Detectors for Dosimetry Measurements in Ultra-High Dose Rate (UHDR) Beams Used for Flash Radiotherapy Applications
Description
This session is jointly organized by the Working Group on Radiation Dosimetry and Task Group 359 on FLASH (ultra-high dose rate) radiation dosimetry. The session will begin with an educational review of currently available radiation dosimeters used for both conventional and UHDR beams. Information will be provided regarding the underlying physics of the working principles for radiation detection for each detector type, including detector-specific characteristics which can affect measured signal under varying irradiation and dose rate conditions. Practical guidelines and common pitfalls regarding the use of each detector type will also be provided. The session will focus on radiation dosimeters that are commonly used in radiation therapy clinics for machine commissioning, quality assurance testing, and research. Devices considered will include ionization chambers, diodes, diamond detectors, plastic scintillators, and radiochromic film. Other dose rate independent detectors such as absorbed dose calorimeters and alanine dosimeters, more commonly employed by standards or research laboratories, will also be described due to their extensive use for dose verification in UHDR beams. The session will then describe the challenges associated with applying commonly used detectors for dose measurement and standardization in UHDR beams, highlighting the work of AAPM Task Group 359. In particular, the session will describe the dosimetric characteristics related to beam delivery that differ in UHDR mode compared to standard delivery, and the suitability of various radiation detectors for measurements in UHDR beams.