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McElligott O, Nikandrovs M, McCavana P, McClean B, León Vintró L. Estimation of the relative biological effectiveness for double strand break induction of clinical kilovoltage beams using Monte Carlo simulations. Med Phys 2024; 51:3796-3805. [PMID: 38588477 DOI: 10.1002/mp.17060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 02/05/2024] [Accepted: 03/06/2024] [Indexed: 04/10/2024] Open
Abstract
BACKGROUND The Relative Biological Effectiveness (RBE) of kilovoltage photon beams has been previously investigated in vitro and in silico using analytical methods. The estimated values range from 1.03 to 1.82 depending on the methodology and beam energies examined. PURPOSE The focus of this work was to independently estimate RBE values for a range of clinically used kilovoltage beams (70-200 kVp) while investigating the suitability of using TOPAS-nBio for this task. METHODS Previously validated spectra of clinical beams were used to generate secondary electron spectra at several depths in a water tank phantom via TOPAS Monte Carlo (MC) simulations. Cell geometry was irradiated with the secondary electrons in TOPAS-nBio MC simulations. The deposited dose and the calculated number of DNA strand breaks were used to estimate RBE values. RESULTS Monoenergetic secondary electron simulations revealed the highest direct and indirect double strand break yield at approximately 20 keV. The average RBE value for the kilovoltage beams was calculated to be 1.14. CONCLUSIONS TOPAS-nBio was successfully used to estimate the RBE values for a range of clinical radiotherapy beams. The calculated value was in agreement with previous estimates, providing confidence in its clinical use in the future.
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Affiliation(s)
- Oran McElligott
- School of Physics, University College Dublin, Dublin, Ireland
| | - Mihails Nikandrovs
- School of Physics, University College Dublin, Dublin, Ireland
- St. Lukes Radiation Oncology Network, Dublin, Ireland
| | - Patrick McCavana
- St. Lukes Radiation Oncology Network, Dublin, Ireland
- Centre for Physics in Health and Medicine, University College Dublin, Dublin, Ireland
| | - Brendan McClean
- St. Lukes Radiation Oncology Network, Dublin, Ireland
- Centre for Physics in Health and Medicine, University College Dublin, Dublin, Ireland
| | - Luis León Vintró
- School of Physics, University College Dublin, Dublin, Ireland
- St. Lukes Radiation Oncology Network, Dublin, Ireland
- Centre for Physics in Health and Medicine, University College Dublin, Dublin, Ireland
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Iseri T, Tanabe Y, Onizuka R, Torigoe Y, Horikirizono H, Itamoto K, Sunahara H, Itoh H, Tani K, Nakaichi M. A Monte Carlo study on dose distribution of an orthovoltage radiation therapy system. Phys Eng Sci Med 2023; 46:623-632. [PMID: 36940063 DOI: 10.1007/s13246-023-01237-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 02/23/2023] [Indexed: 03/21/2023]
Abstract
It is important to plan radiotherapy treatment and establish optimal dose distribution to reduce the chances of side effects and injury. Because there are no commercially available tools for calculating dose distribution in orthovoltage radiotherapy in companion animals, we developed an algorithm to accomplish this and verified its characteristics using tumor disease cases. First, we used the Monte Carlo method to develop an algorithm to calculate the dose distribution of orthovoltage radiotherapy (280 kVp; MBR-320, Hitachi Medical Corporation, Tokyo, Japan) using BEAMnrc at our clinic. Using development of Monte Carlo method, dose distribution for tumor and normal organs were evaluated in brain tumors, squamous cell carcinomas of the head, and feline nasal lymphomas. In all cases of brain tumors, the mean dose delivered to the GTV ranged from 36.2 to 76.1% of the prescribed dose due to the decrease through the skull. In the nasal lymphoma in cats, the eyes with covered a 2 mm-thick lead plate, the respective average dose to the eyes was 71.8% and 89.9% less than that to the uncovered eyes. The findings may be useful for informed decision making in orthovoltage radiotherapy with more effective and targeted irradiation and data collection allowing detailed informed consent.
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Affiliation(s)
- Toshie Iseri
- Department of Veterinary Radiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi, Yamagishi, Japan.
| | - Yoshinori Tanabe
- Graduate School of Health Sciences, Okayama University, Okayama, Japan
| | - Ryouta Onizuka
- Department of Therapeutic Radiology, Yamaguchi University Hospital, Yamaguchi, Japan
| | - Yuri Torigoe
- Department of Veterinary Radiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi, Yamagishi, Japan
| | - Hiro Horikirizono
- Department of Veterinary Radiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi, Yamagishi, Japan
| | - Kazuhito Itamoto
- Animal medical center, Joint faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Hiroshi Sunahara
- Department of Veterinary Surgery, Joint faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Harumichi Itoh
- Animal medical center, Joint faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Kenji Tani
- Department of Veterinary Surgery, Joint faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Munekazu Nakaichi
- Department of Veterinary Radiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi, Yamagishi, Japan
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Nikandrovs M, McClean B, Shields L, McCavana P, Vintró LL. Clinical treatment planning for kilovoltage radiotherapy using EGSnrc and Python. J Appl Clin Med Phys 2023; 24:e13832. [PMID: 36444164 PMCID: PMC9924114 DOI: 10.1002/acm2.13832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/22/2022] [Accepted: 10/05/2022] [Indexed: 12/02/2022] Open
Abstract
Kilovoltage radiotherapy dose calculations are generally performed with manual point dose calculations based on water dosimetry. Tissue heterogeneities, irregular surfaces, and introduction of lead cutouts for treatment are either not taken into account or crudely approximated in manual calculations. Full Monte Carlo (MC) simulations can account for these limitations but require a validated treatment unit model, accurately segmented patient tissues and a treatment planning interface (TPI) to facilitate the simulation setup and result analysis. EGSnrc was used in this work to create a model of Xstrahl kilovoltage unit extending the range of energies, applicators, and validation parameters previously published. The novel functionality of the Python-based framework developed in this work allowed beam modification using custom lead cutouts and shields, commonly present in kilovoltage treatments, as well as absolute dose normalization using the output of the unit. 3D user-friendly planning interface of the developed framework facilitated non-co-planar beam setups for CT phantom MC simulations in DOSXYZnrc. The MC models of 49 clinical beams showed good agreement with measured and reference data, to within 2% for percentage depth dose curves, 4% for beam profiles at various depths, 2% for backscatter factors, 0.5 mm of absorber material for half-value layers, and 3% for output factors. End-to-end testing of the framework using custom lead cutouts resulted in good agreement to within 3% of absolute dose distribution between simulations and EBT3 GafChromic film measurements. Gamma analysis demonstrated poor agreement at the field edges which was attributed to the limitations of simulating smooth cutout shapes. Dose simulated in a heterogeneous phantom agreed to within 7% with measured values converted using the ratio of mass energy absorption coefficients of appropriate tissues and air.
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Affiliation(s)
- Mihails Nikandrovs
- School of PhysicsUniversity College DublinBelfieldIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Brendan McClean
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Laura Shields
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Patrick McCavana
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Luis León Vintró
- School of PhysicsUniversity College DublinBelfieldIreland
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
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