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

Spiers, F. W.; Whitwell, J.R.; Beddoe, A H

doi:10.1088/0031-9155/23/3/011

Cited by 32 publications

(20 citation statements)

References 8 publications

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“…[13][14][15][16] His results were the first attempt to characterize the trabecular microstructure, and they have since been used as the basis for almost all subsequent skeletal dosimetry models. [17][18][19][20][21][22][23][24] Today, Spiers' research still serves as a reference data source in trabecular bone dosimetry and his distributions are used to compare the results of this present study.…”

Section: A Previous Studies In Trabecular Bone Dosimetrymentioning

confidence: 99%

Voxel size effects in three‐dimensional nuclear magnetic resonance microscopy performed for trabecular bone dosimetry

et al. 2000

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An important problem in internal dosimetry is the assessment of energy deposition by beta particles within trabecular regions of the skeleton. Recent dosimetry methods for trabecular bone are based on Monte Carlo particle transport simulations within three-dimensional (3D) images of real human bone samples. Nuclear magnetic resonance (NMR) microscopy is a 3D imaging technique of choice due to the large signal differential between bone tissue and the water-filled marrow cavities. Image voxel sizes currently used in NMR microscopy are between 50 microm and 100 microm, but the images are time consuming to acquire and can only be performed at present for in vitro samples. It is therefore important to evaluate what resolution is best suitable in order to properly characterize the trabecular microstructure, to adequately predict the tissue dosimetry, and to minimize imaging time. In this work, a mathematical model of trabecular bone, composed of a distribution of spherical marrow cavities, was constructed. The mathematical model was subsequently voxelized with different voxel sizes (16 microm to 1,000 microm) to simulate 3D NMR images. For each image, voxels are assigned to either bone or marrow according to their enclosed marrow fraction. Next, the images are coupled to the EGS4 electron transport code and absorbed fractions to bone and marrow are calculated for a marrow source of monoenergetic electrons. Radionuclide S values are also determined for the voxelized images with results compared to data calculated for the pure mathematical sample. The comparison shows that for higher energy electrons (>400 keV), good convergence of the results is seen even within images of poor resolution. Above 400 keV, a voxel resolution as large as 300 microm results in dosimetry errors below 5%. For low-energy electrons and high-resolution images, the self-dose to marrow is also determined to within 5% accuracy. Nevertheless, increased voxelization of the image overestimates the surface area of the bone-marrow interface leading to errors in the cross-dose to bone as high as 25% for some low-energy beta emitters.

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Section: A Previous Studies In Trabecular Bone Dosimetrymentioning

confidence: 99%

Voxel size effects in three‐dimensional nuclear magnetic resonance microscopy performed for trabecular bone dosimetry

et al. 2000

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“…Radiation doses to the skeleton in 25g mice assuming 20% ID g-were calculated using a computer model already described by Vaughan et al (1987), and modified to estimate bone marrow doses as described by Spiers (1978). The effects of CaDTPA chelation therapy were calculated similarly but including the decorporation data.…”

Section: Dosimetrymentioning

confidence: 99%

Yttrium-90-EDTMP: a radiotherapeutic agent in the treatment of leukaemias

Keeling

Vaughan²,

Beaney³

1989

Br J Cancer

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Sm_nuary Yttrium-90 chelated by the tetraphosphonate EDTMP achieved a high uptake in bone and a rapid clearance from all soft tissues compared with 90Y nitrilotriacetate, citrate and acetate. The biological half-life of 90Y in the bone was greater than 72h. but the quantity, and therefore dose, could be reduced by 50% using repeated, non-toxic chelation therapy with the calcium salt of DTPA. This treatment should be able to supplement current treatments for leukaemia where the dose of external beam radiation is associated with considerable morbidity.Radiotherapy followed by allogeneic bone marrow transplantation is now a common procedure in the curative therapy of leukaemias. Specific deposition of yttrium into the skeleton demands its delivery in a chemical form with affinity for bone mineral alone. In the past, this has been difficult to achieve because even when chelated, liver uptake has been substantial, presumably because the stabilities of the complexes are insufficient to prevent transferrin binding or colloid formation in vivo. Ideally therefore, targeting agents are required with an intrinsically high affinity for bone, and also a high affinity for the yttrium ion. Compounds with these properties are the phosphonate analogues of polyaminocarboxylic acids, and one in particular (ethylene diamine tetra methylene phosphonate; EDTMP) has already been used to target 153Sm to bone mineral with considerable success (Goeckeler et al.. 1987). Because of chemical similarities between yttrium and the rare earths, EDTMP should form stable complexes with yttrium and carry it-specifically to the bone with comparable efficiency. Here, 90Y-EDTMP complexes have been prepared and compared with other chelating agents for targeting 90Y to the bone in vivo. Similar experiments are also described using the gamma-emitter yttrium-88 to determine the effects of carrier yttrium on tissue distnrbution.The adsorption of yttrium on hydroxyapatite is essentially irreversible under static conditions but elution in vivo is determined by rates of mineral resorption and new-bone formation. When considering its use in leukaemia therapy and bone marrow ablation, it would be advantageous to control the bone marrow dose by removing yttrium from the bone. Early studies aimed at lowering skeletal contamination by yttrium produced in nuclear accidents used repeated EDTA injections, and over a 14-day period, skeletal uptake was reduced to 70% of the control values (Cohn et al.. 1953). Conventionally, diethylene tnramine pentaacetic acid (DTPA) has been the agent of choice for the treatment of heavy metal overdose (Catsch, 1961), and yttnrum also has a high affinity for this chelator. A further aim of this work was to manipulate the biological half-life of 90Y and 88Y in bone by chelation therapy using DTPA, and determine the amount of isotope that could be removed from skeletal tissue. Materials and methods Production of carrier-free yttriwn-90A Dowex 50 W-X8 cation exchange column was loaded with ,20pCi 90Sr-mntrate and washed extensively ...

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“…Spiers and coworkers pioneered much work in this area, and evaluated absorbed dose to the marrow from electron and beta emitters in the volume of mineral bone. 1,2,3 In their method, electrons originating in bone lose energy in the original trabecula, as well as in adjacent marrow cavities and surrounding bone trabeculae, under the continuous slowing down approximation (CSDA). The electrons path through the trabeculae and marrow cavities were chosen stochastically from frequency distributions of chord lengths determined from optical scanning measurements on trabecular bone samples from a few human specimens.…”

Section: Introductionmentioning

confidence: 99%

Evolution and Status of Bone and Marrow Dose Models

Stabin

Eckerman

Bolch

et al. 2002

Cancer Biotherapy and Radiopharmaceuticals

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Investigations at the University of Leeds under the direction of F.W. Spiers in the early 1960s through the late 1970s established the first comprehensive assessment of marrow dose conversion factors (DCFs) for beta-emitting radionuclides within the volume or on the surface of trabecular bone. These DCFs were subsequently used in deriving radionuclide S values for skeletal tissues published in MIRD Pamphlet No. 11. Eckerman re-evaluated this work and extended the methods of Spiers to radionuclides within the marrow to provide DCFs for fifteen skeletal regions in computational models representing individuals of six different ages. These results were used in the MIRDOSE3 software. Bouchet et al. used updated information on regional bone and marrow masses, as well as 3D electron transport techniques, to derive radionuclide S values in skeletal regions of the adult. Although these two efforts are similar in most regards, the models differ in three respects in: (1) the definition of the red marrow region, (2) the definition of a surface source of activity, and (3) the assumption applied in transporting electrons through the trabecular endosteum. In this study, a review of chord-based skeletal models is given, followed by a description of the differences in the Eckerman and Bouchet et al. transport models. Finally, new data from NMR microscopy and radiation transport in trabecular bone is applied to address item (1) above. Dose conversion factors from MIRD 11, the Eckerman model, the Bouchet et al. model, and a revised model are compared for several radionuclides important to internal emitter therapy.

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

Cited by 32 publications

References 8 publications

Voxel size effects in three‐dimensional nuclear magnetic resonance microscopy performed for trabecular bone dosimetry

Voxel size effects in three‐dimensional nuclear magnetic resonance microscopy performed for trabecular bone dosimetry

Yttrium-90-EDTMP: a radiotherapeutic agent in the treatment of leukaemias

Evolution and Status of Bone and Marrow Dose Models

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