A5051852408- Advanced Radiotherapy Techniques
- Radiation Therapy and Dosimetry
- Radiation Dose and Imaging
- Radiation Detection and Scintillator Technologies
- Radiation Effects and Dosimetry
- Advanced X-ray and CT Imaging
- Spectroscopy Techniques in Biomedical and Chemical Research
- Radioactive Decay and Measurement Techniques
- Medical Imaging Techniques and Applications
- Calibration and Measurement Techniques
- Nuclear Physics and Applications
- Advanced MRI Techniques and Applications
- Radiation Effects in Electronics
- Plant Genetic and Mutation Studies
- Advances in Oncology and Radiotherapy
- thermodynamics and calorimetric analyses
- Advanced Semiconductor Detectors and Materials
- Radioactivity and Radon Measurements
- Lanthanide and Transition Metal Complexes
- Spacecraft Design and Technology
- Glioma Diagnosis and Treatment
- Neurotransmitter Receptor Influence on Behavior
- Ethics in Clinical Research
- Energy Harvesting in Wireless Networks
- Scientific Measurement and Uncertainty Evaluation
National Research Council Canada
2015-2025
Carleton University
2010-2016
National Academies of Sciences, Engineering, and Medicine
2011-2016
Ottawa Hospital
2015-2016
McGill University
2015
ChemCentre
2013
Purpose: To use EGSnrc Monte Carlo simulations to directly calculate beam quality conversion factors, , for 32 cylindrical ionization chambers over a range of qualities and quantify the effect systematic uncertainties on calculations . These factors are required TG‐51 or TRS‐398 clinical dosimetry protocols calibrating external radiotherapy beams. Methods: Ionization modeled either from blueprints manufacturers' user's manuals. The dose‐to‐air in chamber is calculated using user‐code...
The IAEA is currently coordinating a multi-year project to update the TRS-398 Code of Practice for dosimetry external beam radiotherapy based on standards absorbed dose water. One major aspect determination new quality correction factors, k Q , megavoltage photon beams consistent with developments in and technology since publication 2000. Specifically, all values must be on, or with, key data ICRU Report 90. Data sets obtained from Monte Carlo (MC) calculations by advanced users measurements...
Abstract Background Ultra‐high dose rate radiotherapy (UHDR) delivers therapeutic doses at rates >40 Gy/s in a fraction of second, aiming to enhance the ratio through FLASH effect. The substantial increase UHDR beam current poses serious challenges for conventional active dosimeters. Integrating transformers (ICT) offer nondestructive solution accurate monitoring, enabling type fast transient readout that will be crucial treatment verification. Purpose aim this study is build and...
The TG-51 protocol describes methods for obtaining reference dosimetry measurements external photon and electron beams. Since the publication of in 1999, research on has allowed revisiting procedures data recommended protocol. An Addendum to beam was published 2024, which revises formalism provides updated kQ$k_{Q}$ data. To compare clinical beams obtained using original American Association Physicists Medicine's (AAPM) its associated (AAPM WGTG51 report 385). Measurements were performed...
Purpose: The journal Medical Physics recently published two papers that determine beam quality conversion factors, k Q , for large sets of ion chambers. In the first paper [McEwen Med. Phys. 37 2179–2193 (2010)], was determined experimentally, while second [Muir and Rogers 5939–5950 (2010)] provides factors calculated using Monte Carlo simulations. This work investigates a variety additional consistency checks to verify accuracy in each publication comparison data sets. Uncertainty...
Purpose: To investigate the behavior of plane-parallel ion chambers in high-energy photon beams through measurements and Monte Carlo simulations. Methods: Ten chamber types were obtained from major manufacturers. Absorbed dose-to-water calibration coefficients are measured for these factors determined. In process, behaviors characterized leakage currents, settling cobalt-60, polarity recombination behavior, long-term stability. calculations absorbed dose to air water calculate factors....
Purpose: To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations the response 10 plane‐parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on determination optimal shift chambers’ effective point measurement (EPOM) quality conversion factors. Methods: The EGSnrc system used for calculations absorbed dose to gas in models water as function depth phantom which cobalt‐60 several source are incident. EPOM shifts chambers...
Purpose: Recent Monte Carlo calculations of beam quality conversion factors for ion chambers that use high‐Z electrodes [B. R. Muir and D. W. O. Rogers, Med. Phys., – (2010)] have shown large deviations values from calculated using the same techniques as TG‐51 TRS‐398 protocols. This report investigates central electrode correction factor, , these chambers. Methods: Ionization are modeled is EGSnrc user code egs_chamber three cases: in photon electron beams under reference conditions; a...
Purpose: To investigate recommendations for reference dosimetry of electron beams and gradient effects the NE2571 chamber to provide beam quality conversion factors using Monte Carlo simulations PTW Roos ion chambers. Methods: The EGSnrc code system is used calculate absorbed dose‐to‐water dose gas in fully modeled chambers as a function depth water. Electron are realistic accelerator well collimated point sources from spectra or monoenergetic electrons. Beam calculated with ratios doses...
Practical guidelines that are not explicit in the TG-51 protocol and its Addendum for photon beam dosimetry presented implementation of reference external high-energy electron beams. These pertain to: (i) measurement depth-ionization curves required to obtain quality specifiers selection conversion factors, (ii) considerations system specifications a reference-class ionization chamber, (iii) commissioning frequency measurements, (iv) positioning/aligning water tank chamber depth dose (v)...
Abstract Background The newly available ZAP‐X stereotactic radiosurgical system is designed for the treatment of intracranial lesions, with several unique features that include a self‐shielding, gyroscopic gantry, wheel collimation, non‐orthogonal kV imaging, short source‐axis distance, and low‐energy megavoltage beam. Systematic characterization its radiation as well other properties imperative to ensure safe effective clinical application. Purpose To accurately determine output special...
Purpose Cherenkov emission (CE)‐based external beam dosimetry is envisioned to involve the detection of CE directly in water with placement a high‐resolution detector out field, avoiding perturbations encountered traditional dosimeters. In this work, we lay groundwork for its implementation clinic and motivate CE‐based dosimeter design efforts. To that end, examine formalism broad‐beam in‐water radiotherapy beams, test Monte Carlo (MC) simulation framework calculation CE‐to‐dose conversion...
To provide results of water calorimetry and ion chamber measurements in high-energy electron beams carried out at the National Research Council Canada (NRC). There are three main aspects to this work: (a) investigation behavior ionization chambers different energies with focus on long-term stability, (b) determine absorbed dose for direct calibration chambers, (c) using response relative reference determination beam quality conversion factors, kQ , several types.Measurements made between 8...
Purpose: To analyze absorbed dose calibration coefficients, N D , w measured at accredited dosimetry laboratories (ADCLs) for client ionization chambers to study (i) variability among coefficients of the same type calibrated each ADCL investigate ion chamber volume fluctuations and manufacturing tolerances; (ii) equivalency different ADCLs by intercomparing type; (iii) long‐term stability types investigating repeated calibrations. Methods: Large samples several over time period between 1998...
Cherenkov emission (CE) is ubiquitous in external radiotherapy. It also unique that it carries the promise of 3D, micrometer-resolution, perturbation-free, in-water dosimetry with a beam quality-independent detector response calibration. Our aim to bring CE-based into clinic and we motivate this here electron beams. We Monte Carlo (MC) calculate characterize broad-beam CE-to-dose conversion factors water for clinically representative library qualities, address quality specification reference...
To assess the impact of ICRU report 90 recommendations on beam-quality conversion factor, k
Beam current transformers (BCT) are promising detectors for real-time beam monitoring in ultra-high dose rate (UHDR) electron radiotherapy. However, previous studies have reported a significant sensitivity of the BCT signal to changes source-to-surface distance (SSD), field size, and phantom material which until now been attributed fluctuating levels electrons backscattered within BCT. The purpose this study is evaluate hypothesis, with goal understanding mitigating variations due...
A method is presented to obtain ion chamber calibration coefficients relative secondary standard reference chambers in electron beams using depth-ionization measurements. Results are obtained as a function of depth and average energy at 4, 8, 12 18 MeV from the NRC Elekta Precise linac. The PTW Roos, Scanditronix NACP-02, Advanced Markus NE 2571 investigated. challenges limitations discussed. proposed produces useful data shallow depths. At depths past depth, small shifts positioning or...
To investigate the use of cylindrical chambers for electron beam dosimetry independent energy by studying variability relative ion chamber perturbation corrections, one main concerns with chambers.Measurements are made sets and plane-parallel reference-class as a function depth in water 8 MeV 18 beams. The ratio readings similar is normalized high-energy can be thought corrections. Data plotted mean at range depths close to phantom surface R80 , which ionization falls 80% its maximum value....
To present the results and discuss potential insights gained through surveys on reference dosimetry practices.Two were sent to medical physicists learn about current state of practices at radiation oncology clinics worldwide. A short survey designed maximize response rate was made publicly available distributed via AAPM website a physics list server. Another, much more involved survey, smaller group gain insight detailed practices. The questions diverse, covering topics like measurements...
Purpose To present and demonstrate the accuracy of a modified formalism for electron beam reference dosimetry using updated Monte Carlo calculated quality conversion factors. Methods The proposed, simplified allows use cylindrical ionization chambers in all beams (even those with low energies) does not require measured gradient correction factor. Data from previous publication are used is tested compared to AAPM TG‐51 protocol measurements made Elekta Precise energies between 4 MeV 22 fields...
The aim of this study is to reduce the uncertainty associated with determining dose-to-water using an amorphous silicon electronic portal imaging detector (EPID) under reference conditions by identifying and accounting for operational environmental factors influencing long-term stability EPID response.Measurements relative response, corrected variations in linear accelerator (linac) output, were performed regularly over a period 12 months. For every acquired image set, measurements supply...
Abstract Objective . While the accuracy of dose calculations in water with Acuros XB is well established, experimental validation bone limited. reports both dose-to-medium and dose-to-water, these values differ bone, but there are no measurements bone. This work compares to absolute aluminum (medium similar bone). The validity using selected relative dosimeters also investigated. Approach A calorimeter an core embedded phantom was as surrogate for measurement dose. Matching medium allowed...
Purpose The purpose of this work is to develop a new approach for high spatial resolution dosimetry based on Raman micro‐spectroscopy scanning radiochromic film (RCF). goal generate dose calibration curves over an extended range from 0 50 Gy and with improved sensitivity low (<2 Gy) doses, in addition evaluating the uncertainties estimation associated curves. Methods Samples RCF (EBT3) were irradiated at broad 0.03–50 using Elekta Synergy clinical linear accelerator. spectra acquired...