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List the steps in interpretation of medical imaging



emphasizing the type of image and the orientation, limitations

1. X-ray techniques-- X-ray attenuation to produce images (absorb & scatter x-ray beam different degrees). Produce shadows=image; ionizing radiation.
-plain radiography--planar images, bone/chest, ionization

-mammography- breast tissue, high spatial resolution, ionization

-fluoroscopy-"live action" x-ray; visualize dynamic process i.e.. swallowing, can take spot images, video, rapid-sequence images; ionization

-angiography-fluroscopy, vessels inject contrast, DSA (digital subtraction angiography) subtracts bones and structures from images; ionization

-DEXA- (Dual-energy x-ray absorptiometry); quantitative determine bone mineral density=osteoporosis; ionization

-CT-computed tomography, CAT scan uses x-rays & computations to produce cross sect images throughout body; ionization

2. Ultrasound-
-doppler--emits high-frquency sound & detects echoes from tissues; image by magnitude & delay echoes, sonar. NO ionization
-fluid= dark, organ=gray, fat+air=bright
-fetal, echocardiography, abd, pelvic, prostate, vascular
-flow velocity in vessels, doppler shift by moving RBCs, waveform and color doppler images

3. MRI-magnetic resonance imaging; manipulate H+ in magnetic field produces cross sect images; NO ionization
-many applications= musculoskeletal, CNS

4. Nuclear Medicine- radioactive agent in body, emits gamma ray imaged by gamma camera; planar, SPECT, SPECT?CT; ionization
-show physiologic processes
-ventilation/perfusion lungs, tagged WBC scan, octreoscan (find carinoid & tumors), bone scan

-PET/CT-positron emission tomography.
-images positron decay--higher resolution, usually combine with CT
-common agent=FDG; F-18 fluorodeoxyglucose
-goes to areas of high metabolism
-oncology, neurologic, cardiac applications


Describe the four basic densities that are visible on plain films



Describe how x-rays are produced and the role they play in image production in plain film radiography.



Define the terminology used to describe images: upright, supine, PA, AP



Explain how position of the patient can affect magnification, organ position, blood flow, and affect image interpretation



Discuss how the use of contrast agents can permit visualization of anatomic structures that are not normally seen



Describe how contrast agents can be administered