Slideshow is from the University of Michigan Medical
School's M2 Hematology / Oncology sequence
View additional course materials on Open.Michigan: openmi.ch/med-M2Hematology
This document summarizes key aspects of the International Commission on Radiation Units and Measurements (ICRU) Report 83 from 2010 on prescribing, recording, and reporting photon beam intensity-modulated radiation therapy (IMRT). The ICRU Report 50 from 1993 and Report 62 from 1999 established guidelines for defining target volumes like gross tumor volume, clinical target volume, and planning target volume. ICRU Report 83 aimed to update these guidelines for IMRT, which uses non-uniform fluence and dose distributions compared to earlier conformal radiation techniques. Key changes included separating the planning target volume into internal and setup margins, classifying organs at risk, and defining new metrics like the planning organ at risk volume and conformity index for evaluating IM
Treatment planning in Radiotherapy - field shaping, separation and matchingSACHINS700327
This document discusses various techniques for field shaping, separation, and skin dose management in radiation therapy. It describes methods for shaping treatment fields including custom blocks, independent jaws, and multileaf collimators. It also covers techniques for separating adjacent fields to minimize hot and cold spots at the field junction, including geometric and dosimetric methods. Finally, it addresses factors that influence skin dose such as photon energy, field size, absorber distance, and beam obliquity and methods for improving skin sparing including electron filters.
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.
1) Hypoxic cell sensitizers are agents that increase the lethal effects of radiation specifically on hypoxic tumor cells. An ideal sensitizer selectively sensitizes hypoxic cells at concentrations that do not greatly increase toxicity to normal tissues.
2) Several hypoxic cell sensitizers have been evaluated clinically including nitroimidazoles like misonidazole, metronidazole, and nimorazole. Nimorazole showed benefit for head and neck cancers with less toxicity.
3) Other approaches to overcoming tumor hypoxia include hyperbaric oxygen, carbogen breathing, blood transfusions, and bioreductive drugs that selectively kill hypoxic cells. A meta-analysis found that
Introduction
Time dose & fractionation
Therapeutic index
Four R’s Of Radiobiology
Radiation response
Survival Curves Of Early & Late Responding Cells
Various fractionation schedules
Clinical trials of altered fractionation
Importance of Planning CT Simulation(3D) in Radiothrapy/Radiation oncology.Saikat Roy
CT simulation is an important part of the radiotherapy planning process. It allows for 3D visualization of patient anatomy using CT scans. Various immobilization devices are used to accurately position the patient for treatment planning and delivery. The summary describes the key steps in CT simulation including patient setup using immobilization devices, obtaining CT images with appropriate parameters, and noting important details in the patient record for their specific diagnosis and treatment area. CT simulation provides critical 3D information to optimize radiotherapy treatment planning.
Altered fractionation schedules in radiation oncologyAbhishek Soni
Altered fractionation schedules aim to optimize tumor control and normal tissue sparing by manipulating total dose, dose per fraction, time interval between fractions, dose rate, and overall treatment time based on tumor and tissue radiosensitivity and repair characteristics. Hyperfractionation uses a higher total dose with smaller, more frequent fractions to exploit tumor reoxygenation and cell cycle effects while hypofractionation uses fewer, larger fractions which is more effective for tumors with low α/β ratios. Accelerated fractionation decreases treatment time to limit tumor repopulation at the cost of increased acute toxicity. Phase III trials show hyperfractionation and accelerated fractionation improve local control for head and neck cancers with acceptable toxicity.
LDR and HDR Brachytherapy: A Primer for non radiation oncologistsSantam Chakraborty
A small presentation I made for a 30 minutes class comparing and contrasting LDR and HDR brachytherapy. Good for a person with non radiation oncology background to grasp the basics.
This document summarizes key aspects of the International Commission on Radiation Units and Measurements (ICRU) Report 83 from 2010 on prescribing, recording, and reporting photon beam intensity-modulated radiation therapy (IMRT). The ICRU Report 50 from 1993 and Report 62 from 1999 established guidelines for defining target volumes like gross tumor volume, clinical target volume, and planning target volume. ICRU Report 83 aimed to update these guidelines for IMRT, which uses non-uniform fluence and dose distributions compared to earlier conformal radiation techniques. Key changes included separating the planning target volume into internal and setup margins, classifying organs at risk, and defining new metrics like the planning organ at risk volume and conformity index for evaluating IM
Treatment planning in Radiotherapy - field shaping, separation and matchingSACHINS700327
This document discusses various techniques for field shaping, separation, and skin dose management in radiation therapy. It describes methods for shaping treatment fields including custom blocks, independent jaws, and multileaf collimators. It also covers techniques for separating adjacent fields to minimize hot and cold spots at the field junction, including geometric and dosimetric methods. Finally, it addresses factors that influence skin dose such as photon energy, field size, absorber distance, and beam obliquity and methods for improving skin sparing including electron filters.
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.
1) Hypoxic cell sensitizers are agents that increase the lethal effects of radiation specifically on hypoxic tumor cells. An ideal sensitizer selectively sensitizes hypoxic cells at concentrations that do not greatly increase toxicity to normal tissues.
2) Several hypoxic cell sensitizers have been evaluated clinically including nitroimidazoles like misonidazole, metronidazole, and nimorazole. Nimorazole showed benefit for head and neck cancers with less toxicity.
3) Other approaches to overcoming tumor hypoxia include hyperbaric oxygen, carbogen breathing, blood transfusions, and bioreductive drugs that selectively kill hypoxic cells. A meta-analysis found that
Introduction
Time dose & fractionation
Therapeutic index
Four R’s Of Radiobiology
Radiation response
Survival Curves Of Early & Late Responding Cells
Various fractionation schedules
Clinical trials of altered fractionation
Importance of Planning CT Simulation(3D) in Radiothrapy/Radiation oncology.Saikat Roy
CT simulation is an important part of the radiotherapy planning process. It allows for 3D visualization of patient anatomy using CT scans. Various immobilization devices are used to accurately position the patient for treatment planning and delivery. The summary describes the key steps in CT simulation including patient setup using immobilization devices, obtaining CT images with appropriate parameters, and noting important details in the patient record for their specific diagnosis and treatment area. CT simulation provides critical 3D information to optimize radiotherapy treatment planning.
Altered fractionation schedules in radiation oncologyAbhishek Soni
Altered fractionation schedules aim to optimize tumor control and normal tissue sparing by manipulating total dose, dose per fraction, time interval between fractions, dose rate, and overall treatment time based on tumor and tissue radiosensitivity and repair characteristics. Hyperfractionation uses a higher total dose with smaller, more frequent fractions to exploit tumor reoxygenation and cell cycle effects while hypofractionation uses fewer, larger fractions which is more effective for tumors with low α/β ratios. Accelerated fractionation decreases treatment time to limit tumor repopulation at the cost of increased acute toxicity. Phase III trials show hyperfractionation and accelerated fractionation improve local control for head and neck cancers with acceptable toxicity.
LDR and HDR Brachytherapy: A Primer for non radiation oncologistsSantam Chakraborty
A small presentation I made for a 30 minutes class comparing and contrasting LDR and HDR brachytherapy. Good for a person with non radiation oncology background to grasp the basics.
1) The four Rs of radiobiology are repair, re-assortment, repopulation, and re-oxygenation. They influence how tumors and normal tissues respond to fractionated radiation treatment.
2) When radiation is delivered in two fractions separated by time, cell survival increases due to repair of sublethal damage between fractions. The increase peaks at 2-3 hours and then levels off due to repopulation.
3) Lowering the radiation dose rate generally decreases biological effects because it allows more time for repair of sublethal damage.
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.
TISSUE PHANTOM RATIO - THE PHOTON BEAM QUALITY INDEXVictor Ekpo
TPR(20,10) is the recommended photon beam quality index by IAEA TRS-398 for megavoltage clinical photons generated by linear accelerators. This presentation goes through the basics of Tissue Phantom Ratio (TPR).
Adaptive radiotherapy (ART) can improve treatment for head and neck cancer patients. ART involves modifying the treatment plan based on anatomical changes observed during radiation therapy delivery. For head and neck cancer, target volumes and organs at risk often change significantly over the course of treatment due to factors like weight loss or tumor shrinkage. Studies have shown ART can improve dose distribution by reducing dose to organs at risk while maintaining or improving tumor dose coverage. Clinical benefits of ART include improved local tumor control and fewer treatment toxicities. ART is most beneficial for patients experiencing greater anatomical changes, such as those with more advanced tumors or significant weight loss.
Beam direction techniques are used to accurately direct radiation beams towards the tumor while sparing surrounding healthy tissues. Key steps include patient localization using imaging like CT/MRI to delineate the tumor and organs, patient positioning and immobilization, field selection using beam directing devices like lasers, collimators and pointers, and dose distribution analysis to calculate and verify the prescribed dose. Proper beam direction allows obtaining conformal dose distributions and reproducible treatments for better therapeutic outcomes.
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 guidelines for evaluating radiotherapy treatment plans for primary brain tumors. It provides indications for radiotherapy based on tumor type and extent of resection. Key factors in treatment planning include: contouring target volumes and organs at risk, optimizing dose distribution to cover the target while sparing organs at risk, and quantitatively evaluating plans using tools like isodose distributions, dose volume histograms and indices like coverage, conformity and homogeneity. Plan evaluation ensures the target receives adequate and uniform dose while respecting organ at risk tolerances.
Craniospinal irradiation involves delivering radiation to the entire cranial-spinal axis and is used to treat cancers that may spread through the cerebrospinal fluid, such as medulloblastoma. It is delivered in two phases, with the first phase irradiating the brain and spinal cord, and the second phase boosting the radiation to the posterior fossa. Proper patient immobilization and treatment planning are important to ensure adequate radiation dose to target areas while minimizing dose to nearby organs at risk. Newer radiation techniques such as VMAT, helical tomotherapy, and proton therapy may further improve treatment by reducing normal tissue dose.
This document provides an overview of interstitial brachytherapy principles and concepts. It discusses the history and evolution of brachytherapy sources from radium to modern radioactive sources like iridium-192. Key concepts covered include dose rate calculations, implant systems like the Paris system, and factors that influence dose distribution from a radioactive source like distance, absorption and scattering. The document also describes temporary and permanent brachytherapy sources and different methods of source application including preloading, afterloading and remote afterloading.
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 document summarizes the oxygen effect and reoxygenation in radiation therapy. It discusses the mechanism of oxygen enhancement, how oxygen acts at the level of free radicals to fix radiation damage. It describes chronic and acute hypoxia in tumors and the process of reoxygenation that can occur between fractions of radiation therapy. Reoxygenation allows previously hypoxic cells to become oxygenated again and be more susceptible to radiation damage.
This document discusses stereotactic radiosurgery and radiotherapy. It begins with an introduction to stereotaxy and how it allows for highly precise radiation targeting. It then covers radiobiology concepts relevant to stereotactic radiation and lists some common indications for its use, including brain metastases and early stage prostate cancer. The document provides details on patient immobilization, planning techniques, and treatment procedures for conditions like pituitary adenomas, trigeminal neuralgia, and arteriovenous malformations.
multiple filed arrangement in Radiotherapy, Medical College KolkataKazi Manir
The document discusses various radiation therapy techniques for dose distribution in matter using multiple fields and wedge fields. It covers:
1) Using multiple fields allows more uniform dose distribution in the tumor compared to a single field, while limiting dose to normal tissues.
2) Parallel opposed fields provide simplicity but can excessively dose normal tissues above and below the tumor. Larger field sizes are needed for adequate coverage.
3) Patient thickness, beam energy, and field size must be considered to minimize lateral tissue effects and ensure uniform dose distribution.
4) Multiple techniques like wedges, isocentric beams, and field matching seek to further optimize dose distribution while sparing critical structures. Proper planning and verification is important.
1) The document discusses measurement of dose distribution in external beam radiation therapy, including beam profiles, isodose curves, and percentage depth dose.
2) Beam profiles measure dose variation across a radiation beam, while isodose curves connect points of equal absorbed dose.
3) Several parameters can affect dose distribution, including beam quality, field size, and distance from the source. Proper measurement and modeling of dose distribution is important for treatment planning.
The document discusses intensity modulated radiation therapy (IMRT) and its advantages over conventional radiotherapy. It describes how IMRT uses non-uniform beam intensities to optimize dose distribution and improve tumor targeting while sparing nearby healthy tissues. Treatment planning for IMRT involves determining optimal fluence profiles for multiple beams and inverse planning. Key benefits of IMRT include better tissue sparing to reduce side effects and potentially higher doses to more effectively treat tumors.
The document summarizes key reports from the International Commission on Radiation Units and Measurements (ICRU), including Report 50 from 1993 and Report 62 from 1999. These reports provide recommendations for prescribing, recording, and reporting radiation therapy treatments. They define important treatment volumes like the gross tumor volume, clinical target volume, planning target volume, and organs at risk. Report 62 adds definitions for internal and setup margins to account for anatomical variations and uncertainties in treatment delivery. Both reports provide guidelines for reporting dose values and distributions to ensure consistent documentation of radiation therapy treatments.
Brachytherapy is a form of radiation therapy where radioactive sources are placed inside or next to the area requiring treatment. The document discusses brachytherapy for cervical cancer, including its history, different systems used (Stockholm, Paris, Manchester), and key aspects like intracavitary vs interstitial placement and dose specification points (point A, B, bladder/rectal reference points). It provides details on the evolution of brachytherapy techniques and applicators over time to optimize dose delivery to the tumor while sparing surrounding healthy tissues.
This document discusses various beam modification devices used in radiation therapy to modify the spatial distribution of radiation within the patient. It describes different types of devices such as shielding blocks, wedges, compensators, multileaf collimators, and bolus. Shielding blocks are used to protect critical organs and reduce unnecessary dose to surrounding normal tissues. Wedge filters are used to tilt the isodose curves. Compensators even out skin surface contours and allow normal dose distributions to be applied to irregular surfaces. Multileaf collimators can dynamically shape radiation fields and are important for intensity-modulated radiation therapy. Bolus is used to reduce the depth of maximum dose for superficial lesions.
1) Radiotherapy plays an important role in managing carcinoma of the cervix by delivering high doses through a combination of external beam radiotherapy and brachytherapy.
2) The disease has central and peripheral components - the central component confined to the cervix is best treated with brachytherapy, while the peripheral component involving surrounding tissues is treated with both external beam radiotherapy and brachytherapy.
3) External beam radiotherapy techniques include 3D conformal radiotherapy and IMRT to improve dose distribution and spare surrounding organs-at-risk.
Blocking anti-inflammatory antibodies to histamine/serotonin receptors is a prospective method of medical management of Acute Radiation Disease and can inhibit pro inflammatory cascades and possible damage of internal organs of irradiated mammals.
1) The four Rs of radiobiology are repair, re-assortment, repopulation, and re-oxygenation. They influence how tumors and normal tissues respond to fractionated radiation treatment.
2) When radiation is delivered in two fractions separated by time, cell survival increases due to repair of sublethal damage between fractions. The increase peaks at 2-3 hours and then levels off due to repopulation.
3) Lowering the radiation dose rate generally decreases biological effects because it allows more time for repair of sublethal damage.
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.
TISSUE PHANTOM RATIO - THE PHOTON BEAM QUALITY INDEXVictor Ekpo
TPR(20,10) is the recommended photon beam quality index by IAEA TRS-398 for megavoltage clinical photons generated by linear accelerators. This presentation goes through the basics of Tissue Phantom Ratio (TPR).
Adaptive radiotherapy (ART) can improve treatment for head and neck cancer patients. ART involves modifying the treatment plan based on anatomical changes observed during radiation therapy delivery. For head and neck cancer, target volumes and organs at risk often change significantly over the course of treatment due to factors like weight loss or tumor shrinkage. Studies have shown ART can improve dose distribution by reducing dose to organs at risk while maintaining or improving tumor dose coverage. Clinical benefits of ART include improved local tumor control and fewer treatment toxicities. ART is most beneficial for patients experiencing greater anatomical changes, such as those with more advanced tumors or significant weight loss.
Beam direction techniques are used to accurately direct radiation beams towards the tumor while sparing surrounding healthy tissues. Key steps include patient localization using imaging like CT/MRI to delineate the tumor and organs, patient positioning and immobilization, field selection using beam directing devices like lasers, collimators and pointers, and dose distribution analysis to calculate and verify the prescribed dose. Proper beam direction allows obtaining conformal dose distributions and reproducible treatments for better therapeutic outcomes.
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 guidelines for evaluating radiotherapy treatment plans for primary brain tumors. It provides indications for radiotherapy based on tumor type and extent of resection. Key factors in treatment planning include: contouring target volumes and organs at risk, optimizing dose distribution to cover the target while sparing organs at risk, and quantitatively evaluating plans using tools like isodose distributions, dose volume histograms and indices like coverage, conformity and homogeneity. Plan evaluation ensures the target receives adequate and uniform dose while respecting organ at risk tolerances.
Craniospinal irradiation involves delivering radiation to the entire cranial-spinal axis and is used to treat cancers that may spread through the cerebrospinal fluid, such as medulloblastoma. It is delivered in two phases, with the first phase irradiating the brain and spinal cord, and the second phase boosting the radiation to the posterior fossa. Proper patient immobilization and treatment planning are important to ensure adequate radiation dose to target areas while minimizing dose to nearby organs at risk. Newer radiation techniques such as VMAT, helical tomotherapy, and proton therapy may further improve treatment by reducing normal tissue dose.
This document provides an overview of interstitial brachytherapy principles and concepts. It discusses the history and evolution of brachytherapy sources from radium to modern radioactive sources like iridium-192. Key concepts covered include dose rate calculations, implant systems like the Paris system, and factors that influence dose distribution from a radioactive source like distance, absorption and scattering. The document also describes temporary and permanent brachytherapy sources and different methods of source application including preloading, afterloading and remote afterloading.
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 document summarizes the oxygen effect and reoxygenation in radiation therapy. It discusses the mechanism of oxygen enhancement, how oxygen acts at the level of free radicals to fix radiation damage. It describes chronic and acute hypoxia in tumors and the process of reoxygenation that can occur between fractions of radiation therapy. Reoxygenation allows previously hypoxic cells to become oxygenated again and be more susceptible to radiation damage.
This document discusses stereotactic radiosurgery and radiotherapy. It begins with an introduction to stereotaxy and how it allows for highly precise radiation targeting. It then covers radiobiology concepts relevant to stereotactic radiation and lists some common indications for its use, including brain metastases and early stage prostate cancer. The document provides details on patient immobilization, planning techniques, and treatment procedures for conditions like pituitary adenomas, trigeminal neuralgia, and arteriovenous malformations.
multiple filed arrangement in Radiotherapy, Medical College KolkataKazi Manir
The document discusses various radiation therapy techniques for dose distribution in matter using multiple fields and wedge fields. It covers:
1) Using multiple fields allows more uniform dose distribution in the tumor compared to a single field, while limiting dose to normal tissues.
2) Parallel opposed fields provide simplicity but can excessively dose normal tissues above and below the tumor. Larger field sizes are needed for adequate coverage.
3) Patient thickness, beam energy, and field size must be considered to minimize lateral tissue effects and ensure uniform dose distribution.
4) Multiple techniques like wedges, isocentric beams, and field matching seek to further optimize dose distribution while sparing critical structures. Proper planning and verification is important.
1) The document discusses measurement of dose distribution in external beam radiation therapy, including beam profiles, isodose curves, and percentage depth dose.
2) Beam profiles measure dose variation across a radiation beam, while isodose curves connect points of equal absorbed dose.
3) Several parameters can affect dose distribution, including beam quality, field size, and distance from the source. Proper measurement and modeling of dose distribution is important for treatment planning.
The document discusses intensity modulated radiation therapy (IMRT) and its advantages over conventional radiotherapy. It describes how IMRT uses non-uniform beam intensities to optimize dose distribution and improve tumor targeting while sparing nearby healthy tissues. Treatment planning for IMRT involves determining optimal fluence profiles for multiple beams and inverse planning. Key benefits of IMRT include better tissue sparing to reduce side effects and potentially higher doses to more effectively treat tumors.
The document summarizes key reports from the International Commission on Radiation Units and Measurements (ICRU), including Report 50 from 1993 and Report 62 from 1999. These reports provide recommendations for prescribing, recording, and reporting radiation therapy treatments. They define important treatment volumes like the gross tumor volume, clinical target volume, planning target volume, and organs at risk. Report 62 adds definitions for internal and setup margins to account for anatomical variations and uncertainties in treatment delivery. Both reports provide guidelines for reporting dose values and distributions to ensure consistent documentation of radiation therapy treatments.
Brachytherapy is a form of radiation therapy where radioactive sources are placed inside or next to the area requiring treatment. The document discusses brachytherapy for cervical cancer, including its history, different systems used (Stockholm, Paris, Manchester), and key aspects like intracavitary vs interstitial placement and dose specification points (point A, B, bladder/rectal reference points). It provides details on the evolution of brachytherapy techniques and applicators over time to optimize dose delivery to the tumor while sparing surrounding healthy tissues.
This document discusses various beam modification devices used in radiation therapy to modify the spatial distribution of radiation within the patient. It describes different types of devices such as shielding blocks, wedges, compensators, multileaf collimators, and bolus. Shielding blocks are used to protect critical organs and reduce unnecessary dose to surrounding normal tissues. Wedge filters are used to tilt the isodose curves. Compensators even out skin surface contours and allow normal dose distributions to be applied to irregular surfaces. Multileaf collimators can dynamically shape radiation fields and are important for intensity-modulated radiation therapy. Bolus is used to reduce the depth of maximum dose for superficial lesions.
1) Radiotherapy plays an important role in managing carcinoma of the cervix by delivering high doses through a combination of external beam radiotherapy and brachytherapy.
2) The disease has central and peripheral components - the central component confined to the cervix is best treated with brachytherapy, while the peripheral component involving surrounding tissues is treated with both external beam radiotherapy and brachytherapy.
3) External beam radiotherapy techniques include 3D conformal radiotherapy and IMRT to improve dose distribution and spare surrounding organs-at-risk.
Blocking anti-inflammatory antibodies to histamine/serotonin receptors is a prospective method of medical management of Acute Radiation Disease and can inhibit pro inflammatory cascades and possible damage of internal organs of irradiated mammals.
This document discusses the radiobiological basis of fractionated radiation therapy. It covers the classic "4 R's" of radiobiology - repair, reassortment, repopulation and reoxygenation. Repair and reoxygenation make tumor cells more sensitive to radiation between fractions, while repopulation and reassortment make them more resistant. The document also proposes a "5th R" of radiossensitivity based on tissue maturity and metabolism. Finally, it briefly mentions the potential "6th R" of bystander effects and abscopal effects, where radiation triggers immune responses against distant tumor cells. Fractionation exploits repair in normal tissues while counteracting resistance mechanisms in tumors through its scheduling over multiple doses.
The document discusses key concepts in radiation oncology including dose fractionation, tumor lethal dose, normal tissue tolerance, and factors that affect radiosensitivity. Fractionating the total radiation dose into smaller daily doses allows time for repair of sublethal damage in normal tissues, improving the therapeutic ratio by reducing side effects while still effectively treating the tumor.
4D radiotherapy aims to adapt treatment plans based on organ and tumor motion over time. This requires 4D data management systems to record treatment delivery and portal images over time. Image processing tools like deformable registration and model-based segmentation can help automate identifying organ motion between 3D scans. Adaptive planning approaches could modify plans at intervals of multiple fractions, daily, or intra-fraction to account for changes. Determining if daily replanning is practical requires considering workload, data management, and the incremental clinical benefits versus costs.
DNA repair is a collection of processes cells use to identify and correct damage to DNA. Failure to repair damaged DNA leads to mutations, which are permanent changes in the DNA sequence. There are several types of DNA damage including mismatches, modified DNA bases, and single or double strand breaks. Cells use multiple repair pathways like direct reversal, base excision repair, nucleotide excision repair, recombination repair, and translesion DNA synthesis to fix different types of DNA damage. Homologous recombination repairs double strand breaks by exchanging DNA between similar molecules, while site-specific and transposon recombination involve movement of DNA between defined sequences.
Radiotherapy uses radiation to treat cancer and can involve two main techniques: radiotherapy and brachytherapy. Radiotherapy involves delivering radiation from an external source using machines like linear accelerators to generate x-rays or gamma rays. Brachytherapy places radioactive sources directly inside the body near the tumor. The choice of treatment depends on factors like tumor size and position. Both techniques aim to maximize the radiation dose to cancer cells while minimizing it to healthy cells.
This document discusses different types of radiation and their effects on humans. It describes ionizing radiation as radiation that deposits enough energy to break molecular bonds or remove electrons from atoms. Examples given are alpha and beta particles, gamma rays, x-rays, and neutrons. It also discusses units used to measure radiation dose like grays and sieverts. The linear no-threshold model, which assumes there is no safe level of radiation exposure, is compared to the radiation hormesis theory, which posits that low doses may be beneficial. Background radiation levels and radiation doses from activities like dental x-rays and living near Chernobyl are provided.
Electromagnetic radiation_Environmental Health Hussain Raufi
This presentation illustrate the propagation of radiation, types, effects on various occasions to the human body. Moreover; the presentations also reflects the severity and its relations to the diseases.Further the benefits and uses of the radiation is also brought into consideration for the treatment of various diseases.
This presentation illustrate the propagation of radiation, types, effects on various occasions to the human body. Moreover; the presentations also reflects the severity and its relations to the diseases.Further the benefits and uses of the radiation is also brought into consideration for the treatment of various diseases.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
Use of radiation in medicine (medical use of radiation)Dr Arvind Shukla
Radiation can be classified as ionizing or non-ionizing. Ionizing radiation such as gamma rays and X-rays have enough energy to remove electrons from atoms, while non-ionizing radiation such as visible light does not. Sources of ionizing radiation include nuclear reactors, X-ray machines, and radionuclides. Radiation exposure can cause both stochastic effects like cancer that have no threshold dose and deterministic effects like burns that become more severe above a threshold dose. International guidelines establish limits for radiation exposure to protect occupational workers and the public.
LASER - Presentation on Laser in Electrotherapy ZaherRahat1
This document provides an overview of laser therapy. It discusses the introduction, properties, types, wavelengths and components of laser production. The physiological and therapeutic effects of laser therapy are explained, along with its use for conditions like wound healing and musculoskeletal disorders. The document also covers the principles of laser application, including dosage parameters and potential dangers. It concludes by listing the most commonly used laser types and their wavelengths.
Principles of Radiotherapy1 Darren Fray DM 1 mj.pptxMiguelJohnson8
Radiation therapy uses ionizing radiation to control cancer cells. It has been used for over 100 years since Rontgen discovered x-rays in 1895. Modern radiation therapy employs linear accelerators to deliver targeted photon beams via techniques like external beam radiation therapy, brachytherapy, and stereotactic radiation. The radiation damages cancer cell DNA to cause cell death while sparing normal tissues through fractionated low doses. Side effects depend on treatment area and can include nausea, skin irritation, fatigue, and long term effects like fibrosis and second cancers.
This document provides an overview of non-ionizing radiation and its biological effects on the human body. It discusses the electromagnetic spectrum and different types of non-ionizing radiation such as optical radiation, radiofrequency, microwaves, and electric and magnetic fields. The document outlines sources of non-ionizing radiation, potential biological effects including thermal and non-thermal interactions, and international standards and guidelines for limiting exposure to avoid known health risks.
There are both immediate and long-term biological effects that can result from radiation exposure. While direct DNA damage can cause immediate radiation sickness, indirect damage through radiolysis of water producing reactive oxygen species can also lead to long-term effects like cancer that may only appear years later. Both acute high dose exposures and prolonged low dose exposures are considered, with the severity of acute radiation sickness depending strongly on the total absorbed dose. Reliable quantification of long-term cancer risks is challenging due to uncertainties in risk models and lack of statistical data from human radiation victims.
The objectives of radiation protection according to international organizations are to provide appropriate protection for humans without unduly limiting beneficial practices involving radiation exposure. The goal is to prevent serious radiation-induced health effects and reduce stochastic effects to an acceptable level relative to the benefits of radiation-related activities. Radiation is measured using various units depending on the type of radiation and its effects, with the main units being Roentgen, Gray, Sievert, and quality factor. The biological effects of radiation can be deterministic, occurring above a threshold dose and increasing in severity with higher doses, or stochastic, occurring probabilistically with no safe threshold.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
This document discusses ionizing radiation and its effects on tissues. It describes two types of ionizing radiation: electromagnetic (X-rays, gamma rays) and particulate (alpha and beta particles). It explains that ionizing radiation can come from natural sources like the sun or radioactive substances in small amounts, or it can be artificially produced. The effects of radiation depend on its absorption, intensity, and rate of administration. Tissues vary in their sensitivity, with some being more radiosensitive and others more radioresistant. Both immediate and delayed effects of radiation exposure are described, including burns, necrosis, malignancy, genetic abnormalities, and cataracts.
Radiation causes damage to living tissues and can cause both somatic (harmful to the person) and genetic (reflected in offspring) effects. The main mechanisms of damage are ionization, where radiation forms ions that interact with matter, and indirect effects where radiation breaks water molecules which generate reactive radicals that damage cells. Early effects include radiation sickness, while later effects include increased risk of cancer and shortened lifespan. Principles of radiation safety include increasing distance from the source, limiting exposure time, and using protective barriers like lead aprons and gloves.
This document provides an overview of key concepts in radiobiology for radiotherapy. It discusses the biological effects of ionizing radiation, including deterministic effects which have a dose threshold and include tissue injuries, and stochastic effects which have no threshold and include cancer induction. Fractionation of radiation doses is explained, along with the 5 R's that influence radiation response: repair, repopulation, reoxygenation, redistribution, and radiosensitivity. Direct and indirect radiation actions on DNA are also summarized.
This document provides an overview of the lessons that will be covered in a module about radiation and waves. It focuses on lesson P6.7, which discusses electromagnetic waves with frequencies higher than visible light, including ultraviolet (UV) rays, X-rays, and gamma rays. The lesson objectives are to understand that these waves are ionizing radiation that can alter or damage living cells. Examples of sources, detectors, and uses of each type of wave are provided. Key concepts explained are that frequency increases and wavelength decreases as you move from radio waves to gamma rays in the electromagnetic spectrum.
The document discusses ionizing radiation and its biological effects. It defines ionizing radiation as radiation that has enough energy to ionize atoms and break molecular bonds. Exposure to ionizing radiation can cause both acute and long-term somatic effects as well as genetic effects. The main biological effects are damage to DNA and chromosomes, which can lead to cell death, mutations, and increased cancer risk over time. The severity of effects depends on factors like total radiation dose, dose rate, and which tissues are exposed.
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01.07.09(a): Introduction to Radiation Oncology, Pre-Clinical
1. Author(s): Theodore Lawrence, M.D., Ph.D., 2011
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3. Introduction to Radiation Oncology
Pre-clinical
Ted Lawrence, MD, PhD
Department of Radiation Oncology
University of Michigan
Winter 2009
4. Overview
Radiation Oncology depends on the fields of
radiation physics, radiation biology and medicine
The understanding and application of each is
enhanced by a knowledge of the other
In these lectures, we will review how radiation
interacts with tissue physically and biologically, and
then focus on how to apply these concepts to treat
patients
5. What is a radiation oncologist?
An oncologist
A specialist and a generalist (all parts of the body)
A person expert in applications of radiation
- Uses radiation in a clinic and in an operating room
- Directs therapists (who place patients on the machines),
dosimetrists (who do dose calculations), and physicists
A member of a multidisciplinary team
A teacher
7. Kinds of radiation - Photons
Gamma rays and x-rays
Penetratesdeeply, so that the dose to the skin is less
than the deep dose ( skin sparing )
Depthof penetration moderately dependent on the
energy of the beam.
This
is the main form of radiation used because it
permits us to treat deep tumors without skin damage.
8. Kinds of radiation - Electrons
Electronsinteract directly with tissues, so that the
dose to the skin tends to be high compared to deeper
tissues
Depthof penetration is strongly dependent on the
energy of the beam
Thistype of radiation is used to treat skin cancers, or
other cancers that are relatively close to the surface
of the body (< 6 cm)
9. Kinds of radiation - Charged particles
Charged particles (protons and carbon nuclei) have
better depth dose characteristics than photons and
electrons
- Depth of penetration is strongly dependent on the
energy of the beam
- Can go deeper than electrons with more skin sparing
Carbon nuclei can kill hypoxic cells as effectively as
well oxygenated cells
However- MUCH (at least 20x) more expensive
11. How radiation is produced-teletherapy
Teletherapy – radiation delivered by a machine
Cobalt (rarely used in the modern era)
- Radioactive material (activated in a cyclotron) and placed in the
head of a machine
Linear accelerator
- Electrons are accelerated and made very energetic
- Can be used directly
- Can be directed at a metal target to produces high energy
photons (x-rays)
12. Brachytherapy-basics
The placement of radioactive sources into or next to the tumor
Depends on the inverse square rule of radiation
The intensity of the radiation depends on the square of the
distance from the source (2x the distance, decrease the
intensity by 4x)
13. Brachytherapy-concepts
Advantage: can permit much more radiation to be
given to the tumor compared to the normal tissue
Disadvantage: harder to make the dose uniform to
the tumor
Placement can be permanent or temporary (minutes
to days)
17. High dose rate brachy (HDR) Example –
Ring and Tandem
Source Undetermined
Source Undetermined
Used to treat cervical and
endometrical cancer
Source Undetermined
18. Interaction of radiation
with cells
Electrons can interact directly (direct effect)
Electronscan produce free radicals (particularly OH•,
O•, and H202) which then interact
19. OH
photon
e
H 20
NEGATIVE INDIRECT
p
ION ACTION
photon
e
DIRECT
p
ACTION
20Å
Source Undetermined
20. Effects at the cellular level
Free radicals exist for microseconds to milliseconds
after the radiation
Biological effects occur over hours, days, and years
Molecular and cellular targets of radiation
- DNA
- Cell membrane
24. Effects of radiation on DNA
Single and double strand breaks
Single strand breaks are well repaired, because there
is an intact (correct) template in the other strand
Repair occurs during next 6 hours
25. Sublethal damage repair
Repeated fraction
curve
Surviving
fraction
Single dose curve
0 1.5 3
Dose (Gy)
T. Lawrence
27. Results of DNA damage
The double strand break appears to be the lethal
lesion- cell must guess what to put back in place
One double strand break can kill a cell
Can lead to mutations and second cancers (≈ 1/1000
patients)
28. Mechanisms of cell death after
DNA damage-mitosis
During mitosis, chromosomes become condensed ,
align, and move to the two daughter cells
Cells
with chromosomal damage cannot perform
mitosis properly and die in the attempt
This
explains why it can take months to years for
tumors to shrink
30. Mechanisms of cell death after
DNA damage- Apoptosis
Programmed cell death
DNA damage can cause some cells to activate a
death pathway
Oftenhappens during a phase of the cell cycle other
than mitosis
Mechanismfor cell death of lymphocytes
(lymphomas) and spermatocytes (seminoma)
33. Effects of radiation
on the cell membrane
The cell membrane is the origin of many
life (growth factor receptor) and
death (apoptotic) signals
Radiation can activate or suppress the former and
activate the latter
34. Effects of RT depend on biology
Genetics
Oxygen status
- Hypoxic cells (in tumors) are resistant
Cell cycle
- S phase resistant, M is sensitive
Chemical modifiers (protectors/sensitizers)
35. Effect of radiation depends on physics
• Kind of radiation (High LET vs Low LET)
How fast radiation is given (1 Gy/min causes more effects than 1
Gy/hr)
How many fractions
- 30 Gy in 3 Gy fractions causes more effects than 30 Gy in 2 Gy fractions
The total time
- 60 Gy in 2 Gy fractions given 6 times a week causes more effects than
60 Gy in 2 Gy fractions given 5 times a week
How much tissue is irradiated (normal tissue)
36. Effects at the tumor/organ level
The 4 R s
Fractionation
- Hyperfractionation
- Accelerated fractionation
Radiation modifying drugs
Parallel and serial organs
Therapeutic index
Why does radiation cure cancers?
37. 4 R s of Radiation Biology
Repopulation - tumor cells can grow back during a
course of radiation
- Accelerated repopulation
Reoxygenation- tumor O2 increases as cells die
Redistribution - cell cycle distribution changes
Repair - cells can repair damage between fractions
38. Hyperfractionation
Standard: 1.8 to 2 Gy per day
Hyperfractionation: two treatments per day
- Each treatment is with less dose than standard (1.1-1.2 Gy)
- Overall treatment time about the same as standard
Rapidly proliferating cancers (head and neck)
- Normal cells repair damage of many fractions better than tumor
Clinical result: for same anti-tumor effect, less late toxicity
39. Accelerated fractionation
Standard: 1.8 to 2 Gy per day
Accelerated fractionation
- Giving 2 treatments a day (same as hyperfractionation)
- Each treatment is about the same dose as standard
- This means more dose per day than standard
- Overall treatment time is shorter than standard
Goal:
prevent tumor from growing during treatment (accelerated
repopulation)
41. Normal Tissues: Parallel and Serial Organs
Parallel organ
- Damage to small fraction has no clinical toxicity
- Clinical toxicity occurs when pass a threshold for fraction of the
organ injured
- Examples: lung and liver
Serial organ
- Damage to a small fraction produces toxicity
- Examples: esophagus and spinal cord
46. Effect of radiation on normal
organs
Organs vary in radiation tolerance
- Kidney - 20 Gy in daily 2 Gy fractions
- Liver - 30 Gy
- Spinal cord - 46 Gy
Parenchyma of the organ
Vasculature leading to the organ
47. Therapeutic index
Definition:
selectivity of radiation for killing the cancer
compared to the normal cells
The therapeutic index for a single radiation treatment is small
How can we increase the therapeutic index?
- Multiple fractions (1.230 = 36)
- Drugs that selectively sensitize tumor cells
- Drugs that selectively protect normal cells
48. Fractionation versus single fraction
Small tumors not abutting critical structures can be treated with a
single fraction
- Usually 10-20 Gy
- Concept is ablation
- Metastases to brain, lung, and liver
Larger tumors or tumors that contain normal tissues
- Concept is therapeutic index: treatment causes at least slightly
more tumor kill than normal tissue damage
- By giving 20-40 treatments of 1.8 to 2 Gy each, this effect is
multiplied
49. Why does radiation fail?
Tumor size
- Can t give enough radiation to kill every tumor stem cell without
intolerable damage to normal tissue [fractionation; tumor
sensitization; normal tissue protection]
- Genetic radiation resistance [tumor sensitization]
Tumor physiology
- Hypoxic cells are relatively resistant to radiation, and may reside
in the center of tumors [fractionation; tumor sensitization]
- Rapidity of tumor cell growth [accelerated fractionation; tumor
sensitization]
50. Why does radiation cure cancers?
Normal cells migrate back into irradiated field
Cancer cells may not repair DNA damage correctly
- Cancer cells often have disordered cell cycle checkpoints
- May attempt to replicate DNA before it is properly repaired
Greater dependence of tumor on new vasculature, which may be
more sensitive to radiation
Probably not due to initial damage from radiation
- For same dose of radiation, cancer cells and normal cells have same number
of DNA double strand breaks
51. Summary
Radiation affects tissues through the generation of free radicals
Cell death is caused chiefly by DNA double strand breaks
The effects of radiation can be modified by
- Physical factors (fraction size, total time, total dose, dose rate,
and radiation type)
- Volume of organ irradiated
- Tumor genetics
- Tumor physiology (the 4 R s)
- Chemical modifiers
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