Calculation of Organ Dose Distribution (in?field and Out-of-field) in Breast Cancer Radiotherapy on RANDO Phantom Using GEANT4 Application for Tomographic Emission (Gate) Monte Carlo Simulation
DOI: 10.4103/jmss.jmss_25_23
Abstract
Introduction: Organ dose distribution calculation in radiotherapy and knowledge about its side effects
in cancer etiology is the most concern for medical physicists. Calculation of organ dose distribution
for breast cancer treatment plans with Monte Carlo (MC) simulation is the main goal of this study.
Materials and Methods: Elekta Precise linear accelerator (LINAC) photon mode was simulated
and verified using the GEANT4 application for tomographic emission. Eight different radiotherapy
treatment plans on RANDO’s phantom left breast were produced with the ISOgray treatment planning
system (TPS). The simulated plans verified photon dose distribution in clinical tumor volume (CTV)
with TPS dose volume histogram (DVH) and gamma index tools. To verify photon dose distribution
in out?of?field organs, the point dose measurement results were compared with the same point doses
in the MC simulation. Eventually, the DVHs for out?of?field organs that were extracted from the
TPS and MC simulation were compared. Results: Based on the implementation of gamma index
tools with 2%/2 mm criteria, the simulated LINAC output demonstrated high agreement with the
experimental measurements. Plan simulation for in-field and out-of-field organs had an acceptable
agreement with TPS and experimental measurement, respectively. There was a difference between
DVHs extracted from the TPS and MC simulation for out-of-field organs in low?dose parts. This
difference is due to the inability of the TPS to calculate dose distribution in out?of?field organs.
Conclusion and Discussion: Based on the results, it was concluded that the treatment plans with the
MC simulation have a high accuracy for the calculation of out?of?field dose distribution and could
play a significant role in evaluating the important role of dose distribution for second primary cancer
estimation.
in cancer etiology is the most concern for medical physicists. Calculation of organ dose distribution
for breast cancer treatment plans with Monte Carlo (MC) simulation is the main goal of this study.
Materials and Methods: Elekta Precise linear accelerator (LINAC) photon mode was simulated
and verified using the GEANT4 application for tomographic emission. Eight different radiotherapy
treatment plans on RANDO’s phantom left breast were produced with the ISOgray treatment planning
system (TPS). The simulated plans verified photon dose distribution in clinical tumor volume (CTV)
with TPS dose volume histogram (DVH) and gamma index tools. To verify photon dose distribution
in out?of?field organs, the point dose measurement results were compared with the same point doses
in the MC simulation. Eventually, the DVHs for out?of?field organs that were extracted from the
TPS and MC simulation were compared. Results: Based on the implementation of gamma index
tools with 2%/2 mm criteria, the simulated LINAC output demonstrated high agreement with the
experimental measurements. Plan simulation for in-field and out-of-field organs had an acceptable
agreement with TPS and experimental measurement, respectively. There was a difference between
DVHs extracted from the TPS and MC simulation for out-of-field organs in low?dose parts. This
difference is due to the inability of the TPS to calculate dose distribution in out?of?field organs.
Conclusion and Discussion: Based on the results, it was concluded that the treatment plans with the
MC simulation have a high accuracy for the calculation of out?of?field dose distribution and could
play a significant role in evaluating the important role of dose distribution for second primary cancer
estimation.
Keywords
Breast cancer, dosimetry, Monte Carlo simulation, radiation therapy, second primary cancer
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ISSN : 2228-7477