改變動態多葉式準直儀移動型態應用於臨床放射線治療：呼吸中移動腫瘤同步追蹤照射及全身放射線治療

Modification of leaf sequences of dynamic multileaf collimator in radiotherapy: respiratory motion target tracking and total body irradiation

陳合興(Ho-Hsing Chen)

指導教授 ： 莊克士

國立清華大學/原子科學院/生醫工程與環境科學系/博士(2013年)

https://doi.org/10.6843/NTHU.2013.00593

摘要

本研究使用編修直線加速器內建之多葉式準直儀（MultiLeaf Collimator）之葉片移動描述檔案（leaf sequences file），改變其放射線照野強度分布，進而應用在臨床放射治療以解決技術上的難題而達到準確的劑量給予。本研究中處理兩個問題：1. 呼吸運動造成放射治療劑量與預期劑量會不一致。針對此議題本研究提出使用動態式多葉準直儀技術（DMLC）做動態追蹤照射（dynamic tracking）之可行性研究，確認在良好的同步追蹤前提下可以達到正確的照射劑量。2. 在空間受限的小治療室中難以兼顧照射劑量均勻及準確降低肺部劑量之臨床需求。本研究使用編修之DMLC雙照野銜接方法施行正反面（AP/PA）照射，經使用假體做劑量驗證後顯示可符合臨床之需求。

關鍵字

強度調控放射治療 ； 呼吸運動 ； 全身放射治療 ； 動態照野交界 ； 多葉式準值儀 ； 及時動態追蹤

並列摘要

we applied an aperture adaptive technique with a visual guiding system to tackle the problem of respiratory motion. A homemade computer program showing a cyclic respiratory pattern was projected onto the ceiling to visually help the patient adjust their respiration. Once the respiratory motion became regular, the leaf sequence could be synchronized with the target motion. An oscillator was employed to simulate the patient’s breathing pattern. Two simple fields and one IMRT field were measured to verify the accuracy. Preliminary results showed that after appropriate training, the amplitude and duration of a volunteer’s breathing could be well controlled by the visual guiding system. The high dose gradient at the edges of the radiation fields were successfully retained. The aperture adaptive technique with the visual guiding system can be an inexpensive and feasible alternative without compromising delivery efficiency in clinical practice.
this study was to develop a total body irradiation technique that does not require additional devices or sophisticated procedures to overcome the space limitation of a small treatment room by modifying the leaf sequences of intensity modulated fields.The technique treated the patient lying on the floor anteriorly and posteriorly. For each AP/PA treatment, two complementary fields with dynamic field edges were matched over an overlapped region defined by the marks on the body surface.The results confirmed that the technique is capable of delivering a uniform dose distribution to the midline of the body in a small treatment room while keeping the lung dose within the tolerance level.

並列關鍵字

Dynamic multileaf collimator ； Leaf sequences ； respiratory motion ； Dynamic tracking ； Total body irradiation ； Dynamic field matching

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