Evaluation of a commercial MRI Linac based Monte Carlo dose calculation algorithm with <scp>geant</scp> 4

Ahmad, Syed Bilal; Sarfehnia, Arman; Paudel, Moti; Kim, Anthony; Hissoiny, Sami; Sahgal, Arjun; Keller, Brian

doi:10.1118/1.4939808

Cited by 86 publications

(91 citation statements)

References 37 publications

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“…Although both the GPUMCD and XVMC algorithms were well within the uncertainty of the film measurements in these two phantoms, the systematic dose difference of up to 2% in the tumor‐in‐lung phantom and 3% in the lung phantom needs to be explored further. In a recent simulation study (26) comparing the performance of a standalone GPUMCD code with GEANT4, similar underestimated results were found when the lung density of 0.26 g/cc was used in the GEANT4 simulations. The currently used radiological data in Monaco are obtained from ICRP‐46 (14) where the density of 1.05 g/cc is used for lung tissue.…”

Section: Discussionsupporting

confidence: 58%

Experimental evaluation of a GPU‐based Monte Carlo dose calculation algorithm in the Monaco treatment planning system

Paudel

Kim

Sarfehnia

et al. 2016

J Applied Clin Med Phys

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A new GPU‐based Monte Carlo dose calculation algorithm (GPUMCD), developed by the vendor Elekta for the Monaco treatment planning system (TPS), is capable of modeling dose for both a standard linear accelerator and an Elekta MRI linear accelerator. We have experimentally evaluated this algorithm for a standard Elekta Agility linear accelerator. A beam model was developed in the Monaco TPS (research version 5.09.06) using the commissioned beam data for a 6 MV Agility linac. A heterogeneous phantom representing several scenarios — tumor‐in‐lung, lung, and bone‐in‐tissue — was designed and built. Dose calculations in Monaco were done using both the current clinical Monte Carlo algorithm, XVMC, and the new GPUMCD algorithm. Dose calculations in a Pinnacle TPS were also produced using the collapsed cone convolution (CCC) algorithm with heterogeneity correction. Calculations were compared with the measured doses using an ionization chamber (A1SL) and Gafchromic EBT3 films for 2×2 cm2,5×5 cm2, and 10×2 cm2 field sizes. The percentage depth doses (PDDs) calculated by XVMC and GPUMCD in a homogeneous solid water phantom were within 2%/2 mm of film measurements and within 1% of ion chamber measurements. For the tumor‐in‐lung phantom, the calculated doses were within 2.5%/2.5 mm of film measurements for GPUMCD. For the lung phantom, doses calculated by all of the algorithms were within 3%/3 mm of film measurements, except for the 2×2 cm2 field size where the CCC algorithm underestimated the depth dose by ∼5% in a larger extent of the lung region. For the bone phantom, all of the algorithms were equivalent and calculated dose to within 2%/2 mm of film measurements, except at the interfaces. Both GPUMCD and XVMC showed interface effects, which were more pronounced for GPUMCD and were comparable to film measurements, whereas the CCC algorithm showed these effects poorly.PACS number(s): 87.53.Bn, 87.55.dh, 87.55.km

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Section: Discussionsupporting

confidence: 58%

Experimental evaluation of a GPU‐based Monte Carlo dose calculation algorithm in the Monaco treatment planning system

Paudel

Kim

Sarfehnia

et al. 2016

J Applied Clin Med Phys

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“…For constructions where the magnetic field is orthogonal to the radiation beam, there are adverse effects on the patient dose distribution due to the Lorentz effect, causing high dose depositions at air-tissue interfaces as well as shifted beam profiles. 23 As a result, for any MRIgRT solution where the beam passes through a magnetic field, dose distributions must be modeled using a Monte Carlo-based treatment planning system. 24 Electron recoils that are adversely affected by the magnetic field (such as at air-tissue interfaces) can be at least partially addressed by judicious selection of incoming beam angles as well as inverse optimization, as long as these are correctly modeled in a Monte Carlo TPS.…”

Section: Daily In-room Treatment Imagingmentioning

confidence: 99%

Online Adaptive Radiation Therapy

Lim‐Reinders

Keller

Al-Ward

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

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“…and Paudel et al. demonstrated this in studies validating the accuracy of Monaco's GPUMCD algorithm with and without the magnetic field, and in heterogeneous phantoms of varying material types and densities 19, 22, 23. With increasing numbers of beam angles (from TAN to IMRT to VMAT geometries) more and more beam angles enter the patient closely to the tumor location.…”

Section: Discussionmentioning

confidence: 80%

“…This raises the questions: in this study, was it realistic to neglect EC liberated in the cryostat if the B 0 field was turned off, and is the EC a large contribution to skin dose in a standard linac? To resolve this, we adapted work we performed validating Monaco's GPUMCD algorithm using the Geant4 MC platform 19. A model of the MRI‐Linac beam and cryostat were modeled in Geant4 with a 30 × 30 × 30 cm phantom in the path of the beam.…”

Section: Discussionmentioning

confidence: 99%

“…Monaco uses a Monte Carlo radiation transport method accelerated by a fast graphics processing unit currently under evaluation for clinical deployment, called the Graphics Processing Unit Monte Carlo Dose algorithm (GPUMCD) 18, 19. This Monte Carlo dose calculation algorithm can account for the magnetic field effects on the dose deposition by the radiation beam, which for the MRI‐Linac has an energy of 7 MV.…”

Section: Methodsmentioning

confidence: 99%

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Magnetic field dose effects on different radiation beam geometries for hypofractionated partial breast irradiation

Kim

Lim‐Reinders

McCann

et al. 2017

J Applied Clin Med Phys

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PurposeHypofractionated partial breast irradiation (HPBI) involves treatment to the breast tumor using high doses per fraction. Recent advances in MRI‐Linac solutions have potential in being applied to HPBI due to gains in the soft tissue contrast of MRI; however, there are potentially deleterious effects of the magnetic field on the dose distribution. The purpose of this work is to determine the effects of the magnetic field on the dose distribution for HPBI tumors using a tangential beam arrangement (TAN), 5‐beam intensity‐modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT).MethodsFive patients who have received HPBI were selected with two patients having bilateral disease resulting in a total of two tumors in this study. Six planning configurations were created using a treatment planning system capable of modeling magnetic field dose effects: TAN, IMRT and VMAT beam geometries, each of these optimized with and without a transverse magnetic field of 1.5 T.ResultsThe heart and lung doses were not statistically significant when comparing plan configurations. The magnetic field had a demonstrated effect on skin dose: for VMAT plans, the skin (defined to a depth of 3 mm) D1cc was elevated by +11% and the V30 by +146%; for IMRT plans, the skin D1cc was increased by +18% and the V30 by +149%. Increasing the number of beam angles (e.g., going from IMRT to VMAT) with the magnetic field on reduced the skin dose.ConclusionThe impact of a magnetic field on HPBI dose distributions was analyzed. The heart and lung doses had clinically negligible effects caused by the magnetic field. The magnetic field increases the skin dose; however, this can be mitigated by increasing the number of beam angles.

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Evaluation of a commercial MRI Linac based Monte Carlo dose calculation algorithm with geant 4

Cited by 86 publications

References 37 publications

Experimental evaluation of a GPU‐based Monte Carlo dose calculation algorithm in the Monaco treatment planning system

Experimental evaluation of a GPU‐based Monte Carlo dose calculation algorithm in the Monaco treatment planning system

Online Adaptive Radiation Therapy

Magnetic field dose effects on different radiation beam geometries for hypofractionated partial breast irradiation

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