Unit 21: Medical Physics Applications Test Bank Completely Verified

ses of radiofrequency waves and strong magnets - ANSWER-produce detailed images of soft tissues in the body what is magnetic resonance imaging? - ANSWER-use of electromagnetic energy to produce an image of soft tissues in any plane of the body What body parts is MRI used on? - ANSWER-brain and spine, joints, blood vessels, heart conditions, abnormal body water conditions Benefits of MRI - ANSWER-non-contact, non-invasive, painless main types of medical lasers - ANSWER-carbon dioxide, argon, yttrium aluminium garnet (YAG), pulsed dye uses of medical lasers - ANSWER-eye surgery, removal of kidney stones, removal of tumours benefits of medical lasers - ANSWER-can focus on a small area and damage less tissue surrounding the area to be treated; less pain, swelling and scarring than using traditional surgery How do lasers work? - ANSWER-• Light of specific wavelength passes through a gain medium, which amplifies light with higher energy by stimulated emission. • Reflectors send the light backwards and forwards in the gain medium until it has gained enough energy. • High-energy amplified light emitted as a narrow beam or is spread out, depending on application, through a laser oscillator What does infrared thermography (IRT) do? - ANSWER-produces thermal images (thermograms) that show areas of abnormal body temperature, 'hot spots' on the skin that result from higher blood flow due to tumours Uses of IRT - ANSWER-in screening programmes, cardiovascular/circulatory disorders, respiratory problems, dentistry Benefits of IRT - ANSWER-fast, passive, non-contact and non-invasive, maps body surface temperature remotely. Instrumentation of ultrasound - ANSWER-earthed case, coaxial cable, absorber, crystal and plastic cover, monitor screen. How does an ultrasound work? - ANSWER-• Pulses of ultrasound transmitted from the probe in the transducer into the body and reflected back. • The density characteristics of the different structures inside the body are displayed as an image types of ultrasounds - ANSWER-o external ultrasound scan, e.g. screening of fetus o internal ultrasound scan - produces images of organs in more detail o endoscopic ultrasound - long, thin flexible tube (endoscope) inserted into the body through mouth to examine stomach, gullet or lymph nodes in chest Ultrasound treatment uses - ANSWER-kidney stones, benign and malignant tumours ultrasound diagnosis uses - ANSWER-narrowing of blood vessels, strokes and heart attacks; echocardiogram to measure blood flow rates Where are x-rays absorbed? - ANSWER-by bones, they appear white; other areas are dark on the photographic film principles and production of x-rays - ANSWER-o heated cathode filament produces negatively charged electrons o electrons accelerate to a positively charged tungsten anode, where some of their kinetic energy is transformed into x-rays. uses of x-rays - ANSWER-cancers and breaks in bones, pneumonia, tuberculosis, screening for breast cancer, mammograms computerised tomography - ANSWER-CT scan is created by an x-ray tube that rotates around the body: the body is inside a tunnel and is moved continuously through a rotating beam of x-rays, a detector is on the opposite side of the body uses of computerised tomography or computerised axial tomography - ANSWER-brain tumours, certain bone conditions, injuries to internal organs such as the kidneys, liver and spleen, and the heart. Uses of positron emission tomography (PET) - ANSWER-imaging scans for diagnosis of cancer, detection of recurrent tumours benefits of PET - ANSWER-high-energy, penetrating power radiotherapy - ANSWER-treatment of tumors using doses of radiation; radiation oncology gamma knife surgery - ANSWER-o a highly accurate therapeutic dose of gamma radiation for brain tumours o dose volume controlled for treatment required