Aly F, Miller A A, Jameson M G, Metcalfe P E
Illawarra Cancer Care Centre, Wollongong Hospital, 348 Crown Street, Wollongong, NSW, 2500, Australia.
Centre for Medical Radiation Physics, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.
Australas Phys Eng Sci Med. 2019 Mar;42(1):43-51. doi: 10.1007/s13246-018-0707-y. Epub 2018 Nov 8.
This prospective study of weekly CT scanning and plan adaption during H&N IMRT reports on the frequency of plan adaptations based on dosimetric differences between original and re-optimised IMRT plans. The volumetric and geometric change occurring in target volumes and salivary glands is also described. Ten H&N cancer patients underwent weekly planning CT imaging and re-optimisation of the IMRT plan if PTV or OAR coverage was unacceptable. Comparisons of PTV and parotid gland dosimetry between the original and adaptive plans were made. Parotid and submandibular gland volume changes and shift were calculated. Eight of ten patients required one or more plan adaptations, with 41% of adaptations occurring by fraction ten. Salivary glands reduced in volume, with a medial shift of the lateral border of the parotid gland and a superior shift of the submandibular gland. Change in PTV coverage did not correlate with weight loss or nutritional score. Inadequate PTV coverage, requiring plan adaptation, occurs early in the course of IMRT. A weekly Adaptive RT (ART) protocol results in significant improvement of PTV coverage. Implementation of a clinical ART protocol should include imaging and dose calculation within the first ten fractions.
这项关于头颈部调强放疗（IMRT）期间每周进行CT扫描及计划调整的前瞻性研究，报告了基于原始IMRT计划与重新优化后的IMRT计划之间剂量差异的计划调整频率。还描述了靶区体积和唾液腺中发生的容积及几何形状变化。十名头颈部癌症患者每周接受计划CT成像检查，若计划靶区（PTV）或危及器官（OAR）的覆盖情况不可接受，则对IMRT计划进行重新优化。对原始计划和适应性计划之间的PTV及腮腺剂量学进行了比较。计算了腮腺和颌下腺的体积变化及移位情况。十名患者中有八名需要进行一次或多次计划调整，其中41%的调整发生在第十次分割时。唾液腺体积减小，腮腺外侧边界向内移位，颌下腺向上移位。PTV覆盖情况的变化与体重减轻或营养评分无关。在IMRT疗程早期会出现PTV覆盖不足，需要进行计划调整。每周一次的自适应放疗（ART）方案可显著改善PTV覆盖情况。临床ART方案的实施应包括在前十个分割内进行成像和剂量计算。
