Distribution of absorbed energy from a point beta-source in a tissue-equivalent medium

Бочкарев, В. В.; Radzievsky, G.B.; Timofeev, Lev; Demianov, N.A.

doi:10.1016/0020-708x(72)90131-7

Cited by 21 publications

(3 citation statements)

References 5 publications

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“…Recently an improvement has been reached by Berger (1971) who recalculated the dose distributions around point sources of different p -emitters in homogeneous media interpolating the Spencer tables in a slightly different way. Also Bochkarev (1972) calculated absorbed dose distributions around point sources but with an alternative method. He constructed his dose distributions around point sources using the dose distribution for a thin plane isotropic source of monoenergetic electrons.…”

Section: Computed Datamentioning

confidence: 99%

Dosimetry of beta sources in radiotherapy. I. The beta point source dose function

Vynckier

Wambersie

1982

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The dose distribution around a point source of a beta-emitting radionuclide in an homogeneous medium is considered. The beta point dose function proposed by Loevinger in 1956 is discussed with respect to the most recent experimental and theoretical available data of Cross and Berger. The Loevinger function provides a reasonable evaluation of the dose distribution at distances of clinical interest. A re-evaluation of the parameters can still improve the situation. A slightly modified formula provides a description of the dose distribution around 32P and 90Y point sources, which is in close agreement, at all relevant distances, with the data of Cross and Berger. This formula can be integrated to provide the dose distribution around beta sources of other shapes.

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Section: Computed Datamentioning

confidence: 99%

Dosimetry of beta sources in radiotherapy. I. The beta point source dose function

Vynckier

Wambersie

1982

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“…If the source distribution is modelled as a collection of radiation point sources, the energy dose per decay D E = dE 2 /dmdN (Gy/deacy), where E (J) denotes absorbed radiation energy, m (kg) denotes mass and N denotes the number of nuclear disintegrations, caused by an individual isotropic point source in a homogeneous medium, is called a dose-point-kernel (Bochkarev et al 1972, Pérez et al 2011. DPKs represent the radial distribution of absorbed dose around an isotropic point source in an infinite homogeneous propagation medium (Bardiès et al 2003).…”

Section: Voxel-wise Dosimetrymentioning

confidence: 99%

A comparison of methods for adapting 177Lu dose-voxel-kernels to tissue inhomogeneities

et al. 2019

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In radionuclide therapies, dosimetry is used for determining patient-individual dose burden. Standard approaches provide whole organ doses only. For assessing dose heterogeneity inside organs, voxel-wise dosimetry based on 3D SPECT/CT imaging could be applied. Often, this is achieved by convolving voxel-wise time-activity-curves with appropriate dose-voxel-kernels (DVK). The DVKs are meant to model dose deposition, and can be more accurate if modelled for the specific tissue type under consideration. In literature, DVKs are often not adapted to these inhomogeneities, or simple approximation schemes are applied. For 26 patients, which had previously undergone a -PSMA or -DOTATOC therapy, decay maps, mass-density maps as well as tissue-type maps were derived from SPECT/CT acquisitions. These were used for a voxel-based dosimetry based on convolution with DVKs (each of size ) obtained by four different DVK methods proposed in literature. The simplest only considers a spatially constant soft-tissue DVK (herein named ‘constant’), while others either take into account only the local density of the center voxel of the DVK (herein named ‘center-voxel’) or scale each voxel linearly according to the proper mass density deduced from the CT image (herein named ‘density’) or considered both the local mass density as well as the direct path between the center voxel and any voxel in its surrounding (herein named ‘percentage’). Deviations between resulting dose values and those from full Monte-Carlo simulations (MC simulations) were compared for selected organs and tissue-types. For each DVK method, inter-patient variability was considerable showing both under- and over-estimation of energy dose compared to the MC result for all tissue densities higher than soft tissue. In kidneys and spleen, ‘constant’ and ‘density’-scaled DVKs achieved estimated doses with smallest deviations to the full MC gold standard (∼ underestimation). For low and high density tissue types such as lung and adipose or bone tissue, alternative DVK methods like ‘center-voxel’- and ‘percentage’- scaled achieved superior results, respectively. Concerning computational load, dose estimation with the DVK method ‘constant’ needs about 1.1 s per patient, center-voxel scaling amounts to 1.2 s, density scaling needs 1.4 s while percentage scaling consumes 860.3 s per patient. In this study encompassing a large patient cohort and four different DVK estimation methods, no single DVK-adaption method was consistently better than any other in case of soft tissue kernels. Hence in such cases the simplest DVK method, labeled ‘constant’, suffices. In case of tumors, often located in tissues of low (lung) or high (bone) density, more sophisticated DVK methods excel. The high inter-patient variability indicates that for evaluating new algorithms, a sufficiently large patient cohort needs to be involved.

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“…Such point kernels were calculated for monoenergetic electrons by Spencer (1955Spencer ( , 1959, using a numerical solution of the transport equation, and his results were averaged over a number of beta-ray spectra by Cross (1967a), Berger ( 197 l), and Cross et al ( 1982) to give dose distributions for beta emitters. Such calculations can serve as a standard against which much more approximate empirical expressions for dose distributions (e.g., Loevinger 1956;Bochkarev et al 1972;Vynckier and Wambersie 1982;Chabot et al 1988;Prestwich et al 1989) can be compared. Spencer's (1955Spencer's ( , 1959 results are based on the continuous slowing-down approximation (CSDA) and, because they neglect statistical fluctuations in energy losses, they underestimate doses at large distances.…”

Section: Introductionmentioning

confidence: 99%

Estimates of Absorption of Radiofrequency Radiation by the Embryo and Fetus During Pregnancy

No²,

Py³

1992

Health Physics

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The ACCEPT Monte Carlo code has been used to calculate radial dose distributions around isotropic point sources of monoenergetic electrons between 0.01 and 10 MeV in an infinite water medium. The results were averaged over beta spectra to derive distributions for 147 beta emitters of which 32 are presented. More extensive tables of distributions will be presented in a report. Distributions for monoenergetic electrons agree with recent ETRAN-code calculations of Berger and Seltzer within 2%, except at very short distances where there are differences up to several percent. Results calculated by the EGS4 code differ by up to a few percent. Distributions for beta emitters are in excellent agreement with both experimental results and ETRAN and EGS4 calculations, except at very short distances.

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Distribution of absorbed energy from a point beta-source in a tissue-equivalent medium

Cited by 21 publications

References 5 publications

Dosimetry of beta sources in radiotherapy. I. The beta point source dose function

Dosimetry of beta sources in radiotherapy. I. The beta point source dose function

A comparison of methods for adapting 177Lu dose-voxel-kernels to tissue inhomogeneities

Estimates of Absorption of Radiofrequency Radiation by the Embryo and Fetus During Pregnancy

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