Aspects of the dosimetry of alpha-emitting radionuclides in bone with particular emphasis of <sup>226</sup>Ra and <sup>239</sup>Pu

Thorne, M C

doi:10.1088/0031-9155/22/1/005

Cited by 21 publications

(8 citation statements)

References 10 publications

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“…Figure 4a gives a plot of the absorbed dose, D , versus cellular radial position in the marrow cavity. The limited range of the dose deposition is clearly illustrated in this plot and is consistent with results from previous publications (9, 33). Figure 4b shows the dose cell histograms for cells within both the shallow marrow and endosteal layer.…”

Section: Resultssupporting

confidence: 92%

A bone marrow toxicity model for²²³Ra alpha-emitter radiopharmaceutical therapy

et al. 2012

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Purpose Ra-223, an α-particle emitting bone-seeking radionuclide, has recently been used in clinical trials for osseous metasteses of prostate cancer. We investigated the relationship between absorbed fraction-based red marrow dosimetry and cell level-dosimetry using a model that accounts for the expected localization of this agent relative to marrow cavity architecture. We show that cell level-based dosimetry is essential to understanding potential marrow toxicity. Methods The GEANT4 software package was used to create simple spheres representing marrow cavities. Ra-223 was positioned on the trabecular bone surface or in the endosteal layer and simulated for decay, along with the descendants. The interior of the sphere was divided into cell-size voxels and the energy was collected in each voxel and interpreted as dose cell histograms. The average absorbed dose values and absorbed fractions were also calculated in order to compare those results with previously published values. Results The absorbed dose was predominantly deposited near the trabecular surface. The dose cell histograms results were used to plot the percentage of cells that received a potentially toxic absorbed dose (2 or 4 Gy) as a function of the average absorbed dose over the marrow cavity. The results show (1) a heterogeneous distribution of cellular absorbed dose, strongly dependent on the position of the cell within the marrow cavity; and (2) that increasing the average marrow cavity absorbed dose, or equivalently, increasing the administered activity resulted in only a small increase in potential marrow toxicity (i.e., the number of cells receiving more than 4 or 2 Gy), for a range of average marrow cavity absorbed doses from 1 Gy to 20 Gy. Conclusion The results from the trabecular model differ markedly from a standard absorbed fraction method while presenting comparable average dose values. These suggest that increasing the amount of radioactivity may not substantially increase the risk of toxicity, a result unavailable to the absorbed fraction method of dose calculation.

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Section: Resultssupporting

confidence: 92%

A bone marrow toxicity model for²²³Ra alpha-emitter radiopharmaceutical therapy

et al. 2012

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“…The formula also assumes uniform deposition of energy along the a-particle track. Thorne (1977) has calculated the same dose factors, SDS/Dskel, for 239Pu using a Monte Carlo method, realistic data for the variation of energy loss along the a-particle track and a value of S/V of 48.5 cm2/cm3. If the results of Marshall et al and Thorne are adjusted to our value of S/V = 60.8 cm2/cm3, the dose factors averaged over a layer of tissue 0-10 pm from the plane source are respectively 10.0 (Marshall et al) and 8.1 (Thorne).…”

Section: Discussionmentioning

confidence: 99%

“…Both Marshall et al (1974) and Thorne (1977) give results for SDS/Dskel averaged over plane layers of thickness varying from 5 to 30 pm adjacent to a thin plane source, and these are given in fig. 3, where both sets of data are Thlckness of endosteal layer (pm1 It is to be expected that the assumption of a uniform energy deposition along the u-particle track will overestimate the average dose in layers of small thickness where much of the energy is delivered by the initial low-LET parts of the tracks.…”

Section: Discussionmentioning

confidence: 99%

Calculated dose factors for the radiosensitive tissues in bone irradiated by surface-deposited radionuclides

Spiers

Whitwell

Beddoe

1978

pmb

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The method of calculating dose factors for the haemopoitic marrow and endosteal tissues in human trabecular bone, used by Whitwell and Spiers for volume-seeking radionuclides, has been developed for the case of radionuclides which are deposited as very thin layers on bone surfaces. The Monte Carlo method is again used, but modifications to the computer program are made to allow for a surface rather than a volume source of particle emission. The principal change is the introduction of a surface-orientation factor which is shown to have a value of approximately 2, varying slightly with bone structure. Result are given for beta-emitting radionuclides ranging from 171Tm (E (E beta=0.025 MeV) to 90Y(E beta = 0.93MeV), and also for the alpha-emitter 239Pu. It is shown that where the particle ranges are short compared with the dimensions of the bone structures the dose factors for the surface seekers are much greater than those for the volume seekers. For long range particles the dose factors for surface and volume-seeking radionuclides converge. Comparisons are given relating the dose factors calculated in this paper on the basis of measured bone structures to those of other workers based on single plane geometry.

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“…Radium, as a `bone-volume'-seeker, preferentially irradiates cells closest to the bone surface, notably those within 40µm (Thorne 1977) . The above results suggest that this is not the case .…”

Section: Distribution Of Cell Populationsmentioning

confidence: 99%

Meeting Report (with Extended Abstracts)

1988

International Journal of Radiation Biology

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Aspects of the dosimetry of alpha-emitting radionuclides in bone with particular emphasis of ²²⁶Ra and ²³⁹Pu

Cited by 21 publications

References 10 publications

A bone marrow toxicity model for²²³Ra alpha-emitter radiopharmaceutical therapy

A bone marrow toxicity model for²²³Ra alpha-emitter radiopharmaceutical therapy

Calculated dose factors for the radiosensitive tissues in bone irradiated by surface-deposited radionuclides

Meeting Report (with Extended Abstracts)

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Aspects of the dosimetry of alpha-emitting radionuclides in bone with particular emphasis of 226Ra and 239Pu

Cited by 21 publications

References 10 publications

A bone marrow toxicity model for223Ra alpha-emitter radiopharmaceutical therapy

A bone marrow toxicity model for223Ra alpha-emitter radiopharmaceutical therapy

Calculated dose factors for the radiosensitive tissues in bone irradiated by surface-deposited radionuclides

Meeting Report (with Extended Abstracts)

Contact Info

Product

Resources

About

Aspects of the dosimetry of alpha-emitting radionuclides in bone with particular emphasis of ²²⁶Ra and ²³⁹Pu

A bone marrow toxicity model for²²³Ra alpha-emitter radiopharmaceutical therapy

A bone marrow toxicity model for²²³Ra alpha-emitter radiopharmaceutical therapy