van Leeuwen Ruud G H, Verwegen Drean, van Kollenburg Peter G M, Swinkels Marc, van der Maazen Richard W M
Department of Radiotherapy, Radboudumc, Huispost 874, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
Phys Imaging Radiat Oncol. 2020 Oct 1;16:12-17. doi: 10.1016/j.phro.2020.09.004. eCollection 2020 Oct.
Total body irradiation (TBI) is a treatment used in the conditioning of patients prior to hematopoietic stem cell transplantation. We developed an extended-distance TBI technique using a conventional linac with multi-leaf collimator to deliver a homogeneous dose, and spare critical organs.
Patients were treated either in lateral recumbent or in supine position depending on the dose level. A conventional linac was used with the patient midline at 350 cm from the beam source. A series of beams was prepared manually using a 3D treatment planning system (TPS) aiming to improve dose homogeneity, spare the organs at risk and facilitate accurate patient positioning. An optimized dose calculation model for extended-distance treatments was developed using phantom measurements. During treatment, in-vivo dosimetry was performed using electronic dosimeters, and accurate positioning was verified using a mobile megavoltage imager. We analyzed dose volume histogram parameters for 19 patients, and in-vivo measurements for 46 delivered treatment fractions.
Optimization of the dose calculation model for TBI improved dose calculation by 2.1% at the beam axis, and 17% at the field edge. Treatment planning dose objectives and constraints were met for 16 of 19 patients. Results of in-vivo dosimetry were within the set limitations (±10%) with mean deviations of 3.7% posterior of the lungs and 0.6% for the abdomen.
We developed a TBI treatment technique using a conventional linac and TPS that can reliably be used in the conditioning regimen of patients prior to stem cell transplantation.
全身照射（TBI）是造血干细胞移植前用于患者预处理的一种治疗方法。我们开发了一种使用配备多叶准直器的传统直线加速器的远距离TBI技术，以提供均匀剂量并保护关键器官。
根据剂量水平，患者采用侧卧位或仰卧位进行治疗。使用传统直线加速器，患者中线距离束源350 cm。使用三维治疗计划系统（TPS）手动准备一系列射束，旨在提高剂量均匀性、保护危险器官并便于准确的患者定位。利用体模测量开发了一种用于远距离治疗的优化剂量计算模型。在治疗过程中，使用电子剂量计进行体内剂量测定，并使用移动兆伏级成像仪验证准确的定位。我们分析了19例患者的剂量体积直方图参数以及46个治疗分次的体内测量结果。
TBI剂量计算模型的优化使射束轴线上的剂量计算提高了2.1%，射野边缘提高了17%。19例患者中有16例达到了治疗计划的剂量目标和限制。体内剂量测定结果在设定的限制范围内（±10%），肺部后方的平均偏差为3.7%，腹部为0.6%。
我们开发了一种使用传统直线加速器和TPS的TBI治疗技术，可可靠地用于干细胞移植前患者的预处理方案。
