Abstract

A Monte Carlo simulation has been developed to evaluate the quality of the images obtained by time resolved transillumination particularly in the field of breast cancer detection. The 3-D Monte Carlo simulation computes the transport of a light pulse through biological tissues, each photon trajectory being determined by the Heynyey-Greenstein phase function. The simulation suggests that time resolved imaging by transillumination of the breast should be invaluable in the near infra-red (NIR) range. The enhancement of the transfer function by the introduction of time resolved detection is however limited by the contribution of noise for short integration times. With the theory of the Image Quality Index^[1] derived from the statistical decision theory, the estimated smallest diameter of a detectable carcinoma located in the breast has been computed on the basis of the signal to noise ratio. This signal to noise ratio is determined from the transfer function of the system and the Wiener noise spectrum. The estimated diameter of the smallest detectable sphere is defined as the Image Quality Index (or IQI) and its minimal value in function of the time integration is around 3 mm for a 20 mm thick slab (Fig. 1). Furthermore, the simulated images of an absorbing sphere (approximating the carcinoma) within a homogeneous medium (approximating the surrounding tissue) show a significant improvement of the image with short integration time (Fig. 2).

© 1992 IQEC