Takemura Akihiro, Shoji Saori, Ueda Sinichi, Kurata Yuichi, Kumano Tomoyasu, Takamatsu Shigeyuki, Suzuki Masayuki
Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kodatsuno, Kanazawa, Japan.
Radiol Phys Technol. 2009 Jul;2(2):151-8. doi: 10.1007/s12194-009-0059-0. Epub 2009 May 1.
Recent linear accelerators can perform cone-beam computed tomography to correct setup errors immediately before dose delivery. We calculated the dose distribution with setup errors acquired from cone-beam computed tomography to determine a more realistic and individual effect of setup errors. The differences in dose distribution were analyzed. The setup errors of three patients who were irradiated in the neck, esophagus, and pelvic area were obtained retrospectively. We found that the maximum dose variances for the three cases were 19.9-35.9%. The maximum dose variance points were relatively far from the isocenter. The volume of the 10% dose difference had widths of 1.3-1.85 cm around the beam edges. The V95 and mean doses at the clinical target volume were mostly unchanged. Doses around the beam edges were more varied than those around the isocenter for every case. The dose on the spinal cord located near the beam edges varied by 5-10% compared with the dose of the radiotherapy plan in two of the cases. We demonstrated the individual dose distributions of the cases affected by daily setup errors for all fractions.
近期的直线加速器能够在剂量输送前即刻进行锥形束计算机断层扫描，以校正摆位误差。我们根据从锥形束计算机断层扫描获取的摆位误差计算剂量分布，以确定摆位误差更实际且个体化的影响。分析了剂量分布的差异。回顾性获取了三名在颈部、食管和盆腔区域接受照射患者的摆位误差。我们发现这三例的最大剂量变化率为19.9% - 35.9%。最大剂量变化率点相对远离等中心。10%剂量差异的体积在射束边缘周围的宽度为1.3 - 1.85厘米。临床靶区内的V95和平均剂量大多未改变。每例中射束边缘周围的剂量比等中心周围的剂量变化更大。在两例中，位于射束边缘附近的脊髓上的剂量与放射治疗计划的剂量相比变化了5% - 10%。我们展示了所有分次受每日摆位误差影响病例的个体化剂量分布。
