Microwave thermotherapy is a type of ultrasound treatment in which body tissue is exposed to high temperatures. Focused ultrasound waves with high intensity damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs.
Examples for such treatments are the transurethral microwave thermotherapy (TUMT) and transurethral needle ablation (TUNA) that are used for benign prostatic hyperplasia.

See also High Intensity Focused Ultrasound and Ultrasound Therapy.

Transurethral echography or sonography is used to detect small tumors of the urinary bladder or to visualize the urethra and surrounding muscles with special transducers. The bladder neck can be visualized using a transrectal probe.
In addition, high intensity focused ultrasound provides treatment of benign prostatic hyperplasia and adenocarcinoma of the prostate. Small catheter-based sectored tubular or planar transducers with highly directional energy deposition and rotational control are used for precise treatment. Regions of the prostate can be selective coagulatet while monitoring and controlling the treatment with MRI.

See also Urologic Ultrasound, Lithotripsy, Reflux Sonography, Ultrasound Therapy, Interventional Ultrasound and Thermotherapy.

An ultrasound (US) scanning gel has the same conductivity as the human body and is applied between the transducer and the skin surface. Air is a bad conductor of US, so this acoustic gel is used to conducts the sound beam and allows the ultrasound probe to pass smoothly over the skin.
The gel will be removed after the examination, and it will not stain skin or clothing. The basic dermatological requirement of a scanning gel is that it be free of skin irritants or sensitizers. In addition, effective preservatives with low incidence of skin reaction are required to prevent microbiological degradation of the gel. The broad range of patients imaged with ultrasound, from pregnant women and infants to the infirm or elderly dictates that the risk of skin reaction must be minimized.
The effect of small bubbles in the ultrasound couplant under the transducer is to disperse the ultrasound which results in clouding of the image. This effect is most clearly seen on anechoic regions of the image which becomes cloudy. Air bubbles, regardless of their size, degrade the performance of ultrasound in all medical applications including imaging, Lithotripsy and physical therapy.
There are some chemicals, including mineral oil, silicone oil, alcohol, surfactants, and fragrances that can degrade the acoustic lens, destroy bonding, or change the acoustic properties of the lens. The use of scanning gels or lotions in diagnostic ultrasound containing these chemicals should be avoided. In therapeutic ultrasound, ultrasound transmission gels and lotions commonly contain oils and other chemicals not intended for use with diagnostic imaging transducers.

See also Ultrasound Therapy and Ultrasound Physics.

Urologic ultrasound includes the examination of the kidneys, renal vessels, urinary tract, bladder, prostate, and scrotum.
Usual gray scale ultrasound equipment and standard probes are sufficient to examine the kidney parenchyma and renal pelvis, the urinary tract and bladder. Doppler ultrasound is a useful adjunct to kidney ultrasound. High ultrasound system performance is desirable to show the arterial system, because advanced power Doppler is significantly more sensitive to blood flow than standard color Doppler.
Transurethral sonography may be used to examine the bladder and urethra. Transrectal sonography is used to scan and treat the prostate e.g., with brachytherapy or high intensity focused ultrasound. Very small probes are used for these applications. Reflux sonography is especially used in pediatric ultrasound.

See also Ultrasound Imaging Procedures, Ultrasound Picture, Ultrasound Imaging Modes, Lithotripsy, Thermotherapy, Brachytherapy and Ultrasound Therapy.

(HIFU / FUS) High intensity focused ultrasound is used in thermotherapy or thermoablation e.g., for the treatment of benign prostate hyperplasia or under study for the treatment of cancer.
An applied ultrasound probe (see transrectal sonography) focuses sound waves at one spot, elevating the tissue temperature to a point that the tissue destroys. Generally, lower frequencies (from 250 kHz to 2000 kHz) are used than for medical diagnostic ultrasound, but significantly higher time-averaged intensities.

See also Magnetic Resonance Guided Focused Ultrasound, Low Intensity Pulsed Ultrasound, and Lithotripsy.