Systematic measurements of whole-body imaging dose distributions in image-guided radiation therapy
Systematic measurements of whole-body imaging dose distributions in image-guided radiation therapy
复制标题
DOI：
10.1118/1.4758065
复制
发表时间：
2012-12-01
期刊：
影响因子：
3.8
通讯作者：
Schneider, Uwe
中科院分区：
文献类型：
--
作者：
Haelga, Roger A.;Besserer, Juergen;Schneider, Uwe
目的：只有保证患者定位的准确性，才能充分利用现代治疗技术提高精度的全部好处。因此，在放射治疗的临床常规中，越来越多的成像模态被用于患者设置的过程中。然而，患者定位的改进的准确性导致对积分患者剂量的额外剂量贡献。为了量化这一点，在一个完整的治疗过程中，在拟人体模中测量了图像引导放射治疗治疗中涉及的典型成像程序的吸收剂量测量值。实验设置（包括体模中的测量位置）与先前放射治疗杂散剂量测量研究中的设置完全相同。这允许直接组合的成像剂量分布与therapeutic dose distribution.Methods：单独校准的热释光剂量计被用来测量吸收剂量在拟人模型在184个位置。确定了与制造商Accuray、Elekta、Siemens和Varian的治疗机配合使用的成像设备以及GE Healthcare的计算机断层扫描仪的剂量分布，并计算了产生的有效剂量。研究的成像技术包括锥形束计算机断层扫描（千伏和兆伏），兆伏扇形束计算机断层扫描，千伏和兆伏平面成像，计划计算机断层扫描有和没有门控方法和平面侦察视图。传统的3D计划CT导致除了治疗体积外小于1 mSv的治疗杂散剂量之外的有效剂量，而4D计划CT导致10倍的剂量。对于在断层治疗装置上使用两个平面千伏图像或扇形束CT对患者进行的日常设置，分别测量了治疗体积之外的小于0.4 mSv和1.4 mSv的额外有效剂量。使用千伏或兆伏辐射获得锥形束计算机断层扫描导致额外剂量为8-46 mSv。对于治疗验证图像每周一次使用双曝光技术，额外的有效剂量高达18毫希measured.Conclusions：每日设置成像使用千伏平面图像或TomoTherapy兆伏扇形束CT成像可以作为一个标准程序，在临床常规。每日千伏和兆伏锥形束计算机断层扫描设置成像应根据个人或适应症方案进行。根据所应用的成像方案，与没有图像引导的治疗相比，可以在不增加治疗体积之外的剂量的情况下施用图像引导的放射治疗。(C)2012年美国医学物理学家协会。[http：//dx.doi.org/10.1118/1.4758065]
Purpose: The full benefit of the increased precision of contemporary treatment techniques can only be exploited if the accuracy of the patient positioning is guaranteed. Therefore, more and more imaging modalities are used in the process of the patient setup in clinical routine of radiation therapy. The improved accuracy in patient positioning, however, results in additional dose contributions to the integral patient dose. To quantify this, absorbed dose measurements from typical imaging procedures involved in an image-guided radiation therapy treatment were measured in an anthropomorphic phantom for a complete course of treatment. The experimental setup, including the measurement positions in the phantom, was exactly the same as in a preceding study of radiotherapy stray dose measurements. This allows a direct combination of imaging dose distributions with the therapy dose distribution.Methods: Individually calibrated thermoluminescent dosimeters were used to measure absorbed dose in an anthropomorphic phantom at 184 locations. The dose distributions from imaging devices used with treatment machines from the manufacturers Accuray, Elekta, Siemens, and Varian and from computed tomography scanners from GE Healthcare were determined and the resulting effective dose was calculated. The list of investigated imaging techniques consisted of cone beam computed tomography (kilo-and megavoltage), megavoltage fan beam computed tomography, kilo-and megavoltage planar imaging, planning computed tomography with and without gating methods and planar scout views.Results: A conventional 3D planning CT resulted in an effective dose additional to the treatment stray dose of less than 1 mSv outside of the treated volume, whereas a 4D planning CT resulted in a 10 times larger dose. For a daily setup of the patient with two planar kilovoltage images or with a fan beam CT at the TomoTherapy unit, an additional effective dose outside of the treated volume of less than 0.4 mSv and 1.4 mSv was measured, respectively. Using kilovoltage or megavoltage radiation to obtain cone beam computed tomography scans led to an additional dose of 8-46 mSv. For treatment verification images performed once per week using double exposure technique, an additional effective dose of up to 18 mSv was measured.Conclusions: Daily setup imaging using kilovoltage planar images or TomoTherapy megavoltage fan beam CT imaging can be used as a standard procedure in clinical routine. Daily kilovoltage and megavoltage cone beam computed tomography setup imaging should be applied on an individual or indication based protocol. Depending on the imaging scheme applied, image-guided radiation therapy can be administered without increasing the dose outside of the treated volume compared to therapies without image guidance. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4758065]