ABSTRACT
Monte Carlo modeling of the transmission and attenuation of internal radiation sources has led to a better understanding of the image formation process in diagnostic radiology. Since much higher statistics are necessary to model imaging simulations (compared to dosimetry simulations), the speed of computing individual gamma ray histories is of paramount importance for imaging physics calculations. As a result, the software phantoms modeled in these imaging simulations have historically been highly simpli‰ed, limited to simple point, rod, and slab shapes of sources and attenuating media, in order to achieve reasonable turnaround times for Monte Carlo simulations. Such simple geometries are useful in studying more fundamental issues of scatter and attenuation, but clinically realistic distributions cannot be adequately evaluated. The modeling of the intricate protuberances and convolutions of human internal structures are necessary for such evaluations. It is, therefore, essential in imaging research to enhance our computer models in order to insure that our simulations are representative of the reality we try to emulate. Due to the current availability of inexpensive memory and disk storage as well as ever-increasing execution speeds, software models are currently being made more complex in order to model the human anatomy more realistically and still permit statistical Monte Carlo computations to be completed within acceptable time limits. In this chapter, we discuss some of
CONTENTS
Early Anthropomorphic Phantoms .................................................................... 32 Mathematical Phantoms ......................................................................................33 Voxel-Based Phantoms .........................................................................................35 Hybrid Phantoms .................................................................................................. 37 Discussion .............................................................................................................. 39 References ...............................................................................................................42
