Radiation Shielding for Mega-voltage Photon Therapy Machines
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Radiation shielding is needed for megavoltage photon therapy machines to limit radiation exposure and reduce effective dose outside of treatment rooms. Approximately 50% of cancer patients receive radiation therapy. Shielding barriers like lead and concrete are used to reduce radiation levels in uncontrolled and controlled areas like corridors and waiting rooms based on factors like workload, use, and occupancy. Proper machine orientation and maze or direct door designs can further reduce dose near room entrances. Ducting and electrical routing must also consider radiation protection. Skyshine radiation from scattered photons above the treatment room requires special consideration in shielding design.
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Setting a new radiotherapy facility-steps involved. Explains what all things to be done to setup new oncology centre.
Flattening filter Free
1. The document discusses commissioning parameters for flattening filter free (FFF) photon beams from a linear accelerator, including profile normalization methods, dosimetric field size, penumbra, and slope.
2. Profile normalization can be done using the inflection point or renormalization value to compare FFF and flattened beams. Dosimetric field size is measured as the 50% dose width. Penumbra is defined as the 20-80% distance for FFF beams after normalization.
3. Slope describes the peak shape of FFF profiles, and flatness/unflatness parameters are discussed to characterize beam homogeneity for both FFF and flattened beams.
SRS & SBRT - Unflattened Beam
1.Stereotactic Radiosurgery (SRS)
SRS is a precise and focused delivery of a single, high dose of irradiation to a small and critically located intracranial volume while sparing normal structure
2.Stereotactic Body Radiation Therapy (SBRT)
SBRT is a treatment procedure similar to SRS, except that it deals extra-cranial radiosurgery
3.Flattening Filter Free (FFF) mode
FFF beam is produced without the use of flattening Filter
In the 1990s, several groups studied about FFF high-energy photon beams. The main interest for that, is to increase the dose rate for radiosurgery or the "physics interest”.
Need of increase in dose rate from traditional 300-600 to 1400-2400MU/min to overcome time-inefficiency and to improve patients comfort specially in SRS/SBRT
Flattening Filter Free (FFF) mode
FFF beam is produced without the use of flattening Filter
In the 1990s, several groups studied about FFF high-energy photon beams. The main interest for that, is to increase the dose rate for radiosurgery or the "physics interest”.
Need of increase in dose rate from traditional 300-600 to 1400-2400MU/min to overcome time-inefficiency and to improve patients comfort specially in SRS/SBRT
Seminar 2 .beam modification devices
Beam modification devices are used to modify the spatial distribution of radiation within the patient. Shielding blocks protect normal tissues and critical structures by altering the shape of the radiation beam. Compensators compensate for missing tissues to achieve a uniform spatial distribution. Multileaf collimators are the principal shielding device and can generate complex field shapes through computer control. Wedge filters tilt the isodose curves to modify the dose distribution.
Shielding Design
This document summarizes the shielding design for a radiation oncology facility containing a linear accelerator room, brachytherapy suite, and PET/CT area. Assumptions are provided about expected workloads and dose rates. Calculations are shown for determining the necessary wall thicknesses to limit doses to specified limits for both primary and scattered radiation. An error is noted in the initial report where a wall was calculated for the wrong dose limit, leading to overestimated thickness. The document demonstrates the detailed calculations involved in radiation shielding design.
Radiation Generating equipments of LINAC
A linear accelerator (LINAC) is a device that uses radiofrequency electromagnetic waves to accelerate electrons to high energies in a linear path inside a tube. The electrons are then collided with a heavy metal target to produce high-energy x-rays. The x-rays are directed to the patient's tumor from any angle by rotating the gantry and moving the treatment couch. LINACs have evolved from early machines with limited motion and lower energies to modern machines with wider ranges of beam energies, dose rates, field sizes, and operating modes that provide more precise and accurate radiation treatment for cancer patients. Key components of a LINAC include the drive stand containing the klystron or magnetron to generate microwave power, the accelerator waveguide
Quality assurance of linear accelerator DHX
This document outlines the daily quality assurance procedure for a linear accelerator. It describes turning on the machine, performing mechanical checks like gantry and couch movement tests, warming up the machine using various electron and photon energies, and performing dosimetry measurements to ensure parameters are within tolerance levels. Results are documented in a QA sheet for record keeping. The purpose is to ensure consistent machine quality and patient safety by verifying proper dose delivery and checking for any mechanical or software errors.
Dose Distribution Measurement (part 1)
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.
Tomotherapy
Tomotherapy is a form of intensity-modulated radiation therapy (IMRT) that utilizes a radiation therapy device designed on a CT scanner-based platform. It delivers radiation via a fan beam using a ring gantry that rotates continuously around the patient. This allows for radiation to be delivered from all angles and precise tumor targeting while minimizing dose to surrounding healthy tissues. Daily MVCT imaging is used for image-guided radiation therapy (IGRT) to precisely locate tumors prior to each treatment for enhanced accuracy. Tomotherapy combines IMRT and IGRT capabilities into a single integrated platform.
Linear accelerator vinay
The document summarizes a medical linear accelerator (LINAC). Key points:
- LINAC uses high-frequency waves to accelerate electrons which are used to treat tumors through electron beams or x-ray beams produced by electron impacts on a target.
- Early LINACs from the 1950s-1980s were large, bulky, and had limited motion. Modern LINACs have improved acceleration, more treatment options, and greater reliability.
- LINAC consists of an electron gun, microwave generator, waveguide, treatment head with collimation/target, monitoring devices, and safety systems. It accelerates electrons to treat cancer through precise x-ray beams.
Dosimetry
This document summarizes key aspects of acceptance testing and commissioning for a new radiation therapy machine. It describes the necessary measurement equipment, including radiation survey meters, ionization chambers, and phantoms. Acceptance tests and commissioning involve measuring various beam properties to ensure the machine meets specifications and performs reliably before clinical use. This process establishes the machine's baseline performance values which are then monitored ongoing through periodic quality assurance tests.
Radiation emergencies and preparedness in radiotherapy
In a Radiotherapy Department where cancer patients are being treated with high energy photons,gamma rays,electrons; all the radiation workers should be alert regarding radiation accidents & how to face the situation.
Isodose lines
Isodose lines represent points of equal absorbed radiation dose on a dose distribution map. They are depicted as curves on isodose charts showing the volumetric and planar variations in absorbed dose. Factors influencing isodose curves include beam quality, field size, source-to-skin distance, beam modifiers like wedges or bolus, and depth. Isodose curves are used in radiation therapy treatment planning to evaluate dose distributions and ensure tumor coverage while sparing surrounding healthy tissues. They provide critical information about the radiation dose profile essential for safe and effective treatment.
What's hot (20)
Linear Accelerator Acceptance, Commissioning and Annual QA
Linear Accelerator Acceptance, Commissioning and Annual QA
Particle beam – proton,neutron & heavy ion therapy
Particle beam – proton,neutron & heavy ion therapy
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Setting a new radiotherapy facility-steps involved
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Radiation emergencies and preparedness in radiotherapy
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Principles of Radiotherapy1 Darren Fray DM 1 mj.pptx
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.
2012_TMI
This document describes a new microwave imaging system for breast cancer detection that produces 3D tomographic images much faster than previous systems. The system uses an array of antennas to illuminate the breast and collects data in under 2 minutes. It then uses a discrete dipole approximation algorithm to reconstruct the 3D images in less than 20 minutes, overcoming the enormous time burdens of prior algorithms. The document presents the first clinical 3D microwave tomographic images of the breast from over 400 patient exams. Two clinical examples are shown, one demonstrating potential for breast cancer screening and another focusing on monitoring therapy response.
RT-GRID: Grid Computing for Radiotherapy
The document discusses using grid computing resources to perform Monte Carlo dose calculations for radiotherapy treatment planning, as Monte Carlo simulations can provide more accurate dose calculations but are computationally expensive; grid computing allows simulations to be run simultaneously across many computers to reduce calculation time from weeks to hours or days, making Monte Carlo planning clinically feasible on a national scale.
Radiation Oncology in 21st Century - Changing the Paradigms
Since its inception radiation therapy has been used as one of
the essential treatment options in the management of malignant and some benign tumors. With better understanding of tumor biology many new molecules have been added to the armamentarium of an oncologist. There is continuous improvement in surgical techniques with more emphasis on minimally invasive, organ- and function-preserving techniques. Neoadjuvant chemotherapy with or without addition of radiation therapy has helped surgeon downsizing the tumor and obtaining clearer margins.
Medical Equipment Radiotherapy1
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.
Quality Assurance in Radiotherapy and Dosimetry
“Training Course on Radiation Protection for Radiation Workers and RCO’s of BAEC”
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Radiotherapy With Protons
The document discusses proton beam radiotherapy and its advantages over traditional x-ray radiotherapy. It describes the equipment used for proton beam therapy including cyclotrons, treatment rooms with rotating gantries, patient immobilization devices, and beam shaping tools. It also provides examples of treatment plans comparing proton and x-ray intensity modulated radiotherapy for tumors in brain and spine.
Radiotherapy With Protons
The document discusses proton beam radiotherapy and its advantages over traditional x-ray radiotherapy. It describes the equipment used for proton beam therapy including cyclotrons, treatment rooms with rotating gantries, patient immobilization devices, and beam shaping components. It also compares treatment plans using proton therapy to those using intensity-modulated x-ray therapy, showing that protons can lower doses to surrounding healthy tissues. The case for developing a proton therapy facility at University College Hospital in London is made due to its location in a center of medical expertise and research.
Pumps and Pipes: Medical Imaging, pumpsandpipesmdhc
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2. Modern medical imaging techniques like computed tomography, magnetic resonance imaging, ultrasound, and positron emission tomography use pumps, pipes, and computers to generate digital images of the inside of the body.
3. Future interventional medicine may involve seamless integrated platforms using visualization, robotics, treatment planning, and monitoring with feedback loops to precisely target and treat areas of the body.
Introduction to radiation therapy
This document provides an overview of radiotherapy techniques used to treat cancer. It discusses the basic principles of radiotherapy, including the linear-quadratic model which describes the effects of radiation on cell survival. It describes the two main approaches of external beam radiotherapy using x-rays, electrons, protons, neutrons or heavy ions, and brachytherapy involving radioactive sources placed inside the body. Key stages of the radiotherapy process including imaging, planning, treatment and verification are also outlined.
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This document describes a new cancer therapy technique using tunable, monochromatic X-rays being developed by the company MXISystems. The technique shows promise in precisely targeting radiation therapy to cancer cells while sparing healthy tissue. However, commercializing the technology faces challenges including high capital costs, lack of supply chain for key components, and investor reluctance over perceived long-term risk. The document applies the framework of accelerated radical innovation to analyze MXISystems' innovation and determine how to accelerate its widespread clinical use by addressing challenges it faces in commercialization.
Proton therapy
Proton therapy is an advanced form of particle therapy that uses a beam of protons to treat cancer. It more precisely targets radiation dosage to the tumor compared to other radiotherapy. Proton accelerators produce protons with energies between 70-250 MeV that cause DNA damage only in the targeted cells, sparing nearby tissue. Protons deposit most of their energy at the "Bragg peak" at the end of their range, penetrating no further. This allows proton therapy to avoid side effects of standard radiation and make it preferable for pediatric cases. While preliminary studies show few side effects, it remains the most precise radiation treatment available.
Proton therapy
Proton therapy is an advanced form of particle therapy that uses a beam of protons to treat cancer. It more precisely targets radiation dosage to the tumor compared to other radiotherapy. Proton accelerators produce protons with energies between 70-250 MeV that cause DNA damage only in the targeted cells, sparing nearby tissue. This allows protons to deliver maximum dose to just the tumor site via the Bragg peak effect, with very few protons penetrating beyond the target depth. Proton therapy has advantages over x-ray therapy in being more precise with avoiding usual radiation side effects and is preferred for pediatric cases.
Proton therapy
Proton therapy is an advanced form of particle therapy that uses a beam of protons to treat cancer. It more precisely targets radiation dosage to the tumor compared to other radiotherapy. Proton accelerators produce protons with energies between 70-250 MeV that cause DNA damage only in the targeted cells, sparing nearby tissue. This allows protons to deliver maximum dose to just the tumor site via the Bragg peak. Proton therapy has advantages over x-ray radiation in being more precise with avoiding usual side effects, and is preferred for pediatric cases due to reduced injury risk.
AN ANALYSIS OF THE BENEFITS AND ADVANTAGES TO SRT
1) Stereotactic radiosurgery (SRS), stereotactic radiotherapy (SRT), and stereotactic body radiotherapy (SBRT) use focused radiation beams and precise targeting to deliver high doses of radiation to small, well-defined tumors with minimal damage to surrounding healthy tissue.
2) Studies have found stereo treatments improve survival rates for certain brain tumors compared to traditional treatments and offer an effective non-invasive option for inoperable lung tumors.
3) The advantages of stereo treatments include targeting small tumors with high radiation doses using fewer treatment sessions, resulting in reduced side effects and improved quality of life for patients.
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This document discusses the use of radiotherapy and chemotherapy in the management of oral cancer. It provides details on different treatment modalities including external beam radiation therapy, intensity modulated radiation therapy, brachytherapy, and chemotherapy. It also covers topics like dental preparation before radiation treatment, acute and late side effects of radiation therapy including xerostomia, and approaches to manage radiation-associated complications.
EAR BUD PUBLICATION
This document describes a dosimetric feasibility study for using a plastic earbud and stethoscope earpiece as an applicator for brachytherapy to treat early-stage squamous cell carcinoma of the external auditory canal. The plastic earbud is inserted into the ear canal along with an interstitial needle. The earpiece stabilizes the earbud. A simulation was performed and plan was generated to demonstrate the dosimetric viability. The proposed arrangement could provide an effective method of precisely delivering high radiation doses for radical brachytherapy treatment, with potential benefits over surgery such as organ preservation and better cosmetic and functional outcomes. Further studies are still needed to validate this approach.
An approach for radiation dose reduction in computerized tomography
Minimization of radiation dose plays an important role in human wellbeing. Excess of radiation dose leads to cancer. Radiation greatly affects young children less than 10 years of age as their life span is longer. Radiation can be reduced by hardware and/or by software techniques. Hardware methods deal with variation of parameters such as tube voltage, tube current, exposure time, focal distance and filter type. Software techniques include image processing methods. The originally acquired X-ray images may be contaminated with noise due to the fact of instability in the case of sensors, electrical power or X-ray source, that is responsible for the degradation of the image attributes. An enhanced image denoising algorithm has been proposed which decreases Gaussian noise combined with salt and pepper noise that retains most information particulars.
Neuroradiologia
Neuroradiology is the subspecialty of radiology focused on imaging the central and peripheral nervous systems. The document discusses several key imaging modalities used in neuroradiology including CT, MRI, ultrasound, angiography, and myelography. It provides details on the techniques, advantages, and limitations of each modality. CT and MRI are currently the main modalities used for evaluating neurological pathology, though each has specific scenarios where it is particularly useful over the other. Recent technological advances have improved imaging capabilities and increased accessibility of various modalities.
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Radiation Shielding for Mega-voltage Photon Therapy Machines
- 1. Radiation Shielding for Megavoltage Photon Therapy Machines RADIATION PROTECTION 1 Daryoush khoramian
- 2. 2 The International Agency for Research on Cancer(IARC) recently estimated that 7.6 million deaths worldwide were due to cancer with 12.7 million new cases per year being reported worldwide Breast cancer in females and lung cancer in males are the most frequently diagnosed cancers ( Freddie Bray et al 2011) Approximately 50% of all cancer patients will receive radiation therapyradiation therapy during their course of illness ( Basker et al 2012 )
- 3. Basic principles The purpose of radiation shielding : To limit radiation exposures to members of the public and employees to an acceptable level. ( NCRP report no.151 ) Areas Uncontrolled areas 1 mSv/yr Controlled areas 5 mSv/yr NCRP,2007 NCRP,2007 3
- 4. The purpose of radiation shielding : To reduce the effective equivalent dose from a linear accelerator to a point outside the room to a sufficiently low level. 4 In radiation therapy rooms
- 5. Workload Use factor Occupancy factor Use factor Walls 1/4 Floor 1/2 Ceiling 1/4 or 1/2 T Full occupancy Work areas, offices, nurses’ stations 1 Partial occupancy Corridors, restrooms, .. 1/4 Occasional occupancy Waiting rooms, stairways, … 1/6 Or 1/16 5
- 6. 6 Barriers
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- 13. 13 TVL in 16 MV TVL in 16 MV
- 14. 14 It’s toxic lead is not self supporting needs to be held in place Relatively transparent to neutrons but decrease energy of neutrons by inelastic scattering
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- 20. 20 Overall size The couch radius : 9’ Back wall end of couch : 21’ 22’×20’ clear area Height : 9’-10’
- 21. 21 Machine orientation Parallel to the maze Orthogonal to the maze Special design
- 22. 22 Maze vs. direct door Where the available space is minimal Doors are Very heavy ( several tons ) Very expensive In order to reduce the radiation dose near the entrance Is a route for ventilation ducts and electrical conduits
- 23. 23 Ducts
- 27. 27 References : 1.Baskar, Rajamanickam, Lee, Kuo Ann, Yeo, Richard, & Yeoh, Kheng-Wei. (2012). Cancer and radiation therapy: current advances and future directions. International journal of medical sciences, 9(3), 193. 2.Biggs, Peter J. (2010). Radiation Shielding for Megavoltage Photon Therapy Machines: Boston: sn. 3.Deye, James A, Rodgers, JE, Wu, RK, Biggs, PJ, McCall, RC, & McGinley, PH. (2005). Structural Shielding Design and Evaluation from Megavoltage X-and Gamma-Ray Radiotherapy Facilities. National Cancer Institute, Rockville, Maryland. 4.INTERNATIONAL ATOMIC ENERGY AGENCY, RADIATION PROTECTION IN THE DESIGN OF RADIOTHERAPY FACILITIES, IAEA, Vienna (2005). 5.Khan, Faiz M, & Khan, FM. (2003). The physics of radiation therapy (Vol. 3): Lippincott Williams & Wilkins Philadelphia. 6.Turner, James Edward, & Kelsey, Charles A. (1995). Atoms, radiation, and radiation protection: Wiley New York.
- 28. Thank you Any question ?