Azzarouali Sana, Goudschaal Karin, Visser Jorrit, Bel Arjan, Daniëls Laurien, den Boer Duncan
Radiation Oncology, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, NLD.
Radiation Oncology, Amsterdam UMC location University of Amsterdam, Meibergdreef 9, Amsterdam, NLD.
Cureus. 2024 Sep 7;16(9):e68863. doi: 10.7759/cureus.68863. eCollection 2024 Sep.
Bladder radiotherapy is challenging due to daily anatomical variations and unpredictable bladder filling, particularly affecting tumors in the cranial part. Conventional radiotherapy requires large planning target volume margins to manage these uncertainties, but this can expose healthy tissue to high radiation doses, increasing the risk of acute and late toxicity. Our aim was to study the potential to limit high-dose exposure to healthy tissue by comparing daily online adaptive radiotherapy (oART) with conventional, non-adaptive radiotherapy (non-ART). The comparison was performed on a bladder cancer patient treated with a simultaneous integrated boost while having a challenging tumor location in the cranial part of the bladder. Liquid fiducial markers aided during the localization of the tumor bed to deliver this focal boost. The dose distribution of oART fractions performed in the clinic was compared with simulated non-ART fractions on the post-treatment cone-beam computed tomography (CBCT). The results showed that while maintaining target coverage of the bladder and gross tumor volume in 100% of the fractions for both workflows, the high dose exposure to organs-at-risk was lower for oART. The small bowel received statistically significantly (p ≤ 0.05) less dose with oART compared to non-ART, with a median volume difference of 20 cm receiving 95% of the prescribed dose (55 Gy). The total volume of tissue outside the target receiving 95% of the prescribed dose was also smaller for oART compared to non-ART (p ≤ 0.05). The follow-up of two years showed that the patient had no long-term toxicity effects. Therefore, CBCT-guided oART has been shown to offer a conformal treatment for a challenging patient and can provide a clear advantage in the treatment of bladder cancer.
由于膀胱的每日解剖结构变化以及膀胱充盈情况不可预测，膀胱放疗颇具挑战性，尤其是对膀胱上部的肿瘤影响较大。传统放疗需要较大的计划靶区边缘来应对这些不确定性，但这可能会使健康组织暴露于高辐射剂量下，增加急性和晚期毒性的风险。我们的目的是通过比较每日在线自适应放疗（oART）与传统非自适应放疗（non-ART），研究限制健康组织高剂量暴露的潜力。该比较是在一名膀胱癌患者身上进行的，该患者在接受同步整合加量放疗时，肿瘤位于膀胱上部，位置具有挑战性。在肿瘤床定位过程中使用液体基准标记来进行这种局部加量放疗。将临床中进行的oART分次剂量分布与治疗后锥形束计算机断层扫描（CBCT）上模拟的non-ART分次剂量分布进行比较。结果表明，在两种放疗流程中，100%的分次均能维持膀胱和大体肿瘤体积的靶区覆盖的同时，oART对危及器官的高剂量暴露更低。与non-ART相比，oART照射下小肠接受的剂量在统计学上显著更低（p≤0.05），接受95%处方剂量（55 Gy）的小肠中位体积差异为20 cm³。与non-ART相比，oART中接受95%处方剂量的靶区外组织总体积也更小（p≤0.05）。两年的随访显示该患者没有长期毒性反应。因此，CBCT引导下的oART已被证明可为具有挑战性的患者提供适形治疗，并且在膀胱癌治疗中具有明显优势。
