiology courseManoj Gupta
This document provides an overview of key concepts in clinical radiobiology. It discusses how ionizing radiation interacts with matter and cells, causing ionization which can lead to cell death. The attenuation of radiation as it passes through different tissues is described, as well as different radiation interactions like the photoelectric effect. Cell survival curves are introduced, showing their exponential nature and how factors like oxygenation and fractionation affect the curves. The linear quadratic model is explained. Finally, the four R's of radiobiology - reoxygenation, redistribution, repopulation and repair - are summarized as the basis for fractionated radiotherapy.
This document discusses normal tissue tolerance doses from radiation therapy. It describes the formation of a task force to establish tolerance protocols, with an emphasis on partial volume effects. The earliest publication of tolerance doses is cited from 1972. 28 critical organ sites were included and considered in terms of dose, time factors, and partial volumes irradiated. The significance of these parameters and a quantitative model for normal tissue complication probability are provided. Limitations of the available data and ongoing areas of research are also outlined.
This document discusses radiation therapy options for prostate cancer. It notes that treatment depends on risk level: low risk may receive external beam radiation or seeds alone, intermediate risk should receive some external beam, and high risk should receive hormone therapy plus radiation. Newer techniques like IMRT and IGRT reduce side effects by more precisely targeting the prostate. Side effects of radiation include short term issues like urinary frequency and diarrhea as well as long term risks like radiation cystitis and impotence in some cases.
Radioisotopes and dose rates used for brachytherapySubhash Thakur
Radioisotopes and dose rates used for brachytherapy
This is the seminar about different radioisotopes used in brachytherapy beginning from radium to iradium and different dose rates, low dose rate, high dose rate used in brachytherapy. The significance of different dose rates and its radiobiology along with the clinical results.
Sealed radioactive sources are radioactive material permanently sealed in a capsule. Common sealed sources used in brachytherapy include cesium-137, iridium-192, cobalt-60, iodine-125, gold-198, and radium-226. Each isotope has different properties such as half-life, photon energy emitted, and exposure rate constant. Sources are constructed of radioactive material encapsulated in stainless steel, gold or platinum capsules to prevent leakage and are available in various geometries like seeds, ribbons, or tubes to suit different clinical applications in brachytherapy.
This document summarizes key considerations for intensity-modulated radiation therapy (IMRT) treatment planning and dosimetry. It discusses beam modeling, dose calculation, inverse planning, and quality assurance. Accurate modeling of beam penumbra, multileaf collimator characteristics, output factors for small fields, and dose calculation algorithms are essential for ensuring dosimetric accuracy. Proper target and organ-at-risk delineation and appropriate margins are also important for effective IMRT planning.
This document discusses various particle beams used in radiation therapy, including their properties and effectiveness. It states that proton beams have superior dose distribution compared to photon beams but lower LET. Neutron beams have high LET properties but poor dose distribution. Heavy charged particle beams like carbon ions have both superior distribution and high LET. BNCT uses boron compounds and neutrons to specifically target tumor cells but is limited by availability and cost. Overall, the document provides an overview of different particle therapies and their advantages over conventional photon radiation.
Proton beam therapy uses protons to treat cancer. It can reduce the dose to healthy tissues compared to photon therapy by depositing most of the energy at a specific depth. Proton therapy has potential applications in tumors near critical structures where dose escalation may improve outcomes. However, more evidence from controlled trials is still needed to demonstrate comparative effectiveness versus other radiation therapies.
This document discusses Intra-cavitary Brachytherapy (ICBT) for treating cervical cancer. It describes different historical ICBT systems like Paris, Stockholm, and Manchester systems. It also discusses modern techniques like remote afterloaders and recommendations for reporting absorbed doses and volumes in ICBT. Key points include different dose rates (LDR, MDR, HDR), advantages of remote afterloaders in maintaining geometry and dose distribution, and recommending specifying absorbed dose to the target volume rather than at a single point for ICBT.
This document provides information about brachytherapy dosimetry systems. It discusses different brachytherapy treatment techniques including intracavitary, interstitial, and permanent vs. temporary implants. Common radionuclides used in brachytherapy are described. Dosimetry systems for interstitial and intracavitary brachytherapy like Patterson-Parker, Quimby, Paris, Manchester, Stockholm, and ICRU systems are summarized. Key aspects of these systems including reference points, volumes, and dose specifications are highlighted.
The ICRU was conceived in 1925 to propose a unit for measuring radiation in medicine. It is now responsible for defining units of measure for radiation quantities and developing recommendations on their safe application. The ICRU works with committees to publish reports on topics like radiation therapy, dosimetry, and protection. Its goals are to evaluate data on ionizing radiation and maintain contacts to benefit radiation science.
This document discusses the history and techniques of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). It begins by outlining the early development of SRS by Lars Leksell in the 1950s. It then defines key terms like SRS, SBRT, and fractionated stereotactic radiosurgery. The document goes on to discuss the rationale and advantages of SRS/SBRT, including its ability to deliver high radiation doses with steep dose gradients using multiple beams and image guidance. It also covers topics like tumor oxygenation, cell kill mechanisms, and recent technological advances in the field like VMAT, flattening filter free beams, and 4D
This slide includes physical, biological properties of proton and its advantage over the photon. It also provides information from beam production to treatment planning system of proton therapy, its potential applications, cost effectiveness and demerits.
Future Developments In Radiation Therapy For Prostate Cancerfondas vakalis
This document discusses future developments in radiation therapy for prostate cancer. It summarizes that dose escalation improves disease control but can increase toxicity risks. Newer radiation techniques like IMRT, fiducial markers, on-board imaging, and protons may allow safer dose escalation by better sparing nearby organs. Further refinements include selective dose painting within the prostate using MRI/MRS imaging fusion to guide treatment. The document also reviews the history and ongoing improvements in brachytherapy techniques for localized prostate treatments.
A novel technique of radiation delivery with ultrahigh dose rate radiation therapy delivered in milisecond of time. Although, still in investigational phase
1. Re-irradiation involves delivering a second course of radiation to patients who develop recurrent or new primary tumors in an area previously treated with radiation. It requires careful patient selection and consideration of normal tissue tolerance to minimize toxicity risks.
2. A multidisciplinary evaluation is necessary to determine if re-irradiation provides a survival or palliative benefit over other treatment options like chemotherapy or surgery. Factors like tumor type, initial treatment details, disease control, and patient performance status must be considered.
3. Advanced radiation techniques like IMRT can help spare nearby organs-at-risk and lower toxicity when used for re-irradiation. Close monitoring during treatment is still needed to watch for normal tissue complications.
Isodose curves depict absorbed dose distributions and variations in volume and planes. They join points of equal dose. Isodose charts show the variation in dose as a function of depth and transverse distance from the central beam axis. Factors like beam energy, field size, and distance affect isodose curve shape through penumbra and dose deposition. Multiple beams are often needed to adequately treat tumors while sparing surrounding tissues. Beam arrangements, weights, and modifiers must be optimized for each plan.
Management of cacrinoma cervix: Techniques of radiotherapy (2D conventional, 3D Conformal radiotherapy (3DCRT) and IMRT with a review of various contouring guidelines.
Carcinoma cervix brachytherapy- dr upasnaUpasna Saxena
Dr. Upasna Saxena presented on brachytherapy. Brachytherapy involves placing radioactive sources close to or inside the tumor. It has advantages like high localized dose and sparing of surrounding tissues. Intracavitary brachytherapy is commonly used to treat cervical cancer using applicators like tandems and ovoids. Key planning points include Point A which is 2cm lateral and 2cm superior to the cervical os. Dose to organs at risk like bladder and rectum are also important. Proper placement and geometry of applicators is important for adequate dose coverage and sparing of organs at risk.
The vmat vs other recent radiotherapy techniquesM'dee Phechudi
VMAT is a new type of intensity-modulated radiation therapy (IMRT) treatment technique that uses the same hardware (i.e. a digital linear accelerator) as used for IMRT or conformal treatment, but delivers the radiotherapy treatment using a rotational or arc geometry rather than several static beams.
This technique uses continuous modulation (i.e. moving the collimator leaves) of the multileaf collimator (MLC) fields, continuous change of the fluence rate (the intensity of the X rays) and gantry rotation speed across a single or multiple 360 degree rotations
1. Isodose curves represent the dose distribution from radiation beams and are lines connecting points of equal percentage depth dose. They are used to depict the volumetric and planar variations in absorbed dose.
2. The parameters that affect the shape of isodose curves include beam quality, source size, SSD, SDD, field size, and beam modifiers like wedges and flattening filters. Lower beam energy results in greater lateral scatter and more bulging curves.
3. Multiple radiation fields can be combined using appropriate beam weights, sizes, angles and modifiers to deliver a more uniform dose to the tumor while sparing surrounding tissues. Parameters like setup accuracy and plan practicality are also considered.
Glimpse of clinical radiobiology courseManoj Gupta
This document provides an overview of key concepts in clinical radiobiology. It discusses how ionizing radiation interacts with matter and cells, causing ionization which can lead to cell death. The attenuation of radiation as it passes through different tissues is described, as well as different radiation interactions like the photoelectric effect. Cell survival curves are introduced, showing their exponential nature and how factors like oxygenation and fractionation affect the curves. The linear quadratic model is explained. Finally, the four R's of radiobiology - reoxygenation, redistribution, repopulation and repair - are summarized as the basis for fractionated radiotherapy.
This document discusses normal tissue tolerance doses from radiation therapy. It describes the formation of a task force to establish tolerance protocols, with an emphasis on partial volume effects. The earliest publication of tolerance doses is cited from 1972. 28 critical organ sites were included and considered in terms of dose, time factors, and partial volumes irradiated. The significance of these parameters and a quantitative model for normal tissue complication probability are provided. Limitations of the available data and ongoing areas of research are also outlined.
This document discusses radiation therapy options for prostate cancer. It notes that treatment depends on risk level: low risk may receive external beam radiation or seeds alone, intermediate risk should receive some external beam, and high risk should receive hormone therapy plus radiation. Newer techniques like IMRT and IGRT reduce side effects by more precisely targeting the prostate. Side effects of radiation include short term issues like urinary frequency and diarrhea as well as long term risks like radiation cystitis and impotence in some cases.
Radioisotopes and dose rates used for brachytherapySubhash Thakur
Radioisotopes and dose rates used for brachytherapy
This is the seminar about different radioisotopes used in brachytherapy beginning from radium to iradium and different dose rates, low dose rate, high dose rate used in brachytherapy. The significance of different dose rates and its radiobiology along with the clinical results.
Sealed radioactive sources are radioactive material permanently sealed in a capsule. Common sealed sources used in brachytherapy include cesium-137, iridium-192, cobalt-60, iodine-125, gold-198, and radium-226. Each isotope has different properties such as half-life, photon energy emitted, and exposure rate constant. Sources are constructed of radioactive material encapsulated in stainless steel, gold or platinum capsules to prevent leakage and are available in various geometries like seeds, ribbons, or tubes to suit different clinical applications in brachytherapy.
Radium and radium equivalent materialsJyoti Sharma
Radium-226 and other radioactive isotopes like cesium-137, iridium-192, gold-198, and iodine-125 are discussed as alternatives to radium for brachytherapy applications. Each isotope is described in terms of its discovery method, half-life, decay process, photon energies, common physical forms, and historical medical uses. Newer isotopes discussed for emerging applications include ruthenium-106, vanadium-49, holmium-166, and praseodymium-144. The document provides a comprehensive overview of various radiological sources used in brachytherapy treatments.
Brachytherapy involves placing radioactive sources inside or near the target tissue. It began in 1898 with radium and has evolved with different radioactive isotopes and delivery methods. Common isotopes used today include iridium-192, cesium-137, palladium-103, iodine-125, and gold-198, which are used for interstitial, intracavitary, or permanent implantation depending on the clinical application and isotope properties.
The document discusses radioisotopes and their use in brachytherapy. It defines radioisotopes as unstable elements that emit radiation during decay to a stable form. Common radioisotopes used in brachytherapy like iodine-125, palladium-103, cesium-137, and iridium-192 are discussed. Their properties such as half-life and type of radiation emitted make them suitable for brachytherapy applications. Both temporary and permanent brachytherapy seed implants are described. External beam radiotherapy using cobalt-60 or cesium-137 sources is also summarized.
it's all about the brachytherapy sources HDR & LDR sources with their properties and decay schemes. In this ppt, topic covered as half life, gamma energy, beta energy, HVL, daughter particles, etc. all the elements have their decay scheme.
This document describes a passively Q-switched Nd:YAG ceramic laser using a single wall carbon nanotube saturable absorber. The laser generated pulses with a maximum duration of 1.2 ms, repetition rate varying from 14 to 95 kHz, and maximum pulse energy of 4.5 mJ at a repetition rate of 31.8 kHz. The laser achieved a maximum output power of 376 mW and optical-to-optical conversion efficiency of 4.3% at a pump power of 8.68 W. Characterization of the Nd:YAG ceramic gain medium showed scattering and absorption losses similar to a crystal, with the ceramic laser demonstrating output power only 6.3% lower than an equivalent
Types of laser used in laser cutting machinesMarwan Shehata
The document discusses different types of lasers used in machining. It describes solid-state lasers like ruby and YAG lasers. Gas lasers like CO2 are commonly used for machining nonmetals. Neodymium-glass lasers can produce very short, high power pulses for research. Neodymium-YAG lasers can produce over 1 kW of continuous power and are used for machining and laser fusion research. Excimer lasers have short ultraviolet wavelengths and can precisely machine materials through direct vaporization without heat damage.
This document provides information on radioactivity and radioactive isotopes used in clinical medicine. It discusses the properties of natural and artificial radioactivity and types of radioactive decay. Common medical radioisotopes used for therapy and diagnosis like radium-226, cesium-137, cobalt-60, iridium-192, gold-198, and iodine-125 are described in terms of their production, half-lives, emissions, and clinical applications and source forms. The ideal properties of radioisotopes for use in teletherapy and brachytherapy are also summarized.
This document discusses composite light curing units. It begins by introducing light activated resin systems and the advantages of light cure composites over self cure. It describes the components of light cure composites including camphorquinone and amine activators. The document then covers the characteristics of curing light, types of light curing units including quartz tungsten halogen, plasma arc, laser and LED lights. It discusses factors that influence polymerization such as exposure time, irradiance, and techniques like continuous and discontinuous curing.
Different types of lasers and laser delivery systemKrati Gupta
This document discusses different types of lasers and their delivery systems used in ophthalmology. It begins by defining what a laser is and providing a brief history of their development. It then describes the key properties of lasers and the physics behind how they are produced. The document outlines different types of solid state, gas, metal vapor, and other lasers. It discusses the interactions between light and tissue, including photocoagulation, photoablation, photodisruption, and photovaporization. The closing paragraphs cover laser parameters and modes of operation such as continuous wave, pulsed, and Q-switched lasers.
This document provides an overview of lasers used in ophthalmology. It discusses the basic properties and types of lasers and their applications in treating different parts of the eye, including the skin, anterior chamber, lens, vitreous, and retina. Specific lasers are used to perform procedures like photocoagulation, capsulotomy, trabeculoplasty, and cyclophotocoagulation. The document also covers laser-tissue interactions and lenses used to deliver laser treatment to different ocular structures.
This document discusses the use of nanomaterials in radiochemical separations for biomedical applications. It summarizes the development of four radiochemical separation systems/generators using nanomaterials: 1) 99Mo/99mTc generator for SPECT imaging, 2) 68Ge/68Ga generator for PET imaging, 3) 188W/188Re generator for therapy, and 4) 77Ge/77As generator. The nanomaterial-based generators demonstrated excellent separation yields and purity of daughter radionuclides, as well as consistent performance throughout shelf-life. This novel approach overcomes limitations of conventional generators and establishes protocols for global acceptance of new radiochemical separation systems.
Scientific & Technological Perspective:
Future of Energy Storage With
Graphene Oxide (GO)
Paper Presentation
By
Radhey Shyam Meena
In
International Conference On
Advanced in Power Generation From
Renewable Energy Sources
APGRES 2015, June 15-16, 2015
Rajasthan Technical University Kota
The document discusses erbium-doped fiber lasers (EDFLs). EDFLs emit light at 1.55μm, which lies in the eye-safe region of the spectrum and is preferred for long-distance fiber optic communications. They consist of an optical fiber doped with erbium ions as the gain medium, pump lasers to excite the erbium ions, and dielectric mirrors or fiber Bragg gratings to form the optical resonator. EDFLs have revolutionized fiber optic communications and next generation versions may be integrated onto single chips.
This study investigates copper iodide (CuI) as an inorganic hole conductor for organolead halide perovskite solar cells. The researchers fabricated solar cells using CuI deposited via an automated drop casting technique. Compared to the conventional organic hole conductor spiro-OMeTAD, the CuI-based devices showed higher photocurrent stability and fill factor but lower open-circuit voltage. Impedance spectroscopy indicated the lower voltage was due to higher recombination rates in the CuI devices. However, CuI exhibited nearly two orders of magnitude higher hole conductivity than spiro-OMeTAD, suggesting its potential as a lower-cost replacement for organic hole transport materials.
The document discusses various applications of nanomaterials. It describes how nanotechnology is used in industries like automotive, engineering, medicine, cosmetics and textiles. It also discusses energy applications like nanofabrication for new ways to capture, store and transfer energy. Pharmaceutical applications of nanomaterials include drug delivery, tissue engineering, medical implants and diagnostics. Nanotechnology is also used in water purification through processes like nanofiltration and reverse osmosis. Thin film solar cells and dye sensitized solar cells that use nanomaterials are discussed as energy applications. Perovskite solar cells which can achieve high efficiencies are also summarized.
1) The document discusses the cell cycle, which includes interphase and the M phase. Interphase consists of G1, S, and G2 phases where the cell grows and replicates its DNA in preparation for division.
2) The M phase is when the cell divides, known as mitosis, which has four stages - prophase, metaphase, anaphase, and telophase. During these stages the chromosomes condense and align, separate, and decondense respectively.
3) Cell division, along with DNA replication and growth, must be coordinated through the cell cycle to ensure daughter cells receive intact genomes. The cycle allows a single cell to multiply into millions through repeated growth and division.
The document discusses principles and methods of immobilization in radiotherapy. It describes the role of immobilization in reducing geometric uncertainties and lists the ideal properties of an immobilization device. The history of immobilization devices is explored, from early uses of plastic cups and masking tapes to today's body conformal devices and stereotactic equipment. Various head and neck immobilization tools are presented, including thermoplastic molds, base plates, and accessories like mouth bites. Body conformal devices like alpha cradles and vacuum-lock bags are explained. Immobilization methods for specific treatment sites like breast, prostate, and intracranial regions are outlined.
This document discusses cytotoxic drugs and the origins of chemotherapy. It provides information on various classes of cytotoxic drugs including alkylating agents, antimetabolites, plant alkaloids, and mitotic inhibitors. Key events in the development of chemotherapy are noted, such as the observation that nitrogen mustards caused bone marrow destruction in WWII, which led to their application against Hodgkin's disease. The mechanisms of cytotoxic drugs and their effects on the cell cycle are also summarized.
This document discusses brachytherapy techniques for treating carcinoma of the cervix. It describes the advantages of brachytherapy including its ability to deliver high radiation doses to tumors while sparing surrounding normal tissues. Several historical brachytherapy systems are summarized, including the Stockholm, Paris, and Manchester systems. The Manchester system defines dosimetry points A and B and provides rules for standardized applicator placement and radioactive source loading to achieve consistent dose distributions.
Epidemiology, Etiopathogenesis, Pathology, Staging of Plasma Cell Dyscrasias....adityasingla007
Plasma cell dyscrasias are a spectrum of monoclonal gammopathies involving overproduction of myeloma proteins by plasma cells. Key points include:
- Plasma cells normally secrete antibodies but in plasma cell dyscrasias a clone overproduces a single antibody type.
- Risk factors include radiation exposure and genetic predispositions. Cytogenetic abnormalities involving immunoglobulin loci and cell cycle genes contribute to pathogenesis.
- Presentations include bone pain, fatigue, infections due to anemia or renal impairment. Investigations show monoclonal protein and clonal bone marrow plasma cells.
- Multiple myeloma, monoclonal gammopathy of unknown significance (MGUS), and smoldering
This document discusses the late effects of radiotherapy. It notes that while radiotherapy effectively treats cancer by damaging DNA in cancer cells, it can also affect normal cells, leading to both acute and late effects. Late effects occur more than 3 months after treatment and involve tissues with slow turnover rates. Common late effects include fibrosis, atrophy, necrosis, vascular damage, and secondary malignancies. The document outlines late effects for various organs and tissues. It emphasizes the importance of prevention strategies like treatment planning and education to minimize complications and improve patient outcomes and quality of life.
Colorectal cancer begins in the inner lining of the colon or rectum and can spread deeper into the wall of the colon/rectum and to other parts of the body. Risk factors include increasing age, family history, lifestyle factors like smoking, obesity, and lack of physical activity. Symptoms often include changes in bowel habits and bleeding. Screening is recommended regularly beginning at age 50. Treatment depends on the stage and may include surgery, radiation, chemotherapy, and targeted therapies. Prognosis depends on tumor stage and extent at diagnosis.
This document provides information on principles of chemotherapy. It discusses how chemotherapy works by damaging rapidly dividing cells like cancer cells, outlines the cell cycle and phases cells go through when dividing, and explains how chemotherapy targets specific phases to kill cancer cells. It also describes common side effects of chemotherapy like nausea, vomiting, fatigue, bone marrow depression leading to neutropenia, thrombocytopenia and anemia. The document discusses approaches to managing these side effects.
Brachytherapy involves placing small radioactive sources inside or near a tumor. It allows a high radiation dose to be delivered to the tumor while sparing surrounding normal tissues. There are several types of brachytherapy classified by source placement (interstitial, intracavitary), loading pattern (pre-loading, after-loading), dose rate (LDR, HDR), and duration of implant (temporary, permanent). Common radioactive sources used include cesium-137, iridium-192, and iodine-125 seeds. Brachytherapy provides advantages of high tumor control with minimal side effects due to rapid dose fall-off and short treatment times.
This document discusses gastrointestinal stromal tumors (GISTs). It defines GISTs as mesenchymal neoplasms that originate in the interstitial cells of Cajal in the gut wall. The majority of GISTs have a mutation in either the KIT or PDGFRA gene. KIT mutations are present in around 95% of cases and result in uncontrolled KIT signaling. Treatment involves surgical resection with adjuvant imatinib therapy for higher risk cases. For advanced or imatinib-resistant GISTs, other tyrosine kinase inhibitors like sunitinib may be used.
Vulvar cancer is a rare malignancy that represents less than 1% of cancers in women. It occurs most commonly in two age groups - younger women who smoke and are HPV-positive, and older women who may have epithelial dystrophies as risk factors. Lymphatic drainage is primarily to the superficial inguinal lymph nodes, with potential spread to deep femoral and pelvic nodes. Positive lymph nodes, particularly those over 5mm or with extracapsular spread, are the strongest prognostic factors and reduce 5-year survival by 50%. Surgical margins of at least 8mm are also important to reduce the risk of local recurrence after resection. Radiation may help reduce recurrence risk when margins are close. Distant metastases generally occur
1. Carcinoma of the oral cavity is most commonly found on the tongue, floor of mouth, and lips. It spreads locally and via lymphatics, most often to cervical lymph nodes. Distant metastases occur in 15-20% of cases, most commonly to lungs.
2. Diagnosis involves history, physical exam, biopsy of the lesion and lymph nodes, imaging like OPG, CT/MRI to assess bone and lymph node involvement. Staging helps determine prognosis and management.
3. Treatment involves surgery, radiation, chemotherapy depending on stage. Close surveillance is needed due to high risk of recurrence and second primary cancers.
The document discusses radiation and its effects on the human body. It provides information on deterministic effects, which have a threshold dose below which no effect is observable, and severity increases with dose. Examples of deterministic effects like cataracts and sterility are given along with their dose thresholds. International standards from organizations like ICRP, IAEA, and UNSCEAR are mentioned. Occupational and public dose limits are provided. Methods of measuring radiation exposure through film, TLD and electronic dosimeters are listed. Information is also given on calculating effective dose and the tissues and organs considered. Background radiation exposures from cosmic, terrestrial and internal sources are detailed. Finally, fatal accident rates per million workers are shown for different occupations along with the radiation
- The document provides information on Acute Myeloid Leukemia (AML), including its etiology, pathogenesis, signs and symptoms, diagnosis, classification, and treatment.
- AML arises from the abnormal clonal expansion of immature myeloid precursors in the bone marrow that have impaired differentiation. It is diagnosed based on finding at least 20% myeloid blasts in the bone marrow.
- Classification involves cytogenetic and molecular testing to identify recurrent genetic abnormalities that inform prognosis and treatment approach.
Radiation therapy has evolved significantly in its use and techniques for managing Hodgkin lymphoma over the past century. Early approaches used low dose X-rays to treat only involved lymph node regions, but this led to high recurrence rates. Later approaches in the 1950s used extended field radiation therapy to treat both involved and adjacent uninvolved lymph node regions, improving outcomes. However, this also increased long-term toxicity risks. More recent decades have seen a shift to involved node radiation therapy and combined modality treatment with chemotherapy to improve cure rates while reducing radiation doses and volumes to minimize side effects like secondary cancers. Ongoing clinical trials continue refining therapies to maximize benefit and safety.
This randomized controlled trial compared preoperative chemoradiotherapy to immediate surgery for resectable or borderline resectable pancreatic cancer. It found no significant difference in overall survival between the two groups based on intention-to-treat analysis. However, the preoperative chemoradiotherapy group had higher R0 resection rates and more favorable pathological outcomes. Compliance with preoperative treatment was also better. For borderline resectable disease specifically, preoperative chemoradiotherapy showed a prolonged overall survival compared to immediate surgery.
Concomitant chemotherapy provides the greatest benefit for patients with locally advanced head and neck cancer according to the MACHNC 2021 meta-analysis. It improves 5-year overall survival by 6.5% and event-free survival by 5.8%, with the greatest decrease in locoregional failure rates. Induction chemotherapy provides smaller benefits of 2.2% for overall survival and 1.45% for event-free survival, as well as a significant decrease in distant failure rates. Adjuvant chemotherapy does not improve survival and increases 120-day mortality. Cisplatin-based regimens are preferred for concomitant and induction chemotherapy. This may be the final MACHNC analysis as no new patients have been
This study retrospectively analyzed exclusive radiotherapy (ERT), surgery, and both as local regional therapies (LRT) for denovo metastatic breast cancer patients. It found that both ERT and surgery plus radiotherapy (BMT) were associated with improved overall survival compared to no LRT or surgery alone. ERT showed similar overall survival as BMT and could be an acceptable alternative to avoid invasive surgeries. However, the study had limitations as a retrospective analysis and larger prospective studies are still needed to provide stronger evidence and guidelines on the role of LRT like ERT for metastatic breast cancer.
Hypofractionation delivers a full course of radiation treatment over a shorter period by using larger daily doses compared to conventional fractionation. Several trials have shown hypofractionation to be as effective as conventional fractionation for early stage breast cancer patients, with acceptable toxicity and cosmetic outcomes. Hypofractionation schedules of 42.9Gy/13#/5wk and 39Gy/13#/5wk were found to have 10-year local relapse rates of 9.6% and 14.8% respectively in one trial, comparable to the conventional dose of 50Gy/25#/5wk which had a rate of 12.1%. Other trials have also found hypofractionation to have similar rates of locoregional
1) BRCA1 and BRCA2 are tumor suppressor genes whose mutations significantly increase the risk of breast and ovarian cancers. Testing for BRCA mutations can help determine appropriate cancer screening and prevention strategies.
2) The HER2 receptor promotes cancer cell growth in around 20-30% of breast cancers. Drugs like trastuzumab, pertuzumab, lapatinib, and T-DM1 target HER2 and have improved outcomes for HER2-positive breast cancer.
3) Newer agents for breast cancer treatment include CDK4/6 inhibitors, PI3K inhibitors, everolimus, neratinib and immunotherapies which are being used alone or in combination with other drugs for
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
2. RADIOISOTOPES
⚫An unstable form of element that emit radiation to
transform into stable form
⚫These are mostly artificially produced in research
reactor or accelerators by exposing the target material
to particles such as neutron or protons.eg.
⚫ Co59 + neutron = Co60
3. Brachytherapy
⚫ Definition:
It is a method of treatment in which sealed
radioactive source are used to deliver
radiation at a short distance by various
methods.
⚫Brachytherapy developed largely through the use
of sealed radium and radon sources.
⚫In the 1950s, alternative artificially produced
nuclides became available.
⚫Gradually radium and radon were replaced with
137Cs, 192Ir, 60Co, 198Au, and 125I sources
4. Properties of brachytherapy
sources and radionucleides
⚫Clinical utility of any radionuclide depends on
⚫Half life
⚫Radiation output per unit activity
⚫Specific activity (Ci/gm)
⚫Photon energy
⚫Whereas
⚫Methods of producing radionuclide, its physical
and chemical properties determine its cost
effectiveness and toxicity
5. Some Terms which will be used
frequently :
⚫Radioisotopes
⚫Brachytherapy
⚫Activity
⚫Half life
⚫Specific activity
⚫Air Kerma
⚫Reference air Kerma rate
⚫Exposure rate
⚫Exposure rate constant
6. IMPORTANT DEFINITIONS
Radioactivity:
No. of disintegrations per unit time (sec ,min,hrs.)
expressed in curies
• 1 curie (ci)=3.7x1010 disintegration /sec
• 1 Bequerel (Bq) =1 disintegration / sec.
(S.I.unit)
Half life(T1/2):
“The time required for a radioactive isotope to
lose half of its original activity .”
Half Value layer (HVL):
The thickness of the specified substance that
when introduced into the path of radiation
coming from source, reduces the exposure rate
7. ⚫Kerma (dEtr/dm)
⚫Where dEtr is the sum of initial kinetic energy
of all the charged ionizing particles released by
uncharged particles in a material of mass dm.
⚫Unit : J/Kg
⚫Air Kerma Strength
⚫Air kerma strength is defined the product of
air kerma rate in free space and the square of
distance of the calibration point for the source
center along the perpendicular bisector.
⚫Unit : J m2/kg-hr
8. ⚫REFERENCE AIR KERMA RATE (RAKR)
“the kerma rate to air, in air, at a reference distance of 1
m,corrected for air attenuation and scattering”.
µGy/ h at 1 m
µGy /s at 1 m and mGy /h at 1 m
LDR
HDR
9. TOTAL REFERENCE AIR KERMA
⚫There are steep dose gradients in the region of the
sources, so that specifying a treatment in terms of
the dose at a point is not recommended.
⚫TRAK IS THE SUM OF THE PRODUCTS OF RAKR
AND THE DURATION OF THE APPLICATION FOR
EACH SOURCE
⚫independent of the source geometry and
proportional to the integral dose to the patient.
⚫compare treatments within one centre or between
different centres and to explain possible differences
in the delivered dose or in the treatment volume
dimensions.
⚫useful index for radiation protection of personnel
11. Radioisotopes in
Brachytherapy
Radium
1. Discovered by Madam
Curie in 1898
2. Naturally occuring
radionucleide
3. Complex decay
scheme
4. 1st used in 1906 in
clinics, led to Radiation
Necrosis due to
intense beta ray dose
from the Radium
5. 1920 : successful
filtration of the beta
rays was achieved
13. RADIUM-226
88Ra226 →
86Rn222 + 4He2
H
1. Gamma Energy 0.184 -2.54 MeV (avg. energy -0.83
MeV)
2. Beta Energy
3. Half life
4. Specific activity
5. HVL
6. Exposure Rate Const.
7. Spectrum
8. Encapsulation
9. Physical form
0.07 - 3.25 MeV
1600 years
0.97 Ci /gm
12mm of Pb.
8.25 Rcm2/mg-hr
wide range of 49 gamma rays
0.5 mm Platinum.
Tubes, Needles
14. ⚫ Radium sources are
specified by (a) active
length, the distance
between the ends of the
radioactive material;
⚫ (b) physical length, the
distance between the
actual ends of the source;
⚫ (c)activity or strength of
source, milligrams of
radium content;
⚫ (d) filtration, transverse
thickness of the capsule
wall, usually expressed in
terms of millimeters of
platinum.
15. WHY RADIUM IS NOT USED NOW A
DAYS
Daughter products, RADON is an alpha emitter.
It is a Gas which is soluble in tissue.
Not easily detected by a visual check
can escape through hairline crack in the radium
capsule
Radium and its daughter products may become
deposited more or less permanently in the bone if
ruptured within patients body
Radiation protection for these sources requires large
thicknesses of lead, which can cause problems when it
comes to:
⚫ Transporting sources in heavy containers.
⚫ Using very heavy protective screens around the
patient.
⚫ The need for a heavy rectal shield in applicators used
for gynecological treatment.
⚫ Sources of higher activity are bulky and not suitable for
16. Properties of the Ideal
Brachytherapy Source.
⚫ Ideal radionuclide should produce a single gamma ray
spectrum with energy of around 0.5 MeV.
⚫ acceptable half life
⚫ Cheap and easily produced
⚫ Preferably solid
⚫ Stable solid decay products
⚫ High specific activity
⚫Closest to the ideal radionuclide for LDR at present time is
Cesium 137
17. Radium Substitutes
⚫The first sources to be used as alternatives to
radium were
⚫ Cobalt-60,
⚫Gold-198,
⚫Cesium-137 and
⚫ Iridium-192.
18.
19. Cesium
⚫ discovered in the late 1930s by Glenn Seaborg and
Margaret Melhase
Product of nuclear fission
with beta rays
0.662 MeV.
0.5-1.17 MeV
30 yrs
10 Ci/gm.
5.5 mm of Pb
3.26 R cm 2/mCi-hr.
Single Gamma ray
0.5 mm of Pt.
Needles, microspheres, powder
• Gamma Energy -
• Beta Energy -
• Half life -
• Specific activity -
• HVL -
• Exposure Rate Const -
• Spectrum-
• Encapsulation -
• Physical form-
• 2% annual reduction in source activity occurs
20. Source specification
⚫ insoluble powders or ceramic microspheres,
labeled with 137Cs, and doubly encapsulated in
stainless steel needles and tubes.
21.
22. Cobalt 60
Properties of Cobalt 60
⚫Production : by neutron activation of the stable
isotope cobalt-59
⚫Half Life : 5.27 years
⚫Decay Scheme : 27Co60
28 Ni60 + -1 β + γ
⚫ Beta energies : 0.318 MeV
⚫Photon energies : 1.17 MeV and 1.33 MeV
⚫ Beta filtration : typical source wall thickness
⚫ Half value layer in lead : 10 mm
23. Form of source Co60
⚫Cobalt brachytherapy sources are usually
fabricated in the form of needle
⚫An alloy wire composed of 45% cobalt & 55%
nickel, so called cobanic
⚫Encapsulated in a sheath of platinum of stainless
steel
⚫Because cobalt tends to be corrosive, it is usually
nickel plated;
⚫encapsulation with 0.1 mm to 0.2 mm platinum-
equivalent is necessary to filter the b-particles.
24. Iridium192
⚫ Used for HDR brachytherapy
Properties of Iridium192
⚫ Production : by neutron activation of the stable
isotope Iridium191
⚫ Half Life : 73.83 days
⚫ Decay Scheme : 77Ir192
78Pt192
+ -1e0
+ γ
⚫ Beta energies : 0.079-0.672 MeV
⚫ Photon energies : 0.2 – 1.06 MeV
⚫ Beta filtration : 0.1 Platinum
⚫ Half value layer in lead : 4.5 mm
25. ⚫Most common form of source : wire in 1 m length
coils, wire consists of an active iridio platinum
core, 0.1 mm thick, encased in a sheath of
platinum, 0.1 mm thick
26. ⚫iridium seeds
⚫seeds are 3 mm long and
0.5 mm in diameter
⚫Made up of 30% Ir + 70%
Pt surrounded by 0.2 mm
thick stainless wall
⚫pure iridium is very hard
and brittle, and is difficult
to fabricate.
27. GOLD198
Au 197 + 1n
0 → Au198 +Υ
0.412 MeV
0.69 MeV.
2.7 days
2.5 mm Pb
2.38 Rcm2/mCi–
seed
• Gamma Energy:
• Beta Energy
• Half Life
• HVL :
• Exposure rate const. :
hr
• Physical form:
• Used for permanent implant
• Gold seeds of size 2.5 mm long & 0.8 mm
diameter
28. Advantages of Gold over
others
⚫The average photon energy of gold is 0.406 Mev,
making the radiation protection requirements
much easier and cheaper to implant than those of
Ra226 , Rn, Co or Cs
⚫Very short half life so useful for permanent
implants
29. IODINE125
• Xe124 0n Xe I
+ 1 → 125 → 125
0.028 MeV (avg).
None
59.4days
1739 Ci/gm
0.025 mm OF Pb
Three gamma rays
1.46 Rcm2/mCi–hr
0.5 mm titanium
seed
• Allen Reid and Albert keston discovered I125 in 1946
• Gamma Energy -
• Beta Energy-
• Half life -
• Specific activity -
• HVL -
• Spectrum -
• Exposure rate const. -
• Encapsulation -
• Physical form-
• Used for permanent interstitial implants.
30. 125I decays by electron capture to an excited state of
125Te which decays to ground state releasing
35.5keV .
⚫IODINE FROM FM KHAN
31. ⚫The high specific activity of I125 enables the
production of miniature sources sufficient activity
for use in both permanent and temporary
implants
⚫The main current application field of I125 is
permanent interstitial implant for prostate
cancer
32. Palladium103
46Pd102 + 0n1 → Pd103
46
• Gamma Energy :
• Beta Energy:
• Half life :
• Specific activity
• HVL :
• Encapsulation :
• Exposure rate constant:
0.021 MeV (avg)
None
17days
7448 Ci/gm
0.008 mm of Pb
Titanium
1.48 Rcm2/mCi–hr.
• 103Pd decays by electron capture (20-23 keV x
rays)
33. ⚫Pd10
3
has been introduced as replacement for
I125 sources for permanent implant
⚫Its short half life of 17 days makes Pd103 only
appropriate for permanent implants
⚫Its short half life and high specific activity enables
dose delivery at initial dose rate higher than that
of I125
⚫This feature is beneficial when used for rapidly
proliferating tumors
34. Advantages of one over
another
⚫ Cs over Radium
⚫Reduced amout of shielding is required and absence of
gaseous daughter product
⚫ Cs over Cobalt
⚫Longer half life of 30.07 years compared with 5.27 years
of Co, which enables the clinical use of Cs source over a
long period of time
⚫Low production cost
⚫Smaller amount of shielding required
⚫ Disadvantages of Cs
⚫Lowest specific activity, doesnot allow the production of
miniature sources of very high activity for HDR remote
controlled loading BT
⚫Thus appropriate only for LDR
35. ⚫ Cobalt over Cs
⚫Due to high specific activity, Co is appropriate for
fabrication of small high activity source
⚫ Cobalt over Radium
⚫Cobalt wires can be bent to conform to the shape of
tumor
⚫No danger of leakages or breakages
⚫ cobalt over iridium
⚫Half life of cobalt is much more than of iridium, hence it
need not to be replaced as frequently as iridium
⚫25 source exchanges are required for 192Ir for one
exchange of a 60Co source
⚫THOUGH INTEGRAL DOSE IS HIGHER IN CO60
36. Types of Brachytherapy……
⚫Depending on source loading pattern:
⚫Preloaded: inserting needles/tubes containing
radioactive material directly into the tumor
⚫After loaded: first, the non-radioactive tubes
inserted into tumor
⚫ Manual: Ir192 wires, sources manipulated into applicator by
means of forceps & hand-held tools
⚫ Computerized remote controlled after loaded: consists of
pneumatically or motor-driven source transport system
37. Preloading pattern
⚫ Advantage:
⚫ Loose & flexible system(can be inserted even
in distorted cervix)
⚫ Excellent clinical result
⚫ Cheap
⚫ Long term results with least morbidity (due to
LDR)
⚫ Disadvantages:
⚫ Hasty application -Improper geometry in dose
distribution
⚫ Loose system – high chance of slipping of
applicators – improper geometry
⚫ Application needed special instruments to
maintain distance.
⚫ Radiation hazard
38. After loading pattern
MANUALAFTERLOADING
Advantages
1. Circumvents radiation protection problems of preloading
2. Allows better applicator placement and verification prior
to source placement.
3. Radiation hazard can be minimized in the OT / bystanders
as patient loaded in ward.
4. Advantages of preloading remain.
Disadvantages:
specialized applicators are required.
39. REMOTE AFTERLOADING
Advantages :
1. No radiation hazard
2. Accurate applicator placement
-ideal geometry maintained
-dose homogeneity achieved
-better dose distribution
3. Information on source positions available
4. Individualization & optimization of treatment possible
5. Higher precision , better control
6. Decreased treatment time- opd treatment possible
7.Chances of source loss nil .
Disadvantages :
1. costly
40. Different dose rates used for
brachytherapy
⚫treatment dose rates fall into these categories:
⚫Ultra LDR : 001 to 0.3 Gy/hr : dose rate used in
permanent implants with I125 and Pd103
⚫LDR : 0.4 to 2 Gy/hr, compatible with conventional
manual or automatic after loading technique
⚫MDR : 2 – 12 Gy/hr, can also be delivered by manual or
automatic afterloading, although the latter is far more
frequent
⚫HDR : >12 Gy/hr and only automatic afterloading can
be used because of the high source activity
⚫PDR : pulses of 1 to 3 Gy/hr, delivers the dose in a
large number of small fractions with short intervals
⚫Permanent Implants : deliver a high total dose (eg.
41. Sources for LDR intracavitary
brachytherapy
⚫Active length should be 1.3 to 1.5 cm
⚫Half Life should be 5 to 10 years working life
without variation in prescription dose rates
⚫Average photon energy : 60 to 100 keV
⚫Sources : Radium226 and Cesium137
42. Sources for permanent Interstitial
Brachytherapy
2 Basic approach
1. Classical LDR permanent brachytherapy
⚫Radon 222
⚫Au 198 seeds
⚫HALF LIFE : FEW DAYS
⚫High energy photons
⚫Patient must be confined to the hospital until the
source strength decays to safe level (10 days)
43. 2. ULDR brachytherapy
⚫Larger lives but low energy emitters – Pd103 and I125
⚫ Patients tissue or thin lead foils are sufficient to
limit exposure to negligible levels
⚫No need to hospitalize patients solely for radiation
protection
⚫During the implant procedure, decreased radiation
exposure to O.T. persons
44. Sources for HDR brachytherapy
⚫Uses high intensity source to deliver discrete
fractions ranging from 3 to 10 Gy
⚫A remote after loading device must be used
⚫Radio-nuclide with high specific activity (Ci/gm) is
needed so that treatment dose rates of at least 12
Gy/hr can be achieved.
⚫ A miniature source no longer than 1 mm
diameter and 4 mm length with an exposure rate
of 1 R/sec at 1cm is required.
45. The radiobiology of
brachytherapy
⚫Brachy : not only short treatment distance but
also short treatment time
⚫Short overall treatment time, compared to EBRT
minimizes tumor repopulation in rapidly growing
tumors
⚫Short overall treatment time in brachytherapy are
likely to contribute significantly to clinical efficacy
for tumor sites like cervix, head and neck and
lung where long overall treatment time is
associated with reduced local control.
46. Radiobiology of the brachytherapy
and Dose Rate Effect
⚫The biological effects of radiotherapy depends on
⚫Dose distribution
⚫Treated volume
⚫Dose rate
⚫Fractionation and
⚫Treatment duration
⚫However these are of different importance in
determining the outcome of EBRT and of
brachytherapy
47. Radiobiological difference between
EBRT and brachytherapy
Factors EBRT Brachytherapy
Volume treated Large Very small
Dose homogenity -5 to +7% acceptable Very inhomogenous
Volume effect
relationship
>tolerance dose, not
well toleraable
Very high doses
tolerated well
Time dose factors Small daily fractions of
few seconds/minutes
Continuous deliver and
short treatment
48. Radiobiological Mechanisms
⚫The bilogical damage inflicted by irradiation of
human cells can be divided into three consecutive
steps :
⚫Physical phase : short initial phase, excitation of
electrons and ionisation, energy deposition phase
⚫Chemical Phase : ionized and excited atoms
interact directly or indirectly through the formation of
free radicals to the breakage of chemical bonds.
⚫Biological Phase : Longer phase, seconds to years,
cells reaction to inflicted chemical damage, specific
repair enzymes successfully repair the majority of
DNA lesions, however few may not repair and lead
to cell death.
⚫ Early reactions
⚫ Late reactions
49. Radiobiology – LDR Vs HDR
In terms of 4Rs
⚫Repair :
⚫LDR : allows time for sublethal damage repair in
normal tisues
⚫HDR : short treatment time prohibits this repair
⚫Reassortment :
⚫LDR : theoretic advantage of an improved result
⚫HDR : ---
⚫Only shown in vitro, but in vivo the effect of
reassortment has not been shown to give a true
advantage, possibly due to disruption of the
mechanism of cell cycle in cancer cells
50. ⚫Repopulation
⚫LDR & PDR : probably prevents repopulation during
treatment
⚫HDR : short treatment time, so no issue of
repopulation
⚫Reoxygenation :
⚫2 types of hypoxia : chromic and transient
⚫LDR : transient hypoxia may correct during
treatment time
⚫HDR : not possible
⚫If brachytherapy is fractionated, tumor shrinkage
and re-oxygenation of areas of chroni hypoxia may
occur between insertions
51. Biophysical Modeling of
Brachytherapy
⚫In 1970s, before the diffrential response of early
and late responding tissues was understood, the
most widespread approach for designing
alternative fractionation schedule was Nominal
Standard dose equation (NSD)
⚫This equation was based on data from early
responding tissues and it didn’t account for
diffrential response to fraction size/dose rate of
early Vs Late effects
52. Linear Quadratic Model
⚫Distinguishes between early and late response
⚫Based on mechanistic notion and how cells are
killed by radiation
⚫After several decades of investigation and use,
LQ model have been well supported by clinical
experience and outcome date
53. Mechanistic basis of LQ model
⚫In this approach radiotherapeutic response is
primarily related to cell survival
⚫Cell killing is the dominant determinant of
radiotherapeutic response both for early and late
responding end points
⚫S(D)=e-αD-βD2
54. The Linear Quadratic Model
⚫ TypeAdamages:
⚫ Two Critical Target within a cell are
simultaneously damaged (hit) in a
single radiation interaction event
leading to cell death
⚫ Type B damages:
⚫ Two critical Target are damaged in
separate events, after which the
damaged sites interacts to produce
cell death
⚫ Sub Lethal damages:
⚫ The damages which are not so
effective for lethality of cell
55. Linear component related to single
track events,
Quadratic component related to
interaction of multi-track events
low dose radiation
⚫ single track events predominate and
are far apart in time to produce any
significant double track events. The
high dose radiation
⚫ Multiple track events predominate.
Survival curve bends and becomes
curved.
dose
E
f
curve is straight with no shoulder. f
e
c
t
e-
e-
e-
Linear
EαD
Quadratic
EαD2
Basis of LQ model
56. The Linear Quadratic Model
Sparsely
ionizing
particles
Densely
ionizing
particles
βD2
αD
α/β
4 8 12
The expression for cell survival curve by this model
P(survival) or SF = exp (-αd -βd2)
2 components of cell killing:
TypeAdamages –
Cell Killing proportional to dose D
i.e E, effect proportional to D
Type B damages –
Cell Killing proportional to the
square of the dose D2.
i.e E, effect proportional to D2
Fowler (1989)
57. Low Dose Rate continuous
Brachytherapy
BED = D [1+g. R /(α/β)]
Where
Total dose = D = Dose Rate x Time = R.T
g = incomplete repair factor
g = (2/µT).[1-(1/µT).{1-exp(-µT)}]
and µ = 0.693/t1/2
58. Use of LQ model in Brachytherapy
quantifing the rationale for LDR
⚫Lowering the dose rate generally reduces
radiobilogical damage.
⚫For high dose rates, the dose reduction needed
to match the late effects is larger than the dose
reduction needed to match tumor control
⚫For any selected dose, increasing the dose rate
will increase late effects much more than it will
increase tumor control
⚫Conversly
⚫ Decreasing dose rate will decrease late effects
much more than it will decrease tumor control
⚫Thus the therapeutic ratio increases as the dose
rate decreases
59. Use of LQ model in Brachytherapy
quantifing the rationale for LDR
60. High Dose Rate Brachytherapy
BED = D [1+d/(α/β)]
Where
D = n.d
n = no. of fractions
d = dose per fraction
DNA Repairs doesn’t occurred in a short period of time
of 10 min.
DNA repairs occurs between two successive fractions
only
Bur for well spaced fraction >>12 hrs, Correction for
incomplete Repairs is not required
61. Radiobiological principles involved in
moving from LDR to HDR
⚫ This is the
case for
cervical
brachythera
py because
bladder and
rectum are
generally
some
significant
distance
from
implant
62. Brachytherapy for prostate cancer
Optimized dose protraction for
prostate cancer Brachytherapy
⚫Prostate tumors contain unusually small fractions
of cycling cells
Low α/β ratio
So they behave like late responding
normal tissues
63. Ca prostate : Brachytherapy
Radiobiological Basis
⚫ α/β value for prostate cancer is similar to that for
surrounding late responding normal tissue, HDR could be
employed to match conventional fractionated regimen with
respect to tumor control and late sequalae while reducing
early urinary sequalae
⚫ The α/β value for grade 2 or higher late rectal toxicity is
4.8 and this value is larger than of the prostate tumor α/β
ratio
⚫ This suggests that HDR prostate Brachytherapy might
actually improve the therapeutic outcomes of prostate cancr
Brachytheapy
64. Advantages of HDR Over LDR
⚫ Radiation Protection
⚫After loading
⚫No source preparation and transportation
⚫Only one source, there is no risk of losing a radioactive
source
⚫ Short treatment times
⚫Less discomfort to patient
⚫Low risk of applicator movement during therapy
⚫Treat large no of patients
⚫ Smaller diameter
⚫Reduced dilation of cetvix
⚫After loading
⚫ Treatement dose optimization Possible
65. Disadvantages of HDR over LDR
⚫Radiobilogic
⚫Short treatment times : no sublethal damage repair,
no reassortment , redistribution and reoxygenation
⚫Limited experience
⚫The economic disadvantages
⚫Costly remote after loaders
⚫Required shielded room and more labor intensive
⚫Greater potential Risk
⚫High specific activity source used, if machine
malfunctions or there is calculation error, there is
very short time to detect and correct errors
66. Difference between LDR & HDR
brachytherapy treatment Planning
⚫ HDR BT differs from LDR BT in 3 Ways :-
⚫1st difference : time Course
⚫ The patient waits in the treatment position during the treatment
plan generation in HDR while
⚫ Treatment plan generation performed with the patient
elsewhere in LDR
⚫2nd difference : quantities involved with dose calculation
⚫ HDR : one source strength and many different dwell times
⚫ LDR : input – source strength input by user, many sources
⚫In both case, dose calculation algorithm uses the
product of source strength and time at a given location
⚫3rd difference : role of quantities as input or output
⚫ LDR : input : source strength and treatment duration
⚫ HDR : reverse process start with dose pattern disingned and
working backward to the dwell time distributing necessary to
achieve that dose
67. Conversion from Low to High Dose
rate Brachytherapy
⚫Biggest questions : How many fractions to use
???
What dose/fraction ????
⚫Increasing the number of fractions increases
therapeutic ratio but each additional fraction
brings
⚫Costs for departmental resources and
⚫Inconvenience to patient
⚫So Most regimens use 5 or 6 #s if applicator
insertions involved and 8 -12 #s if applicators can
be left in place
68. Dose/# ????
⚫BEDHDR = BEDLDR
⚫ calculate dose/#
⚫α/β : comes into play again
⚫If normal tissue toxicity is kept constant, α/β = 3
⚫If tumor cure is kept constant then α/β = 10 (or value
of particular type of tumor)
⚫If late complications are to be kept constant then α/β=2
⚫For intracavitary applications, normal tissue can be
kept away from the applicator, which allow us to
calculate dose based on equivalent tumor control
69. Experimental Results
⚫In vitro studies in sixties have shown that there is an
effect of dose rate on cell survival
⚫This effect differs with cell type
⚫The dose needed for 1% survival is roughly 1.5-3
times higher at 1 Gy/hr than it is at 1 Gy/min
70. Pulse Dose Rate (PDR)
⚫Combined physical advantage of HDR BT and
radiobiological advantage of LDR BT
⚫PDR BT was proposed and introduced as a
method to replace continuous LDR
⚫advantages of PDR brachytherapy compared with
LDR
⚫ full radiation protection for caregivers
⚫no source preparation necessary
⚫no extensive source inventory, that is, only one
iridium-192 source per afterloader to be replaced
every 2 or 3 months
71. Compared with HDR
brachytherapy,
⚫PDR offers similar quality of dose distribution, and
similar treatment procedure and technical
verification, both being stepping source
technologies
Clinical results : Ca Cervix
source
72. ⚫Most Studies
⚫Local control : 80-90%
⚫Overall survival : 4 yrs for 55% Patients
⚫Low incidence of gr II GI and GU late toxicity
⚫Disadvantage of PDR
⚫PDR delivered by stepping source
might behave more like HDR than LDR,
⚫Especially for tissues with a
substantial component of repair of very
short T1/2
73. ⚫1990-1992, 180 patients, St IIB-III
⚫All patients received EBRT@ 45 Gy/25#/4.5 weeks
⚫Divided into two arms
⚫Dose reduction arm (30%) – 2450 cGy to Pt A
⚫Dose reduction arm (12.5%) – 3060 cGy to Pt A
Vs
Previously treated IIB and III patients with LDR
(55-65 cGy/hr)
74. ⚫MDR – 30 : results were comparable to LDR group, so
this group was retained
⚫MDR – 12.5 : discontinued due to increased morbidity
⚫So, decided to evaluate dose reduction between LDR
and MDR 30
⚫20% dose reduction was decided upon
2nd
⚫1st : MDR –30 : MDR – 20
75. ⚫Summary
⚫No statistical difference in local control between
LDR, MDR – 30, MDR -20 and MDR – 12.5
⚫However significant increase in late complications
with MDR -12.5 and higher trend seen with MDR -
20
⚫So its important to know the absolute dose received
by critical organs _ rectum and bladder
76. Clinical Results : LDR, MDR and
HDR brachytherapy
⚫Many clinical data have been accumulated over
the years in brachytherapy, but very few
randomized trials.
⚫These retrospective studies help to better
understand the biological background of
brachytherapy and devise the rules that can be
followed in clinical practise.
77. Results of HDR Vs LDR
Cervical Cancer
⚫LDR brachytherapy : experience > 100 years
⚫It is very important to critically analyze how the
results obtained with HDR Brachytherapy which
has a much shorter history to be compared with
LDR
⚫Meta Analysis By Orton et al, 56 institutes
⚫HDR : 17068 patients
⚫LDR : 5666 patients
⚫5 year survival date was available for 6639 HDR
S
pta
at
g
ie
ents and 33
H
6
D
5
RLDR patientLsDR
I 82.7% 82.4%
II 66.6% 66.8%
III 47.2% 42.6%
78. ⚫1999, Pertreit and Peracy, Literature review
⚫5619 patients with HDR treatment
⚫5 year pelvic control rates were 91% for stage I, 82% for
stage II and 71% for Stage III Patients
⚫5 years OS was similar to previous metaanalysis
⚫4 Randomised Studies by
⚫Shigematu et al
⚫Hareyama et al
⚫Patel et al and recently
⚫Teshima et al (2004) from thailand
⚫Which all of them have showed no difference in OS,
RFS or Pelvic Control and
⚫No statistical difference in complication rates for rectum,
bladder or small Bowel
79. ⚫Total no of patients = 423, EBRT @ 45 Gy/20# f/b
⚫Two groups
⚫LDR group : 220 pts, dose rate @ 55cGy/hr to 90
cGy/hr, dose 35 Gy in single inserrtion with Cs137
⚫HDR group : 203 patients, radionucleide Co60 , dose
8.5 to 9.5 Gy to point A, 2 sessions
80. Results
⚫Patients with complete response after completion
of treatment : 90 % LDR Vs 89 % HDR
⚫Recurrence cervical : 9 % LDR Vs 10 % HDR
⚫Parametrial : 12% LDR Vs 11% HDR, at last f/u,
end of 5 yrs
⚫Overall control of disease : 72% with LDR and
72% with HDR
81. Ca Prostate
⚫Permanent implantation of I125 or Pd103 is the
most common type of prostate Brachytherapy
⚫However several centers have used HDR
Brachytherapy as a boost to EBRT with
encouraging results
⚫Potential advantage of HDR Brachytherapy in
prostate cancer is the theoretical consideration
that prostate cancer cells behave more like late
reacting tissues with low α/β , they should therefore
respond more favourably to HDR fractions rather than
LDR Brachytherapy
82. ⚫Galalae et al, 611 patients treated at 3 institutes
with EBRT followed by Brachytherapy for
localized prostate cancer
⚫Five year biochemical control :
Low risk 96%
Intermediate risk 88%
High Risk 69%
85. Carcinoma Breast
⚫EBRT is standard radiation modality after
Lumpectomy
⚫Over the past decade, increasing use of
Brachytherapy as the sole modality of treatment
to decrease the treatment time from 6 weeks to
about 5 days
⚫ABS recommends : 34 Gy/10# to CTV when HDR
Brachytherapy is used as the sole modality
⚫Data on use of HDR as boost is very limited
86. ⚫Polgar et al, 207 patients with stage I and stage II
patients
⚫All patients underwent BCS f/b WBRT
⚫Two arms :
⚫No further treatment
⚫Radiation boost by either 16 Gy of electrons or HDR
BT12 to 14 Gy
⚫52 patients with HDR Boost
⚫5 year local tumor control was 91.4%
⚫And excellent to good cosmesis : 88.5%
⚫Same results were obtained with electron
irradiation
87. Esophageal Carcinoma
⚫Brachytherapy is relatively simple to perform
because a single catheter is used for treatment
⚫Largest diameter applicator should be used to
minimize the mucosal dose relative to dose at
depth
⚫ABS recommends : HDR dose of 10 Gy in 2 #,
prescribed at 1cm from source to boost 50Gy of
EBRT
88. ⚫Sur et al, 1992, 50 patients with squamous cell
carcinoma
⚫One arm : EBRT alone
EBRT + HDBT
44% Vs
⚫Another arm :
(12Gy/2#)
⚫12 month survival
78%
⚫Relief of dysphagia at 6 months 53.5% Vs
90.5%
89. ⚫ For medically inoperable patients with submucosal
esophageal cancer, EBRT with ILBT is an attractive
approach
⚫ Ishikawa et al, 5 year cause specific survival to be
86% with EBRT and ILBT and 62% with EBRT alone
⚫ In pallilative setting to relieve dysphagia HDBT is
more defined
⚫Sur et al, 50 Patients, EBRT @ 35 Gy/15#,
⚫1st arm : kept on f/u
⚫2nd arm : 12 Gy/2# HDR
⚫ 6 month relief of dysphagia : 84% Vs 13%
⚫ 1 year survival : 69% Vs 16%
90. Head and Neck Cancers
⚫Head and Neck area doesnot tolerate high dose
per fraction
⚫Nasopharynx : Easily accessed by intracavitary
HDR applicator
⚫Lovenderg et al, have shown patients most suitable
for HDR BT boost are tghose with T1 and T2 lesion
following 60 to 70 Gy of EBRT
⚫HDR of 18 Gy/6 # are delivered by special
nasopharynx applicator
⚫T3, T4 : better suited to be boosted by IMRT
91. HDR Brachytherapy as salvage in
H&N Cancer
⚫Loco-regional recurrence is the primary pattern of
failure in H&N caners despite of advancement in
surgery, concurrent CCT and EBRT
⚫Surgical Treatment is the preferred treatment,
however it is not possible in all cases
⚫EBRT is as effective as salvage treatment but
with high toxicity
⚫HDR BT has been used in previously irradiated
patients, initial results appear to be comparable to
other modalities
92. Conclusion
⚫Beginning of brachytherapy started with the
discovery of Radium.
⚫With the improvement in specific activity of
sources the era of HDR came along with the
decreased radiation exposure to the persons
involved .
⚫Though theoritically , LDR is radio biologically
better than HDR , clinical trials have shown the
result of HDR as good as LDR .