The prostate is a walnut-shaped gland surrounding the beginning of the urethra in front of the rectum and below the bladder. The prostate can become enlarged (particularly in men over age 50) and develop diseases like prostate cancer or inflammation (prostatitis). A large tumor can be felt by a rectal examination. The most effective way of detecting the early signs of prostate cancer is a combination of a prostate-specific antigen (PSA) blood test and a prostate ultrasound examination.
An abnormally high level of PSA can indicate prostate cancer or other prostate diseases such as benign prostatic hypertrophy or prostatitis. The transrectal sonography is an important diagnostic ultrasound procedure in determining whether there is any benign enlargement of the prostate or any abnormal nodules.
The imaging is performed with a rectal probe, yielding high resolution. High resolution 3D ultrasound provides reliable and accurate determination of the size and the location of cancer. Additionally, ultrasound elastography is a technique in development to improve the specificity and sensitivity of cancer detection. Ultrasound is also used to detect whether cancerous tissue is still only within the prostate or whether it has begun to spread out and to guide a diagnostic biopsy or ultrasound therapy.

See also Brachytherapy, and High Intensity Focused Ultrasound.

The proximity sensor is designed to measure the distance from the sensor face to a target. The level sensor is the same as a proximity sensor except with the surface of a fluid or bulk solid as the target.

Biological flows vary throughout the cardiac cycle. The analog output can be filtered to give a pulsatile flow or mean flow signal.

(PI) The pulsatility index quantifies the shape of the blood velocity waveform by the ratio of the flow volume amplitude and mean flow volume.

See also Pulsatile Flow.

(IPA) The pulse average intensity is the average intensity during the ultrasound pulse.