Radiology Flashcards
Compensate for casting in radiographic images
mAs controls density Dry plaster cast: mAs increased 2x wet plaster cast: mAs increased 3x Wet fiberglass: mAs increased 60% dry fiberglass: mAs increased 40%
Bremsstrahlung
aka breaking radiation electron reacts with Tungsten nucleus and causes change in velocity (losing energy) and being deflected –> produces x-ray broad range energy
Characteristic x-ray
collision btwn high speed electron and electron in shell of target tungsten atom –> electron is ejected from atom and vacancy is filled by higher orbit –> radiation is released discrete energy
Law of Bergonie and Tribondeau
tissues sensitive to radiation (most to least) bone marrow (leukocytes) –> GI –> CNS
According to Law of Bergonie and Tribondeau, sensitivity of tissue to radiation depends on:
proliferative capacity and differentiation –> more rapidly dividing tissues are more sensitive
Radiographic findings of hyperparathyroidism
resorption and lysis of distal tufts of phalanges subperiosteal resorption at medial aspect of middle phalanx shaft vertebral endplate sclerosis which creates alternating dense-lucent appearance (aka rugger jersey spine) WHY? HyperPTH increases osteoclastic activity –> increased resorption
Occupational exposure doses
MRI indicated for: _____
CT indicated for: ____
- bone tumors, infections (osteo), stress fractures
- articular surfaces, cartilage and interface of 2 joint surfaces, skeletal alignment and deformity correction planning
Stochastic effects
probability of occurrence but not severety increases with dose (cancer)
Peroneal tenogram
extravasation of contrast medium from peroneal sheaths (indicated calcaneofibular ligament tear)
Nonstochastic effects
What will absorb the least to most density?
air-fat-soft tissue-calcium-XR contrast-bone-metal
