Calculated beta-ray dose factors for trabecular bone

Whitwell, J.R.; Spiers, F. W.

doi:10.1088/0031-9155/21/1/002

Cited by 69 publications

(60 citation statements)

References 7 publications

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“…A Monte Carlo method of calculating /^-particle dose factors in trabecular bone (Whitwell & Spiers, 1976) has overcome the principal difficulties of bone dosimetry referred to in the introduction. The method is based on a quantitative description of trabecular structure as an omni-directional distribution of path lengths through the marrow spaces and through the trabeculae and this avoids assumptions of simple geometrical shapes for cavities in what is essentially an "irregular" assemblage of cavities and trabeculae.…”

Section: Calculation Of the Theoretical Dose Enhancement In Experimenmentioning

confidence: 99%

Photoelectron Enhancement of the Absorbed Dose from X Rays to Human Bone Marrow: Experimental and Theoretical Studies

King¹,

Spiers²

1985

BJR

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A technique is described by which lithium fluoride powder is introduced into the marrow cavities in specimens of human trabecular bone to determine the excess photoelectron dose to marrow, when bone is irradiated by X rays of energies between 20 keV and 140 keV. Three specimens of trabecular bone, containing respectively 10, 15 and 25% bone by volume, were investigated and the results compared with those derived on the basis of earlier calculations for mono-energetic electrons by Whitwell. Reasonable agreement was found between the experimental and theoretical results, although there was some indication that scatter influenced the practical measurements at the higher photon energies. Theoretical calculations are then used to derive photoelectron dose enhancements for complete bones from the measured results on the bone specimens, and mean enhancements of the marrow dose for the whole human skeleton are calculated for subjects aged 44, 9 and 1.7 years.

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Section: Calculation Of the Theoretical Dose Enhancement In Experimenmentioning

confidence: 99%

Photoelectron Enhancement of the Absorbed Dose from X Rays to Human Bone Marrow: Experimental and Theoretical Studies

King¹,

Spiers²

1985

BJR

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“…Spiers and his students at the University of Leeds in the late 1960's to late 1970's (Spiers 1966;Spiers et al 1978Spiers et al , 1981. The Leeds research group developed a novel optical scanning system from which chord-length distributions were acquired in the lumbar vertebrae for several subjects, as well as at several skeletal sites of a 1.7-y-old child (5 sites), a 9-y-old child (5 sites), and a 44-y-old male (7 sites) (Beddoe 1976;Beddoe et al 1976;Whitwell 1973;Whitwell and Spiers 1976). These chord-length distributions were used by Whitwell to derive dose factors (marrow and endosteal doses per unit skeletal activity burden) for several radionuclides of interest in radiation protection (Whitwell 1973;Whitwell and Spiers 1976).…”

Section: Icrp Skeletal Model For the Adult Male Radiation Workermentioning

confidence: 99%

A Comparison of Skeletal Chord-Length Distributions in the Adult Male

Shah

Rajon²,

Jokisch³

et al. 2005

Health Physics

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In radiation protection, skeletal dose estimates are required for the tissues of the hematopoietically active bone marrow and the osteogenic cells of the trabecular and cortical endosteum. Similarly, skeletal radiation dose estimates are required in therapy nuclear medicine in order to develop dose-response functions for myelotoxicity where active bone marrow is generally the dose-limiting organ in cancer radioimmunotherapy. At the present time, skeletal dose models in both radiation protection and medical dosimetry are fundamentally reliant on a single set of chord-length distribution measurements performed at the University of Leeds in the late 1970's for a 44-y-old male subject. These distributions describe the relative frequency at which linear pathlengths are seen across both the marrow cavities and bone trabeculae in seven individual bone sites: vertebrae (cervical and lumbar), proximal femur (head and neck), ribs, cranium (parietal bone), and pelvis (iliac crest). In the present study, we present an alternative set of chord-length distribution data acquired within a total of 14 skeletal sites of a 66-y-old male subject. The University of Florida (UF) distributions are assembled via 3D image processing of microCT scans of physical sections of trabecular spongiosa at each skeletal site. In addition, a tri-linear interpolation Marching Cube algorithm is employed to smooth the digital surfaces of the bone trabeculae while chord-length measurements are performed. A review of mean chord lengths indicate that larger marrow cavities are noted on average in the UF individual for the cervical vertebrae (1,038 vs. 910 microm), lumbar vertebrae (1,479 vs. 1,233 microm), ilium (1,508 vs. 904 microm), and parietal bone (812 vs. 389 microm), while smaller marrow cavities are noted in the UF individual for the femoral head (1,043 microm vs. 1,157 microm), the femoral neck (1,454 microm vs. 1,655 microm), and the ribs (1,630 microm vs. 1,703 microm). The mean chord-lengths for the bone trabeculae show close agreement for both individuals in the ilium (approximately 240 microm) and cervical vertebrae (approximately 280 microm). Thicker trabeculae were seen on average in the UF individual for the femoral head (ratio of 1.50), femoral neck (ratio of 1.10), lumbar vertebrae (ratio of 1.29), and ribs (ratio of 1.14), while thinner trabeculae were seen on average in the UF individual for the parietal bone of the cranium (ratio of 0.92). In two bone sites, prominent discrepancies in chord distribution shape were noted between the Leeds 44-y-old male and the UF 66-y-old male: (1) the bone trabeculae in the ribs, and (2) the marrow cavities and bone trabeculae within the cranium.

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“…Recent calculations of the energy deposition in the endosteal layer of trabecular bone (Eckerman, in preparation) indicates that in the earlier work of Whitwell and Spiers (1976) the energy deposition was underestimated. In their study, the assumption had to be made that the energy deposited per beta particle traversing the endosteal region was the same as the energy deposited by a particle traversing an average path through the region.…”

Section: \ U1mentioning

confidence: 99%

“…Using these data and Monte Carlo sampling techniques, the flight of beta particles can be simulated, as outlined above. The results of such calculations by Whitwell and Spiers (1976) are shown in Table A-1 along with the discriptive parameters for the various bones.…”

Section: As Estimation Of Energy Depositionmentioning

confidence: 99%