目的：閉孔神經病變是子宮頸癌放射治療及化學合併放射治療的晚期併發症之一，閉孔內的閉孔神經位於骨盆放射治療之高劑量範圍，藉由界定閉孔內之閉孔神經，以評估降低閉孔神經劑量之治療計畫的結果及可行性。材料及方法：10位子宮頸癌病人的電腦斷層影像資料中，依據教科書資料圈選閉孔神經及周邊結構，分析降低閉孔神經放射治療中接受之劑量對治療計畫參數的影響，例如：靶體積或危急器官劑量體積組織圖、最高劑量、標的處方劑量包覆度及順形指標等。結果：閉孔神經界定指引運用於強度調控放射治療，降低閉孔神經劑量的治療計畫於體外照射接受之最大劑量可減少達18.3±4.1%，並且對於計劃靶體積之順形指標、劑量分佈及危急器官之劑量體積關係於統計上並無明顯影響。結論：降低閉孔神經劑量的治療計畫在強度調控放射治療中是可行的，除可降低閉孔內之閉孔神經所接受劑量，同時不增加其他正常器官劑量及不影響腫瘤處方劑量包覆度。

Purpose: Obturator neuropathy is a late complication of radiotherapy (RT) and chemo-radiation in cervical cancer patients. We studied the feasibility of sparing the obturator nerves in patients receiving intensity-modulated radiotherapy (IMRT) by delineating the obturator nerves in obturator canals near to the high dose region in pelvis irradiation.Materials and Methods: Volumetric computed tomography (CT) images of ten patients with cervical cancers were retrieved. Anatomical orientation of obturator canals were gathered based on published knowledge in textbooks. Target volume of obturator nerves and pertinent normal structures were contoured and reconstructed for IMRT planning. Dosimetric parameters including dose-volume histograms (DVHs), maximal dose, prescription dose coverage and conformal index were compared between plans with and without obturator nerves as organ of avoidance.Result: A guideline for delineation of obturator canals for IMRT on axial contrast CT images was derived. The use of sparing the obturator nerve technique resulted in an average of 18.3±4.1 % decrease in the calculated maximum dose of the obturator nerves (p<0.05). No significant impact on the conformality and coverage of planning target volume (PTV) of cervical cancer and neither significant dosimetric impact on other critical normal organs in pelvic area.Conclusion: We found that sparing the obturator nerve technique is feasible for patients with cervical cancer and treated with IMRT. The reduction of doses to OBN did not compromise target coverage of tumor and DVHs of other normal organs.