Mínguez Pablo, Gustafsson Johan, Flux Glenn, Gleisner Katarina Sjögreen
Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, 22185 Lund, Sweden. Department of Medical Physics, Gurutzeta/Cruces University Hospital, 48903 Barakaldo, Spain.
Phys Med Biol. 2016 Mar 21;61(6):2532-51. doi: 10.1088/0031-9155/61/6/2532. Epub 2016 Mar 7.
In this work, the biologically effective dose (BED) is investigated for fractionated molecular radiotherapy (MRT). A formula for the Lea-Catcheside G-factor is derived which takes the possibility of combinations of sub-lethal damage due to radiation from different administrations of activity into account. In contrast to the previous formula, the new G-factor has an explicit dependence on the time interval between administrations. The BED of tumour and liver is analysed in MRT of neuroblastoma with (131)I-mIBG, following a common two-administration protocol with a mass-based activity prescription. A BED analysis is also made for modified schedules, when due to local regulations there is a maximum permitted activity for each administration. Modifications include both the simplistic approach of delivering this maximum permitted activity in each of the two administrations, and also the introduction of additional administrations while maintaining the protocol-prescribed total activity. For the cases studied with additional (i.e. more than two) administrations, BED of tumour and liver decreases at most 12% and 29%, respectively. The decrease in BED of the tumour is however modest compared to the two-administration schedule using the maximum permitted activity, where the decrease compared to the original schedule is 47%.
在这项工作中，对分次分子放射治疗（MRT）的生物有效剂量（BED）进行了研究。推导了Lea-Catcheside G因子的公式，该公式考虑了由于不同给药活度的辐射导致的亚致死损伤组合的可能性。与先前的公式不同，新的G因子明确依赖于给药之间的时间间隔。在采用基于质量的活度处方的常见两次给药方案后，用（131）I-间碘苄胍对神经母细胞瘤进行MRT时，分析了肿瘤和肝脏的BED。当由于当地法规对每次给药有最大允许活度时，还对修改后的方案进行了BED分析。修改包括在两次给药中的每次都给予这种最大允许活度的简单方法，以及在保持方案规定的总活度的同时引入额外的给药。对于研究的有额外（即超过两次）给药的情况，肿瘤和肝脏的BED分别最多降低12%和29%。然而，与使用最大允许活度的两次给药方案相比，肿瘤BED的降低幅度较小，与原始方案相比降低了47%。
