Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator
An integrated system of a linear accelerator and a magnetic resonance imaging (MRI) device may provide real-time imaging during radiotherapy treatments. This work investigated changes affecting the dose deposition caused by a magnetic field (B-field) transverse to the beam direction by means of Mont...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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De Gruyter
2017-09-01
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| Series: | Current Directions in Biomedical Engineering |
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| Online Access: | https://doi.org/10.1515/cdbme-2017-0058 |
| _version_ | 1797848770902228992 |
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| author | Richter Sebastian Pojtinger Stefan Mönnich David Dohm Oliver S. Thorwarth Daniela |
| author_facet | Richter Sebastian Pojtinger Stefan Mönnich David Dohm Oliver S. Thorwarth Daniela |
| author_sort | Richter Sebastian |
| collection | DOAJ |
| description | An integrated system of a linear accelerator and a magnetic resonance imaging (MRI) device may provide real-time imaging during radiotherapy treatments. This work investigated changes affecting the dose deposition caused by a magnetic field (B-field) transverse to the beam direction by means of Monte Carlo simulations. Two different phantoms were used: A water phantom (Ph1) and a water-air phantom (Ph2) with a 4-2-4 cm water-air-water cross section. Dose depositions were scored for B-field values of 0 T, 0.35 T, 0.5 T, 1.5 T, 3 T and 5 T. Beams were based on a precalculated photon spectrum taken from an earlier simulated Elekta 6 MV FFF accelerator. All lateral profiles in Ph1 showed a Lorentz force driven shift w.r.t. the B-field strength, presenting a steeper penumbra in the shift's direction. Depositions were shifted up to 0.3 cm for 5 T, showing a constant central axis plateau-dose or an increase by 2.3 % for small fields. Depth-dose curves in Ph1 showed a shift of the dose maximum towards the beam entrance direction for increasing B-field of up to 1.1 cm; the maximum dose was increased by 6.9 %. In Ph2, an asymmetric dose increase by up to 36.9 % was observed for 1.5 T at the water-air boundary, resulting from the electron return effect (ERE). In our scenario, B-field dependent dose shifts and local build-ups were observed, which consequently affect the resulting dose distribution and need to be considered in magnetic resonance guided radiotherapy treatment planning. |
| first_indexed | 2024-04-09T18:32:43Z |
| format | Article |
| id | doaj.art-20a9ccf2595045e2a69abaaa86536cc4 |
| institution | Directory Open Access Journal |
| issn | 2364-5504 |
| language | English |
| last_indexed | 2024-04-09T18:32:43Z |
| publishDate | 2017-09-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Current Directions in Biomedical Engineering |
| spelling | doaj.art-20a9ccf2595045e2a69abaaa86536cc42023-04-11T17:07:13ZengDe GruyterCurrent Directions in Biomedical Engineering2364-55042017-09-013228128510.1515/cdbme-2017-0058cdbme-2017-0058Influence of a transverse magnetic field on the dose deposited by a 6 MV linear acceleratorRichter Sebastian0Pojtinger Stefan1Mönnich David2Dohm Oliver S.3Thorwarth Daniela4University Hospital Tübingen, Department of Radiation Oncology, Section for Biomedical Physics, Hoppe-Seyler-Str. 3, 72076 Tübingen, GermanyUniversity Hospital Tübingen, Department of Radiation Oncology, Section for Biomedical Physics, Hoppe-Seyler-Str. 3, 72076 Tübingen, GermanyUniversity Hospital Tübingen, Department of Radiation Oncology, Section for Biomedical Physics, Hoppe-Seyler-Str. 3, 72076 Tübingen, GermanyUniversity Hospital Tübingen, Department of Radiation Oncology, Division for Medical Physics, Hoppe-Seyler-Str. 3, 72076 Tübingen, GermanyUniversity Hospital Tübingen, Department of Radiation Oncology, Section for Biomedical Physics, Hoppe-Seyler-Str. 3, 72076 Tübingen, GermanyAn integrated system of a linear accelerator and a magnetic resonance imaging (MRI) device may provide real-time imaging during radiotherapy treatments. This work investigated changes affecting the dose deposition caused by a magnetic field (B-field) transverse to the beam direction by means of Monte Carlo simulations. Two different phantoms were used: A water phantom (Ph1) and a water-air phantom (Ph2) with a 4-2-4 cm water-air-water cross section. Dose depositions were scored for B-field values of 0 T, 0.35 T, 0.5 T, 1.5 T, 3 T and 5 T. Beams were based on a precalculated photon spectrum taken from an earlier simulated Elekta 6 MV FFF accelerator. All lateral profiles in Ph1 showed a Lorentz force driven shift w.r.t. the B-field strength, presenting a steeper penumbra in the shift's direction. Depositions were shifted up to 0.3 cm for 5 T, showing a constant central axis plateau-dose or an increase by 2.3 % for small fields. Depth-dose curves in Ph1 showed a shift of the dose maximum towards the beam entrance direction for increasing B-field of up to 1.1 cm; the maximum dose was increased by 6.9 %. In Ph2, an asymmetric dose increase by up to 36.9 % was observed for 1.5 T at the water-air boundary, resulting from the electron return effect (ERE). In our scenario, B-field dependent dose shifts and local build-ups were observed, which consequently affect the resulting dose distribution and need to be considered in magnetic resonance guided radiotherapy treatment planning.https://doi.org/10.1515/cdbme-2017-0058radiotherapymagnetic fieldmonte carlo simulationdose depositionerelinear acceleratormrgrtmr-linac |
| spellingShingle | Richter Sebastian Pojtinger Stefan Mönnich David Dohm Oliver S. Thorwarth Daniela Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator Current Directions in Biomedical Engineering radiotherapy magnetic field monte carlo simulation dose deposition ere linear accelerator mrgrt mr-linac |
| title | Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator |
| title_full | Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator |
| title_fullStr | Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator |
| title_full_unstemmed | Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator |
| title_short | Influence of a transverse magnetic field on the dose deposited by a 6 MV linear accelerator |
| title_sort | influence of a transverse magnetic field on the dose deposited by a 6 mv linear accelerator |
| topic | radiotherapy magnetic field monte carlo simulation dose deposition ere linear accelerator mrgrt mr-linac |
| url | https://doi.org/10.1515/cdbme-2017-0058 |
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