Halperin Edward C, Laurie Fran, Fitzgerald T J
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Int J Radiat Oncol Biol Phys. 2002 Jul 15;53(4):1001-4. doi: 10.1016/s0360-3016(02)02833-x.
The Pediatric Oncology Group Protocol 9404 was a prospective clinical trial of two forms of chemotherapy in childhood T-cell acute lymphoblastic leukemia and advanced stage T-cell lymphoblastic non-Hodgkin's lymphoma. The protocol called for prophylactic C1 whole brain external beam irradiation, 18 Gy in 2 Gy/fraction for 9 fractions. We hypothesized that a correlation would be found between the number of children irradiated on protocol by an institution and the compliance rate of that institution with radiotherapy quality assurance (QA) guidelines. We also hypothesized that QA compliance would improve as the study progressed.
We scored the radiation dose as a minor deviation from protocol guidelines if the dose to the prescription point differed from the protocol by 6-10%, and a major deviation if it differed from protocol by > 10%. Treatment volumes were scored as a minor deviation if the margins were less than specified or the fields were excessively large. A major deviation was defined as the transection of a potential leukemia-bearing volume such as would be caused by blocking the cribriform plate, optic nerve, or temporal lobe. When the treating physician submitted a treatment plan and simulator film at the initiation of therapy to the Quality Assurance Review Center (QARC), a rapid turn-around review of the plan and suggestions for improvement was provided. At the end of therapy, all simulator and port films were reviewed at the QARC.
We reviewed the data from 353 patients treated at 73 institutions in the United States, Canada, and Europe. Of these patients, 2% (n = 7) were not assessable for QA because of incomplete information. Minor quality deviations were found in 27.7% of patients (n = 98) and major deviations in 7.9% (n = 28). The frequency of major deviations for institutions placing 1-4 patients on study was 11% vs. 5.5% for institutions placing > or =5 patients (p < 0.09). The frequency of minor deviations was 28.6% for institutions placing 1-4 patients on study vs. 27.1% for institutions placing >5 patients (p not significant). The frequency of major deviations fell over time (1996-1997, 15.5% vs. 1998-2001, 4.7%, p < 0.001). The frequency of minor deviations did not (1996-1997, 29.9% vs. 1998-2001, 26.9%, p not significant).
For a relatively simple radiotherapy field, with clearly written protocol guidelines and rapid turn-around corrections from QARC, the rate of minor deviations was no different between institutions placing 1-4 patients on study and those placing > or =5. A trend (p < 0.09) was noted, however, for major deviations to decrease as a function of institutional experience, as well as over time (p < 0.001), supporting the validity of the hypothesis that pediatric clinical experience matters in QA for C1 whole brain leukemia radiotherapy.
儿童肿瘤学组方案9404是一项针对儿童T细胞急性淋巴细胞白血病和晚期T细胞淋巴母细胞性非霍奇金淋巴瘤的两种化疗形式的前瞻性临床试验。该方案要求进行预防性C1全脑外照射，18 Gy，分9次照射，每次2 Gy。我们假设机构按照方案照射的儿童数量与该机构放疗质量保证（QA）指南的符合率之间存在相关性。我们还假设随着研究的进行，QA合规性会提高。
如果处方点的剂量与方案相差6 - 10%，则将放射剂量评为轻微偏离方案指南；如果相差超过10%，则评为重大偏离。如果边缘小于规定值或射野过大，则将治疗体积评为轻微偏离。重大偏离定义为切断潜在的白血病负荷体积，如因遮挡筛板、视神经或颞叶而导致的情况。当治疗医师在治疗开始时向质量保证审查中心（QARC）提交治疗计划和模拟定位片时，会对该计划进行快速周转审查并提供改进建议。在治疗结束时，QARC会对所有模拟定位片和射野片进行审查。
我们审查了在美国、加拿大和欧洲73个机构接受治疗的353例患者的数据。其中，2%（n = 7）的患者因信息不完整无法进行QA评估。27.7%（n = 98）的患者存在轻微质量偏差，7.9%（n = 28）的患者存在重大偏差。纳入1 - 4例患者进行研究的机构的重大偏差发生率为11%，而纳入≥5例患者的机构为5.5%（p < 0.09）。纳入1 - 4例患者进行研究的机构的轻微偏差发生率为28.6%，纳入>5例患者的机构为27.1%（p无统计学意义）。重大偏差的发生率随时间下降（1996 - 1997年为15.5%，1998 - 2001年为4.7%，p < 0.001）。轻微偏差的发生率没有下降（1996 - 1997年为29.9%，1998 - 2001年为26.9%，p无统计学意义）。
对于一个相对简单的放疗野，有明确的方案指南且QARC能快速周转进行纠正，纳入1 - 4例患者进行研究的机构与纳入≥5例患者的机构之间的轻微偏差率没有差异。然而，注意到一个趋势（p < 0.09），即重大偏差随着机构经验以及时间的推移而减少（p < 0.001），这支持了儿科临床经验在C1全脑白血病放疗QA中很重要这一假设的有效性。
