探討乳癌病患於錐狀射束電腦斷層旋轉軸與平移軸擺位誤差轉換之可行性

To Explore the Feasibility of the Position Deviation Conversion between Rotation Axis and Translational Axis in Cone-Beam Computerized Tomography for Breast Cancer Patients

周淳娟(CHUN-CHUAN CHOU)

指導教授 ： 陳信雄

中臺科技大學/健康科學院/醫學影像暨放射科學系暨研究所/碩士(2019年)

摘要

根據將旋轉軸與平移軸合併轉換為平移軸的公式，套用在回溯性蒐集乳癌病患之錐狀射束電腦斷層（cone beam computed tomography, CBCT）的數值，將經由運算得到轉換後之平移軸數值，比較轉換前後數據之差異與探討該公式能否直接應用在本研究接受乳癌放射治療之病患於沒有旋轉軸修正功能的治療床上。收集 2015 年 1 月 1 日至 2017 年 12 月底，針對乳癌病患執行放射治療前的錐狀射束電腦斷層之數據紀錄，套入 B Sarkar 等人於 2018 年 3 月發表，將旋轉軸與平移軸數值轉換為平移軸數值的公式。分別計算數據轉換前後之三維各軸的平均數，使用成對母數學生 t 檢定比較轉換前後之數據差異。蒐集到 121 位接受乳房放射治療病患的CBCT 數值，在 X、Y、Z 軸的位移平均值與系統誤差的標準差分別為 -0.36±4.10、1.60±2.92、-1.10±2.73；得到三維各軸轉換前後的平均數與 p 值如下：-0.38 vs 1.15，p < 0.001；1.52 vs -0.14，p < 0.001；-1.11 vs 0.03，p <0.001，單位為毫米。Dr. B Sarkar 的公式提供一種方式，讓無法修正旋轉軸的治療床能夠透過新的位移數值使病患得到更好的位移誤差修正。本研究藉此公式獲得的平移軸數值與實際應用的數值在統計上有顯著地差異，顯示此公式套用乳癌病患的 CBCT 數據在無法執行旋轉軸修正之治療床，需要使用更嚴謹的條件作進一步的分析與探討。

關鍵字

乳癌 ； 旋轉軸 ； 擺位誤差 ； 錐狀射束電腦斷層

並列摘要

According to the formula in converting the rotation axis and translation axis into the translation axis, the data from the cone-beam computed tomography (CBCT) of the breast cancer patient is retrospectively collected. Comparing the difference between the data before and after conversion and explore whether the formula can be directly applied to the patient who received breast cancer radiotherapy (RT) on the treatment couch lack of the rotation axis correction function. The CBCT data before RT for breast cancer patients were collected from January 1, 2015 to December 31, 2017. A formula published by B Sarkar et al. in March 2018 that converted the rotation axis and translation axis deviation values to the translation axis deviation values. According to the results of the data conversion, the average value of each axis in three dimensions is calculated separately, and the data difference before and after the conversion is checked using the Paired samples t-test. The CBCT values of 121 patients receiving breast RT in the X, Y, and Z axes were: -0.36±4.10, 1.60±2.92, and
-1.10±2.73, in millimeter, respectively. The mean and p values before and after the three-dimensional transformation were obtained according to the conversion formula as follows: -0.38 vs 1.15, p<0.001, 1.52 vs -0.14, p <0.001, -1.11 vs
0.03, p <0.001, in mm. Dr. B Sarkars formula provided a way for the treatment couch achieve better displacement correction through the new displacement deviation values. In our study, the results are significantly different from the translational axis deviation values found in the clinical patients. It is shown that this conversion formula can not be applied to CBCT data for breast cancer patients on the treatment couch which cannot perform rotation axis correction.
Further analysis and discussion in more rigorous conditions are needed.

並列關鍵字

breast cancer ； rotation axis ； position deviation ； CBCT

參考文獻

1. 衛生福利部國民健康署，2018。健康監測與統計，癌症登記報告，網址：

https://www.hpa.gov.tw/Pages/List.aspx?nodeid=119

2. M van Herk. Errors and margins in radiotherapy. Semin Radiat Oncol, 2004;14(1): 52-64

3. KK Brock, S Mutic, TR McNutt, et al. Use of image registration and fusion algorithms and techniques in radiotherapy: Report of the AAPM Radiation Therapy Committee Task Group No. 132. Med Phys., 2017; 44 (7): e43-76

4. HC Liu, WJ Lin, DY Lu, et al. Investigation of immobilization devices in breast radiotherapy by using systematic reviews and meta-analysis.