Dosimetric advantages of daily adaptive strategy in IMPT for high‐risk prostate cancer

Tamura, Hiroshi; Kobashi, Keiji; Nishioka, Kentaro; Yoshimura, Takaaki; Hashimoto, Takayuki; Shimizu, Satoru; Ito, Yoichi M.; Maeda, Yoshikazu; Sasaki, Makoto; Yamamoto, Kazutaka; Tamamura, Hiroyasu; Aoyama, Hidefumi; Shirato, Hiroki

doi:10.1002/acm2.13531

Cited by 2 publications

(1 citation statement)

References 45 publications

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“…This system automates the process of the calculations on all sets of CT images and uses the results for an analysis of the DVH indices. It was initially developed for a pencil beam scanning system modeled on the VQA treatment planning system (Hitachi, Tokyo) 12 but was later upgraded for a passively scattering system for the present study. We therefore tuned the dose calculation program in the DDCM system to reproduce basic beam parameters 13 calculated in our PTPS in a water phantom at the depth range of 50−200 mm.…”

Section: Methodsmentioning

confidence: 99%

Effectiveness of CT‐image guidance in proton therapy for liver cancer and the importance of daily dose monitoring for tumors and organs at risk

et al. 2023

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Background: It is important to have precise image guidance throughout proton therapy in order to take advantage of the therapy's physical selectivity. Purpose: We evaluated the effectiveness of computed tomography (CT)-image guidance in proton therapy for patients with hepatocellular carcinoma (HCC) by assessing daily proton dose distributions. The importance of daily CT imageguided registration and daily proton dose monitoring for tumors and organs at risk (OARs) was investigated. Methods: A retrospective analysis was conducted using 570 sets of daily CT (dCT) images throughout whole treatment fractions for 38 HCC patients who underwent passive scattering proton therapy with either a 66 cobalt gray equivalent (GyE)/10 fractions (n = 19) or 76 GyE/20 fractions (n = 19) protocol. The actual daily delivered dose distributions were estimated by forward calculation using the dCT sets, their corresponding treatment plans, and the recorded daily couch correction information. We then evaluated the daily changes of the dose indices D 99% , V 30GyE , and D max for the tumor volumes, non-tumorous liver, and other OARs, that is, stomach, esophagus, duodenum, colon, respectively. Contours were created for all dCT sets. We validated the efficacy of the dCT-based tumor registrations (hereafter, "tumor registration") by comparing them with the bone registration and diaphragm registration as a simulation of the treatment based on the positioning using the conventional kV X-ray imaging. The dose distributions and the indices of three registrations were obtained by simulation using the same dCT sets. Results: In the 66 GyE/10 fractions, the daily D 99% value in both the tumor and diaphragm registrations agreed with the planned value with 3%-6% (SD), and the V 30GyE value for the liver agreed within ±3%; the indices in the bone registration showed greater deterioration. Nevertheless, tumor-dose deterioration occurred in all registration methods for two cases due to daily changes of body shape and respiratory condition. In the 76 GyE/20 fractions, in particular for such a treatment that the dose constraints for the OARs have to be cared in the original planning, the daily D 99% in the tumor registration was superior to that in the other registration (p < 0.001), indicating the effectiveness of the tumor registration. The dose constraints, set in the plan as the maximum dose for OARs (i.e., duodenum, stomach, colon, and esophagus) were maintained for 16 patients including seven treated with re-planning. For three patients, the daily 3274

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Section: Methodsmentioning

confidence: 99%

Effectiveness of CT‐image guidance in proton therapy for liver cancer and the importance of daily dose monitoring for tumors and organs at risk

et al. 2023

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Dosimetric advantages of daily adaptive strategy in IMPT for high‐risk prostate cancer

Tamura

Kobashi

Nishioka

et al. 2022

J Applied Clin Med Phys

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Purpose To evaluate the dosimetric advantages of daily adaptive radiotherapy (DART) in intensity‐modulated proton therapy (IMPT) for high‐risk prostate cancer by comparing estimated doses of the conventional non‐adaptive radiotherapy (NART) that irradiates according to an original treatment plan through the entire treatment and the DART that uses an adaptive treatment plan generated by using daily CT images acquired before each treatment. Methods Twenty‐three patients with prostate cancer were included. A treatment plan with 63 Gy (relative biological effectiveness (RBE)) in 21 fractions was generated using treatment planning computed tomography (CT) images assuming that all patients had high‐risk prostate cancer for which the clinical target volume (CTV) needs to include prostate and the seminal vesicle (SV) in our treatment protocol. Twenty‐one adaptive treatment plans for each patient (total 483 data sets) were generated using daily CT images, and dose distributions were calculated. Using a 3 mm set‐up uncertainty in the robust optimization, the doses to the CTV, prostate, SV, rectum, and bladder were compared. Results Estimated accumulated doses of NART and DART in the 23 patients were 60.81 ± 3.47 Gy (RBE) and 63.24 ± 1.04 Gy (RBE) for CTV D99 (p < 0.01), 62.99 ± 1.28 Gy (RBE) and 63.43 ± 1.33 Gy (RBE) for the prostate D99 (p = 0.2529), and 59.07 ± 5.19 Gy (RBE) and 63.17 ± 1.04 Gy (RBE) for SV D99 (p < 0.001). No significant differences were observed between NART and DART in the estimated accumulated dose for the rectum and bladder. Conclusion Compared with the NART, DART was shown to be a useful approach that can maintain the dose coverage to the target without increasing the dose to the organs at risk (OAR) using the 3 mm set‐up uncertainty in the robust optimization in patients with high‐risk prostate cancer.

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Dosimetric advantages of daily adaptive strategy in IMPT for high‐risk prostate cancer

Cited by 2 publications

References 45 publications

Effectiveness of CT‐image guidance in proton therapy for liver cancer and the importance of daily dose monitoring for tumors and organs at risk

Effectiveness of CT‐image guidance in proton therapy for liver cancer and the importance of daily dose monitoring for tumors and organs at risk

Dosimetric advantages of daily adaptive strategy in IMPT for high‐risk prostate cancer

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