Experimental investigation of a fast Monte Carlo photon beam dose calculation algorithm

Abstract

An experimental verification of the recently developed XVMC code, a fast Monte Carlo algorithm to calculate dose distributions of photon beams in treatment planning, is presented. The treatment head is modelled by a point source with energy distribution (primary photons) and an additional head scatter contribution. Utility software is presented, allowing the determination of the parameters for this model using a single measured depth dose curve in water. The simple beam model is considered to be a starting point for more complex models being planned for future versions of the code. This paper is mainly focused on the influence of the different techniques on variance reduction and material property determination for dose distributions. It is demonstrated that XVMC and the simple beam model reproduce measured (by a diamond detector) relative dose distributions with an accuracy of better than +/-2% in various homogeneous and inhomogeneous phantoms. Furthermore, relative dose distributions in solid state phantoms have been measured by film. Also for these cases, measured and calculated dose distributions agree within experimental uncertainty. The short calculation time (depending on voxel resolution, statistical accuracy, field size and energy, a span of 1 min to 1 h using a present-day personal computer) and an interface to a commercial planning system will allow the implementation of the code for routine treatment planning of clinical electron and photon beams.

Verification of IMRT: Techniques and Problems

“…But, of course, a code must be found, which is quick and precise enough, to deliver treatment plans for verification purpose within a reasonable time frame. We use XVMC, including the MC treatment head model VEF, as described by Fippel et al [9][10][11], which we commissioned with data from our linac (Primus, Siemens) for 6 MV photons. The MC code is integrated in our inverse MC optimisation programs, called IMCO ++ /IKO, described by Hartmann et al [13,14].…”

Assessment of Monte Carlo algorithm for compliance with RTOG 0915 dosimetric criteria in peripheral lung cancer patients treated with stereotactic body radiotherapy

“…The XVMC was based on the X‐ray Voxel Monte Carlo algorithm 24 , 25 that consists of source modeling, beam collimating system modeling, and patient dose computation. The dose calculation parameters for XVMC in iPlan are spatial resolution, mean variance, dose result type, and MLC model.…”

Monte Carlo evaluation of tissue heterogeneities corrections in the treatment of head and neck cancer patients using stereotactic radiotherapy

“…Using the identical beam geometry, field sizes, and depths; same number of monitor units was delivered in Solid Water phantom to validate these algorithms. The XVMC was based on the X-ray Voxel Monte Carlo algorithm (8,9) that consists of source modeling, beam collimating system modeling, and patient dose computation. The dose calculation parameters for XVMC in iPlan are spatial resolution, mean variance, dose result type, and MLC model.…”

“…Recently, several commercial TPS have implemented MC-based dose calculation algorithms clinically that could calculate more realistic dose distributions in low-density tissues such as lung or sinus, allowing for more accurate dose distribution in patients with lung tumors or with air cavity interfaces. (8,9,10) However, dosimetric evaluation of MC-based heterogeneity corrections for head and neck SRT patients using XVMC calculations has not been presented. In our clinic, we have implemented X-ray Voxel Monte Carlo (XVMC) algorithm (BrainLab iPlan, version 4.1.2, Feldkirchen, Germany) for dose calculations for SBRT patients.…”