本文探討當病患腫瘤的位置在接近或是生長在皮膚表面，接受強度調控放射治療(Intensity Modulated Radiotherapy； MRT)時，利用等效組織補償器(bolus)的效應提高病患皮膚表面劑量及對體內正常器官劑量分佈的影響。本文使用的設備包括Varian 21EX直線加速器治療能量為6MV，反算式治療計畫系統Eclipse TPS with Hellos (Varian Medical Systems, Palo Alta, CA)，PPC05平板型遊離腔，Scanditronix Wellhofer Dose1電量計，GE NXi電腦斷層模擬定位儀，以及固態水假體。測量深度從距離表面0 mm、2 mm、3 mm、4 mm、6 mm、8 mm、10 mm及15 mm共測量8個深度。另一組在假體加上0.5 cm的等效組織補償器以相同的方式再測量一次，並其將測量值歸一化(normalize)在15 mm的深度以比較表面劑量。同時和治療計畫電腦計算的結果比較計算值和測量值的差異。測量的結果顯示在假體中0-3 mm虛最大差異為50%，而加上等效組織補償器後最大差異只有4.8%。在4-6 mm處有3%的差具：加上等效組織補償器的部份則有2%的差具。在治療計畫中表面劑量的比較上來看，有加等效組織補償器的可以在入射表面得到95%以上的劑量，而另一組沒有加等效組織補償器只能得到82%左右的劑量。腫瘤劑量分佈在最大和最低的比較上，使用等效組織補償器的治療計畫也較未使用的治療計畫好，其他正常器官如腦幹、脊椎、對側唾液腺等在劑量－體積直方圖(Dose-Volume Histogram)的比較來看並沒有太大的差異。但是在腫瘤同側的唾液腺加了等效組織補償器的計畫明顯的優另一組未加等效組織補償器的計畫。

To investigate the patient with growing tumor near the surface or skin the affect of surface and normal organs dose in intensity modulated radiation therapy (IMRT) with bolus. Varian 21EX accelerator, Eclipse TPS with Helios inverse treatment planning system, PPC05 parallel ionization chamber, Scanditronix Wellhofer Dose1 electrometer, GE NXi CT simulator solid water phantom was used in this study. The parallel-plate chamber measurements were taken in a solid water phantom at depths of 0 mm(surface),2-, 3-, 4-, 6-, 8-, 10-, , and 15-mm along the central axis of the beam with and without bolus. The PDDs for the IMRT plan were low by 50%, 4.8% at 0-3mm compared to the measurement PDDs without and with bolus respectively. The PDDs for the IMRT plan were low by 3%, 2% at 4-6mm compared to the measurement PDDs without and with bolus respectively. This study showed that the treatment planning dose calculation algorithm did not accurately describe the superficial dose distribution. The IMRT doses calculated by the planning software were underestimated by compared to the doses measured by the parallel-plate chamber. Therefore, we suggest that surface and build-up region doses should be validated when the target volume extends to the skin and the target dose is required to cover the patient Extending to 3 mm depth, indicating that thin bolus might be necessary when the target dose is required at the patient surface.