Accelerator beam data commissioning equipment and procedures: Report of the TG‐106 of the Therapy Physics Committee of the AAPM

Abstract

For commissioning a linear accelerator for clinical use, medical physicists are faced with many challenges including the need for precision, a variety of testing methods, data validation, the lack of standards, and time constraints. Since commissioning beam data are treated as a reference and ultimately used by treatment planning systems, it is vitally important that the collected data are of the highest quality to avoid dosimetric and patient treatment errors that may subsequently lead to a poor radiation outcome. Beam data commissioning should be performed with appropriate knowledge and proper tools and should be independent of the person collecting the data. To achieve this goal, Task Group 106 (TG-106) of the Therapy Physics Committee of the American Association of Physicists in Medicine was formed to review the practical aspects as well as the physics of linear accelerator commissioning. The report provides guidelines and recommendations on the proper selection of phantoms and detectors, setting up of a phantom for data acquisition (both scanning and no-scanning data), procedures for acquiring specific photon and electron beam parameters and methods to reduce measurement errors (<1%), beam data processing and detector size convolution for accurate profiles. The TG-106 also provides a brief.discussion on the emerging trend in Monte Carlo simulation techniques in photon and electron beam commissioning. The procedures described in this report should assist a qualified medical physicist in either measuring a complete set of beam data, or in verifying a subset of data before initial use or for periodic quality assurance measurements. By combining practical experience with theoretical discussion, this document sets a new standard for beam data commissioning.

Characteristics of a novel treatment system for linear accelerator–based stereotactic radiosurgery

“…Selection of different detectors for water phantom measurements were based on AAPM task group report No. 106 and small field dosimetry specification (23) (Table 1). Field sizes ranged from $1\times 1 {\text{cm}}^2$ to $40\times 40 {\text{cm}}^2$ which were determined by the jaw (i.e., data were acquired with the MLCs parked).…”

Implementation of the validation testing in MPPG 5.a “Commissioning and QA of treatment planning dose calculations–megavoltage photon and electron beams”

“…The use of a 2%/2 mm gamma criteria and more rigorous small field testing was a good complement to the limited dataset recommended by vendors for commissioning. For users who wish to scrutinize their TPS models further, we recommend comparing your results to previous work on the topic of validation found in the literature 2, 3, 4, 5, 6, 7, 8, 9, 10, 11. Finally, we wanted to note what appears to be an error in MPPG 5.a to future users of the guideline.…”

“…The 2008 AAPM Task Group Report No. 10610 discusses equipment and procedures to ensure the accurate and self‐consistent collection of commissioning beam data. The 2009 AAPM Task Group Report No.…”

Determination of MLC model parameters for Monaco using commercial diode arrays

“…Film and diodes have been recommended by Report 22 of the Netherlands Commission on Radiation Dosimetry (14) and AAPM TG‐106 (13) for evaluating finer detail of MLC characteristics, for example discrimination between interleaf and intraleaf leakage. It was recommended by the manufacturer to measure the test fields described in Table 2 with a PSQA measurement device to enable optimization of the TPF MLC model parameters.…”

“…Monaco TPF possesses a number of MLC parameters that can be adjusted based on measurements of test fields with the users PSQA measurement device as recommended by the vendor (12) . AAPM TG‐106 (13) has suggested the use of film, portal images or diodes as measurement devices to determine MLC characteristics. The aim of this study was to explore if it was possible to optimize the TPF MLC parameters of the XVMC dose calculation algorithm and to evaluate the relative merit of MapCHECK 2 and ArcCHECK for this process.…”