Real-time gated proton therapy with a reduced source to imager distance: Commissioning and quality assurance

• Published in: Physica medica 2024-06, Vol.122, p.103380-103380, Article 103380
• Main Authors: Tan, Hong Qi, Koh, Calvin Wei Yang, Lew, Kah Seng, Yeap, Ping Lin, Chua, Clifford Ghee Ann, Lee, James Kuan Huei, Wibawa, Andrew, Master, Zubin, Lee, James Cheow Lei, Park, Sung Yong
• Format: Article
• Language: English
• Subjects: Fiducial Marker; Fiducial Markers; Fluoroscopy; Humans; Motion management; PBS; Proton therapy; Proton Therapy - instrumentation; Quality Assurance, Health Care; Quality Control; Radiometry; Radiotherapy, Image-Guided; RGPT; Time Factors
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2024.103380

•Commissioning measurements for RGPT reported for the first time.•RGPT specific daily and monthly QA are proposed for the first time.•The gating latencies for turning the proton beam on and off are 119.5 and 50.0 ms respectively.•Daily marker localization QA results are all less than 0.2 mm. Real-time gated proton therapy (RGPT) is a motion management technique unique to the Hitachi particle therapy system. It uses pulsed fluoroscopy to track an implanted fiducial marker. There are currently no published guidelines on how to conduct the commissioning and quality assurance. In this work we reported on our centre’s commissioning workflow and our daily and monthly QA procedures. Six commissioning measurements were designed for RGPT. The measurements include imaging qualities, fluoroscopic exposures, RGPT marker tracking accuracy, temporal gating latency, fiducial marker tracking fidelity and an end-to-end proton dosimetry measurement. Daily QA consists of one measurement on marker localization accuracy. Four months daily QA trends are presented. Monthly QA consists of three measurementson the gating latency, fluoroscopy imaging quality and dosimetry verification of gating operation with RGPT. The RGPT was successfully commissioned in our centre. The air kerma rates were within 15 % from specifications and the marker tracking accuracies were within 0.245 mm. The gating latencies for turning the proton beam on and off were 119.5 and 50.0 ms respectively. The 0.4x10.0 mm2 Gold AnchorTM gave the best tracking results with visibility up to 30 g/cm2. Gamma analysis showed that dose distribution of a moving and static detectors had a passing rate of more than 95 % at 3 %/3mm. The daily marker localization QA results were all less than 0.2 mm. This work could serve as a good reference for other upcoming Hitachi particle therapy centres who are interested to use RGPT as their motion management solution.