William Buckland Radiotherapy Centre, The Alfred Hospital.
J Appl Clin Med Phys. 2014 Nov 8;15(6):5055. doi: 10.1120/jacmp.v15i6.5055.
Publications have reported the benefits of using high-dose-rate brachytherapy (HDRB) for the treatment of prostate cancer, since it provides similar biochemical control as other treatments while showing lowest long-term complications to the organs at risk (OAR). With the inclusion of anatomy-based inverse planning opti- mizers, HDRB has the advantage of potentially allowing dose escalation. Among the algorithms used, the Inverse Planning Simulated Annealing (IPSA) optimizer is widely employed since it provides adequate dose coverage, minimizing dose to the OAR, but it is known to generate large dwell times in particular positions of the catheter. As an alternative, the Hybrid Inverse treatment Planning Optimization (HIPO) algorithm was recently implemented in Oncentra Brachytherapy V. 4.3. The aim of this work was to compare, with the aid of radiobiological models, plans obtained with IPSA and HIPO to assess their use in our clinical practice. Thirty patients were calculated with IPSA and HIPO to achieve our department's clinical constraints. To evaluate their performance, dosimetric data were collected: Prostate PTV D90(%), V100(%), V150(%), and V200(%), Urethra D10(%), Rectum D2cc(%), and conformity indices. Additionally tumor control probability (TCP) and normal tissue complication probability (NTCP) were calculated with the BioSuite software. The HIPO optimization was performed firstly with Prostate PTV (HIPOPTV) and then with Urethra as priority 1 (HIPOurethra). Initial optimization constraints were then modified to see the effects on dosimetric parameters, TCPs, and NTCPs. HIPO optimizations could reduce TCPs up to 10%-20% for all PTVs lower than 74 cm3. For the urethra, IPSA and HIPOurethra provided similar NTCPs for the majority of volume sizes, whereas HIPOPTV resulted in large NTCP values. These findings were in agreement with dosimetric values. By increasing the PTV maximum dose constraints for HIPOurethra plans, TCPs were found to be in agreement with IPSA without affecting the urethral NTCPs.
已有文献报道，高剂量率近距离治疗（HDRB）在治疗前列腺癌方面具有优势，因为它在提供类似生化控制效果的同时，对风险器官（OAR）的长期并发症最小。通过采用基于解剖结构的逆向规划优化器，HDRB 具有潜在的剂量递增优势。在使用的算法中，逆向计划模拟退火（IPSA）优化器被广泛应用，因为它能提供足够的剂量覆盖，使 OAR 受到的剂量最小，但它也被认为会在导管的特定位置产生较大的驻留时间。作为替代方案，最近在 Oncentra Brachytherapy V.4.3 中实现了混合逆向治疗计划优化（HIPO）算法。本研究旨在借助放射生物学模型，比较 IPSA 和 HIPO 生成的计划，以评估它们在我们临床实践中的应用。为了满足科室的临床限制，对 30 名患者进行了 IPSA 和 HIPO 计算。为了评估它们的性能，收集了剂量学数据：前列腺 PTV D90（%）、V100（%）、V150（%）和 V200（%）、尿道 D10（%）、直肠 D2cc（%）和适形度指数。此外，还使用 BioSuite 软件计算了肿瘤控制概率（TCP）和正常组织并发症概率（NTCP）。首先对前列腺 PTV（HIPOPTV）进行 HIPO 优化，然后将尿道作为优先级 1（HIPOurethra）进行优化。然后修改初始优化约束条件，观察对剂量学参数、TCP 和 NTCP 的影响。对于所有小于 74cm3 的 PTV，HIPO 优化可将 TCP 降低 10%-20%。对于尿道，IPSA 和 HIPOurethra 为大多数体积大小提供了相似的 NTCP，而 HIPOPTV 则导致较大的 NTCP 值。这些发现与剂量学值一致。通过增加 HIPOurethra 计划的 PTV 最大剂量约束，发现 TCP 与 IPSA 一致，而不会影响尿道 NTCP。
