Dose accuracy check of the 3D electron beam algorithm in a treatment planning system

Abstract

The accuracy of the recently implemented three-dimensional electron beam dose calculating algorithm in CADPLAN version 2.62 manufactured by Varian Dosetek was investigated. The algorithm uses a generalized Gaussian pencil beam model and the dose distributions are calculated as the sum of three weighted Gaussians. To use the calculating program in an optimum way, one needs to know the dose calculation accuracy of the algorithm as well as its limitations. This investigation includes comparisons of measured relative dose distributions with calculated dose distributions and also comparisons of measured and calculated monitor units. The geometries tested were quadratic fields, irregularly shaped fields, oblique fields, irregularly shaped phantom surfaces and internal heterogeneities and were most often irradiated with 8 and 20 MeV electrons. The results indicate that the algorithm is well suited for clinical three-dimensional dose planning. Some deviations occurred but they were most often within the limits of international criteria of acceptability.

Review of electron beam therapy physics

“…The former was useful in evaluating early 3D versions of the pencil-beam algorithms (McShan et al 1994, Cheng et al 1996 and the voxel Monte Carlo (Fippel et al 1997), and the latter has been useful for the evaluation of the PBRA (Boyd et al 2001b) and the macro Monte Carlo algorithm (Popple et al 2005). Similar data were used to test the Lax and Brahme PBA in CADPLAN (Samuelsson et al 1998), the Hogstrom PBA in FOCUS (Muller-Runkel and Cho 1997) and a result based on both PBAs in Helax-TMS (Blomquist et al 1996). Brahme (1985) and Hogstrom and Steadham (1996) reviewed the status of pencil-beam dose algorithms, showing the limitations of the PBA, which was primarily due to the centralaxis approximation.…”

Multiple-source models for electron beams of a medical linear accelerator using BEAMDP computer code

“…Accurate calculation of absorbed dose distribution in patients irradiated by clinical electron beams is very important in radiotherapy treatment. 1 The most accurate method of interest. For example, one can score not only energy deposition in a water phantom, but also the number of particles scattered in a particular region before depositing energy in a small volume of the water phantom.…”

3-D Reconstruction of Medical Image Using Wavelet Transform and Snake Model

“…Surface rendering has two categories. One is based on polygons and the other is based on voxels [3]. When the resolution of the images is high, volume rendering and voxel reconstruction algorithm can produce better 3-d models.…”