Imaging - XR and CT Flashcards
Radiology
Be familiar with modalities
Official readings may not be available
Improves Pt care: accuracy and speed; reduces call backs
Helps in determining what tests to order or avoid
billing
Competency improves with repetitive exposure to normal and abn.
XR Hx
1895 By dutch physicist Roentgen
Electrons boiled off of a cathode when heated; Electrons then strike an anode and produce XR
File is sheet of silver bromide and silver iodide
exposure to XR cuases deposition of metallic silver which appears dark on film.
The more XR that reach the sheet, the darker that portion will appear
Std XR films = plain films
XR types
Digital radiography - uses electronic sensors rather than silver sheets to measure attenuation coefficient of tissue through which XR have been passed through. Data processed into images.
Fluoroscopy - uses plates covered with phosphor which fluoresces when exposed to XR. This exposure is then electronically converted into images. Allows for numerous images top be viewed w/o changing a plate.
XR - Structures visible
FRom highest to lowest density:
Bone/Metal/Glass - white/radioplaque
Muscle/Organs: whitish-grey
Fluid - appears gray to white
Fat - gray-black
Air - black/radiolucent
XR - Veiws
Magnification:
The further the object from the plate the greater the amount of magnification. Important for CXR
PA has the plate over the anterior aspect of Pt and is the preferred view.
AP has the plate posteriorly; aka the portable veiw but distorts some of the features
2 or 3 views are better than 1
XR - Contrast Studies
GI, GU, Vascular
Oral contrasts - barium swallow, upper GI w/ small bowel follow-through, barium enema, HIDA scan for gallbladder function
IV Pyelograms - water soluble salts that will outline the GU tract
Fistulogram - local inj to veiw an abnormal connection b/w 2 organs
Angiography - rapid sequence images of the designated vessels s/p IV contrast
Myelogram - contrast into the SA space to view spinal cord and nerve root
IV contrast is more likely than oral to have ADR/allergic Rxn
Minor rxns - n/v/flushing
Moderate-severe - pulm edema, bronchospasm, apnea, laryngeal edema
Can always give steroids or benadryl IV prior to injection of contrast
XR - Plain films: skeletal
Fx, alignment, bony cysts/masses, arthritis, foreign bodies (fb), infections (gas, periosteal thickening or erosion.
XR - Plain films: CXR
Consolidation (peumonia, mass, lymphadenopathy)
Fluids (CHF, pleural effusion)
Cardiac size (cardiomegaly, pericardial effusion)
Air (pneumthorax, esophageal or tracheal perforation)
GI processes (hiatal hernia, bowel perforations)
Tracheal deviation, other skeletal findings
XR - Plain films: ABD
air perforation or obstruction
stool
organ size
calcifications renal gall pancreatic
fb
XR - Plain films: Soft tissue neck
soft tissue swelling STS
air/gas
airway patency
XR - Plain films: Less useful for
ligament and cartilage
muscle
head injury unless fb
inter-vertebral disks
spinal cord
non-radiopaque fb
renal colon gym masses
CT - Hx
1970 - Math formula for reconstruction of images based on measurement of thier points in space, dev by Radon -1917
Highly restricted XR beam that moves 360 degrees around the indicated area.
Captured by electronic sensors.
data converted to various shade of gray based on tissue density then viewed in axial, coronal, sagittal planes on a monitor
CT - Indications
W/ or w/o contrast iv or po to enhance viscera/vascular structures
CT angiography requese precise timing b/w injection and scanning
renal function needs consideration when ordering IV contrast
Head for hemorrhage or fx w/ IV for malignancy, vascular occlusion
Chest for parenchyma, trauma or w/ contrast for malignancy, anuerysm, PE
abd/pelvis for GB/Renal stones or with contrast for Inflammatory, obstruction, perforation, trauma and aneurysm
Extremities Fx or with IV for vascular occlusion or dissection
CT - less useful for
intracranial patho
spinal/nerve
muscle,
cartilage, ligament, tendon, IVD
Pregnant or pediatric Pt 2nd to radiation
CT - risks
Nodule formation with frequent CT
DNA can be affected at any does, mutations
chromosomal aberrationswill undergo repair, apoptosis, propagation.
Propagation may result in late effects - CA
Pediatric Pt are more susceptible b/c cells prolilferate more rapidly than adults, making each cell more sensitive to radiation
Natural radiation is out there.
CT 2 -3.5 rads w/th significant effects at >20 rads in 1st trimester and 100+ in the rest
No real affect on fetal dev <5 rads
1-2 rads may increase risk for leukemia
CTA has less rad than a V/Q scan
