微束辐射治疗（MBRT）：调试与首次临床应用

Minibeam Radiation Therapy Treatment (MBRT): Commissioning and First Clinical Implementation

INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS

影响因子:6.5

分区:医学1区 Top / 肿瘤学2区核医学2区

发表日期:2024 Dec 01

作者: Michael P Grams, Chrystian Quintero Mateus, Maryam Mashayekhi, Robert W Mutter, Valentin Djonov, Jennifer M Fazzari, Huaping Xiao, Kelsey M Frechette, Adam J Wentworth, Jonathan M Morris, Brandon Klebel, Jack C Thull, Rachael M Guenzel, David J Schembri Wismayer, Fabrice Lucien, Sean S Park, Scott C Lester

DOI: 10.1016/j.ijrobp.2024.06.035

摘要

微束辐射治疗（MBRT）特点为在肿瘤中传递亚毫米宽的“峰”剂量区域与“谷”剂量区域。动物实验已证实其潜力，我们报告了MBRT的首次临床应用。采用临床正电子照射设备，使用不同直径（3、4、5、8、10 cm）的锥体进行调试。180 kVp的输出通过钨钼柱状准直器（缝宽0.5 mm，间距1.1 mm）空间分离成微束。利用胶片剂量测定和塑料水进行深度剂量分布（PDD）测量，记录峰值和谷值剂量。测量中心轴的PDD在偏移0、0.5和1厘米时的变化。计算各深度的峰谷比。在患者运动影响剂量的情况下，制作了个性化的三维打印准直器支架，贴合每位患者的解剖结构，并将钨准直器固定于身体上。共治疗了两名患者，每人接受2次治疗。峰值PDD随着深度逐渐降低，谷值PDD最初略有增加后在2厘米深度后逐渐减弱。峰谷比在表面较高，且在较小的锥体尺寸和偏移下最高。体内胶片剂量验证确认两位患者的峰谷剂量具有明显界线，无剂量模糊。两位患者均表现出症状改善和肿瘤反应。我们报告了MBRT的调试结果、治疗流程以及首批两例临床患者的治疗情况。尽管验证此方法的可行性是迈向更广泛应用的重要第一步，但还需通过临床试验进一步确认其安全性与有效性。

Abstract

Minibeam radiation therapy (MBRT) is characterized by the delivery of submillimeter-wide regions of high "peak" and low "valley" doses throughout a tumor. Preclinical studies have long shown the promise of this technique, and we report here the first clinical implementation of MBRT.A clinical orthovoltage unit was commissioned for MBRT patient treatments using 3-, 4-, 5-, 8-, and 10-cm diameter cones. The 180 kVp output was spatially separated into minibeams using a tungsten collimator with 0.5 mm wide slits spaced 1.1 mm on center. Percentage depth dose (PDD) measurements were obtained using film dosimetry and plastic water for both peak and valley doses. PDDs were measured on the central axis for offsets of 0, 0.5, and 1 cm. The peak-to-valley ratio was calculated at each depth for all cones and offsets. To mitigate the effects of patient motion on delivered dose, patient-specific 3-dimensional-printed collimator holders were created. These conformed to the unique anatomy of each patient and affixed the tungsten collimator directly to the body. Two patients were treated with MBRT; both received 2 fractions.Peak PDDs decreased gradually with depth. Valley PDDs initially increased slightly with depth, then decreased gradually beyond 2 cm. The peak-to-valley ratios were highest at the surface for smaller cone sizes and offsets. In vivo film dosimetry confirmed a distinct delineation of peak and valley doses in both patients treated with MBRT with no dose blurring. Both patients experienced prompt improvement in symptoms and tumor response.We report commissioning results, treatment processes, and the first 2 patients treated with MBRT using a clinical orthovoltage unit. While demonstrating the feasibility of this approach is a crucial first step toward wider translation, clinical trials are needed to further establish safety and efficacy.