A Study on the Dose Distributions in Various Materials from an Ir-192 HDR Brachytherapy Source

Hsu, Shih Ming; Wu, Chin Hui; Lee, Jeng Hung; Hsieh, Ya-Ju; Yu, Chun Yen; Liao, Yi Jen; Kuo, L; Liang, Ji An; Huang, David

doi:10.1371/journal.pone.0044528

Cited by 18 publications

(12 citation statements)

References 21 publications

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“…Dosimetric measurements of HDR sources in various applicators and catheters have been reported 139,140,143,154,326,332–336 . The effect of phantom material and heterogeneity (applicator/catheters) on the dose distributions can be assessed 142,337,338 . For machine QA, RCFs can be used for checking dwell position accuracy 339–341 and relative dwell times in a catheter or applicator based on the autoradiography method 342 previously employing XV‐2 film.…”

Section: Application Of Rcf Dosimetry In Clinical Radiation Therapymentioning

confidence: 99%

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

et al. 2020

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The use of radiochromic film (RCF) dosimetry in radiation therapy is extensive due to its high level of achievable accuracy for a wide range of dose values and its suitability under a variety of measurement conditions. However, since the publication of the 1998 AAPM Task Group 55, Report No. 63 on RCF dosimetry, the chemistry, composition, and readout systems for RCFs have evolved steadily. There are several challenges in using the new RCFs, readout systems and validation of the results depending on their applications. Accurate RCF dosimetry requires understanding of RCF selection, handling and calibration methods, calibration curves, dose conversion methods, correction methodologies as well as selection, operation and quality assurance (QA) programs of the readout systems. Acquiring this level of knowledge is not straight forward, even for some experienced users. This Task Group report addresses these issues and provides a basic understanding of available RCF models, dosimetric characteristics and properties, advantages and limitations, configurations, and overall elemental compositions of the RCFs that have changed over the past 20 yr. In addition, this report provides specific guidelines for data processing and analysis schemes and correction methodologies for clinical applications in radiation therapy.

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Section: Application Of Rcf Dosimetry In Clinical Radiation Therapymentioning

confidence: 99%

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

et al. 2020

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“…These results imply that there are dose distribution differences in water, bone, lung, and inhomogeneous phantoms. It was concluded that clinical parameters do not provide sufficient dose calculation accuracy for different materials, and to improve the brachytherapy treatment quality calculations, TPSs should incorporate material density [ 18 ].…”

Section: Purposementioning

confidence: 99%

Effect of tissue composition on dose distribution in brachytherapy with various photon emitting sources

Ghorbani¹,

Salahshour²,

Haghparast³

et al. 2014

jcb

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PurposeThe aim of this study is to compare the dose in various soft tissues in brachytherapy with photon emitting sources.Material and methods103Pd, 125I, 169Yb, 192Ir brachytherapy sources were simulated with MCNPX Monte Carlo code, and their dose rate constant and radial dose function were compared with the published data. A spherical phantom with 50 cm radius was simulated and the dose at various radial distances in adipose tissue, breast tissue, 4-component soft tissue, brain (grey/white matter), muscle (skeletal), lung tissue, blood (whole), 9-component soft tissue, and water were calculated. The absolute dose and relative dose difference with respect to 9-component soft tissue was obtained for various materials, sources, and distances.ResultsThere was good agreement between the dosimetric parameters of the sources and the published data. Adipose tissue, breast tissue, 4-component soft tissue, and water showed the greatest difference in dose relative to the dose to the 9-component soft tissue. The other soft tissues showed lower dose differences. The dose difference was also higher for 103Pd source than for 125I, 169Yb, and 192Ir sources. Furthermore, greater distances from the source had higher relative dose differences and the effect can be justified due to the change in photon spectrum (softening or hardening) as photons traverse the phantom material.ConclusionsThe ignorance of soft tissue characteristics (density, composition, etc.) by treatment planning systems incorporates a significant error in dose delivery to the patient in brachytherapy with photon sources. The error depends on the type of soft tissue, brachytherapy source, as well as the distance from the source.

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“…This is because there are some effects ignored by the TG-43 method such as human tissue densities, material compositions, body interfaces and dose perturbations; due to the use of applicators, these factors have a significant impact on dose distributions in the patient's body. All these effects can be significant in the brachytherapy photon energy range 4,5 and can be included in modern treatment planning systems (TPS) for brachytherapy by using model-based dose calculation algorithms (MBDCAs). The American Association of Physicists in Medicine TG-186 issued guidelines toward implementing TPS, which can take the abovementioned complexities into account.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of BrachyDose Monte Carlo code for HDR brachytherapy: dose comparison against Acuros®BV and TG-43 algorithms

2019

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Aim:The aim of this study is to investigate the accuracy of dose distributions calculated by the BrachyDose Monte Carlo (MC) code in heterogeneous media for high-dose-rate (HDR) brachytherapy and to evaluate its usability in the clinical brachytherapy treatment planning systems.Materials and methods:For dose comparisons, three different dose calculation algorithms were used in this study. Namely, BrachyDose MC code, Eclipse TG-43 dose calculation tool and Acuros®BV model-based dose calculation algorithm (MBDCA). Dose distributions were obtained using any of the above codes in various scenarios including ‘homogenous water medium scenario’, an ‘extreme case heterogeneous media scenario’ and clinically important ‘a patient with a cervical cancer scenario’. In the ‘extreme case, heterogeneous media scenario’, geometry is a rare combination of unusual high-density and low-density materials and it is chosen to provide a test environment for the propagation of photons in the interface of two materials with different absorption and scattering properties. GammaMed 192Ir Model 12i Source is used as the HDR brachytherapy source in this study. Dose calculations were performed for the cases where there is either a single source or five sources planted into the phantom geometry in all homogenous water phantom and extreme case heterogeneous media scenarios. For the scenario a patient with a cervical cancer, dose calculations were performed in a voxelized rectilinear phantom, which is constructed from a series of computed tomography (CT) slices of a patient, which are obtained from a CT device.Results:In homogeneous water phantom scenario, we observed no statistically significant dose differences among the dose distributions calculated by any of the three algorithms at almost every point in the geometry. In the extreme case heterogeneous media scenario, the dose calculation engines Acuros®BV and BrachyDose are agreed well within statistics in every region of the geometry and even in the points close to the interfaces of low-density and high-density materials. On the other hand, the dose values calculated by these two codes are significantly different from those calculated by the TG-43 algorithm. In the ‘a patient with a cervical cancer scenario’, the calculated D2cc dose difference between Acuros®BV and BrachyDose codes is within 2% in the rectum and 11% for the bladder and sigmoid. There was no meaningful difference in the mean dose values between MBDCAs in the bone structures.Conclusions:In this study, the accurate dose calculation capabilities of the BrachyDose program in HDR brachytherapy were investigated on various scenarios and, as a MC dose calculation tool, its effectiveness in HDR brachytherapy was demonstrated by comparative dose analysis.

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A Study on the Dose Distributions in Various Materials from an Ir-192 HDR Brachytherapy Source

Cited by 18 publications

References 21 publications

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

Effect of tissue composition on dose distribution in brachytherapy with various photon emitting sources

Evaluation of BrachyDose Monte Carlo code for HDR brachytherapy: dose comparison against Acuros®BV and TG-43 algorithms

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