Elhanafy O A, Migahed M D, Sakr H A, Ellithy M, Das R K, Odau H J, Thomadsen B R
Department of Human Oncology, University of Wisconsin, Madison, Wisconsin 53792, USA.
J Appl Clin Med Phys. 2001 Summer;2(3):114-20. doi: 10.1120/jacmp.v2i3.2604.
This report compares the Nucletron NPS and PLATO planning system for patients treated for cervix cancer.
This study compares calculations generated using the older NPS (version 11.43) planning system and the more recent PLATO (version 14.1) system for two cases: 1) a single dwell position and 2) an actual patient application using a tandem and ovoid.
For one dwell position: for NPS planning the dose for points along the source axis forward of the cable was 9.85% more than for symmetrically placed points in the cable direction. For PLATO, the same test gave rise to a difference of 10.2%. Comparing the two systems, NPS calculated doses for points in the forward direction 14% greater than those calculated by PLATO. The entry of points using the digitizer accounted for less than 1% of any difference. For the patient case: the dose difference between NPS and PLATO planning for all patient reference points entered from films ranged from 1 to 4%. The difference in dose between optimized and nonoptimized planning was approximately 0.5% for prescription points (points A), while for the bladder and rectum the differences were 6% and 20%, respectively with NPS, and with PLATO, 8% and 22%, respectively.
This study highlighted the effects of the differences in the calculational algorithm between the older and newer planning systems from Nucletron. While the differences were minimal on the perpendicular bisector of the source, along the axis they become considerable. In a practical gynecological case, these differences mostly affect the dose to the rectum, since that organ receives the greatest proportion of its dose from rays near the same axis. Overall, the PLATO system plan required about 2.5% less integrated reference air kerma than the NPS plan for the same dose to point A. For either planning system, optimization is crucial in decreasing dose to bladder and rectal points.
本报告比较了用于宫颈癌治疗患者的核通NPS和PLATO计划系统。
本研究比较了使用较旧的NPS（版本11.43）计划系统和更新的PLATO（版本14.1）系统针对两种情况所生成的计算结果：1）单个驻留位置；2）使用串形施源器和卵形容器的实际患者应用。
对于单个驻留位置：在NPS计划中，沿电缆前方源轴上各点的剂量比在电缆方向上对称放置的点的剂量高9.85%。对于PLATO，相同测试产生的差异为10.2%。比较这两个系统，NPS计算的前方各点剂量比PLATO计算的剂量大14%。使用数字化仪输入点所造成的差异占任何差异的比例不到1%。对于患者病例：从胶片输入的所有患者参考点，NPS和PLATO计划之间的剂量差异在1%至4%之间。对于处方点（A点），优化计划和未优化计划之间的剂量差异约为0.5%，而对于膀胱和直肠，NPS的差异分别为6%和20%，PLATO的差异分别为8%和22%。
本研究突出了核通新旧计划系统之间计算算法差异的影响。虽然在源的垂直平分线上差异最小，但沿轴方向差异变得相当大。在实际妇科病例中，这些差异主要影响直肠的剂量，因为该器官接收的剂量大部分来自同一轴附近的射线。总体而言，对于相同的A点剂量，PLATO系统计划所需的积分参考空气比释动能比NPS计划少约2.5%。对于任何一种计划系统，优化对于降低膀胱和直肠点的剂量至关重要。
