A user-friendly Monte Carlo system for the accurate simulation of clinical beams and dose distributions in radiotherapy patients

• Applicant: Professor Dr. Lorenzo Brualla Barbera
• Subject Area: Medical Physics, Biomedical Technology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 267890656

• Final Report Year: 2019

Final Report Abstract

PRIMO is a computer software that simulates clinical linear accelerators (linacs) and estimates the subsequent absorbed dose distributions in phantoms and computerized tomographies. It combines a graphical user interface with a radiation transport Monte Carlo engine. The software can be freely downloaded from https:\www.primoproject.net. This project was addressed at improving PRIMO to the point of becoming the first full Monte Carlo program to find daily application in the clinical practice. This objective has been achieved. The list of areas in which relevant advances have been made are the following: • Implementation of IMRT and VMAT modalities on all Varian linacs. • Possibility to import plans from treatment planning systems (TPS) for recalculating them with a Monte Carlo code. • Implementation of a parallelized version of the fast Monte Carlo algorithm DPM as an additional dose computation engine. The distributed computation of the plans with the general-purpose Monte Carlo code PENELOPE is also possible. • Acceleration of the dose computation engine by modifications in the geometry-handling routines and the initialization procedures. As a result a typical IMRT or VMAT plan requires less than 5 minutes to achieve less than 2% standard statistical uncertainty using a modern desktop computer. • Implementation of a method for the reconstruction of treatment plans using the information stored in the Varian dynalog files. The computation of the reconstructed plan uses the same Monte Carlo algorithm employed for the computation of the plan, thus, the comparison of both results reflect only the differences between the planned and the delivered treatment. • Development of an ad-hoc geometrical description of the Varian TrueBeam linac whose results provide better accuracy than those obtained with the phase-space files distributed by Varian. • Implementation of dose analysis and manipulation tools such as 3D gamma analysis, dose export for comparing with MatriXX measurements, new dose metrics, a denoising algorithm, etc. • Implementation of a phase-space analysis environment for energy spectra and fluence studies. • Development of a new graphical user interface. • Development of a scripting language that allows the automatic operation of PRIMO for systematic comparison with plans generated by a TPS and the production of dosimetry reports. These advances have converted PRIMO into the only existing full Monte Carlo dose verification system that does not require programming, coding or compiling from the end user. The system can either be used for the routine quality assurance as well as for research applications. During the project the most important research conducted with PRIMO encompass the following areas: • Study of the applicability of many-integrated core architectures for the Monte Carlo simulation of radiation transport. • Determination of beam quality factors for ionization chambers. • Studies of condensed history algorithms. • Production of energy spectra for several beam qualities. • Study of the perturbation factor of the PMMA holder used in IAEA audits. • Dosimetry of the small fields used in eye treatments. The number of PRIMO users during the project increased from 250 to 1100.

Publications

• A geometrical model for the Monte Carlo simulation of the TrueBeam linac. Phys. Med. Biol. N219–N229, 60, 2015
  M. Rodriguez, J. Sempau, A. Fogliata, L. Cozzi, W. Sauerwein, L. Brualla
  
• Technical Note: Study of the electron transport parameters used in PENELOPE for the Monte Carlo simulation of linac targets. Med. Phys. 2877–2881, 42, 2015
  M. Rodriguez, J. Sempau, L. Brualla
  
• Testing Monte Carlo absolute dosimetry formalisms for a small field ‘D’-shaped collimator used in retinoblastoma external beam radiotherapy. Biomed. Phys. Eng. Express 065008 (pp 1–11), 2, 2016
  P.A. Mayorga, L. Brualla, A. Flühs, W. Sauerwein, A.M. Lallena
  
• Computation of the electron beam quality kQ,Q0 factors for the NE2571, NE2571A and NE2581A thimble ionization chambers using PENELOPE. Phys. Medica 76–80, 38, 2017
  F. Erazo, L. Brualla, A.M. Lallena
  
• Monte Carlo systems used for treatment planning and dose verification. Strahlenther. Onkol. 243–259, 193, 2017
  L. Brualla, M. Rodriguez, A. Lallena
  
• DPM as a radiation transport engine for PRIMO. Radiat. Oncol. 256 (pp. 1–9), 13, 2018
  M. Rodriguez, J. Sempau, C. Bäumer, B. Timmermann, L. Brualla
  
• Many-integrated core (MIC) technology for accelerating Monte Carlo simulation of radiation transport: A study based on the code DPM. Comput. Phys. Commun. 28–35, 225, 2018
  M. Rodriguez, L. Brualla
  
• PENELOPE/PRIMO-calculated photon and electron spectra from clinical accelerators. Radiat. Oncol. 6 (pp. 1–10), 14, 2019
  L. Brualla, M. Rodriguez, J. Sempau, P. Andreo
  
• Treatment verification using Varian’s dynalog files in the Monte Carlo system PRIMO. Radiat. Oncol. 6 (pp. 1–7), 14, 2019
  M. Rodriguez, L. Brualla