PLATO治療計劃系統強度階層之設定對鼻咽癌劑量分布之影響

Influence of Dose Distribution by Adjusting the Intensity Level of PLATO Treatment Planning System for Nasopharyngeal Carcinoma Radiotherapy

許義昌(Yi-Chun Hsu) ； 許義勇(Yi-Yong Hsu) ； 熊敬業(Ching-Yeh Hsiung) ； 曾千惠(Chian-Hui Tseng) ； 陳信雄(Hsin-Hsiung Chen)

《中華放射線技術學雜誌》 37卷3期 (2013/09) Pp. 159-165

摘要

本研究以PLATO治療計劃系統強度階層（intensity level；IL）之設定對鼻咽癌劑量分布之影響為目的。治療計劃系統為Nucletron PLATO V2.6.4，Inverse Treatment Planning（ITP）V1.1.8，ITP中IL共有9種，並以回朔式挑選已完成治療之10位鼻咽癌病患，在不改變原本之劑量限值與其他治療參數下，透過改變IL所產生之計劃結果，以四種指標來作分析，1.劑量順形指標（Conformal Index；CI）；2.劑量均勻指標（Homogeneity Index；HI）；3.監測單位（Monitor Unit；MU）與子照野數量；4.正常組織所接受到的劑量。結果發現CI、HI平均值、子照野數量隨著IL增加而增加，MU值與IL並無明顯關係；而正常組織所接受到之平均劑量與IL亦無明顯關聯，且劑量值都在容許劑量範圍內。以CI、HI平均值來探討，對PLATO系統之演算能力而言，CI與HI計算公式顯得過於嚴苛，但對於臨床評估上仍具參考價值。子照野數量直接反應於治療時間長短，也相對得到不同之CI、HI值。此外以腹部部位進行相同測試，結果與鼻咽癌有相似之數據，經此研究可明確得到各IL與四大指標之關係，並運用於臨床上。

關鍵字

放射治療計劃 ； 強度調控放射治療 ； 鼻咽癌

並列摘要

The goal of this study was to investigate influence of dose distribution by adjusting the intensity level of PLATO treatment planning system for nasopharyngeal carcinoma radiotherapy. The treatment planning system used in this study was Nucletron PLATO V2.6.4, inverse treatment planning (ITP) V1.1.8, and has nine intensity levels (IL). Ten nasopharyngeal carcinoma patients were retrospectively enrolled in this study. They had completed the radiation treatment, and recalculated the dose distribution without changing the original dose constraints and other treatment parameters. We calculated the plans using various IL, and evaluated the following four indicators: 1. Conformal index (CI), 2. Homogeneity index (HI), 3. Monitor units (MU) and segments, 4. Dose of normal tissue. We found that the mean CI, HI and segments were increasing with IL . The MUs was not significant to IL. The mean dose of normal tissue had no significant association with IL. The dose in all normal tissues were acceptable. Although we realized the calculation formula was difficult to obtain the acceptable values for PLATO treatment planning system in CI and HI evaluation, it was useful in clinical evaluation. The values of segment determined the treatment time directly, on the other hand, it refered the value of CI and HI. In addition, involving abdomen patients to the same tests, the results were similar with the nasopharyngeal carcinoma. We can have the relationship of the IL with four indicators and to the clinical application.

並列關鍵字

Radiation Treatment Planning ； Intensity Modulated Radiation Therapy ； Nasopharyngeal Carcinoma