PHSOR08 演讲时间：上午 9:35

IF 1.7 4区医学 Q4 ONCOLOGY

Brachytherapy Pub Date : 2024-10-25 DOI:10.1016/j.brachy.2024.08.082

Margaret Barker MS, Michael Campbell MS, Lisa Turner MS, Nisar Syed MD, Randy Wei MD, PhD, Peyman Kabolizadeh MD, PhD

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引用次数: 0

摘要

目的/目标前列腺间质高分辨近距离放射治疗（HDR Brachytherapy）是通过高剂量梯度对靶点进行精确的局部放射治疗，同时保留邻近的高危器官（OAR）。由于直肠和膀胱靠近目标，模板位置或导管与患者解剖结构的偏差会改变这些结构的剂量。虽然使用塑料间质导管可以让患者在间质治疗过程中接受热疗，但据观察，当移除金属导管进行治疗时，塑料导管会出现明显偏移。这种特殊后加载器的放射源路径的弯曲以前曾被证实在刚性腔内装置中显示出明显的偏差。本研究的目的是评估前列腺间质计划中塑料导管的幅度和偏转，并确定在治疗前成像中使用与源电缆粗细相似的柔性导线进行可视化是否适合重建实际接受的治疗。根据第二次 CT 扫描调整原始治疗停留位置和时间，以评估膀胱、直肠、尿道和目标的三维导管位移和剂量分布。结果所有患者的绝对三维位移为 4.9 mm ± 3.0 mm（所有治疗方案和患者的导管停留位置为 1645 个，平均值 ± SD，p<0.001）。间质治疗的导管绝对偏转幅度随着金属支架的移除而增加，差异为 1.07° ± 0.83°（所有治疗方案和患者的导管数量为 153 个，平均 ± SD，p<0.01）。使用柔性导丝代替支架的方案与不使用支架的方案相比，三维位移和角度偏转的绝对值分别为 1.7 ± 1.1 mm 和 0.36° ± 0.3°（n = 67 个导管，平均值 ± SD，p>0.2）。使用与移除支架后，膀胱 D2cc 整体增加（p<0.01）。膀胱 D2cc、直肠 D2cc 和尿道 D0.1cc 在使用软导线进行可视化与不使用软导线进行可视化之间没有明显差异（p>0.10）。结论通过 CT 成像对前列腺间质治疗中的导管重建显示，一旦移除治疗用的支架，导管定位与 OAR 容积之间就会发生显著变化。虽然导管之间的几何形状保持不变，但它们会随着前列腺整体移动。使用与放射源电缆粗细相似的柔性导线可以在计划过程中进行更精确的跟踪，而不会扭曲患者的解剖结构，从而保持治疗计划的完整性。

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PHSOR08 Presentation Time: 9:35 AM

Purpose/Objectives

Interstitial HDR brachytherapy to the prostate involves precise, localized delivery to targets with high dose gradients, sparing adjacent organs at risk (OAR). Due to the proximity of the rectum and bladder to the target, deviations in the template position or catheter with respect to patient anatomy can change dose to those structures. While utilizing plastic interstitial catheters allows the patient to receive hyperthermia therapy during their course of interstitial treatment, the plastic catheters were observed to show significant deflection when the metal stylets are removed for treatment. The flexion of the source path for this particular afterloader has been previously demonstrated to show significant deviation within rigid intracavitary devices. The purpose of this study is to assess the magnitude and deflection of the plastic catheters for prostate interstitial plans and determine whether using flexible wires of similar thickness to the source cable for visualization on pre-treatment imaging is suitable for reconstructing the actual treatment received.

Materials/Methods

Pre-treatment CT images where the stylets were utilized for catheter visualization were registered to a subsequent CT scan with the metal stylets removed. The original treatment dwell positions and times were adjusted to the second CT to evaluate three-dimensional catheter displacement and dose distributions calculated for the bladder, rectum, urethra, and target. The plans were subsequently reconstructed on a pre-planning CT with flexible 20-gauge wires instead of metal stylets in order to determine their suitability as a surrogate for stylets.

Results

Absolute 3D displacement for all patients was 4.9 mm ± 3.0 mm (n = 1645 catheter dwell positions for all treatment plans and patients, mean ± SD, p<0.001) comparing plans with the stylet in versus out. Absolute catheter deflection magnitude for interstitial treatments increased with the removal of the metal stylets with a difference of 1.07° ± 0.83° (n = 153 catheters for all treatment plans and patients, mean ± SD, p<0.01). The plans utilizing flexible wire instead of stylets are observed to correlate with the plans with no stylets with absolute 3D displacement and angular deflection of 1.7 ± 1.1 mm and 0.36° ± 0.3° respectively (n = 67 catheters, mean ± SD, p>0.2). There was an overall increase in bladder D2cc (p<0.01) with the stylets utilized vs removed. Bladder D2cc, rectal D2cc, and urethra D0.1cc showed no appreciable difference between utilizing flexible wires for visualization and the plans without (p>0.10). There is no appreciable difference in target coverage comparing the plan types (p>0.5).

Conclusions

Catheter reconstruction in interstitial prostate treatments with CT imaging revealed significant changes in catheter positioning with respect to the OAR volumes once the stylets are removed for treatment. While the catheters maintain their geometry relative to each other, they move with the prostate as a whole. Using flexible wires of similar thickness to the source cable allow for more accurate tracking during planning without distorting the patient's anatomy, preserving the integrity of the treatment plan.

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来源期刊

Brachytherapy 医学-核医学

CiteScore

3.40

自引率

21.10%

发文量

119

审稿时长

9.1 weeks

期刊介绍： Brachytherapy is an international and multidisciplinary journal that publishes original peer-reviewed articles and selected reviews on the techniques and clinical applications of interstitial and intracavitary radiation in the management of cancers. Laboratory and experimental research relevant to clinical practice is also included. Related disciplines include medical physics, medical oncology, and radiation oncology and radiology. Brachytherapy publishes technical advances, original articles, reviews, and point/counterpoint on controversial issues. Original articles that address any aspect of brachytherapy are invited. Letters to the Editor-in-Chief are encouraged.