Insight gained from responses to surveys on reference dosimetry practices

Abstract

PurposeTo present the results and discuss potential insights gained through surveys on reference dosimetry practices.MethodsTwo surveys were sent to medical physicists to learn about the current state of reference dosimetry practices at radiation oncology clinics worldwide. A short survey designed to maximize response rate was made publicly available and distributed via the AAPM website and a medical physics list server. Another, much more involved survey, was sent to a smaller group of physicists to gain insight on detailed dosimetry practices. The questions were diverse, covering reference dosimetry practices on topics like measurements required for beam quality specification, the actual measurement of absorbed dose and ancillary equipment required like electrometers and environment monitoring measurements.ResultsThere were 190 respondents to the short survey and seven respondents to the detailed survey. The diversity of responses indicates nonuniformity in reference dosimetry practices and differences in interpretation of reference dosimetry protocols.ConclusionsThe results of these surveys offer insight on clinical reference dosimetry practices and will be useful in identifying current and future needs for reference dosimetry.

On the impact of ICRU report 90 recommendations on kQ factors for high‐energy photon beams

“…It is worth noting that in a recent survey on reference dosimetry practices about 40% of respondents used the PTW 30013 chamber for reference dosimetry of MV photon beams, making it the most commonly used chamber for these measurements. 8 Since the ICRU-90 recommendations are relevant only for graphite and water, results for these representative chambers will demonstrate the impacts of ICRU-90 on k Q factors. The EGSnrc Monte Carlo simulation toolkit 9 is used to model the transport of electrons and photons in matter and estimate the energy deposited in regions of interest.…”

“…These chamber types are specifically selected for this work as they are archetypal of classes of chambers available for photon beam reference dosimetry measurements for which k Q factors could be impacted by ICRU‐90 recommendations — graphite‐walled, plastic‐graphite‐walled, and plastic‐walled chambers. It is worth noting that in a recent survey on reference dosimetry practices about 40% of respondents used the PTW 30013 chamber for reference dosimetry of MV photon beams, making it the most commonly used chamber for these measurements . Since the ICRU‐90 recommendations are relevant only for graphite and water, results for these representative chambers will demonstrate the impacts of ICRU‐90 on k Q factors.…”

A snapshot of medical physics practice patterns

“…Surveys have been a useful tool in understanding and documenting the standard‐of‐care in various topics in radiotherapy physics . Over the past 5 yr, there have been over 250 surveys distributed mainly through the medical physics listserv covering varying topics of interest to clinical physicists (e.g., simulation practices, use of image guidance, and clinical workflow).…”

Technical Note: On the use of cylindrical ionization chambers for electron beam reference dosimetry

“…Recent surveys on reference dosimetry practices have shown that clinical physicists in North America are comfortable using the same cylindrical chambers that they use in photon beams for electron beam calibration . Given the additional complication associated with requiring a cross‐calibration procedure to use plane‐parallel chambers, the issues related to the behavior of plane‐parallel chambers and the demonstrated stability of reference‐class cylindrical chambers over decades, we ask the question in this work, “Can cylindrical reference‐class chambers be used for reference dosimetry of all electron beams, regardless of energy?…”