目的：改善仰臥式側照技術應用於全身放射治療技術的劑量分佈均勻度，並探討此技術的再現
性及肺部劑量的計算和驗證。材料和方法：採用壓克力箱作為提供患者仰臥姿勢的治療床，並於其體表周圍空間以水袋順形填滿空隙，以作為組織填充物之用。治療儀器選擇能量 15 MV 之加速器，射源至體表距離為415 cm ，劑量率調整為每分鐘 5 cGy 。五位病患者接受此項治療，並在患者適當的參考點佈建氟化鋰熱發光劑量計以量測實際劑量。治療劑量為每次 150 cGy ，每日兩次，共分八次，給予總計量 1200 cGy；但肺部則以適當厚度的鉛屏蔽阻擋部份劑量使之低於 960 cGy 。結果：五位病人在所有體表佈設點實際測得劑量均可達到與預定值誤差於可接受範圍內。在肺部的屏蔽也達到滿意的驗證與再現性。整個治療過程可在五十分鐘內完成。結論：以仰臥式側照技術應用於全身放射治療，輔以水袋作為組織填充物，適用於體能狀況較差或無法久立支撐的患者，其劑量均勻度仍在可接受範圍內，並可得到更佳的肺部屏蔽位置及效果，與適當的操作時效。

Purpose : To improve dose homogeneity in total body irradiation (TBI) with lateral technique. Dose homogeneity and dosimetry of lung shielding are investigated.Materials and Methods : Five patients, three with acute lymphocytic leukemia (ALL),one with acute myelocytic leukemia (AML), and one with non-Hodgkin’s lymphoma (NHL), were delivered total body irradiation with lateral technique. An acrylic box was designed for treatment table, and water bags were utilized as tissue compensators
to fill the surrounding space, conforming patients’ body contours as possible. LiF thermoluminescent dosimeters (TLDs) were positioned along the reference points on the body surface. Treatment dose 1200 cGy, using 15 MV photons with dose rate 5cGy/minute, divided in 8 fractions within 4 days was prescribed at the midline of the body, while partial lung block was designed to deliver 900 to 960 cGy to the midline of thorax in sum after lung correction calculation. The mean doses of different reference
points throughout the body were obtained after calculation of three to four measurements for each patient to investigate dose homogeneity.
Results : After application of tissue compensators with water bags thoroughly surrounding the patients, the average dose homogeneity was measured within acceptable difference from the prescribed dose. Postural stability and reproducibility were satisfied. Treatment duration took about 50 minutes and patients tolerated the procedures well.Conclusion : Though anterioposterior TBI technique is commonly used with regard
to better dose uniformity and setup procedures, there is superiority of consistency of lung shielding and patients’ comfort to utilize lateral technique for fragile patients,especially when low dose rate is used and treatment duration prolongs. The application of tissue compensators with water bags as an alternative can be easily setup with acceptable dose homogeneity and treatment time.