Department of Radiation Oncology, IRCCS-CROB, Via S. Pio 1, 85028, Rionero in Vulture (PZ), Italy,
Radiol Med. 2014 Mar;119(3):201-7. doi: 10.1007/s11547-013-0326-3. Epub 2013 Dec 12.
To investigate the correct time point for re-planning by evaluating dosimetric changes in the parotid glands (PGs) during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients.
Patients with head and neck cancer treated with IMRT were enrolled. During treatment all patients underwent cone-beam computed tomography (CBCT) scans to verify the set-up. CBCT scans at treatment days 10, 15, 20 and 25 were used to transfer the original plan (CBCTplan I, II, III, IV, respectively) using rigid registration between the two. The PGs were retrospectively contoured and evaluated with the dose-volume histogram. The mean dose, the dose to 50 % of volume, and the percentage of volume receiving 30 and 50 Gy were evaluated for each PG. The Wilcoxon sign ranked test was used to evaluate the effects of dosimetric variations and values <0.05 were taken to be significant.
From February to June 2011, ten patients were enrolled and five IMRT plans were evaluated for each patient. All the dosimetric parameters increased throughout the treatment course. However, this increase was statistically significant at treatment days 10 and 15 (CBCTplan I, II; p = 0.02, p = 0.03, respectively).
CBCT is a feasible method to assess the dosimetric changes in the PGs. Our data showed that checking the PG volume and dose could be indicated during the third week of treatment.
通过评估头颈部癌症患者调强放疗（IMRT）过程中腮腺（PG）的剂量变化，探讨重新计划的正确时间点。
纳入接受 IMRT 治疗的头颈部癌症患者。在治疗过程中，所有患者均行锥形束 CT（CBCT）扫描以验证摆位。使用两次之间的刚性配准，将治疗第 10、15、20 和 25 天的 CBCT 扫描（分别为 CBCTplan I、II、III、IV）用于转移原始计划。回顾性勾画 PG 并使用剂量-体积直方图进行评估。分别评估每个 PG 的平均剂量、50%体积接受的剂量、接受 30 和 50Gy 的体积百分比。采用 Wilcoxon 符号秩检验评估剂量变化的影响，P 值<0.05 认为差异有统计学意义。
2011 年 2 月至 6 月期间，纳入 10 例患者，每位患者评估 5 个 IMRT 计划。所有剂量参数在整个治疗过程中均增加。然而，在治疗第 10 和 15 天（CBCTplan I、II）时，这种增加具有统计学意义（p=0.02，p=0.03）。
CBCT 是评估 PG 剂量变化的一种可行方法。我们的数据表明，在治疗的第三周检查 PG 体积和剂量可能是必要的。
