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 'Thermal Effect' 
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Result : Searchterm 'Thermal Effect' found in 1 term [] and 11 definitions [], (+ 4 Boolean[] results)
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Thermal EffectMRI Resource Directory:<br> - UltraSound Physics -
 
The thermal effect of ultrasound is caused by absorption of the ultrasound beam energy. As the ultrasound waves are absorbed, their energy is converted into heat. The higher the frequency, the greater the absorbed dose, converted to heat according the equation: f = 1/T where T is the period as in simple harmonic motion. Ultrasound is a mechanical energy in which a pressure wave travels through tissue. Heat is produced at the transducer surface and also tissue in the depth can be heated as ultrasound is absorbed.
The thermal effect is highest in tissue with a high absorption coefficient, particularly in bone, and is low where there is little absorption. The temperature rise is also dependent on the thermal characteristics of the tissue (conduction of heat and perfusion), the ultrasound intensity and the length of examination time. The intensity is also dependent on the power output and the position of the tissue in the beam profile. The intensity at a particular point can be changed by many of the operator controls, for example power output, mode (B-mode, color flow, spectral Doppler), scan depth, focus, zoom and area of color flow imaging. The transducer face and tissue in contact with the transducer can be heated.
See also Thermal Units Per Hour and Ultrasound Radiation Force.
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 Further Reading:
  Basics:
Guidelines for the Safe Use of Diagnostic Ultrasound(.pdf)Open this link in a new window
   by folk.ntnu.no    
US Resources  
Directories - Rental - Education - Vascular - Research Labs - Carotid
 
Absorbed DoseMRI Resource Directory:<br> - UltraSound Physics -
 
In physics, the absorbed dose is the ultrasonic power absorbed per unit of mass of an object, and is measured in watts per kilogram (W/kg). The absorption increases with ultrasound intensity and frequency.
The thermal index describes the potential for heating of the patient's tissue due to the application of energy.
See also Thermal Effect, Ultrasound Safety, Ultrasound Regulations.
Radiology-tip.comRadiation Absorbed Dose
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Radiology-tip.comAbsorbed Dose
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 Further Reading:
  Basics:
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
US Resources  
Renal - Kidney - Intravascular - Services and Supplies - Obstetric - Supplies and Accessories
 
AbsorptionMRI Resource Directory:<br> - UltraSound Physics -
 
Absorption is the transfer of energy from the ultrasound beam to the tissue. Absorption of acoustic energy increases the temperature of the tissue. This phenomenon, known as thermal radiation, has been used with some limited success to treat cancerous lesions in the breast and prostate gland. The absorption is proportional to the frequency.
See also Absorbed Dose, Thermal Effect, Thermotherapy.
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 Further Reading:
  Basics:
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
  News & More:
ultrasound characteristics of breast cancerOpen this link in a new window
   by rad.usuhs.mil    
Ultrasound in diagnostic and therapyOpen this link in a new window
   by www.anst.uu.se    
Searchterm 'Thermal Effect' was also found in the following services: 
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RF Thermal AblationMRI Resource Directory:<br> - Ultrasound Guided Interventions -
 
Radio frequency (RF) thermal ablation is a technique that uses the thermal effect created by radio frequencies to destroy tumors or metastases in the liver.
This treatment for liver cancer can accurately be evaluated by contrast enhanced ultrasound. RF thermal ablation monitored by sonography can lead to immediate re-treatment, preventing a second anesthesia and shortening the hospitalization time.
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 Further Reading:
  Basics:
Radiofrequency Thermal Ablation versus Percutaneous Ethanol Injection for Small Hepatocellular Carcinoma [letter]Open this link in a new window
   by radiology.rsnajnls.org    
Radiofrequency Tissue Ablation: Effect of Hepatic Blood Flow Occlusion on Thermal Injuries Produced in Cirrhotic LiversOpen this link in a new window
2003   by www.ncbi.nlm.nih.gov    
US Resources  
Doppler UltraSound - Supplies and Accessories - Thyroid - Directories - UltraSound Physics - Journals
 
Side EffectMRI Resource Directory:<br> - Safety -
 
Diagnostic ultrasound imaging has no known risks or long-term side effects. Discomfort to the patient is very rare if the sonogram is accurately performed by using appropriate frequencies and intensity ranges. However, the application of the ALARA principle is always recommended.
There are reports of low birth weight of babies after applying more than the recommended ultrasound examinations during pregnancy. Women who think they might be pregnant should raise this issue with the doctor before undergoing an abdominal ultrasound, to avoid any harm to the fetus in the early stages of development.
Since ultrasound is energy, sensitive tissues like the reproductive organs could possibly sustain damage if vibrated to a high degree by too intense ultrasound waves. In diagnostic ultrasonic procedures, such damage would only result from improper use of the equipment.

Possible ultrasound bioeffects:
list_point Ultrasonic heating of tissues can be created by absorption of the ultrasound energy.
list_point Due to increasing of temperature, dissolved gases from microbubbles come out of the contrast solution.
The thermal effect is controlled by the displayed thermal index and the mechanical index indicates the risk of cavitation.
An ultrasound gel is applied to obtain better contact between the transducer and the skin. This has the consistency of thick mineral oil and is not associated with skin irritation or allergy.
Specific conditions for which ultrasound may be selected as a treatment may be attached with higher risks.
See also Ultrasound Imaging Procedures, Fetal Ultrasound and Obstetric and Gynecologic Ultrasound.
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 Further Reading:
  Basics:
International guidelines and regulations for the safe use of diagnostic ultrasound in medicine(.pdf)Open this link in a new window
   by www.radiologymalaysia.org    
  News & More:
Ultrasound: Weighing the Propaganda Against the FactsOpen this link in a new window
   by www.midwiferytoday.com    
Ultrasound Produces Less Unwanted EffectsOpen this link in a new window
2004   by www.annieappleseedproject.org    
US Resources  
Kidney - Musculoskeletal and Joint - Obstetric - Endoscopic - Safety - 4d UltraSound
 
Related Searches:
 • Blood Flow Velocity
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 • Ultrasound Radiation Force
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