IntroductionProstate cancer is the second most common cancer found in men in the United States and a leading factor in cancer-related deaths. It is a major health issue causing a dramatic impact on the lifestyle of elderly men. Treatment is, however, available, but most successful when the cancer is in an early stage; treatment of an advanced cancer, especially if the spread is beyond the prostate, can be very complex and in many cases incurable. To find the cancer still in an early stage it important for men over the age of 50 to get an annual screening. Presently, several different screening techniques are used to diagnose the presence of the prostate carcinoma, the most common of which are digital rectal examination (DRE), prostate specific antigen (PSA) test and transrectal ultrasound (TRUS). In cases where the presence of cancer is highly suspected, a biopsy usually follows the screening to fully confirm the diagnosis.The DRE is a procedure in which the doctor checks the size, shape, and texture of the prostate by inserting a finger into the rectum of the patient. This procedure is not accurate because only the back wall of the prostate is examined (the middle and front of the prostate remain undiagnosed) and only if the cancer is in an already advanced stage, will a noticeable difference in the texture be recognized.The PSA test, which commonly accompanies the DRE, measures the amount of prostate specific antigen in the blood. A high PSA level usually indicates the presence of cancer, however, because common diseases and infections of the prostate, such as benign prostatic hypertrophy (BPH) and prostatitis, cause an elevation in the PSA level the accuracy of the diagnosis cannot be determined. Furthermore, many patients with normal PSA levels were later diagnosed with cancer. TRUS is the most common medical imaging modality used in the screenings, followed by X-ray computer axial tomography (CAT) which is used to diagnose the spread of the cancer beyond the prostate. TRUS is inexpensive, provides the radiologist with enough detail to recognize any abnormalities within the prostate, and can also be used in guiding a biopsy in real-time. TRUS usually accompanies the DRE and PSA test, because it does not provide enough detail to be used as the only screening technique in the diagnosis.In a typical TRUS screening, the prostate is manually delineated in the ultrasound image to calculate its size and volume, which are additional details used to support the diagnosis. Because manual segmentation of the prostate is very tedious and usually prolongs the diagnosis, automated delineation of the prostate is necessary. Computer aided segmentation leads to faster, and more accurate and precise results, without much interference from the doctor, [7]. Segmentation of the prostate within the ultrasound image can be further used for real-time biopsy guidance, automatic volume determination, and computer automated analysis of the prostate for cancer and abnormal regions.Different methods of delineating the prostate, such as t...