1. NAME AND TITLE

MRIPP 1.0: Magnetic Resonance Image Phantom Code System to Calibrate in vivo Measurement Systems.

2. CONTRIBUTORS

Lawrence Livermore National Laboratory, Livermore, California.

Experimental and Mathematical Physics Consultants, Gaithersburg, Maryland.

3. CODING LANGUAGE AND COMPUTER

C++ 4.0; PC 386. (C00655/PC386/00).

4. NATURE OF PROBLEM SOLVED

MRIPP provides relative calibration factors for the in vivo measurement of internally deposited photon emitting radionuclides within the human body. The code includes a database of human anthropometric structures (phantoms) that were constructed from whole body Magnetic Resonance Images. The database contains a large variety of human images with varying anatomical structure. Correction factors are obtained using Monte Carlo transport of photons through the voxel geometry of the phantom. Correction factors provided by MRIPP allow users of in vivo measurement systems (e.g., whole body counters) to calibrate these systems with simple sources and obtain subject specific calibrations. Note that the capability to format MRI data for use with this system is not included; therefore, one must use the phantom data included in this package.

MRIPP provides a simple interface to perform Monte Carlo simulation of photon transport through the human body. MRIPP also provides anthropometric information (e.g., height, weight, etc.) for individuals used to generate the phantom database.

A modified Voxel version of the Los Alamos National Laboratory MCNP4A code is used for the Monte Carlo simulation. The Voxel version Fortran patch to MCNP4 and MCNP4A (Monte Carlo N-Particle transport simulation) and the MCNP executable are included in this distribution, but the MCNP Fortran source is not included. It was distributed by RSICC as CCC-200 but is now obsoleted by the current release MCNP4B.

5. METHOD OF SOLUTION

Magnetic Resonance Image data are used as input to a voxel version of MCNP. The voxel version of MCNP recognizes the presence of voxel data files (material.*) and performs photon transport using a fictitious cross section method. Calculations are performed for a simple source geometry and for a MRI input file. The ratio of these to values for the same energy line provides a correction factor for calibration.

6. RESTRICTIONS OR LIMITATIONS

Some materials may be composed of eight or fewer elements. Other materials may be composed of four or fewer elements. No more than 20 photon energies may be defined. Simple sources may have only one layer of housing/shielding. Up to 10 transformation cards are allowed.

7. TYPICAL RUNNING TIME

Execution of this software requires 1 to 10 hours for a million photon histories through a 12 to 16 million voxel phantom. Execution speed improves with higher energy photons. Multiple photon energies will slow the execution slightly, however execution speed will largely depend on the lowest photon energy. Faster computers are already reducing these times.

8. COMPUTER HARDWARE REQUIREMENTS

PC: 386 (or later), 60 MHz, 80 Mbyte free disk space, 8 Mbyte RAM (16 MB preferred), and compatible printer.

9. COMPUTER SOFTWARE REQUIREMENTS

DOS 5.0 or later. All other required software is provided with MRIPP. MRIPP was compiled in Borland C++ 4.0 under DOS 6 on a Pentium processor. The Voxel patch to MCNP was compiled with Lahey Fortran 5.01 on a 486. Note that the MRIPP source files are included, but the MCNP source is NOT included. MRIPP can be run in a DOS window of Windows95.

10. REFERENCES

D. P. Hickman, M. Firpo, "Magnetic Resonance Image Phantom," UCRL-MA-118455 (June 1997).

J. F. Briesmeister, ed. "MCNP - A General Monte Carlo N-Particle Transport Code, Version 4A," LA-12625-M (November 1993).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one CD-ROM written in self-extracting compressed DOS files which contain MRIPP C++source, MRIPP executables (including the Voxel executable version of MCNP4A), phantom files, and electronic documentation. Note that the MCNP Fortran source files are not included in this distribution.

12. DATE OF ABSTRACT

July 1997.