Human anatomical models have been indispensable to radiation protection dosimetry using Monte Carlo calculations. Existing MIRD-based mathematical models are easy to compute and standardize, but they are simplified and crude compared to human anatomy. This article describes the development of an image-based whole-body model, called VIP-Man, using transversal color photographic images obtained from the National Library of Medicine's Visible Human Project for Monte Carlo organ dose calculations involving photons, electron, neutrons, and protons. As the first of a series of papers on dose calculations based on VIP-Man, this article provides detailed information about how to construct an image-based model, as well as how to adopt it into well-tested Monte Carlo codes, EGS4, MCNP4B, and MCNPX.

A new set of conversion coefficients from kerma free-in-air to absorbed dose and kerma free-in-air to "effective VIP-Man dose" has been calculated for external monoenergetic photon beams from 10 keV to 10 MeV using an image-based whole-body anatomical model. This model, called VIP-Man, was recently developed at Rensselaer from the high-resolution color images of the National Library of Medicine's Visible Human Project. An EGS4-based Monte Carlo user code, named EGS4-VLSI, was developed to efficiently process the extremely large image data in VIP-Man. Irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational, and isotropic geometries. Conversion coefficients from this study are compared with those obtained from two mathematical models, ADAM and EVA. "Effective VIP-Man doses" differ from the previously reported effective dose results by 10%-50% for photons between 100 keV and 10 MeV. Discrepancies are more significant at lower energies and for individual organ doses. Since VIP-Man is a realistic model that contains several tissues that were not previously defined well (or not available) in other models, the reported results offer an opportunity to improve the existing dosimetric data and the mathematical models.

A new set of fluence-to-absorbed dose and fluence-to-effective dose conversion coefficients have been calculated for neutrons below 20 MeV using a whole-body anatomical model, VIP-Man, developed from the high-resolution transverse colour photographic images of the National Library of Medicine's Visible Human Project. Organ dose calculations were performed using the Monte Carlo code MCNP for 20 monoenergetic neutron beams between 1 x 10(-9) MeV and 20 MeV under six different irradiation geometries: anterior-posterior, posterior-anterior, right lateral, left lateral, rotational and isotropic. The absorbed dose for 24 major organs and effective dose results based on the realistic VIP-Man are presented and compared with those based on the simplified MIRD-based phantoms reported in the literature. Effective doses from VIP-Man are not significantly different from earlier results for neutrons in the energy range studied. There are, however, remarkable deviations in organ doses due to the anatomical differences between the image-based and the earlier mathematical models.

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This study presents the results of computations of organ equivalent doses and effective doses for the patient and the primary physician during an interventional cardiological examination. The simulations were carried out for seven x-ray spectra (between 60 kVp and 120 kVp) using the Monte Carlo code MCNP. The voxel-based whole-body model VIP-Man was employed to represent both the patient and the physician, the former lying on the operation table while the latter standing 15 cm from the patient at about waist level behind a lead apron. The x-rays, which were generated by a point source positioned around the table and were directed with a conical distribution, irradiated the patient's heart under five major projections used in a coronary angiography examination. The mean effective doses under LAO45, PA, RAO30, LAO45/CAUD30 and LLAT irradiation conditions were calculated as 0.092, 0.163, 0.161, 0.133 and 0.118 mSv/(Gy cm2) for the patient and 1.153, 0.159, 0.145, 0.164 and 0.027 microSv/(Gy cm2) for the shielded physician. The effective doses for the patient determined in this study were usually lower than the literature data obtained through measurements and/or calculations and the discrepancies could be attributed to the fact that this study computes the effective doses specific to the VIP-Man body model, which lacks an ovarian contribution to the gonadal equivalent dose. The effective doses for the physician agreed reasonably well with the literature data.

A new set of fluence-to-absorbed dose and fluence-to-effective dose conversion coefficients has been calculated for high-energy neutrons using a whole-body anatomical model, VIP-Man, developed from the high-resolution transversal color photographic images of the National Library of Medicine's Visible Human Project. Organ dose calculations were performed using the Monte Carlo code MCNPX for 20 monoenergetic neutron beams between 20 MeV and 10,000 MeV under 6 different irradiation geometries: anterior-posterior, posterior-anterior, left lateral, right lateral, isotropic, and rotational. For neutron Monte Carlo calculations, results based on an image-based whole-body model were not available in the literature. The absorbed dose results for 24 major organs of VIP-Man are presented in the form of tables and selected figures that compare with those based on simplified mathematical phantoms reported in the literature. VIP-Man yields up to 40% larger values of effective dose and many organ doses, thus suggesting that the results reported in the past may not be conservative.

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