Kissick Michael W, Mackie Thomas Rockwell, Jeraj Robert
Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53706, USA.
Phys Med Biol. 2007 May 7;52(9):2355-65. doi: 10.1088/0031-9155/52/9/002. Epub 2007 Apr 10.
The previous theoretical work of a delivery transfer function (DTF) in radiotherapy is expanded to include the unique intensity modulation method of helical tomotherapy. In addition to the collimation of each beamlet, and the Gaussian scatter convolution spreading of the dose that other radiotherapy units have, helical tomotherapy uses 51 small arcs of varying lengths to adjust the intensity. The blurring from these arcs is not taken into account during treatment planning. A theoretical DTF is constructed, and a calculation is performed which includes this unique source motion in relation to the other DTF components. Various typical delivery parameters are used to generate resolution maps for a constant intensity projection. Near the isocenter, the transverse (to a given beam direction) blurring is small but at larger radii (>6 cm), the source blurring dominates over leaf size. For most clinical situations, this inherent source motion blurring is expected to be negligible.
放射治疗中传递函数（DTF）的先前理论工作得到扩展，以纳入螺旋断层放射治疗独特的强度调制方法。除了每个子野的准直以及其他放射治疗设备所具有的剂量高斯散射卷积扩散外，螺旋断层放射治疗使用51个不同长度的小弧来调整强度。在治疗计划期间未考虑这些弧产生的模糊。构建了理论传递函数，并进行了计算，该计算包括这种相对于其他传递函数组件的独特源运动。使用各种典型的传递参数生成恒定强度投影的分辨率图。在等中心附近，横向（相对于给定射束方向）模糊较小，但在较大半径（>6 cm）处，源模糊超过叶片尺寸。对于大多数临床情况，这种固有的源运动模糊预计可忽略不计。
