Dosimetric study of line scanning for prostate cancer in comparison with passive scattering and volumetric modulated arc therapy

Abstract

Abstract Purpose We performed a planning study to compare the dose distribution of the line scanning (LS) method with that of passive scattering (PS) method and volumetric modulated arc therapy (VMAT) for patients with localized prostate cancer. Methods Thirty patients treated in 2017–2019 were randomly selected. The dose constraints were the clinical target volume (CTV) D98 ≥ 73.0 Gy (RBE), rectal wall V65 < 17% and V40 < 35%, and bladder wall V65 < 25% and V40 < 50%. The CTV doses and rectal and bladder wall dose volumes were calculated and evaluated using the Freidman test. P < 0.05 was determined to be statistically significant. Results In all patients, the LS technique satisfied the dose restrictions for the CTV, rectal wall, and bladder wall. Ten (33.3%) and 21 (70.0%) patients using the PS method and five (16.7%) and one (3.3%) patients using the VMAT, respectively, failed to meet the requirements for the rectal and bladder walls. Wide ranges of the rectal and bladder wall volumes of V10–V70 were lower with LS than with PS and VMAT. LS was superior to VMAT in all dose-volume rectal and bladder wall indexes. PS outperformed the other two methods at Dmax. Conclusion Compared with PS and VMAT, the LS method enables further reduction of the rectal and bladder doses while maintaining the CTV dose. Our results suggest that proton therapy for patients with localized prostate cancer could lower gastrointestinal and genitourinary toxicities by changing from PS to LS.