Saito Anneyuko I, Lightsey Judith, Li Jonathan G, Copeland Edward M, Karasawa Kumiko, Vargas Carlos E, Mendenhall Nancy P
Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, Japan.
Am J Clin Oncol. 2009 Aug;32(4):387-95. doi: 10.1097/COC.0b013e3181917170.
To investigate axillary 2-dimensional treatment planning accuracy.
Computed tomography (CT) simulation data for 16 breast cancer cases taken after level I-II axillary dissection were analyzed. An additional 6 patients underwent CT simulation using the historical 90-degree position (HP), and the standard-bore CT position (CT-P). Two physicians identified the lateral and medial borders of the coracoid process (CCP) on digitally reconstructed radiography (DRR). The DRR-identified x coordinates were compared with the CT-measured x coordinates. x coordinates differences between the most medial surgical clip and the borders of the CCP as identified on CT were analyzed. Fields were designed to cover various amounts of the axilla, and treatment plans were generated to compare doses to the most medial surgical clip.
In 11 and 6 cases for each physician, respectively (lateral border), and in all cases for both physicians (medial border), the DRR identification of the CCP was medial to that on CT. In 9 and 8 cases, the most medial surgical clip was lateral to the medial and lateral borders of the CCP, respectively. In all data sets, the average difference was larger in the HP compared with CT position. The number of patients who received more than 90% of the prescribed dose when using the plans with the mid humeral head border, lateral border of the CCP, and medial border of the CCP were as follows: 6, 1, and 0, respectively.
When using 2-dimensional treatment planning, the dose to the undissected axilla can vary depending on the anatomic landmark used to define the lateral border of the axillary field. This may account for outcome differences found in older radiotherapy studies.
研究腋窝二维治疗计划的准确性。
分析16例乳腺癌患者在Ⅰ-Ⅱ级腋窝清扫术后的计算机断层扫描（CT）模拟数据。另外6例患者采用历史90度体位（HP）和标准孔径CT体位（CT-P）进行CT模拟。两名医生在数字重建放射影像（DRR）上确定喙突（CCP）的外侧和内侧边界。将DRR确定的x坐标与CT测量的x坐标进行比较。分析最内侧手术夹与CT上确定的CCP边界之间的x坐标差异。设计射野以覆盖不同范围的腋窝，并生成治疗计划以比较最内侧手术夹的剂量。
每位医生分别在11例和6例中（外侧边界），以及在两名医生的所有病例中（内侧边界），DRR对CCP的识别在内侧，相对于CT上的识别。在9例和8例中，最内侧手术夹分别位于CCP内侧和外侧边界的外侧。在所有数据集中，与CT体位相比，HP体位的平均差异更大。使用肱骨头中点边界、CCP外侧边界和CCP内侧边界的计划时，接受超过规定剂量90%的患者数量分别为：6例、1例和0例。
使用二维治疗计划时，未清扫腋窝所接受的剂量可能因用于定义腋窝射野外边界的解剖标志而异。这可能解释了早期放疗研究中发现的结果差异。
