J. DAnwl B8NrL.nd, Ph.D., isIlssU14nt professor Andhed, Physic Section, Dep.:ntm ent ofR.4dUaion Oncology, Wa e Forest Unit/miry School of Medicine in Winston-Salem, N.G. He ischairman ofthe AAPM Electronic Media Coordinating Committee, chairman ofthe new AAPM Subcommitteeon MoieCHlaTImaging in Clinical Radiation Oncology, and aformer member ofthe AAPM RildiAtion Therllpy Committee. The AAPM is headqNllTtered in College PIlTk, Md. WHO WE ARE The America n Assoc iation of Physicists in Medicine (AAPM) h J S ap proximately 4.62S mcmbers who practice or arc associn ed with medical physics.

American Association of Physicists in Medicine

Central Axis Depth Dose Data for Use in Radiotherapy, in: British Journal of Radiology. British Institute of Radiology, New York (1983)

550 speaker DEVELOPMENT OF PROCEDURES FOR IN VIVO DOSIMETRY IN RADIOTHERAPY

Purpose 

The purpose of this investigation was to assess the angular dependence of a commercial optically stimulated luminescence dosimeter (OSLD) dosimetry system in MV x-ray beams at depths beyondd max and to find ways to mitigate this dependence for measurements in phantoms.

Methods 

Two special holders were designed which allow a dosimeter to be rotated around the center of its sensitive volume. The dosimeter's sensitive volume is a disk, 5 mm in diameter and 0.2 mm thick. The first holder rotates the disk in the traditional way. It positions the disk perpendicular to the beam (gantry pointing to the floor) in the initial position (0°). When the holder is rotated the angle of the disk towards the beam increases until the disk is parallel with the beam (“edge on,” 90°). This is referred to as Setup 1. The second holder offers a new, alternative measurement position. It positions the disk parallel to the beam for all angles while rotating around its center (Setup 2). Measurements with five to ten dosimeters per point were carried out for 6 MV at 3 and 10 cm depth. Monte Carlo simulations using GEANT4 were performed to simulate the response of the active detector material for several angles. Detector and housing were simulated in detail based on microCT data and communications with the manufacturer. Various material compositions and an all-water geometry were considered.

Results

For the traditional Setup 1 the response of the OSLD dropped on average by 1.4% ± 0.7% (measurement) and 2.1% ± 0.3% (Monte Carlo simulation) for the 90° orientation compared to 0°. Monte Carlo simulations also showed a strong dependence of the effect on the composition of the sensitive layer. Assuming the layer to completely consist of the active material (Al2O3) results in a 7% drop in response for 90° compared to 0°. Assuming the layer to be completely water, results in a flat response within the simulation uncertainty of about 1%. For the new Setup 2, measurements and Monte Carlo simulations found the angular dependence of the dosimeter to be below 1% and within the measurement uncertainty. 

Conclusions 

The dosimeter system exhibits a small angular dependence of approximately 2% which needs to be considered for measurements involving other than normal incident beams angles. This applies in particular to clinicalin vivo measurements where the orientation of the dosimeter is dictated by clinical circumstances and cannot be optimized as otherwise suggested here. When measuring in a phantom, the proposed new setup should be considered. It changes the orientation of the dosimeter so that a coplanar beam arrangement always hits the disk shaped detector material from the thin side and thereby reduces the angular dependence of the response to within the measurement uncertainty of about 1%. This improvement makes the dosimeter more attractive for clinical measurements with multiple coplanar beams in phantoms, as the overall measurement uncertainty is reduced. Similarly, phantom based postal audits can transition from the traditional TLD to the more accurate and convenient OSLD.

Angular dependence of the response of the nanoDot OSLD system for measurements at depth in clinical megavoltage beams

Purpose This study was designed to evaluate skin dose in both VMAT and tangent treatment deliveries for the purpose of identifying suitable bolus use protocols that should produce similar superficial doses Methods Phantom measurements were used to investigate skin dose in chest wall radiotherapy with and without bolus for 3D and rotational treatment techniques Optically stimulated luminescence dosimeters (OSLDs) with and without housing and EBT3 film were used Superflab (3, 5, and 10 mm) and brass mesh were considered Measured doses were compared with predictions by the Eclipse treatment planning system Patient measurements were also performed and the bolusing effect of hospital gowns and blankets were highlighted The effect of flash for VMAT plans was considered experimentally by using 2 mm couch shifts Results For tangents, average skin doses without bolus were 064 (EBT3), 062 (bare OSLD), 077 (jacketed OSLD), and 068 (Eclipse) as a fraction of prescription For VMAT, doses without bolus were 053 (EBT3), 053 (bare OSLD), 064 (jacketed OSLD), and 060 (Eclipse) For tangents, the average doses with different boluses as measured by EBT3 were 099 (brass mesh), 102 (3 mm), 103 (5 mm), and 107 (10 mm) For VMAT with bolus, average doses as measured by EBT3 were 083 (brass), 096 (3 mm), 103 (5 mm), and 104 (10 mm) Eclipse doses agreed with measurements to within 5% of measurements for all Superflab thicknesses and within 15% of measurements for no bolus The presence of a hospital gown and blanket had a bolusing effect that increased the surface dose by approximately 10% Conclusions Results of this work allow for consideration of different bolus thicknesses, materials, and usage schedules based on desired skin dose and choice of either tangents or an arc beam techniques

https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1002/acm2.12948

In search of a one plan solution for VMAT post-mastectomy chest wall irradiation

Background Optically stimulated luminescence dosimeters (OSLDs) have a number of advantages in radiation dosimetry making them an excellent dosimeter for in vivo dosimetry. The study aimed to study the dosimetric characteristics of a commercial optically stimulated luminescence (OSL) system by Landauer Inc., before using it for routine clinical practice for in vivo dosimetry in radiotherapy. Further, this study also aimed to investigate the cause of variability found in the literature in a few dosimetric parameters of carbon-doped aluminium oxide (Al2O3:C). Materials and methods The commercial OSLD system uses Al2O3:C nanoDotTM as an active radiation detector and InLightTM microStar® as a readout assembly. Inter-detector response, energy, dose rate, field size and depth dependency of the detector response were evaluated for all available clinical range of photon beam energies in radiotherapy. Results Inter-detector variation in OSLD response was found within 3·44%. After single light exposure for the OSL readout, detector reading decreased by 0·29% per reading. The dose linearity was investigated between dose range 50–400 cGy. The dose response curve was found to be linear until 250 cGy, after this dose, the dose response curve was found to be supra-linear in nature. OSLD response was found to be energy independent for Co60 to 10 MV photon energies. Conclusions The cause of variability found in the literature for some dosimetric characteristics of Al2O3:C is due to the difference in general geometry, construction of dosimeter, geometric condition of irradiation, phantom material and geometry, beam energy. In addition, the irradiation history of detector used and difference in readout methodologies had varying degree of uncertainties in measurements. However, the large surface area of the detector placed in the phantom with sufficient build-up and backscatter irradiated perpendicularly to incident radiation in Co60 beam is a good method of choice for the calibration of a dosimeter. Understanding the OSLD response with all dosimetric parameters may help us in estimation of accurate dose delivered to patient during radiotherapy treatment.

Study of dosimetric characteristics of a commercial optically stimulated luminescence system

Objective To evaluate and analyze entrance surface air kerma (ESAK) of the thyroid during mammographies performed in a breast cancer screening program. Methods The ESAK was measured for the left and right lobes of the thyroid gland for 120 female subjects undergoing routine mammographic screenings. All measurements were single-handedly performed on the Hitachi Hologic LORAD M-IVTM screen-film mammography system. Radiation dose measurements were made using optically stimulated luminescent dosimeters (OSLD) nanoDot™ taped appropriately to the skin overlying the right and left lobes of the thyroid gland. The standard technique of two craniocaudal (CC) views and two mediolateral oblique (MLO) views with appropriate compression was used during the screening. Results The average ESAK was (287 ​± ​102) μGy. The value of radiation dose to the thyroid was estimated as 71.17 ​μGy. Compresssed breast thichness (CBT) was found as key parameter influencing radiation dose to the thyroid gland during mammography. ESAK changed approximately two folds for the CBT range of 2–5 ​cm. Radiation dose to the thyroid gland was increased with higher body mass index (BMI). Conculsions A proper compression of the breast is crucial for the mammographic examination. In addition to applied exposure factors for examination, breast compression is the principal and influencing factor that affects various other parameters used during mammographic examinations, which in turn impact radiation dose to the thyroid gland.

Evaluation and analysis of entrance surface air kerma of the thyroid gland during breast cancer screening mammography

Objective To provide guidance on basic concepts and elements for radiation safety and security measures for a HDR brachytherapy sealed radioactive source in a medical radiation facility. Methods Brachytherapy sources are Category 2 (High risk-very dangerous) radioactive source and Security Level B applied to cover the range of security measures needed for the associated risk with remote afterloading HDR brachytherapy sources. These security measures were applied based on a risk informed graded approach. A series of in-build and operational safety measures were implemented for equipment and radiation installation. Results The medical radiation facility equipped with adequate radiation protection, detection and monitoring equipment such as survey meter, digital contamination monitor, gamma zone monitor, digital radiation monitor, personnel dosimeter, pocket dosimeter, long handled forceps, shielding material and emergency source storage container etc. to deal with radiological incidences. The contingency plan with security objectives for incidents and procedures for action was prepared in order to implement response function to fulfill the goal of adequate security of radioactive source. The emergency response plan documented against emergency scenarios during transport, loss of radioactive source, theft, sabotage, natural calamities/disasters such as fire, flood and earthquake. Conculsions The paper provides various radiation safety and security aspects for the HDR brachytherapy. The HDR brachytherapy radioactive sources are Type A packages. Transport of radioactive material is the responsibility of consignors, consignee and carriers under the legislation, supervision and control of regulatory authority.

Implementation of safety and security standards for high dose rate brachytherapy sealed radioactive source used in a medical radiation facility

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Gourav Kumar Jain

Author Tools

Chat about Author

Papers

Study of dosimetric characteristics of a commercial optically stimulated luminescence system

Evaluation and analysis of entrance surface air kerma of the thyroid gland during breast cancer screening mammography

Implementation of safety and security standards for high dose rate brachytherapy sealed radioactive source used in a medical radiation facility