Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia.
Radiother Oncol. 2012 Jun;103(3):293-8. doi: 10.1016/j.radonc.2012.03.003. Epub 2012 Apr 6.
Daily variations in bladder filling make conformal treatment of bladder cancer challenging. On-line adaptive radiotherapy with a choice of plans has been demonstrated to reduce small bowel irradiation in single institution trials. In order to support a multicentre feasibility clinical trial on adaptive radiotherapy for bladder cancer (TROG 10.01) a credentialing programme was developed for centres wishing to participate.
The credentialing programme entails three components: a facility questionnaire; a planning exercise which tests the ability of centres to create three adaptive plans based on a planning and five cone beam CTs; and a site visit during which image quality, imaging dose and image guidance procedures are assessed. Image quality and decision making were tested using customised inserts for a Perspex phantom (Modus QUASAR) that mimic different bladder sizes. Dose was assessed in the same phantom using thermoluminescence dosimetry (TLD).
All 12 centres participating in the full credentialing programme were able to generate appropriate target volumes in the planning exercise and identify the correct target volume and position the bladder phantom in the phantom within 3mm accuracy. None of the imaging doses exceeded the limit of 5 cGy with a CT on rails system having the lowest overall dose.
A phantom mimicking the decision making process for adaptive radiotherapy was found to be well suited during site visits for credentialing of centres participating in a clinical trial of adaptive radiotherapy for bladder cancer. Combined with a planning exercise the site visit allowed testing the ability of centres to create adaptive treatment plans and make appropriate decisions based on the volumetric images acquired at treatment.
膀胱充盈的日常变化使得膀胱癌的适形治疗具有挑战性。在线自适应放疗结合方案选择已被证明可以减少单机构试验中小肠的照射。为了支持针对膀胱癌的自适应放疗的多中心可行性临床试验（TROG 10.01），开发了一个资格认证计划，供希望参与的中心使用。
资格认证计划包括三个部分：设施问卷；计划练习，测试中心根据计划和五个锥形束 CT 创建三个自适应计划的能力；以及现场访问，在此期间评估图像质量、成像剂量和图像引导程序。使用定制的聚碳酸酯幻像（Modus QUASAR）插入物测试图像质量和决策制定，该插入物模拟不同的膀胱大小。使用热释光剂量测定法（TLD）在相同的幻像中评估剂量。
参加完整资格认证计划的所有 12 个中心都能够在计划练习中生成适当的靶区，并在 3mm 精度内正确识别靶区并定位膀胱幻像。在带有轨道 CT 系统的情况下，没有一个成像剂量超过 5cGy 的限制，总剂量最低。
在参加自适应放疗临床试验的中心的资格认证现场访问中，发现一个模拟自适应放疗决策过程的幻像非常适合。与计划练习相结合，现场访问允许测试中心创建自适应治疗计划并根据治疗期间获得的容积图像做出适当的决策的能力。
