Tomographic needles and catheters for optical imaging of prostatic cancer

Early detection of prostatic cancer currently depends on Prostate Serum Antigen (PSA) or TransRectal UltraSound (TRUS). Unfortunately, these techniques are not always reliable indicators for early small lesions still localized within the prostate. This paper presents a feasibility study on the use of "tomographic needles and catheters" for optical imaging of early lesions. Three needles are inserted perianeally into the prostate or two catheters are inserted into the rectal and urethral passages. Each contains a set of optical fibers which terminate at evenly spaced positions along the needle. Each termination serves as either a source or collector for light transmission as each fiber is sequentially illuminated. Application of a tomographic algorithm based on diffuse light transmission between each source/collector pair yields a fuzzy but spectrally informative image of the prostate. This paper addresses the issue of feasibility by asking whether such a technique can distinguish a large zone of slightly alter optical properties (essentially a region of normal tissue) from a small zone of strongly altered optical properties (a tumor). The paper simulates both steady-state and 3-GHz frequency-domain optical measurements.