Clinical commissioning of intensity‐modulated proton therapy systems: Report of AAPM Task Group 185

Abstract

Proton therapy is an expanding radiotherapy modality in the United States and worldwide. With the number of proton therapy centers treating patients increasing, so does the need for consistent, high-quality clinical commissioning practices. Clinical commissioning encompasses the entire proton therapy system's multiple components, including the treatment delivery system, the patient positioning system, and the image-guided radiotherapy components. Also included in the commissioning process are the x-ray computed tomography scanner calibration for proton stopping power, the radiotherapy treatment planning system, and corresponding portions of the treatment management system. This commissioning report focuses exclusively on intensitymodulated scanning systems, presenting details of how to perform the commissioning of the proton therapy and ancillary systems, including the required proton beam measurements, treatment planning system dose modeling, and the equipment needed.

The root cause analysis on failed patient‐specific measurements of pencil beam scanning protons using a 2D detection array with finite size ionization chambers

“…The PBS delivery system was implemented in the second gantry room at our institute beginning in May 2017. We describe the characteristics of PBS beam delivery and the commissioning of TPS 8 in a separate section. Based on the database of recorded PBS‐QA measurements, the numbers of patients and of PBS‐QA measurements are sorted and listed in Table 1 .…”

Development of a heterogeneous phantom to measure range in clinical proton therapy beams

“…The solid water equivalent materials (SW 1471 and SW 1472, St. Bartholomew's Hospital, London, UK) used in the phantom are epoxy resin based and were previously optimised to match the proton nuclear interaction cross sections of water [13]. Both were shown to provide better water-equivalence in terms of proton fluence compared to commercial solid water equivalent materials [14]. While it was concluded that SW 1472 was the most water equivalent, it is inhomogeneous in nature due to the practicalities of mixing compounds into the epoxy resin mixture, which results in batch variability that impact the measured range and TPS calculations.…”

“…As proton range estimation is a main source of uncertainty, it is important to validate range measurements in more realistic and complex phantom geometries to enable the evaluation of the full patient workflow as a means of an end-to-end audit [11]. Range measurements are typically performed with an ionisation chamber in a water phantom or with the use of array based detectors placed behind slabs of either water, tissue-substitute materials or real biological tissues [12][13][14]. But radiochromic film has also been previously shown to have potential as a detector for measuring proton range [15,16] and the response of different types of radiochromic film (MD 55, MD 55 2, HD 810, EBT, EBT2, EBT3, EBT XD films) in proton beams has been well documented [15][16][17][18][19].…”

Development of a storage phosphor imaging system for proton pencil beam spot profile determination

“…In particular, recommended periodic QA procedures include proton spot placement verification to ±1–2 mm accuracy and spot size verification to ±10% accuracy of baseline commissioning values 11 . Accurate single spot profile data are also important for the commissioning of IMPT systems including treatment planning systems (TPS) that will be used for proton dose calculations 12 . For these purposes, accurate profile data have to be obtained especially proton halo profile measurements around a single spot 13 .…”

“…11 Accurate single spot profile data are also important for the commissioning of IMPT systems including treatment planning systems (TPS) that will be used for proton dose calculations. 12 For these purposes, accurate profile data have to be obtained especially proton halo profile measurements around a single spot. 13 Proton halos arise from inelastic nuclear interactions 14,15 and are typically on the order of 0.1% of the peak proton dose.…”