摘要
背景与目的:鼻咽癌适形射治疗摆位误差是决定计划靶区(planningtargetvolume,PTV)外扩范围(PTVmargin,MPTV)的关键因素,本研究应用“垫内置标记点法(垫法)”测量鼻咽癌适形放射治疗中的摆位误差,并计算出PTV外扩范围。方法:22例行适形放射治疗的鼻咽癌患者制作垫并在其中镶上金属球作为内标记。通过比较射野影像片和定位CT上内标记点的坐标来计算摆位误差。由公式MPTV=2.5!+0.7σ分别计算出考虑和不考虑器官运动的MPTV大小。结果:22例患者在X、Y、Z轴上的摆位系统误差标准差(Σ)分别为1.13mm、1.47mm、1.31mm;摆位随机误差标准差(σ)分别为0.81mm、0.45mm、0.80mm。不考虑器官运动时在X、Y、Z轴上的MPTV大小分别为3.40mm、3.98mm、3.83mm。考虑器官运动时在X、Y、Z轴上的MPTV大小分别为3.75mm、4.35mm、4.16mm。结论:应用垫法能够比较精确地测量出符合实际情况的摆位误差值,并确定了MPTV的大小,从而使制定的适形放疗计划更具有科学性。
BACKGROUND ＆.OBJECTIVE： Setup error is the key factor in determining the margin of planning target volume （MPPV） for conformal radiotherapy of nasopharyngeal carcinoma （NPC）. This study was to establish a method using radiopaque fiducial markers which were embedded in occlusal splint （＂occlusal splint method＂） to acquire setup errors to calculate MPTV in CRT for NPC. METHODS： The occlusal splint method was performed in 22 NPC patients who received CRT. Setup errors were calculated by comparing the coordinates of 3 fiducial markers read from portal images with those read from computed tomography （CT） data. According to the formulation, the size of MPTV with or without consideration of organ motion was also calculated. RESULTS： The standard deviations of systematic errors （∑） were 1.13 mm, 1.47 mm, and 1.31 mm in X （mediolateral）, Y （antero-posterior） and Z （cranio-caudal） axes, respectively; the standard deviations of random errors were 0.81 mm, 0.45 mm, and 0.80 mm in X, Y, and Z axes, respectively. Without consideration of organ motion, the sizes of MPTV were 3.40 mm, 3.98 mm, and 3.83 mm in X, Y, and Z axes, respectively; with consideration of organ motion, the sizes of MPTV were 3.75 mm, 4.35 mm, and 4.16 mm in X, Y, and Z axes, respectively. CONCLUSION： Using the ＂occlusal splint method＂, each institution can precisely calculate setup error data, and stipulate the size of MPTV dequate to one＇s own situation.
出处
《癌症》
SCIE
CAS
CSCD
北大核心
2006年第1期115-118,共4页
Chinese Journal of Cancer
基金
福建省科技计划资助项目(No.2000Z040)~~
关键词
鼻咽癌
摆位误差
[牙合]垫法
适形放射治疗
空间分辨率
Nasopharyngeal neoplasms
Setup error
Occlusal splint
Conformal radiotherapy
Internal markers
