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Terms in this set (21)
Radiography (XR)--- MOA to project picture
Negatively charged cathode and positively charged anode.
Cathode: source of electrons
Anode: tungsten target where XR are produced
Further MOA of XRs
Tubes produces XR beams that pass through the patient. --Absorption varies depending on body tissue
Small percentage of incident radiation exits patient and hits detector.
Finally, it is converted to light and can be displayed on monitor for viewing.
X-Ray Densities: Most to least
What does more dense mean?
Other items that show on XR?
Common contrast agents and what procedures?
2. Soft tissue: muscle, blood vessel, skin
More dense, more you see on XR, because XR is blocking it.
Metal and contrast agents will show up as well and appear bright white.
Iodine for IV and barium for GI studies
What two views both required?
2D presentation on 3D information.
Frontal and lateral.
AP- anterior/posterior where the anterior is facing the x-ray taker.
So why do we do these?
1. Immobile persons
What about if we want to evaluate the spine?
1. Could do one if there were no breasts in the way
P/A: posterior-anterior where the back is facing the x-ray taker: BETTER!
Heart needs to be closer to the detector to be not enlarged and to be CLEARER.
Cardiothoracic ratio: heart should be smaller than the chest cavity. With AP, it can be thrown off and will LOOK BIGGER!
Lungs are inflated when you're standing = diaphragm goes down
L lateral decubitus view
Taken with patient's L-side down
Contrast agent purpose and what if abnormal
Fill a hollow tube (like stomach) OR
anatomic tubular structure like blood vessel, ureter, or common bile duct.
Abnormality: intraluminal, mural, or extrinsic location REQUIRES SEEING ABNORMALITY IN PERPENDICULAR VIEWS.
LOOK AT PIC IN PPT
Fluoroscopy: definition, major use for what procedures
Continuous emitted XRs for real-time visualization USING CONTRAST.
Investigating the GI tract as it follows the course of contrast materials for both STRUCTURE AND FUNCTION.
Monitoring catheter placement during angiography and interventional procedures.
XR tube from under the patient emits continuous beams to continuously fluorescing detector in front of them.
Detector emits faint light that is amplified ELECTRONICALLY to image INTENSIFIER.
Image intensifier absorbs XR photons and produces light on TV monitor.
2. Requires less
3. What does image intensifiers help with?
4. What is important to do?
Image brightness PROPORTIONAL to number of incident photons received.
Images: requires LESS CONTRAST and LOWER RESOLUTION, but HOWEVER LEADS TO MORE EXPOSURE.
Images help with decreasing dose of radiation needed to produce clinical pics.
Important to have baseline film before doing procedure with contrast to ensure that objects APPEARING white are contrast or anatomical structure.
Procedures under Fluoroscopy.
1. Indication for test and to rule out what?
Esophagogram: dysphagia--rule out stricture or mass
Upper GI study: abdominal pain---gastric or duodenal ulcer
Small bowel follow-up: diarrhea or constipation--Crohns or other small bowel
Barium enema: rectal bleeding--ruling out polyp or mass.
Computed Tomography definition and MOA.
Rotating fan of XR beams passing through patient with transmission to thousand points on patient's body.
Computer will evaluate and calculate X-R absorption at each spot of the patient.
Windowing data points: allows more pics to be obtained w/o radiation exposure
XR tube moves continuously around the patient while table moves continuously through the scanner.
Scanners: have multiple rows of XR detectors that obtain more than a 100 image data slicers at a time.
CT densities: measures what?
PHYSICAL DENSITY: That's IT! BUT MUCH MORE SENSITIVE!
Soft tissue: 20-50
Air: -1000 to -200
Further CT definition
2D display of 2D info.
Series of tissue slices are shown if as taken from the foot of patient's bed.
R side of CT=L side of patient and vice versa
CT requirements and what does it help?
Requires IV contrast agent for 75% of studies.
Contrast: 150 mL. 1 mL per pound typically.
1. Allows to see various phases: arterial/venous and delayed.
2. Allows to see multiple structures at the same time.
Procedure-based focused on specific treatments that are less invasive.
Use of imaging (often xray) to guide a catheter or a needle to a particular part of the body instead of surgery.
Less risk, pain, and less recovery time than open procedures.
Common IR procedures
1. Stent placement
3. Biliary drainage
4. Gastrostomy tube
5. Varicose vein
7. Abscess drainage
Selpinger procedure steps and purpose
Medical procedure to obtain safe access to blood vessels and other hollow organs.
Don't have to open invasive surgery.
1. Insert needle
2. Put guide wire in
3. Remove needle
4. Thread catheter into guide wire
5. Remove wire
6. Catheter: access fluid
Radiation doses: lowest->highest
Extremities: low, 0.01
Chest is 10x
Skull is 22x
KUB is 70x
Lumbar spine 150x
Barium enema 800x
CT abdomen and pelvis: 1400x
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