Abstract：
BACKGROUND: Chemoradiation in head and neck carcinoma (HNC) shows significant anatomical resulting in erroneous dose deposition in the target or the organ at risk (OAR). Adaptive radiotherapy (ART) can overcome this. Timing of significant target and OAR changes with dosimetric impact; thus, most suitable time and frequency of ART is unclear.
METHODS: This dosimetric study used prospective weekly non-contrast CT scans in 12 HNC patients (78 scans). OARs and TVs were manually contoured after registration with simulation scan. Dose overlay done on each scan without reoptimization. Dosimetric and volumetric variations assessed.
RESULTS: Commonest site was oropharynx. Gross Tumor Volume (GTV) reduced from 47.5 ± 19.2 to 17.8 ± 10.7 cc. Nodal GTV reduced from 15.7 ± 18.8 to 4.7 ± 7.1 cc. Parotid showed mean volume loss of 35%. T stage moderately correlated with GTV regression.
CONCLUSIONS: Maximum GTV changes occurred after 3 weeks. Best time to do single fixed interval ART would be by the end of 3 weeks.
METHODS: This dosimetric study used prospective weekly non-contrast CT scans in 12 HNC patients (78 scans). OARs and TVs were manually contoured after registration with simulation scan. Dose overlay done on each scan without reoptimization. Dosimetric and volumetric variations assessed.
RESULTS: Commonest site was oropharynx. Gross Tumor Volume (GTV) reduced from 47.5 ± 19.2 to 17.8 ± 10.7 cc. Nodal GTV reduced from 15.7 ± 18.8 to 4.7 ± 7.1 cc. Parotid showed mean volume loss of 35%. T stage moderately correlated with GTV regression.
CONCLUSIONS: Maximum GTV changes occurred after 3 weeks. Best time to do single fixed interval ART would be by the end of 3 weeks.
摘要：
背景：头颈部癌（HNC）的放化疗显示出明显的解剖结构，导致靶或危险器官（OAR）中的错误剂量沉积。自适应放射治疗（ART）可以克服这一点。具有剂量测定影响的显著目标和OAR变化的定时；因此，ART最合适的时间和频率尚不清楚。
方法：这项剂量学研究在12例HNC患者中使用了前瞻性每周非对比CT扫描（78次扫描）。OAR和电视在与模拟扫描注册后手动轮廓化。在每次扫描上完成剂量叠加,而无需重新优化。评估剂量学和体积变化。
结果：最常见的部位是口咽。总肿瘤体积(GTV)从47.5±19.2减少至17.8±10.7cc。节点GTV从15.7±18.8下降到4.7±7.1cc。腮腺显示平均体积损失35%。T分期与GTV回归中度相关。
结论：最大GTV变化发生在3周后。进行单次固定间隔ART的最佳时间是3周结束。
方法：这项剂量学研究在12例HNC患者中使用了前瞻性每周非对比CT扫描（78次扫描）。OAR和电视在与模拟扫描注册后手动轮廓化。在每次扫描上完成剂量叠加,而无需重新优化。评估剂量学和体积变化。
结果：最常见的部位是口咽。总肿瘤体积(GTV)从47.5±19.2减少至17.8±10.7cc。节点GTV从15.7±18.8下降到4.7±7.1cc。腮腺显示平均体积损失35%。T分期与GTV回归中度相关。
结论：最大GTV变化发生在3周后。进行单次固定间隔ART的最佳时间是3周结束。
