Halthore Aditya, Fellows Zachary, Tran Anh, Deville Curtiland, Wright Jean L, Meyer Jeffrey, Li Heng, Sheikh Khadija
Department of Radiation Oncology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Department of Radiation Oncology, The Johns Hopkins Proton Center, Washington, DC, USA.
Int J Part Ther. 2022 Dec 22;9(3):40-49. doi: 10.14338/IJPT-22-00028. eCollection 2023 Winter.
To compare spatially fractionated radiation therapy (GRID) treatment planning techniques using proton pencil-beam-scanning (PBS) and photon therapy.
PBS and volumetric modulated arc therapy (VMAT) GRID plans were retrospectively generated for 5 patients with bulky tumors. GRID targets were arranged along the long axis of the gross tumor, spaced 2 and 3 cm apart, and treated with a prescription of 18 Gy. PBS plans used 2- to 3-beam multiple-field optimization with robustness evaluation. Dosimetric parameters including peak-to-edge ratio (PEDR), ratio of dose to 90% of the valley to dose to 10% of the peak VPDR(D90/D10), and volume of normal tissue receiving at least 5 Gy (V5) and 10 Gy (V10) were calculated. The peak-to-valley dose ratio (PVDR), VPDR(D90/D10), and organ-at-risk doses were prospectively assessed in 2 patients undergoing PBS-GRID with pretreatment quality assurance computed tomography (QACT) scans.
PBS and VMAT GRID plans were generated for 5 patients with bulky tumors. Gross tumor volume values ranged from 826 to 1468 cm. Peak-to-edge ratio for PBS was higher than for VMAT for both spacing scenarios (2-cm spacing, = .02; 3-cm spacing, = .01). VPDR(D90/D10) for PBS was higher than for VMAT (2-cm spacing, = .004; 3-cm spacing, = .002). Normal tissue V5 was lower for PBS than for VMAT (2-cm spacing, = .03; 3-cm spacing, = .02). Normal tissue mean dose was lower with PBS than with VMAT (2-cm spacing, .03; 3-cm spacing, .02). Two patients treated using PBS GRID and assessed with pretreatment QACT scans demonstrated robust PVDR, VPDR(D90/D10), and organs-at-risk doses.
The PEDR was significantly higher for PBS than VMAT plans, indicating lower target edge dose. Normal tissue mean dose was significantly lower with PBS than VMAT. PBS GRID may result in lower normal tissue dose compared with VMAT plans, allowing for further dose escalation in patients with bulky disease.
比较使用质子笔形束扫描（PBS）和光子治疗的空间分割放射治疗（GRID）治疗计划技术。
回顾性地为5例患有巨大肿瘤的患者生成PBS和容积调强弧形治疗（VMAT）GRID计划。GRID靶区沿大体肿瘤的长轴排列，间隔2厘米和3厘米，并给予18 Gy的处方剂量进行治疗。PBS计划采用2至3束多野优化并进行稳健性评估。计算剂量学参数，包括峰边比（PEDR）、谷值剂量的90%与峰值剂量的10%之比（VPDR[D90/D10]）以及接受至少5 Gy（V5）和10 Gy（V10）的正常组织体积。对2例接受PBS-GRID治疗的患者进行前瞻性评估，通过预处理质量保证计算机断层扫描（QACT）扫描来评估峰谷剂量比（PVDR）、VPDR[D90/D10]和危及器官剂量。
为5例患有巨大肿瘤的患者生成了PBS和VMAT GRID计划。大体肿瘤体积值范围为826至1468立方厘米。在两种间隔情况下，PBS的峰边比均高于VMAT（2厘米间隔，P = 0.02；3厘米间隔，P = 0.01）。PBS的VPDR[D90/D10]高于VMAT（2厘米间隔，P = 0.004；3厘米间隔，P = 0.002）。PBS的正常组织V5低于VMAT（2厘米间隔，P = 0.03；3厘米间隔，P = 0.02）。PBS的正常组织平均剂量低于VMAT（2厘米间隔，P = 0.03；3厘米间隔，P = 0.02）。2例接受PBS GRID治疗并通过预处理QACT扫描评估的患者显示出稳健的PVDR、VPDR[D90/D10]和危及器官剂量。
PBS的PEDR显著高于VMAT计划，表明靶区边缘剂量更低。PBS的正常组织平均剂量显著低于VMAT。与VMAT计划相比，PBS GRID可能导致更低的正常组织剂量，从而允许对患有巨大疾病的患者进一步提高剂量。
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