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Abstract：
UNASSIGNED: We analyzed daily pre-treatment- (PRE) and real-time motion monitoring- (MM) MRI scans of patients receiving definitive prostate radiotherapy (RT) with 1.5 T MRI guidance to assess interfractional and intrafractional variability of the prostate and suggest optimal planning target volume (PTV) margin.
UNASSIGNED: Rigid registration between PRE-MRI and planning CT images based on the pelvic bone and prostate anatomy were performed. Interfractional setup margin (SM) and interobserver variability (IO) were assessed by comparing the centroid values of prostate contours delineated on PRE-MRIs. MM-MRIs were used for internal margin (IM) assessment, and PTV margin was calculated using the van Herk formula.
UNASSIGNED: We delineated 400 prostate contours on PRE-MRI images. SM was 0.57 ± 0.42, 2.45 ± 1.98, and 2.28 ± 2.08 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively, after bone localization and 0.76 ± 0.57, 1.89 ± 1.60, and 2.02 ± 1.79 mm in the LR, AP, and SI directions, respectively, after prostate localization. IO was 1.06 ± 0.58, 2.32 ± 1.08, and 3.30 ± 1.85 mm in the LR, AP, and SI directions, respectively, after bone localization and 1.11 ± 0.55, 2.13 ± 1.07, and 3.53 ± 1.65 mm in the LR, AP, and SI directions, respectively, after prostate localization. Average IM was 2.12 ± 0.86, 2.24 ± 1.07, and 2.84 ± 0.88 mm in the LR, AP, and SI directions, respectively. Calculated PTV margin was 2.21, 5.16, and 5.40 mm in the LR, AP, and SI directions, respectively.
UNASSIGNED: Movements in the SI direction were the largest source of variability in definitive prostate RT, and interobserver variability was a non-negligible source of margin. The optimal PTV margin should also consider the internal margin.
UNASSIGNED: Rigid registration between PRE-MRI and planning CT images based on the pelvic bone and prostate anatomy were performed. Interfractional setup margin (SM) and interobserver variability (IO) were assessed by comparing the centroid values of prostate contours delineated on PRE-MRIs. MM-MRIs were used for internal margin (IM) assessment, and PTV margin was calculated using the van Herk formula.
UNASSIGNED: We delineated 400 prostate contours on PRE-MRI images. SM was 0.57 ± 0.42, 2.45 ± 1.98, and 2.28 ± 2.08 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively, after bone localization and 0.76 ± 0.57, 1.89 ± 1.60, and 2.02 ± 1.79 mm in the LR, AP, and SI directions, respectively, after prostate localization. IO was 1.06 ± 0.58, 2.32 ± 1.08, and 3.30 ± 1.85 mm in the LR, AP, and SI directions, respectively, after bone localization and 1.11 ± 0.55, 2.13 ± 1.07, and 3.53 ± 1.65 mm in the LR, AP, and SI directions, respectively, after prostate localization. Average IM was 2.12 ± 0.86, 2.24 ± 1.07, and 2.84 ± 0.88 mm in the LR, AP, and SI directions, respectively. Calculated PTV margin was 2.21, 5.16, and 5.40 mm in the LR, AP, and SI directions, respectively.
UNASSIGNED: Movements in the SI direction were the largest source of variability in definitive prostate RT, and interobserver variability was a non-negligible source of margin. The optimal PTV margin should also consider the internal margin.
摘要：
■我们分析了在1.5TMRI指导下接受确定性前列腺放疗（RT）的患者的每日治疗前（PRE）和实时运动监测（MM）MRI扫描，以评估前列腺的切间和切内变异性，并建议最佳计划目标体积（PTV）边缘。
■根据骨盆骨和前列腺解剖，在PRE-MRI和计划CT图像之间进行了刚性配准。通过比较PRE-MRI上描绘的前列腺轮廓的质心值，评估了分数间设置裕度（SM）和观察者间变异性（IO）。MM-MRI用于内部余量(IM)评估，PTV裕度是使用范·赫克公式计算的。
■我们在PRE-MRI图像上描绘了400个前列腺轮廓。左右（LR）的SM分别为0.57±0.42、2.45±1.98和2.28±2.08mm，前-后(AP),和上-下(SI)方向，分别,骨定位后，LR为0.76±0.57、1.89±1.60和2.02±1.79mm，AP,和SI方向，分别,前列腺定位后。LR的IO值分别为1.06±0.58、2.32±1.08和3.30±1.85mm,AP,和SI方向，分别,骨定位后，LR为1.11±0.55、2.13±1.07和3.53±1.65mm，AP,和SI方向，分别,前列腺定位后。LR平均IM为2.12±0.86、2.24±1.07和2.84±0.88mm,AP,和SI方向，分别。LR中计算的PTV余量为2.21、5.16和5.40mm，AP,和SI方向，分别。
■SI方向的运动是确定性前列腺RT中变异性的最大来源，观察者间的变异性是一个不可忽视的边缘来源。最佳PTV裕度还应考虑内部裕度。
■根据骨盆骨和前列腺解剖，在PRE-MRI和计划CT图像之间进行了刚性配准。通过比较PRE-MRI上描绘的前列腺轮廓的质心值，评估了分数间设置裕度（SM）和观察者间变异性（IO）。MM-MRI用于内部余量(IM)评估，PTV裕度是使用范·赫克公式计算的。
■我们在PRE-MRI图像上描绘了400个前列腺轮廓。左右（LR）的SM分别为0.57±0.42、2.45±1.98和2.28±2.08mm，前-后(AP),和上-下(SI)方向，分别,骨定位后，LR为0.76±0.57、1.89±1.60和2.02±1.79mm，AP,和SI方向，分别,前列腺定位后。LR的IO值分别为1.06±0.58、2.32±1.08和3.30±1.85mm,AP,和SI方向，分别,骨定位后，LR为1.11±0.55、2.13±1.07和3.53±1.65mm，AP,和SI方向，分别,前列腺定位后。LR平均IM为2.12±0.86、2.24±1.07和2.84±0.88mm,AP,和SI方向，分别。LR中计算的PTV余量为2.21、5.16和5.40mm，AP,和SI方向，分别。
■SI方向的运动是确定性前列腺RT中变异性的最大来源，观察者间的变异性是一个不可忽视的边缘来源。最佳PTV裕度还应考虑内部裕度。
