The use of pulsed photon radiation in medical, industrial and security sectors has vastly increased during the recent years. The length of pulse from different X-ray flash generators that are commonly used as either portable, battery-operated or fixed systems can be as low as a few femtoseconds. However, the majority of radiation protection instruments, especially various active electronic dosemeters, have limitations when operated in pulsed fields. This study presents measurements that were performed using the dose-integration mode of the RI-02 and Ram Ion survey metres, which are based on ventilated ionisation chamber, when exposed to different pulsed X-ray sources. An intercomparison between the results that were obtained with the survey metres and those that were obtained with thermoluminescence dosemeter, reference passive dosemeter, show good agreement (deviation lies within 10%).
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http://dx.doi.org/10.1093/rpd/ncw145 | DOI Listing |
J Appl Clin Med Phys
January 2025
University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany.
Purpose: The self-shielding radiosurgery system ZAP-X consists of a 3 MV linear accelerator and eight round collimators. For this system, it is a common practice to perform the reference dosimetry using the largest 25 mm diameter collimator at a source-to-axis distance (SAD) of 45 cm with the PTW Semiflex3D chamber placed at a measurement depth of 7 mm in water. Existing dosimetry protocols do not provide correction for these measurement conditions.
View Article and Find Full Text PDFPhys Med Biol
January 2025
Medical Physics Laboratory, School of Medicine, National and Kapodistrian University of Athens, 75 Mikras Asias, Goudi, Athens, Attica, 11527, GREECE.
Clinical dosimetry in the presence of a 1.5T magnetic field is challenging, let alone in case small fields are involved. The scope of this study is to determine a set of relevant correction factors for a variety of MR-compatible detectors with emphasis on small fields.
View Article and Find Full Text PDFPhys Med
January 2025
Department of Medical Physics, Apollo Proton Cancer Centre, 100 Feet Road Taramani, Chennai, Tamil Nadu, India. Electronic address:
Objectives: The purpose of this study was to investigate the fundamental properties of spot-scanning proton beams and compare them to Monte Carlo (MC) simulations, both with and without CT calibration, using spatially diverse combinations of materials.
Methods: A heterogeneous phantom was created by spatially distributing titanium, wax, and thermocol to generate six scenarios of heterogeneous combinations. Proton pencil beams ranging in energy from 100 to 226.
Phys Med Biol
December 2024
Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, Singapore, Singapore, 169610, SINGAPORE.
Reference dosimetry measurement in a pencil beam scanning system can exhibit dose fluctuation due to intra-spill spot positional drift. This results in a noisy reference dosimetry measurement against energy which could introduce errors in monitor unit calibration. The aim of this study is to investigate the impact of smoothing the reference dosimetry measurements on the type A uncertainty.
View Article and Find Full Text PDFMed Phys
December 2024
Division of Ionizing Radiation Metrology, National Institute of Metrology (NIM), Beijing, China.
Background: The clinical use of flattening filter free (FFF) radiotherapy has significantly increased in recent years due to its effective enhancement of dose rates and reduction of scatter dose. A proposal has been made to adjust the incident electron angle of the accelerator to expand the application of FFF beams in areas such as large planning target volumes (PTVs). However, the inherent softening characteristics and non-uniformity of lateral dose distribution in FFF beams inevitably lead to increased dosimetry errors, especially for ionization chambers widely used in clinical practice, which may result in serious accidents during FFF radiotherapy.
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