WE-E-BRB-04：通过新型可变形三维剂量仪实现的定量剂量跟踪

Juang T, Newton J, Das S, Adamovics J, Oldham M

Duke University Medical Center, Durham, NC.

Rider University, Lawrenceville, NJ.

Med Phys. 2012 Jun;39(6Part27):3956. doi: 10.1118/1.4736146.

PURPOSE

To evaluate and investigate the feasibility of a new method for validating dose tracking algorithms in deforming tissues using a novel deformable 3D dosimeter.

METHODS

A novel deformable 3D Presage dosimeter is reported consisting of a stretchy polyurethane matrix doped with radiochromic leuco-dye. Two deformable cylindrical dosimeters (6 cm diameter, 5 cm long) were manufactured and irradiated with a checkerboard arrangement of 5 mm square pencil beams created by MLC fields. One dosimeter was irradiated under lateral compression by 33% (6 cm down to 4 cm diameter) to simulate a deformed organ. A second control dosimeter was irradiated with the same checkerboard pattern but without deformation applied. High-resolution 3D dose distributions (isotropic 1 mm resolution) were obtained by optical-CT imaging. Physical dose deformation was quantified by comparing checkerboard pencil beam shapes and positions in the deformed and control dosimeters.

RESULTS

Deformation of dose in the deformed dosimeter was clearly visible in all 3 dimensions. The deformed checkerboard dose pattern showed expansion of 16% - 46% along the axis of compression, with higher expansion observed in the central regions of the dosimeter. Perpendicular to the compression axis, the dose pattern contracted by 7% - 13%. Peak dose changes of -6% and +30% were observed parallel and perpendicular to the compression axis respectively. Dose response was linear from 0-8 Gy.

CONCLUSIONS

Dose tracking was successfully quantified in a novel deforming 3D dosimeter. This capability has potential as a powerful new method for validating deformable dose tracking and registration algorithms. NCI R01CA100835.

目的

使用一种新型可变形三维剂量仪评估并研究一种验证变形组织中剂量跟踪算法的新方法的可行性。

方法

报道了一种新型可变形三维Presage剂量仪，它由掺杂有辐射变色无色染料的弹性聚氨酯基质组成。制作了两个可变形圆柱形剂量仪（直径6 cm，长5 cm），并用多叶准直器（MLC）场产生的5 mm见方铅笔束棋盘格排列进行照射。一个剂量仪在侧向压缩33%（直径从6 cm压缩到4 cm）的情况下进行照射，以模拟变形器官。第二个对照剂量仪用相同的棋盘格图案照射，但不施加变形。通过光学CT成像获得高分辨率三维剂量分布（各向同性1 mm分辨率）。通过比较变形剂量仪和对照剂量仪中棋盘格铅笔束的形状和位置来量化物理剂量变形。

结果

在所有三个维度上，变形剂量仪中剂量的变形都清晰可见。变形的棋盘格剂量图案在压缩轴方向上显示出16% - 46%的扩展，在剂量仪的中心区域观察到更高的扩展。垂直于压缩轴，剂量图案收缩了7% - 13%。在平行和垂直于压缩轴的方向上分别观察到峰值剂量变化为-6%和+30%。剂量响应在0 - 8 Gy范围内呈线性。