Report of the AAPM Task Group No. 105: Issues associated with clinical implementation of Monte Carlo‐based photon and electron external beam treatment planning

Abstract

The Monte Carlo (MC) method has been shown through many research studies to calculate accurate dose distributions for clinical radiotherapy, particularly in heterogeneous patient tissues where the effects of electron transport cannot be accurately handled with conventional, deterministic dose algorithms. Despite its proven accuracy and the potential for improved dose distributions to influence treatment outcomes, the long calculation times previously associated with MC simulation rendered this method impractical for routine clinical treatment planning. However, the development of faster codes optimized for radiotherapy calculations and improvements in computer processor technology have substantially reduced calculation times to, in some instances, within minutes on a single processor. These advances have motivated several major treatment planning system vendors to embark upon the path of MC techniques. Several commercial vendors have already released or are currently in the process of releasing MC algorithms for photon and/or electron beam treatment planning. Consequently, the accessibility and use of MC treatment planning algorithms may well become widespread in the radiotherapy community. With MC simulation, dose is computed stochastically using first principles; this method is therefore quite different from conventional dose algorithms. Issues such as statistical uncertainties, the use of variance reduction techniques, the ability to account for geometric details in the accelerator treatment head simulation, and other features, are all unique components of a MC treatment planning algorithm. Successful implementation by the clinical physicist of such a system will require an understanding of the basic principles of MC techniques. The purpose of this report, while providing education and review on the use of MC simulation in radiotherapy planning, is to set out, for both users and developers, the salient issues associated with clinical implementation and experimental verification of MC dose algorithms. As the MC method is an emerging technology, this report is not meant to be prescriptive. Rather, it is intended as a preliminary report to review the tenets of the MC method and to provide the framework upon which to build a comprehensive program for commissioning and routine quality assurance of MC-based treatment planning systems.

Output factor comparison of Monte Carlo and measurement for Varian TrueBeam 6 MV and 10 MV flattening filter‐free stereotactic radiosurgery system

“…The increased differences in the dose buildup regions ($<1\hspace{0.17em}\text{cm}$) for both energies may be due to limitations in performing accurate measurements, as noted by the Report of AAPM Task Group No. 105 (20) . The off‐axis ratios for 6 MV and 10 MV beams using a field size of $10\times 10\hspace{0.17em}{\text{cm}}^2$ at 100 cm SSD and depths of ${\mathrm{D}}_{\text{max}}$, 10 cm, and 30 cm, are shown in 2, 3, respectively.…”

Evaluation of semiempirical VMAT dose reconstruction on a patient dataset based on biplanar diode array measurements

“…The patient CT, dose, and structures are imported from the TPS as DICOM RT objects. ACT number to chemical composition assignment scheme, typically reserved for more sophisticated algorithms such as Monte Carlo, (24) is used to estimate radiological depth for PB calculations. No option to override CT densities is provided.…”

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

“…However, there have been several studies reported in the literature addressing dose specification for radiotherapy treatment, 31 , 32 including the AAPM Task Group report (33) . Using Monte Carlo simulation, Ma and Li (31) have reported that conventional photon dose calculation algorithms computed doses were similar to those simulated by Monte Carlo using water with different electron densities that were within 4% differences to doses to medium.…”

“…Using Monte Carlo simulation, Ma and Li (31) have reported that conventional photon dose calculation algorithms computed doses were similar to those simulated by Monte Carlo using water with different electron densities that were within 4% differences to doses to medium. However, these doses were significantly larger by up to 11% from doses to water converted from dose to medium following AAPM TG‐105 recommendations (33) . Another earlier study by Siebers et al (32) used MCNP Monte Carlo code to simulate water‐to‐medium stopping‐power ratio for air, ICRU tissue, lung, soft bone, and cortical bone using 60 Co to 24 MV beam (see 2, 3).…”