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Updated: Sep 14, 2025
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Target density override in pencil beam scanning proton therapy for different motion target delineation: an
Xianrui Yan1,2, Yungang Wang2, JiaBing Gu3
1Southeast University, Laboratory of Image Science and Technology, The Key Laboratory of Computer Network and Information Integration, Ministry of Education, Jiangsu Provincial Joint International Research Laboratory of Medical Information Processing, Centre de Recherche en Information Biomédicale Sino-français (CRIBs), Nanjing, People's Republic of China.
Abstract:
Objective. This study aims to investigate the impact of target density override (TDO) on delivered dose in pencil beam scanning proton therapy (PBSPT) by experimental measurement.Approach.TDO was developed using the density characteristics of all target voxels, employing a sliding window approach. The density-override value was specified as the statistical mean through traversal calculation. Three motion targets were delineated from 3D plain-scan CT (3DpCT), average intensity projection (AIP), and maximum intensity projection (MIP). The prescription proton dose was 200 cGy (RBE). Dose distribution information at the central coronal plane for all plans was quantified by digitizing the film scan.Main results. The target density of AIP and MIP were -315.59 HU (95% CI: -317.35 HU--313.83 HU), and 76.26 HU (95% CI: 75.59 HU-76.93 HU). The Unconformity Index (UCIunderdose) of the MIP were 0. The MIP and 3DpCT UCIoverdosefailed the Mann-WhitneyUtest (Z= -3.674, -3.606;p= 0). The AIP and MIP prescription dose area for the initial target were 11.42 cm2(95% CI: 9.71 cm2-13.13 cm2) and 20.90 cm2(95% CI: 20.24 cm2-21.55 cm2), while increased to 20.07 cm2(95% CI: 19.36 cm2-20.77 cm2) and decreased to 18.62 cm2(95% CI: 18.27 cm2-18.98 cm2) for TDO target. The initial and TDO target D98of AIP, 3DpCT were 185.40 cGy (95% CI: 180.19-190.60 cGy) and 204.54 cGy (95% CI: 194.76-214.33 cGy), 142.46 cGy (95% CI: 137.37-147.55 cGy) and 145.28 cGy (95% CI: 140.44-150.11 cGy).Significance. TDO improves dose coverage within the tumor and reduces the out-field dose. This method provides a promising strategy to optimize dose delivery in PBSPT, especially for tumors affected by respiratory motion.
