目的:美國物理師學會於1999年發表了度量遠隔治療高能光子及電子射東臨床參考劑量的TG-51號新議定書以取代1983年發表的TG-21號議定書。TG﹒凹的特色是使用鉛-60水中吸收劑量標準校正游離腔，游離腔的校正因子稱為Nfp。另一個特色則是大大簡化劑量計算所需要的參數，且以kQ值作為光子射東晶質轉換因子，P.a9Jk'Rf'i('} ，ke胡作為電子射束品質轉換因子。本篇研究的目的在於撰寫完整的TG-51劑量計算程式，以減少查圖及計算所造成的錯誤。

材料與主法:本篇研究使用微軟公司的VisualBasic 6.0語言撰寫TG-51劑量計算程式。整個程 式設計架構依照TG-51號議定書裡面所提供的worksheet表格流程安排，並使用AAPM放射物理中心提供的TG-51Workshop裡的資料進行程式正確性的驗誼。

結果:與AAPMpff提供的資料驗詣比較，光子劑量之計算差異為﹒0.0269% '電子劑量之計算差異為0.0429%。

結論:此程式提供了方便、正確而且完整的TG-51號議定書劑量計算工具，並可減少人為查團所造成的誤差及實際應用於臨床參考劑量的度量。

Purpose: In 1999， American Association of Physicists in Medicine (AAPM) published the TG-Sl protocol giving “clinicalreference dosimetry of high-energy photon and electron beams" to replace the TG-21 protocol published by AAPM in 1983. One of the characteristics ofTG-SI is being based on the use of the ion chambers calibrated in terms of absorbed dose to water in a ωCo beam. The calibration

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factors of chambers are defined as N;�fj/，. The other is that the parameters needed for dose calculation

are much more simplified than in TG唱21. The conversion factor for beam quality of photon in TG-Sl is kQ' for electron are 1芋，k'旬，kecal' The purpose of由is paper 尬的developa complete TG-Sl dose calculation program to decrease the errors arising from looking up tables and doing calculations.

Materials and Methods: We use Visual Basic 6.0 produced by Microsoft to develop a dose calculation program of TG-Sl. The flowchart of this program follows the procedure of workshe叫in TG-Sl. We verified the accuracy of this program by putting in the data in TG-Sl Workshop provided by AAPM Radiological Physics Center.

Results:Compared with the data provided by AAPM， the differences of photon and electron dose calculations are within 0.0269% and 0.04299丸I芯spectively.

Conclusion: This program is a convenient， accurate and simple tool for dose calculation. Medical physicists can implement it to decrease the errors arising from looking up tables， and apply it in the clinical reference dosimetry practically.