Estimation of Complication Probability for Non-Uniform Normal Tissue Irradiation Using the Effective Volume Method and Normal Distribution

應用有效體積法與常態分配估計正常組織併發症機率

劉幕台(Mu-Tai Liu) ； 葉啓源(Chi-Yuan Yeh) ； 林招膨(Jao-Perng Liu) ； 黃勝賢(Shing-Sheng Huang) ； 李宗其(Chung-Chi Lee) ； 劉裕明(Yu-Ming Liu) ； 陳光耀(Kuang-Y. Chen)

《放射治療與腫瘤學》 4卷1期 (1997/03) Pp. 39-43

https://doi.org/10.6316/TRO/199704(1)39

摘要

目的：估算正常組織併發症機率(NTCP)以評估放射治療計劃，特別是三度空間治療計劃。
材料與方法：劑量體積直方圖可由電腦斷層攝影資料與放射劑量分佈計算而得。有效體積法是一種劑量體積直方圖之轉換技術。可將非均勻照射直方圖轉換成均勻照射直方圖，使此圖之體積為有效體積而劑量則等於最大劑量。非均勻照射之正常組織併發症機率(NTCP)可由已知之均勻照射全部及部分器官之併發症機率利用公式計算而得。
結果：各器官之劑量體積直方圖由Render-Plan治療計劃系統計算而得。各器官之有效體積用 Kutcher有效體積法計算而得。利用Lyman公式與常態分配表可估算得各器官之NTCP。
結論： NTCP的估算對放射治療計劃，特別是三度空間治療計劃的評估十分重要。在評估治療計劃時，除了審視劑量分佈圖與劑量體積直方圖外，最好加上NTCP之估算，以便計劃評估更為有效與正確。

關鍵字

劑量體積直方圓 ； 有效體積法 ； 正常組織併發症機率

並列摘要

Purpose: To estimate normal tissue complication probability (NTCP) for nonuniform irradiation.
Materials and Methods: Before calculation of NTCP, dose volume histograms are calculated for the organs of interest and tolerance doses for uniform whole and partial organ irradiation are obtained from published data. The calculation of dose volume histograms is straightforward if there are an adequate number of CT scans and dose distributions for organs of interest. The effective volume method transforms the histogram into a uniform one of height (effective volume) and dose (D(subscript max))equal to the maximum dose in the histogram. NTCP can be obtained using Lyman's model and table of the normal distribution.
Results: Dose volume histograms for various organs are obtained by calculation with Render-Plan treatment planning system. Effective volumes for these organs are obtained by calculation with Kutcher's effective volume method. Calculation using Lyman's model and table of the normal distribution, we obtained the NTCP values for these organs.
Conclusion During radiotherapy normal tissues are irradiated along with the tumor. Radiation oncologists try to minimize the dose to normal tissues while delivering a high dose to the tumor. Often this is difficult and complications arise due to irradiation of normal tissues. Estimation of NTCP is important for evaluation of 3-dimensional treatment plans. It is preferable to use NTCP as an additional tool for plan evaluation, in conjunction with a review of graphical dose distributions and dose volume histograms.

並列關鍵字

Dose volume histogram ； Effective volume method ； Normal tissue complication probability