Skeletal absorbed fractions for electrons in the adult male: considerations of a revised 50- m definition of the bone endosteum

Bolch, Wesley E.; Shah, Amish P.; Watchman, Christopher J; Jokisch, Derek W.; Patton, Phillip W.; Rajon, Didier A.; Zankl, M.; Petoussi-Henss, Nina; Eckerman, K.F.

doi:10.1093/rpd/ncm268

Cited by 31 publications

(24 citation statements)

References 9 publications

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“…The MASH2 bone endosteum mass is almost 16% smaller than the reference value given in ICRP110. ICRP110 refers to a paper of Bolch et al (2007), but unfortunately the authors did not provide enough information which could help to explain the disagreement. However, good agreement was found with data published by Watchman et al (2007), who used a completely different method for the calculation of skeletal tissue masses.…”

Section: Segmentation Of Skeletal Tissuesmentioning

confidence: 99%

Electron absorbed fractions of energy andS-values in an adult human skeleton based on µCT images of trabecular bone

Kramer¹,

Richardson²,

Cassola³

et al. 2011

Phys. Med. Biol.

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When the human body is exposed to ionizing radiation, among the soft tissues at risk are the active marrow (AM) and the bone endosteum (BE) located in tiny, irregular cavities of trabecular bone. Determination of absorbed fractions (AFs) of energy or absorbed dose in the AM and the BE represent one of the major challenges of dosimetry. Recently, at the Department of Nuclear Energy at the Federal University of Pernambuco, a skeletal dosimetry method based on µCT images of trabecular bone introduced into the spongiosa voxels of human phantoms has been developed and applied mainly to external exposure to photons. This study uses the same method to calculate AFs of energy and S-values (absorbed dose per unit activity) for electron-emitting radionuclides known to concentrate in skeletal tissues. The modelling of the skeletal tissue regions follows ICRP110, which defines the BE as a 50 µm thick sub-region of marrow next to the bone surfaces. The paper presents mono-energetic AFs for the AM and the BE for eight different skeletal regions for electron source energies between 1 keV and 10 MeV. The S-values are given for the beta emitters (14)C, (59)Fe, (131)I, (89)Sr, (32)P and (90)Y. Comparisons with results from other investigations showed good agreement provided that differences between methodologies and trabecular bone volume fractions were properly taken into account. Additionally, a comparison was made between specific AFs of energy in the BE calculated for the actual 50 µm endosteum and the previously recommended 10 µm endosteum. The increase in endosteum thickness leads to a decrease of the endosteum absorbed dose by up to 3.7 fold when bone is the source region, while absorbed dose increases by ∼20% when the beta emitters are in marrow.

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Section: Segmentation Of Skeletal Tissuesmentioning

confidence: 99%

Electron absorbed fractions of energy andS-values in an adult human skeleton based on µCT images of trabecular bone

Kramer¹,

Richardson²,

Cassola³

et al. 2011

Phys. Med. Biol.

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“…12 However, it has recently been suggested that in addition to cortical bone surfaces adjacent to spongiosa, medullary cortical bone surfaces of arm and leg bones should also be taken into account when determining the equivalent dose to the BSC. 19 Medullary cortical bone surfaces form the walls of large, tubelike cavities in the upper and lower arm and leg bones, also called "long bones," filled for adults only with yellow bone marrow ͑YBM͒, which is not considered to be a target tissue for skeletal dosimetry.…”

Section: Iic Medullary Cortical Bone Surfacesmentioning

confidence: 99%

Skeletal dosimetry for external exposures to photons based on images of spongiosa: Consideration of voxel resolution, cluster size, and medullary bone surfaces

et al. 2009

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Skeletal dosimetry based on microCT images of trabecular bone has recently been introduced to calculate the red bone marrow (RBM) and the bone surface cell (BSC) equivalent doses in human phantoms for external exposure to photons. In order to use the microCT images for skeletal dosimetry, spongiosa voxels in the skeletons were replaced at run time by so-called micromatrices, which have exactly the size of a spongiosa voxel and contain segmented trabecular bone and marrow micro-voxels. A cluster (=parallelepiped) of 2 x 2 x 2 = 8 micromatrices was used systematically and periodically throughout the spongiosa volume during the radiation transport calculation. Systematic means that when a particle leaves a spongiosa voxel to enter into a neighboring spongiosa voxel, then the next micromatrix in the cluster will be used. Periodical means that if the particle travels through more than two spongiosa voxels in a row, then the cluster will be repeated. Based on the bone samples available at the time, clusters of up to 3 x 3 x 3 = 27 micromatrices were studied. While for a given trabecular bone volume fraction the whole-body RBM equivalent dose showed converging results for cluster sizes between 8 and 27 micromatrices, this was not the case for the BSC equivalent dose. The BSC equivalent dose seemed to be very sensitive to the number, form, and thickness of the trabeculae. In addition, the cluster size and/or the microvoxel resolution were considered to be possible causes for the differences observed. In order to resolve this problem, this study used a bone sample large enough to extract clusters containing up to 8 x 8 x 8 = 512 micro-matrices and which was scanned with two different voxel resolutions. Taking into account a recent proposal, this investigation also calculated the BSC equivalent dose on medullary surfaces of cortical bone in the arm and leg bones. The results showed (1) that different voxel resolutions have no effect on the RBM equivalent dose but do influence the BSC equivalent dose due to voxel effects by up to 5% for incident photon energies up to 200 keV, (2) that the whole-body BSC equivalent dose calculated with a cluster with 2 x 2 x 2 = 8 micromatrices is consistent with results received with clusters of up to 8 x 8 x 8 = 512 micromatrices, and (3) that for external whole-body exposure the inclusion of the BSC on medullary surfaces of cortical bone has a negligible effect on the whole-body BSC equivalent dose.

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“…BSC can also be found on the surfaces of cortical bone, but "because cell proliferation is greater on trabecular than on cortical surfaces, it is to be expected that malignant transformation will occur more readily in the endosteum of trabecular bone" (Spiers 1974). Discussion about the location and the distribution of the two skeletal tissues at risk is still ongoing with respect to the revision of the thickness of the BSC layer from 10 to 50 m, the exclusion of the Haversian canals of cortical bone, the inclusion of cortical surfaces of the medullary cavities (Bolch et al 2007), the consideration of trabecular bone remodelling (Richardson et al 2007) and the inhomogeneous distribution of RBM cells in the marrow (Watchman et al 2007a).…”

Section: The Skeletal Tissues At Riskmentioning

confidence: 99%

Skeletal dosimetry for external exposure to photons based on µCT images of spongiosa from different bone sites

et al. 2007

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Micro computed tomography (microCT) images of human spongiosa have recently been used for skeletal dosimetry with respect to external exposure to photon radiation. In this previous investigation, the calculation of equivalent dose to the red bone marrow (RBM) and to the bone surface cells (BSC) was based on five different clusters of micro matrices derived from microCT images of vertebrae, and the BSC equivalent dose for 10 microm thickness of the BSC layer was determined using an extrapolation method. The purpose of this study is to extend the earlier investigation by using microCT images from eight different bone sites and by introducing an algorithm for the direct calculation of the BSC equivalent dose with sub-micro voxel resolution. The results show that for given trabecular bone volume fractions (TBVFs) the whole-body RBM equivalent dose does not depend on bone site-specific properties or imaging parameters. However, this study demonstrates that apart from the TBVF and the BSC layer thickness, the BSC equivalent dose additionally depends on a so-called trabecular bone structure (TBS) effect, i.e. that the contribution of photo-electrons released in trabecular bone to the BSC equivalent dose also depends on the bone site-specific structure of the trabeculae. For a given bone site, the TBS effect is also a function of the thickness of the BSC layer, and it could be shown that this effect would disappear almost completely, should the BSC layer thickness be raised from 10 to 50 microm, according to new radiobiological findings.

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Skeletal absorbed fractions for electrons in the adult male: considerations of a revised 50- m definition of the bone endosteum

Cited by 31 publications

References 9 publications

Electron absorbed fractions of energy andS-values in an adult human skeleton based on µCT images of trabecular bone

Electron absorbed fractions of energy andS-values in an adult human skeleton based on µCT images of trabecular bone

Skeletal dosimetry for external exposures to photons based on images of spongiosa: Consideration of voxel resolution, cluster size, and medullary bone surfaces

Skeletal dosimetry for external exposure to photons based on µCT images of spongiosa from different bone sites

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