摘要
目的：宫颈癌近距离放射治疗（BT）的现代涂抹器有使用间隙针的集成选项。尽管这可以提高大肿瘤的剂量覆盖率，但在某些情况下，涂抹器内的预置针安排并不理想。在这种情况下，可以不使用涂抹器的位置，将自由针（FHN）插入肿瘤。不过，这需要专业人员的熟练操作，因为必须在没有插针工具的帮助下估计组织深度，而且针的角度也很关键。如果使用 FHNs 所耗费的时间和可能增加的并发症风险与肿瘤剂量覆盖率的提高和对重要器官剂量的影响有关，则尚有待估算：在这项工作中，将使用 FHN 的临床近距离放射治疗计划与假定计划进行了比较，在假定计划中，尽了最大努力来制定不使用 FHN 的可接受治疗计划。对 24 例使用 FHN 的宫颈癌患者进行了重新规划，未使用 FHN。计算了靶体积（高危临床靶体积[HR-CTV]、肿瘤总体积[GTV]和中危临床靶体积[IR-CTV]）和危险器官的生物总剂量。将体外射束放射治疗（EBRT）剂量分布与近距离放射治疗计划相加，并对总剂量进行比较：结果：观察到使用 FHNs 在统计学上有明显差异，HR-CTV D90 (p = 0.043)、膀胱 (D2cc) (p = 0.017)、直肠 (D2cc) (p = 0.022) 和乙状结肠 (D2cc) (p = 0.065)。无/有 FHN 的平均 2 Gy 等效总剂量和 p 值分别为HR-CTV D90 = 88.8/91.5 (p = 0.043)；膀胱 (D2cc) = 87.5/86.2 (p = 0.017)；直肠 (D2cc) = 70.2/69.2 (p = 0.022)；乙状结肠 (D2cc) = 70.1/69.3 (p = 0.065)（靶点的 α/β = 10 Gy，OARs 的 α/β = 3 Gy）：结论：使用FHNs可提高HR-CTV的剂量覆盖率，降低膀胱和直肠的剂量。GTV、肠道或阴道点剂量没有差异。Purpose: Modern applicators in cervical cancer brachytherapy (BT) have an integrated option for using interstitial needles. Even though this allows improved dose coverage in large tumors, there are cases where pre-positioned needle arrangements within applicator are not optimal. In such cases, free-hand needles (FHNs) can be inserted into tumor without using applicator's positions. However, this requires a skilled professional, because the depth of tissue must be estimated without any help of needle insertion tools, and the angle of needle is critical. Improved dose coverage of the tumor and the effect on critical organ doses are yet to be estimated, if they constitute the time used and possible additional complication risk using FHNs.
Material and methods: In this work, clinical brachytherapy treatment plans using FHNs were compared with hypothetical plans, in which the best possible effort was applied to produce acceptable treatment plans without FHNs. Twenty-four cervix cancer patients with FHNs were re-planned without FHNs. Biological total doses were calculated for target volumes (high-risk clinical target volume [HR-CTV], gross tumor volume [GTV], and intermediate-risk clinical target volume [IR-CTV]) and organs at risk. External beam radiation therapy (EBRT) dose distributions were summed to brachytherapy plans, and total doses were compared.
Results: The statistically significant differences favoring FHNs usage were observed, with HR-CTV D90 (p = 0.043), bladder (D2cc) (p = 0.017), rectum (D2cc) (p = 0.022), and sigmoid (D2cc) (p = 0.065). The average 2 Gy equivalent total doses and p-values, without/with FHNs were respectively: HR-CTV D90 = 88.8/91.5 (p = 0.043); bladder (D2cc) = 87.5/86.2 (p = 0.017); rectum (D2cc) = 70.2/69.2 (p = 0.022); sigmoid (D2cc) = 70.1/69.3 (p = 0.065) (α/β = 10 Gy for targets and α/β = 3 Gy for OARs, respectively).
Conclusions: The utilization of FHNs resulted in higher dose coverage to HR-CTV, and lower doses to bladder and rectum. There was no difference in GTV, bowel, or vaginal point doses.
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