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Nakamura S, Murakami N, Suzuki S, Ito K, Takemori M, Nakayama H, Kaga K, Chiba T, Iijima K, Takahashi K, Goka T, Itami J, Okamoto H, Igaki H. Monte Carlo simulation of tilted contact plaque brachytherapy placement for juxtapapillary retinoblastoma. Radiat Oncol 2022; 17:16. [PMID: 35073956 PMCID: PMC8785594 DOI: 10.1186/s13014-022-01986-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 01/10/2022] [Indexed: 11/24/2022] Open
Abstract
Background The 106-Ruthenium contact plaque applicator is utilized for the treatment of intraocular tumor within a thickness of less than 6 mm. If anything obstructs the placement of the plaque applicator, the treatment is generally difficult because the applicator has to be temporarily located just on the opposite side of the retinal tumor. Furthermore, the plaque applicator edge of approximately 1 mm does not contain 106Ru, estimating the delivered radiation dose for eccentric tumor is challenging because the lateral dose profile is inadequately provided by the manufacture’s certification. This study aims to simulate tumor coverage of the tilted applicator placement for treating an infant with juxtapapillary retinoblastoma and to achieve the effective treatment. Case presentation We present an infant with retinoblastoma whose tumor involved macular and was invading just temporal side of the optic disc. Additionally, posterior staphyloma was induced by a series of previous treatments, making it more difficult to treat the standard plaque placement. Thus, the applicator type of CCA was intentionally tilted to the eyeball and the distance between the posterior edge of the applicator and the eyeball had to be then equal to or more than 2 mm based on the dose distribution of the applicator calculated using Monte Carlo simulation to minimize damage to surrounding tissues while covering the tumor. It was then comparable to the certification and previous reports. Based on the acquired dose distribution, the optimal placement of the applicator was derived from varying the distance between the applicator’s edge and the eyeball, and the distance was then determined to be 2 mm. In this case, the minimum dose rate in the tumor was 25.5 mGy/min, and the time required to deliver the prescribed dose was 26.2 h. Therefore, the tilted 106Ru plaque applicator placement could deliver the required dose for the treatment. The physical examination revealed no active tumor as a result of the treatment. Conclusions Optimizing the placement of the 106Ru plaque applicator, it was possible to guarantee that the prescribed dose will be delivered to the tumor even if the standard placement is not possible for the juxtapapillary tumor.
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Kamrani S, Aghamiri SMR, Hashemi S. Dose characteristics of Au-198 eye brachytherapy applicator: A Monte Carlo study. Appl Radiat Isot 2021; 176:109866. [PMID: 34293507 DOI: 10.1016/j.apradiso.2021.109866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 07/09/2021] [Accepted: 07/13/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE The use of ocular plaques is a promising treatment option for eye melanoma brachytherapy. Although several studies have been done on various ocular plaques, little is known about the dose characterization of 198Au plaque. MATERIALS AND METHOD The full mathematical model of the eye phantom, tumor, 106Ru/106Rh CCA, and 198Au plaque were simulated using the Monte Carlo MCNPX code. The dose distribution was measured in the plaque's central axis direction, and a dose profile was also measured at a distance of 2.5 mm from the plaque surface. RESULTS The findings showed that 198Au plaque has superior dosimetric characteristics than CCA plaque for tumors with a thickness of greater than 3.5 mm, while CCA plaque is better for tumors with a thickness of less than 3.5 mm. The dose to the sclera and choroid is higher in the case of CCA plaque, while the dose to the organs at risk (lens and optic nerve) is greater in the case of 198Au applicator. In the case of 198Au plaque, however, the dose to sensitive organs was within their permissible dose range. CONCLUSION In the treatment of medium and large tumors, 198Au plaque is more successful than CCA plaque. It can produce a much more homogeneous lateral dose profile in the target. In the treatment of dome-shaped tumors, 198Au plaque may be more successful than CCA plaque. As a result, the tumor's shape influences the plaque type selection.
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Affiliation(s)
- Samira Kamrani
- Medical Radiation Department, Shahid Beheshti University, Tehran, Iran
| | | | - Samaneh Hashemi
- Medical Radiation Department, Shahid Beheshti University, Tehran, Iran
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Zaragoza FJ, Eichmann M, Flühs D, Timmermann B, Brualla L. Monte Carlo Computation of Dose-Volume Histograms in Structures at Risk of an Eye Irradiated with Heterogeneous Ruthenium-106 Plaques. Ocul Oncol Pathol 2020; 6:353-359. [PMID: 33123529 DOI: 10.1159/000508113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/18/2020] [Indexed: 11/19/2022] Open
Abstract
Background/Aims The aim of this work is to compare Monte Carlo simulated absorbed dose distributions obtained from <sup>106</sup>Ru eye plaques, whose heterogeneous emitter distribution is known, with the common homogeneous approximation. The effect of these heterogeneities on segmented structures at risk is analyzed using an anthropomorphic phantom. Methods The generic CCA and CCB, with a homogeneous emitter map, and the specific CCA1364 and CCB1256 <sup>106</sup>Ru eye plaques are modeled with the Monte Carlo code PENELOPE. To compare the effect of the heterogeneities in the segmented volumes, cumulative dose-volume histograms are calculated for different rotations of the aforementioned plaques. Results For the cornea, the CCA with the equatorial placement yields the lowest absorbed dose rate while for the CCA1364 in the same placement the absorbed dose rate is 33% higher. The CCB1256 with the hot spot oriented towards the cornea yields the maximum dose rate per unit of activity while it is 44% lower for the CCB. Conclusions Dose calculations based on a homogeneous distribution of the emitter substance yield the lowest absorbed dose in the analyzed structures for all plaque placements. Treatment planning based on such calculations may result in an overdose of the structures at risk.
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Affiliation(s)
| | - Marion Eichmann
- Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
| | - Dirk Flühs
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
| | - Beate Timmermann
- West German Proton Therapy Center Essen (WPE), Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,University Hospital Essen, Essen, Germany.,German Cancer Consortium (DKTK), Essen, Germany.,Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Lorenzo Brualla
- West German Proton Therapy Center Essen (WPE), Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,University Hospital Essen, Essen, Germany
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Pre and post operative radiation protection in Ru-106 brachytherapy ophthalmic plaque surgery and related material shielding properties. Phys Med 2018; 57:245-250. [PMID: 30573352 DOI: 10.1016/j.ejmp.2018.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/03/2018] [Accepted: 11/05/2018] [Indexed: 11/23/2022] Open
Abstract
Pre and post-operative exposure levels of medical staff and people from public in intra-operative Ru-106 ophthalmic brachytherapy are reported, together with attenuation properties of selected shielding materials. In particular radiation exposure of workers during plaque transportation and during medical assistance of implanted plaque patient was measured. Taking into account dose rates and considering standard assistance procedure of hospitalized patients, the exposure of medical staff and people of the public were evaluated for a given workload. In order to provide tools to optimize radiation protection, considering social and economic aspects due to possible hospital discharge or hospital stay, the attenuation properties of common shielding materials (lead, concrete, red brick, PMMA and gypsum) were measured, considering both narrow and broad beam setups. The eye was simulated using a water equivalent phantom and plaque was fixed on it. All measurements were performed with calibrated survey meters. Results were compared with numerical simulation of bremsstrahlung X-ray radiation spectra emitted from patient eye. Exposure levels measured at 1 m distance in front of the implanted eye are 0.05 µSv/h/MBq, at 10 cm from patient head, 0.44 µSv/h/MBq (plaque side), 0.4 µSv/h/MBq (front), 0.25 µSv/h/MBq (lateral, opposed to plaque), 0.2 µSv/h/MBq (back). Average exposure levels, under conservative assumptions, for medical staff is 17 µSv/patient and less than 23 µSv/patient for careers and comforters. TVLs in lead and concrete are about 1.6 cm and 11.5 cm respectively.
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Zaragoza FJ, Eichmann M, Flühs D, Wittig A, Sauerwein W, Brualla L. Monte Carlo Simulation of the Treatment of Uveal Melanoma Using Measured Heterogeneous 106Ru Plaques. Ocul Oncol Pathol 2018; 5:276-283. [PMID: 31367591 DOI: 10.1159/000492599] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/31/2018] [Indexed: 11/19/2022] Open
Abstract
Background/Aims Ruthenium plaques are used for the treatment of ocular tumors. The aim of this work is the comparison between simulated absorbed dose distributions tallied in an anthropomorphic phantom, obtained from ideal homogeneous plaques, and real eye plaques in which the actual heterogeneous distribution of <sup>106</sup>Ru was measured. The placement of the plaques with respect to the tumor location was taken into consideration to optimize the effectiveness of the treatment. Methods The generic CCA and CCB, and the specific CCA1364 and CCB1256 <sup>106</sup>Ru eye plaques were modeled with the Monte Carlo code PENELOPE. To compare the suitability of each treatment for an anterior, equatorial and posterior tumor location, cumulative dose-volume histograms for the tumors and structures at risk were calculated. Results Eccentric placements of the plaques, taking into account the inhomogeneities of the emitter map, can substantially reduce the dose delivered to structures at risk while maintaining the prescribed dose at the tumor apex. Conclusions The emitter map distribution of the plaque and the computerized tomography of the patient used in a Monte Carlo simulation allow an accurate determination of the plaque position with respect to the tumor with the potential to reduce the dose to sensitive structures.
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Affiliation(s)
| | - Marion Eichmann
- Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
| | - Dirk Flühs
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
| | - Andrea Wittig
- Klinik für Strahlentherapie und Radioonkologie, Universitätsklinikum Jena, Jena, Germany
| | | | - Lorenzo Brualla
- West German Proton Therapy Centre Essen (WPE), Essen, Germany
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Zaragoza FJ, Eichmann M, Flühs D, Sauerwein W, Brualla L. Monte Carlo Estimation of Absorbed Dose Distributions Obtained from Heterogeneous 106Ru Eye Plaques. Ocul Oncol Pathol 2017; 3:204-209. [PMID: 29071271 DOI: 10.1159/000456717] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/12/2017] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND The distribution of the emitter substance in 106Ru eye plaques is usually assumed to be homogeneous for treatment planning purposes. However, this distribution is never homogeneous, and it widely differs from plaque to plaque due to manufacturing factors. METHODS By Monte Carlo simulation of radiation transport, we study the absorbed dose distribution obtained from the specific CCA1364 and CCB1256 106Ru plaques, whose actual emitter distributions were measured. The idealized, homogeneous CCA and CCB plaques are also simulated. RESULTS The largest discrepancy in depth dose distribution observed between the heterogeneous and the homogeneous plaques was 7.9 and 23.7% for the CCA and CCB plaques, respectively. In terms of isodose lines, the line referring to 100% of the reference dose penetrates 0.2 and 1.8 mm deeper in the case of heterogeneous CCA and CCB plaques, respectively, with respect to the homogeneous counterpart. CONCLUSIONS The observed differences in absorbed dose distributions obtained from heterogeneous and homogeneous plaques are clinically irrelevant if the plaques are used with a lateral safety margin of at least 2 mm. However, these differences may be relevant if the plaques are used in eccentric positioning.
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Affiliation(s)
| | - Marion Eichmann
- Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany
| | - Dirk Flühs
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
| | | | - Lorenzo Brualla
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
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Sommer H, Ebenau M, Spaan B, Eichmann M. Monte Carlo simulation of ruthenium eye plaques with GEANT4: influence of multiple scattering algorithms, the spectrum and the geometry on depth dose profiles. Phys Med Biol 2017; 62:1848-1864. [DOI: 10.1088/1361-6560/aa5696] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Asadi S, Vaez-zadeh M, Masoudi SF, Rahmani F, Knaup C, Meigooni AS. Gold nanoparticle-based brachytherapy enhancement in choroidal melanoma using a full Monte Carlo model of the human eye. J Appl Clin Med Phys 2015; 16:344–357. [PMID: 26699318 PMCID: PMC5690168 DOI: 10.1120/jacmp.v16i5.5568] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 04/15/2015] [Accepted: 04/08/2015] [Indexed: 12/20/2022] Open
Abstract
The effects of gold nanoparticles (GNPs) in 125I brachytherapy dose enhancement on choroidal melanoma are examined using the Monte Carlo simulation technique. Usually, Monte Carlo ophthalmic brachytherapy dosimetry is performed in a water phantom. However, here, the compositions of human eye have been considered instead of water. Both human eye and water phantoms have been simulated with MCNP5 code. These simulations were performed for a fully loaded 16 mm COMS eye plaque containing 13 125I seeds. The dose delivered to the tumor and normal tissues have been calculated in both phantoms with and without GNPs. Normally, the radiation therapy of cancer patients is designed to deliver a required dose to the tumor while sparing the surrounding normal tissues. However, as the normal and cancerous cells absorbed dose in an almost identical fashion, the normal tissue absorbed radiation dose during the treatment time. The use of GNPs in combination with radiotherapy in the treatment of tumor decreases the absorbed dose by normal tissues. The results indicate that the dose to the tumor in an eyeball implanted with COMS plaque increases with increasing GNPs concentration inside the target. Therefore, the required irradiation time for the tumors in the eye is decreased by adding the GNPs prior to treatment. As a result, the dose to normal tissues decreases when the irradiation time is reduced. Furthermore, a comparison between the simulated data in an eye phantom made of water and eye phantom made of human eye composition, in the presence of GNPs, shows the significance of utilizing the composition of eye in ophthalmic brachytherapy dosimetry Also, defining the eye composition instead of water leads to more accurate calculations of GNPs radiation effects in ophthalmic brachytherapy dosimetry.
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Brualla L, Zaragoza FJ, Sauerwein W. Monte Carlo Simulation of the Treatment of Eye Tumors with (106)Ru Plaques: A Study on Maximum Tumor Height and Eccentric Placement. Ocul Oncol Pathol 2014; 1:2-12. [PMID: 27175356 PMCID: PMC4864522 DOI: 10.1159/000362560] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 03/31/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Ruthenium plaques are used for the treatment of ocular tumors. There is, however, a controversy regarding the maximum treatable tumor height. Some advocate eccentric plaque placement, without a posterior safety margin, to avoid collateral damage to the fovea and optic disc, but this has raised concerns about marginal tumor recurrence. There is a need for quantitative information on the spatial absorbed dose distribution in the tumor and adjacent tissues. We have overcome this obstacle using an approach based on Monte Carlo simulation of radiation transport. METHODS CCA and CCB (106)Ru plaques were modeled and their geometry embedded in a computerized tomography scan of the eye of a patient. Different tumor sizes and locations were simulated with the general-purpose Monte Carlo code PENELOPE. RESULTS Cumulative dose-volume histograms were obtained for the tumors and the tissues at risk considered. Plots of isodose lines for both plaques were obtained in a computerized tomography study. CONCLUSIONS Ruthenium eye plaques are an adequate treatment option for tumors up to around 5 mm in height. According to our results, assuming a correct placement of the plaque, a tumor of 6.5 mm apical height is about the maximum size that can be treated safely with the large CCB plaque.
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Affiliation(s)
- Lorenzo Brualla
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
| | - Francisco J. Zaragoza
- Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Barcelona, Spain
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Fili M, Lundell G, Lundell M, Seregard S. High dose rate and low dose rate ruthenium brachytherapy for uveal melanoma. No association with ocular outcome. Br J Ophthalmol 2014; 98:1349-54. [DOI: 10.1136/bjophthalmol-2014-305055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Fuss M, Sanz A, Muñoz A, Blanco F, Brunger M, Buckman S, Limão-Vieira P, García G. Current prospects on Low Energy Particle Track Simulation for biomedical applications. Appl Radiat Isot 2014; 83 Pt B:159-64. [DOI: 10.1016/j.apradiso.2013.01.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 12/28/2012] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
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Hermida-López M. Calculation of dose distributions for 12 106
Ru/106
Rh ophthalmic applicator models with the PENELOPE Monte Carlo code. Med Phys 2013; 40:101705. [DOI: 10.1118/1.4820368] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Accurate estimation of dose distributions inside an eye irradiated with 106Ru plaques. Strahlenther Onkol 2012; 189:68-73. [DOI: 10.1007/s00066-012-0245-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 09/17/2012] [Indexed: 10/27/2022]
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Brualla L, Sempau J, Sauerwein W. Comment on Monte Carlo calculation of the dose distributions of two 106Ru eye applicators [Radiother Oncol 49 (1998) 191–196]. Radiother Oncol 2012; 104:267-8. [DOI: 10.1016/j.radonc.2012.07.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 07/05/2012] [Accepted: 07/08/2012] [Indexed: 11/25/2022]
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Gueli A, Mannino G, Troja S, Asero G, Burrafato G, De Vincolis R, Greco C, Longhitano N, Occhipinti A, Pansini F, Stella G. 3D dosimetry on Ru-106 plaque for ocular melanoma treatments. RADIAT MEAS 2011. [DOI: 10.1016/j.radmeas.2011.07.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Energy deposition by a 106Ru/106Rh eye applicator simulated using LEPTS, a low-energy particle track simulation. Appl Radiat Isot 2011; 69:1198-204. [DOI: 10.1016/j.apradiso.2011.04.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 11/24/2022]
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Dose distribution in water for monoenergetic photon point sources in the energy range of interest in brachytherapy: Monte Carlo simulations with PENELOPE and GEANT4. Radiat Phys Chem Oxf Engl 1993 2007. [DOI: 10.1016/j.radphyschem.2006.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Yoriyaz H, Sanchez A, dos Santos A. A new human eye model for ophthalmic brachytherapy dosimetry. RADIATION PROTECTION DOSIMETRY 2005; 115:316-9. [PMID: 16381737 DOI: 10.1093/rpd/nci105] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The present work proposes a new mathematical eye model for ophthalmic brachytherapy dosimetry. This new model includes detailed description of internal structures that were not treated in previous works, allowing dose determination in different regions of the eye for a more adequate clinical analysis. Dose calculations were determined with the MCNP-4C Monte Carlo particle transport code running n parallel environment using PVM. The Amersham CKA4 ophthalmic applicator has been chosen and the depth dose distribution has been determined and compared to those provide by the manufacturer. The results have shown excellent agreement. Besides, absorbed dose values due to both 125I seeds and 60Co plaques were obtained for each one of the different structures which compose the eye model and can give relevant information in eventual clinical analyses.
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Affiliation(s)
- Hélio Yoriyaz
- Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN-SP, Av. Lineu Prestes, 2242, Cidade Universitária, P.O. Box 11049, 05508-000 São Paulo, Brazil.
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Torres J, Buades MJ, Almansa JF, Guerrero R, Lallena AM. Dosimetry characterization of 32P intravascular brachytherapy source wires using Monte Carlo codesPENELOPEandGEANT4. Med Phys 2004; 31:296-304. [PMID: 15000615 DOI: 10.1118/1.1637970] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Monte Carlo calculations using the codes PENELOPE and GEANT4 have been performed to characterize the dosimetric parameters of the new 20 mm long catheter-based 32P beta source manufactured by the Guidant Corporation. The dose distribution along the transverse axis and the two-dimensional dose rate table have been calculated. Also, the dose rate at the reference point, the radial dose function, and the anisotropy function were evaluated according to the adapted TG-60 formalism for cylindrical sources. PENELOPE and GEANT4 codes were first verified against previous results corresponding to the old 27 mm Guidant 32P beta source. The dose rate at the reference point for the unsheathed 27 mm source in water was calculated to be 0.215 +/- 0.001 cGy s(-1) mCi(-1), for PENELOPE, and 0.2312 +/- 0.0008 cGy s(-1) mCi(-1), for GEANT4. For the unsheathed 20 mm source, these values were 0.2908 +/- 0.0009 cGy s(-1) mCi(-1) and 0.311 0.001 cGy s(-1) mCi(-1), respectively. Also, a comparison with the limited data available on this new source is shown. We found non-negligible differences between the results obtained with PENELOPE and GEANT4.
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Affiliation(s)
- Javier Torres
- Servicio de Radiofísica y Protección Radiológia, Hospital Universitario Virgen de la Arrixaca, E-30120 Murcia, Spain
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Rojas EL, Al-Dweri FMO, Lallena AM, Bodineau C, Galán P. Dosimetry for radiocolloid therapy of cystic craniopharyngiomas. Med Phys 2003; 30:2482-92. [PMID: 14528970 DOI: 10.1118/1.1599653] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The dosimetry for radiocolloid therapy of cystic craniopharyngiomas is investigated. Analytical calculations based on the Loevinger and the Berger formulas for electrons and photons, respectively, are compared with Monte Carlo simulations. The role of the material of which the colloid introduced inside the craniopharyngioma is made of as well as that forming the cyst wall is analyzed. It is found that the analytical approaches provide a very good description of the simulated data in the conditions where they can be applied (i.e., in the case of a uniform and infinite homogeneous medium). However, the consideration of the different materials and interfaces produces a strong reduction of the dose delivered to the cyst wall in relation to that predicted by the Loevinger and the Berger formulas.
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Affiliation(s)
- E Leticia Rojas
- Departamento de Física Moderna, Universidad de Granada, E-18071 Granada, Spain
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Asenjo J, Fernández-Varea JM, Sánchez-Reyes A. Characterization of a high-dose-rate 90Sr-90Y source for intravascular brachytherapy by using the Monte Carlo code PENELOPE. Phys Med Biol 2002; 47:697-711. [PMID: 11931465 DOI: 10.1088/0031-9155/47/5/301] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Radiation treatment with catheter-based beta-emitter sources is currently under clinical trial to prevent restenosis. In the present paper, we address the characterization of the high-dose-rate 90Sr-90Y seeds of the Beta-Cath system supplied by Novoste Corporation, one of the commercially available sources for intravascular brachytherapy. The Monte Carlo code PENELOPE has been used to simulate the transport of electrons emitted by the encapsulated 90Sr-90Y seeds. The calculated radial dose function and anisotropy function for a single seed in water are compared with simulation results from other authors. Regarding g(r), the present result lies between the ITS3 and EGS4 curves, being somewhat closer to ITS3, while in the case of F(r, theta) some differences appear for certain angular intervals and radial distances. In order to put the observed differences into perspective, we have calculated radial doses for point isotropic sources in water. Our results for 0.5 and 1 MeV electrons are in good agreement with simulations using EGSnrc, and an excellent agreement is obtained with ITS for point 90Sr-90Y emitters. Dose distributions in water are calculated for source 'trains' consisting of 1, 2, 3, 4, 5, 9 and 12 seeds. The dose at the source midplane is enhanced if the number of seeds is up to 4, and saturates for trains with 5 or more seeds. We also compare the dose distribution obtained by simply adding the contributions of individual seeds with the simulation of the complete source train. It is found that both calculation procedures yield essentially the same result for distances greater than about 2 mm. Finally, the contribution of bremsstrahlung photons to the dose is briefly analysed.
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Affiliation(s)
- J Asenjo
- Servicio de Oncología Radioterápica, Hospital Clínic de Barcelona, Spain
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