Improvement of radiotherapy treatment delivery accuracy using an electronic portal imaging device.
Improvement of radiotherapy treatment delivery accuracy using an electronic portal imaging device.
复制标题
DOI：
10.1093/rpd/ncl097
复制
发表时间：
2006-12
影响因子：
1
通讯作者：
M. Dirkx;J. D. de Boer;B. Heijmen
中科院分区：
文献类型：
--
作者：
M. Dirkx;J. D. de Boer;B. Heijmen
可靠地应用先进的外照射技术（如调强放疗）治疗癌症患者，需要一个充分的质量保证计划来验证剂量传递。由于肿瘤体积外的剂量梯度很陡，准确的患者摆位是必不可少的。由于治疗计划和传递技术日益复杂，在实际患者治疗前和治疗过程中对剂量传递进行验证同样重要。为此，我们诊所建立了一个质量保证计划，该计划主要基于电子射野影像装置的测量。为了尽量减少系统性摆位误差，在最初的几个治疗分次中对患者摆位进行测量，并在后续分次中进行摆位校正。在第一个治疗分次之前，使用电子射野影像装置对每个治疗野进行射野剂量测量，以验证计划的注量分布在治疗设备上是否正确传递。在患者治疗过程中也进行剂量学测量，以得出实际传递的注量图。通过将这些信息与患者摆位的知识相结合，可以评估肿瘤和敏感器官所接受的三维剂量分布。然而，为了达到最高的准确性，需要准确了解治疗过程中（体内的）患者几何形状，例如使用锥形束CT。
Reliable application of advanced external beam techniques for the treatment of patients with cancer, such as intensity modulated radiotherapy, requires an adequate quality assurance programme for the verification of the dose delivery. Accurate patient positioning is mandatory because of the steep dose gradients outside the tumour volume. Owing to the increased complexity of the treatment planning and delivery techniques, verification of the dose delivery before and during the actual patient treatment is equally important. For this purpose, a quality assurance programme has been established in our clinic that is primarily based on measurements with electronic portal imaging devices. To minimise systematic set-up errors, the patient positioning is measured in the first few treatment fractions and a set-up correction is applied in the subsequent ones. Before the first treatment fraction, portal dose measurements are performed for each treatment field with the electronic portal imaging device to verify that the planned fluence distribution is correctly delivered at the treatment unit. Dosimetric measurements are also performed during patient treatment to derive the actually delivered fluence maps. By combining this information with knowledge on the patient set-up, the delivered 3-D dose distribution to both the tumour and sensitive organs may be assessed. However, for the highest accuracy, exact knowledge on the (internal) patient geometry during treatment, e.g. using a cone-beam CT, is required.