Department of Radiation Oncology, Division of Medical Radiation Physics, Comprehensive Cancer Center, Medical University Vienna, Vienna A-1090, Austria and Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Vienna A-1090, Austria.
Med Phys. 2013 Dec;40(12):121718. doi: 10.1118/1.4829595.
To investigate the possibility of detecting patient mispositioning in carbon-ion therapy with particle therapy positron emission tomography (PET) in an automated image registration based manner.
Tumors in the head and neck (H&N), pelvic, lung, and brain region were investigated. Biologically optimized carbon ion treatment plans were created with TRiP98. From these treatment plans, the reference β(+)-activity distributions were calculated using a Monte Carlo simulation. Setup errors were simulated by shifting or rotating the computed tomography (CT). The expected β(+) activity was calculated for each plan with shifts. Finally, the reference particle therapy PET images were compared to the "shifted" β(+)-activity distribution simulations using the Pearson's correlation coefficient (PCC). To account for different PET monitoring options the inbeam PET was compared to three different inroom scenarios. Additionally, the dosimetric effects of the CT misalignments were investigated.
The automated PCC detection of patient mispositioning was possible in the investigated indications for cranio-caudal shifts of 4 mm and more, except for prostate tumors. In the rather homogeneous pelvic region, the generated β(+)-activity distribution of the reference and compared PET image were too much alike. Thus, setup errors in this region could not be detected. Regarding lung lesions the detection strongly depended on the exact tumor location: in the center of the lung tumor misalignments could be detected down to 2 mm shifts while resolving shifts of tumors close to the thoracic wall was more challenging. Rotational shifts in the H&N and lung region of +6° and more could be detected using inroom PET and partly using inbeam PET. Comparing inroom PET to inbeam PET no obvious trend was found. However, among the inroom scenarios a longer measurement time was found to be advantageous.
This study scopes the use of various particle therapy PET verification techniques in four indications. The automated detection of patients' setup errors was investigated in a broad accumulation of data sets. The evaluation of introduced setup errors is performed automatically, which is of utmost importance to introduce highly required particle therapy monitoring devices into the clinical routine.
探讨基于自动图像配准的粒子治疗正电子发射断层扫描（PET）在碳离子治疗中检测患者位置错误的可能性。
研究了头颈部（H&N）、骨盆、肺部和脑部的肿瘤。使用 TRiP98 生成了生物优化的碳离子治疗计划。从这些治疗计划中，使用蒙特卡罗模拟计算参考β（+）-活性分布。通过移动或旋转计算机断层扫描（CT）模拟设置误差。对于每个计划，都计算了移位的预期β（+）活性。最后，使用 Pearson 相关系数（PCC）将参考粒子治疗 PET 图像与“移位”β（+）-活性分布模拟进行比较。为了考虑不同的 PET 监测选项，将腔内 PET 与三种不同的室内场景进行了比较。此外，还研究了 CT 配准错误的剂量学影响。
在所研究的头脚方向 4 毫米及以上的颅尾移位的适应症中，除了前列腺肿瘤外，患者位置的自动 PCC 检测是可能的。在相当均匀的骨盆区域，参考和比较 PET 图像的生成β（+）-活性分布过于相似。因此，无法检测到该区域的设置误差。对于肺部病变，检测结果强烈取决于肿瘤的确切位置：在肺部肿瘤的中心，即使是 2 毫米的移位也可以检测到，而靠近胸壁的肿瘤的移位则更具挑战性。使用室内 PET 和部分使用腔内 PET 可以检测到 H&N 和肺部区域的+6°及以上的旋转移位。将室内 PET 与腔内 PET 进行比较，没有发现明显的趋势。然而，在室内场景中，发现较长的测量时间是有利的。
本研究探讨了在四种适应症中使用各种粒子治疗 PET 验证技术的情况。在广泛的数据集中研究了自动检测患者设置误差的能力。引入的设置误差的评估是自动执行的，这对于将急需的粒子治疗监测设备引入临床常规至关重要。
