Abstract
A new method for calibrating in vivo measurement systems using magnetic resonance imaging and Monte Carlo computations is presented. The method employs the enhanced three-point Dixon technique for producing pure fat and water images of the human body. This information is used to model the scattering media for transport calculations using the current version of the MCNP code (version 4). Development work utilizing a sample fat/water matrix compared well with laboratory measurements. Calibration of an in vivo measurement system using the BOMAB phantom, as compared with Monte Carlo modeling of this procedure, is presented as verification of the MCNP code. Verification of the integrated M RI-MCNP method is shown for a specially designed phantom composed of fat, water, air, and a bone substitute material (acrylic plastic). Implementation of the MRI-MCNP method is demonstrated for an in vivo measurement system. Failures inherent to the current method are discussed, including the inability of the imaging technique to explicitly discriminate between air and bone tissue, and the presence of mismapping errors within the pure fat/water images. Post processing techniques performed on the three-point Dixon images are demonstrated as a potential means of resolving these problems. A modified version of the MCNP code specifically for handling M RI data is also discussed.
Mallett, Michael Wesley (1993). In vivo measurement system calibration using magnetic resonance imaging and Monte Carlo computations. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -1480726.