Intro to Diagnostic Imaging Flashcards
what color will dense objects be on the x-ray?
radio-opaque (white)
what color will non dense objects be on the x-ray?
radio-lucent (black or transparent)
the gray scale order (dark to light)
air, fat, water, muscle, bone, barium, lead
Role of the PT in radiology
1) no formal role in the ordering of assessment
2) vital to appreciate implications of study findings
why use diagnostic imaging?
- localize the anatomic problem
- identify the tissue involved
-identify the nature of the tissue damage - direct treatment
what is x-ray
-form of electromagnetic radiation, ionizing
-made by accelerating electrons hitting a tungsten target
-quality if image depends on kVolts, mA and exposure time
-depends of differential absorption by different tissue
what is the value of routine radiography
documenting bony defects
what is the minimum amount of views that are required for x-raying
2 views are required and are perpendicular to one another.
advantages of x-ray
- quick
-inexpensive
-ideal for boney changes
x-ray disadvantages
- does not show soft tissue changes
-radiation exposure
what does CT stand for
computerized (axial) tomography
what is the CT scan
-a moving x-ray
-provides detailed planar images by progressive visual “slices”
advantages of CT
- cross sectional images
-can enhance with contrast
-better sensitivity than plain film x-ray
-OK with metal - Fast
disadvantages of CT
-high radiation exposure
-less sensitive then MRI
What does MRI stand for
Magnetic Resonance Imaging
what is MRI best for
soft tissue contracts
What does MRI do
-Applies a powerful magnetic field to the patient
-detects the rate of magnetization and demagnetization
-produces “slice” images, can be in any plane
Advantages of MRI
- the gray scale does not apply and any structure can be highlighted
-no radiation exposure involved
-High sensitivity to slight tissue differences
Disadvantages of MRI
-cost
-time lying still
-Limited tube size
-Cannot use metal
-can be too sensitive/ not specific
-not good for bone/ calcified tissue
How does ultrasound work
- sends in 35 MHz range (transmitter)
-picks up receiver and examines timing and amplitude of the reflections for each echo, examines frequency change for doppler
-produces a 2-D image in real time, can be moving
Advantages to Ultrasound
-Biologically harmless
-records and displays motion
-requires no contrast
-portable
-distinguishes solid from fluid
Disadvantages to Ultrasound
-does not penetrate bone well
-does not go through air/ gas
-skill dependent
what images well with ultrasound
-fetus
-children
-abnormal organs (gallstones, kidneys, pelvic organs/masses
-aorta: aortic aneurysms
-blood flow (with doppler)
Bone scan (Skeletal Scintigraphy) is used to test the suspection of
-metastatic disease
-arthritis
-stress fracture
-osteomyelitis
-loosening of implants
-multiple trauma
how does bone scan work?
- patient is given a rapidly decaying radioisotope into their veins
- takes 2-4 hours for radioactive substance to gravitate to areas of bone damage
- one radiation has settled camera is used to image the bones, dark spots indicate damage
what is nuclear imaging
a invasive procedure that uses injected radioactive material and a PET scanner, CT scan or MRI
what images well with nuclear imaging?
- Thyroid masses
-Bone metastases from cancer - lung circulation and ventilation
-cancer - xenon
-cancer
-Gi disease
-Endocrines disease
what to look for when reviewing medical records of imaging
- any abnormalities are reported
- do they correlate with clinical signs and symptoms?
