目的：運用品管圈手法降低頭頸部癌病人在放射治療之擺位誤差。

材料與方法：影響擺位誤差要素分為:身體僵硬或病因性原因無法配合、病人太緊張而導致定位誤差、定位記號線不見了，和不明原因無法與定位時的位置一致，根據三現原則和真因驗證，擬定4個對策群組共10項改進對策。

結果：對策實施後X、Y 和 Z 三軸平移擺位誤差平均值和標準差，分別1.67±0.93mm降至1.49±0.58mm (p =0.141) 、1.43±0.66mm降至1.08±0.45mm (p <0.001)和4.05±1.8mm降至1.16±0.55mm (p <0.001)；3D向量方向從5.00±1.67mm 降至2.54±0.65mm (p <0.001)。Y軸(roll)旋轉方向從0.76±0.37°³降至0.51±0.24° (p <0.001)，而其在3D向量方向>3mm由90%，降低至48%、>5mm則由43%降低至0。

結論：此對策實施後有顯著的降低擺位誤差。

Purpose: To reduce setup errors in the treatment of head and neck cancer patients during radiotherapy by applying quality control circle techniques.

Materials and Methods: The following factors contributed to setup errors: bodily stiffness or medical conditions preventing patient movement, patient anxiety leading to localization errors, the disappearance of localization markers, and discrepancies between the positioning and reference locations for unknown reasons. Based on the Three Real's doctrine and Identify the Root Cause, 4 groups consisting of a total of 10 improvement strategies groups were created.

Results: Following the implementation of these strategies, the means and standard deviations of setup errors in the X, Y, and Z axes improved from 1.67 ± 0.93 mm to 1.49 ± 0.58 mm (p =0.141), from 1.43 ± 0.66 mm to 1.08 ± 0.45mm (p < 0.001), and from 4.05 ± 1.8 mm to 1.16 ± 0.55 mm (p < 0.001), respectively. Additionally, 3D vector directional setup errors decreased from 5.00 ± 1.67 mm to 2.54 ± 0.65 mm (p < 0.001), and the Y-axis (roll) rotation error decreased from 0.76 ± 0.37° to 0.51 ± 0.24° (p < 0.001). For 3D vector directional errors greater than 3 mm, errors decreased from 90% to 48%; for vector directional errors greater than 5 mm, errors decreased from 43% to 0%.

Conclusion: Setup errors were substantially reduced by the adopted strategies.