Monte Carlo Simulation in Nuclear Medicine

This chapter describes an effort to improve both sensitivity and accuracy, by the use of an advanced assay technique calibrated by Monte Carlo simulation. Iodine-123 provides an almost ideal solution; due to its short half life and limited availability, however, many laboratories use 131I or 99mTc. As applied to photon transport for the present problem, the Monte Carlo method can be described as follows. Anatomical and other regions of interest are described by mathematical equations. The geometrical model included neck, head, shoulders and trunk, thyroid gland, trachea, and spinal column, as well as detectors. Most Monte Carlo simulations have been performed on large computing machines. There are many pseudo-random number generators available for these machines. Relative to the usual comparison-to-standard method, advantages of the coincidence method are: thyroid radioiodine can be assayed without reference to a standard, accuracy is improved, and the detection limit is improved about tenfold.