A simulation study on proton computed tomography ( CT) stopping power accuracy using dual energy CT scans as benchmark
A simulation study on proton computed tomography ( CT) stopping power accuracy using dual energy CT scans as benchmark
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DOI：
10.3109/0284186x.2015.1061212
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发表时间：
2015-10-21
期刊：
影响因子：
3.1
通讯作者：
Landry, Guillaume
中科院分区：
文献类型：
--
作者：
Hansen, David C.;Seco, Joao;Landry, Guillaume
背景资料。准确的停止功率估计对于质子治疗中的治疗计划至关重要，而停止功率的不确定性是目前所用剂量裕度的最大贡献因素。双能量X射线计算机断层扫描(CT)(临床可用)和质子CT(正在开发中)都已被提出作为获得患者停车能力图的方法。本工作的目的是利用体模的双能CT扫描来评估质子CT的准确性，以建立参考准确度水平。材料和方法。使用最先进的双能量CT扫描仪，对CT校准体模和含有插入物的腹部横断面体模进行了双能和单能CT扫描。质子CT扫描采用蒙特卡罗方法进行模拟。这些模拟遵循了当前质子CT扫描仪原型中使用的设置，包括探测器的真实建模和相应的噪声特性。计算了所有三次扫描的阻止威力图，并与幻影的地面真实阻止威力进行了比较。质子CT给出的阻止能力估计略好于双能量CT方法，均方根误差分别为0.2%和0.5%(每个模体)，而双能量CT方法的均方根误差分别为0.5%和0.9%。单能量CT均方根误差分别为2.7%和1.6%。质子、双能量和单能量CT的最大误差分别为0.51%、1.7%和7.4%。更好的阻止功率估计可以显著减少质子治疗中的距离误差，但需要对当前方法进行很大改进，这可能是质子CT所能实现的。
Background. Accurate stopping power estimation is crucial for treatment planning in proton therapy, and the uncertainties in stopping power are currently the largest contributor to the employed dose margins. Dual energy x-ray computed tomography (CT) (clinically available) and proton CT (in development) have both been proposed as methods for obtaining patient stopping power maps. The purpose of this work was to assess the accuracy of proton CT using dual energy CT scans of phantoms to establish reference accuracy levels.Material and methods. A CT calibration phantom and an abdomen cross section phantom containing inserts were scanned with dual energy and single energy CT with a state-of-the-art dual energy CT scanner. Proton CT scans were simulated using Monte Carlo methods. The simulations followed the setup used in current prototype proton CT scanners and included realistic modeling of detectors and the corresponding noise characteristics. Stopping power maps were calculated for all three scans, and compared with the ground truth stopping power from the phantoms.Results. Proton CT gave slightly better stopping power estimates than the dual energy CT method, with root mean square errors of 0.2% and 0.5% (for each phantom) compared to 0.5% and 0.9%. Single energy CT root mean square errors were 2.7% and 1.6%. Maximal errors for proton, dual energy and single energy CT were 0.51%, 1.7% and 7.4%, respectively.Conclusion. Better stopping power estimates could significantly reduce the range errors in proton therapy, but requires a large improvement in current methods which may be achievable with proton CT.