模擬頭頸部病人強度調控放射治療皮膚劑量之假體研究

Preliminary Study of Skin Dose for Head and Neck Patients Treated with Intensity-mudulated Radiation Therapy (IMRT)

傅筱如(Hsiao-Ju Fu) ； 羅素花(Su-Hua Lo) ； 曾玉華(Yuk-Wah Tsang) ； 徐椿壽(Chen-Shou Chui) ； 蔡維達(Wei-Ta Tsai)

《放射治療與腫瘤學》 20卷1期 (2013/03) Pp. 31-40

https://doi.org/10.6316/TRO/201320(1)31

摘要

目的：本實驗主要利用假體測量頭頸部病人調強放射治療之皮膚劑量，以及評估頭頸癌病人皮膚劑量量測工具的可信度。材料與方法：本實驗採用薄片型熱發光劑量計以及輻射變色軟片來做為量測工具，並分別做其特性研究以及增建區的測量；在IMRT head/neck phantom和anthropomorphic Rando phantom測量模擬的頸部淋巴區的表面劑量，利用此兩種不同的假體以及Eclipse的治療計畫系統製作處方劑量為180 cGy的7個照野治療計畫，進行此兩種量測工具絕對劑量之測量。結果：本實驗之薄片型TLD變異係數在 3%以內，計讀值與給予劑量間呈現良好線性關係；輻射變色軟片（EBT film）校正區線上每個點之變異係數在1%以內，整體校正曲線呈現穩定的關係；薄片型TLD與EBT film的量測值，在假體模擬方面（腫瘤輪廓內縮3 mm），兩者表面劑量的平均量測值誤差小於5%，當Prescribed Dose（Dp）為180 cGy時IMRT head/neck phantom表面劑量的右側量測值，EBT film 的量測結果為93.25 cGy到104.66 cGy之間；薄片型TLD的量測結果為93.99 cGy到103.72 cGy之間；左側量測值，EBT film的量測結果為99.57 cGy到113.91 cGy之間，薄片型TLD的量測結果為99.77 cGy到116.85 cGy之間。Rando® phantom表面劑量的右側量測值，EBT film的量測結果為99.39 cGy到122.49 cGy之間；薄片型TLD的量測結果為104.43 cGy到120.97 cGy之間左側量測值，EBT film的量測結果為114.54cGy到125.02 cGy之間，薄片型TLD的量測結果為113.15 cGy到 121.80cGy之間。結論與討論：由本實驗得知，薄片型熱發光劑量計以及輻射變色軟片適合用來作為表面劑量的量測工具，未來本研究將統計臨床上人體出現皮膚反應時實際接受的劑量，以期測量到最準確的皮膚劑量並評估臨床不同皮膚反應時的皮膚毒性，確實找出造成病人皮膚反應的劑量評估值。

關鍵字

皮膚劑量 ； 薄片型熱發光劑量計 ； 輻射變色軟片

並列摘要

Purpose: This research was focused on the skin dose of simulated phantoms for head-and-neck patients treated with radiation and the reliability of measured tool for the skin dose in vivo of the headand-neck patients.Materials and Methods: This experiment adopted 0.1 mm ultrathin thermoluminescent dosimeters (ultrathin TLD) and ISP Gafchromic EBT film as the measured tool to establish the characteristics and buildup region. Superficial doses at hypothetical neck lymphatic regions were measured with IMRT head/neck phantom and anthropomorphic Rando phantom. Seven-field IMRT plans with a prescribed dose of 180 cGy were designed using an Eclipse treatment planning system. Two different geometric phantoms were used to measure the absolute dose for two measured tools.Result: In this experiment the variance coefficient of ultrathin TLD was within 3%. The reading values and delivered doses were in a good linear relationship. The points on calibration curve of Gafchromic film were within 1% and in a stable performance. The mean surface measured doses for simulated phantoms with tumor 3 mm shrinkage within 5%. The mean surface measured doses for EBT film and ultrathin TLD with a prescribed dose of 180 cGy were 93.25 cGy~104.66 cGy and 93.99 cGy~103.72 cGy on right side neck of IMRT head/neck phantom, 99.57 cGy~113.91 cGy and 99.77 cGy~116.85 cGy on left side neck of IMRT head/neck phantom, respectively. The mean surface measured doses for EBT film and ultrathin TLD were 99.39 cGy~122.49 cGy and 104.43 cGy~120.97 cGy on right side neck of Rando® phantom, 114.54 cGy~125.02 cGy and 113.15 cGy~121.80 cGy on left side neck of Rando® phantom, respectively.Conclusion and Discussion: From the experimental results, ultrathin TLD and EBT film can be adopted as the measured tools for surface dose. The future work for this research could gather statistics of the skin reactions indeed affected by the skin dose received from radiation for clinical applications. To evaluate severity of skin reaction and measure most accurate skin dose, and this data can be used references for skin reaction gradings.

並列關鍵字

Skin dose ； Ultrathin TLD ； Gafchromic film