Terms of use!
The use of our input files is free of charge.
If you use our input files, please cite the following references:
1. Krstic, D., Nikezic, D. External doses in humans from 137Cs in soil. Health Physics 91 (3): 249-257; 2006.
2. Krstic, D., Nikezic, D. Input files with ORNL-mathematical phantoms of the human body for MCNP-4B, Computer Physics communications (176) 33-37; 2007.
3. Krstic, D., Nikezic, D. Conversion coefficients for age dependent ORNL phantoms from 137Cs in soil as a source of external exposure.Nuclear Instruments and Methods A 580 (1) 540-543; 2007.
INPUT FILES WITH ORNL-MATHEMATICAL PHANTOMS OF THE HUMAN BODY FOR MCNP-4B
Nature of problem:
The human body and all organs are represented with equations of 3-D geometrical bodies. All equations and other relevant data (material composition, densities etc.) were programmed as input files for MCNP-4B [1].
Description of phantoms and input files
Analytical models of the human body were described in Oak Ridge National Laboratory (ORNL) publications [2]. All organs of the human body were represented with analytical equations of various three dimensional geometrical bodies. Inequalities were also used to represent some organs. It is out of the scope of this work to give all equations and inequalities used for organs of human phantoms and only the most important characteristics are given here.
The ORNL phantom consisted of three sections: (1) the trunk and arms were represented as elliptical cylinders; (2) legs and feet were two truncated circular cones; and (3) the neck and head were represented with a circular cylinder on which another elliptical cylinder, covered by half of an ellipsoid was situated. Two ellipsoids representing the female breasts were attached to the trunk (of the female phantom). In addition to the geometrical shapes, the chemical constitution and densities of tissues of particular organs were needed for absorbed dose calculations. Three types of tissues, skeletal, lung and soft, with different densities and elemental compositions were present in ORNL phantoms.
In this kind of geometric problem a suitable choice of coordinate system was very important and can significantly reduce the calculation time in some problems. The coordinate origin was taken at the center of the lower base of the trunk section of the phantom. The z axis was directed vertically upward. The y axis and x axis were horizontally directed to the posterior side and towards the left hand side of the phantom, respectively. External shapes of organs were defined as planes, spheres, cylinders, cones, ellipsoids, elliptical cylinders, tori and combinations of these geometrical bodies.
All equations and inequalities for organs of all phantoms, with other relevant information (elemental compositions, volumes, masses etc), were programmed in input files for MCNP-4B code. By combining surfaces through Bull algebra, MCNP-4B forms cells representing various organs. So far, 46 cells and 175 surfaces were used for a male phantom in the input file. The female phantom was more complicated (due to the breasts). In tota ltwo different input files were created: adult maleand adult female.. The 15 year old phantom represented both a 15 year old male and an adult female with portions of ellipsoids attached to the trunk representing female breasts.
Graphical output from MCNP-4B
MCNP-4B enabled graphical representation of the geometry defined in the input file. The output was obtained on the computer screen and represented the cross section of the phantom with the plane defined by the user.
Numerical example
Point like radioactive sources, 137Cs, with an energy of 661.6 keV were situated in front of the face of each phantom at the distance of 1 m. In this way sources were at different heights (corresponding to the height of the phantom face). The absorbed doses per one emitted photon were calculated in all organs of human phantoms.
The energy deposited tally (F6 in MCNP terminology) was used to calculate the absorbed doses presented here. The number of histories was 107 per one calculation.
References
J.F. Briesmeister (Ed.): MCNP - A General Monte Carlo N- Particle Transport Code, Version 4B, LA-12625- M (Los Alamos National Laboratory, Los Alamos, New Mexico, 1997)
K.F. Eckerman, M. Cristy, and J. C. Ryman, The ORNL mathematical phantom series, available at: http//ornl.gov/vlab/mird2.pdf (1996).
