ACVR Veterinary Radiology flashcards
ACVR Veterinary Radiology · Build recall with a focused review session.
31 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Roentgen (R) definition
- The SI-derived unit of x-ray exposure in air; one roentgen equals 2.58 × 10⁻⁴ coulombs per kilogram of air.
- Gray (Gy) definition
- The SI unit of absorbed radiation dose, equal to one joule per kilogram of tissue; one gray equals 100 rad.
- Effective dose
- A dose quantity in sieverts that weights absorbed dose by radiation type and tissue sensitivity to estimate overall stochastic risk.
- Inverse square law
- Radiation intensity from a point source decreases with the square of distance; doubling distance reduces exposure to one quarter.
- Silhouette sign
- Loss of a normal border between two structures of similar opacity indicates the lesion contacts that border, aiding anatomic localization.
- Aggressive periosteal reaction
- Periosteal new bone that is irregular, interrupted, or sunburst in pattern, suggesting malignant or rapidly progressive bone disease.
- Vertebral heart score
- A canine thoracic cardiac silhouette measurement on lateral radiographs; the sum of long and short axes in vertebral units, normal at or below 10.5.
- Pneumoperitoneum sign
- Free abdominal gas appearing as radiolucent areas outlining serosal surfaces or the diaphragm, suggesting hollow viscus rupture.
- Radiolucent versus radiopaque
- Radiolucent structures (gas) appear dark because they attenuate few x-rays; radiopaque structures (bone, metal) appear white because they attenuate many.
- Four R's of radiobiology
- Repair of sublethal damage, redistribution through the cell cycle, repopulation of surviving cells, and reoxygenation of hypoxic tumor cells.
- Alpha-beta ratio
- The dose at which linear and quadratic components of cell kill are equal; low values indicate late-responding tissues, high values early tissues and tumors.
- Linear-quadratic model
- A radiobiologic model where surviving fraction equals exp(−(αD + βD²)), describing cell kill as a function of radiation dose.
- Fractionation rationale
- Dividing total dose into smaller fractions allows normal tissue repair between treatments while tumor cells are progressively reoxygenated and redistributed.
- Late radiation effects
- Tissue injury such as fibrosis or necrosis that appears months to years after radiotherapy and is characteristic of tissues with low alpha-beta ratios.
- Acute radiation effects
- Early tissue reactions such as mucositis or dermatitis occurring during or shortly after radiotherapy, typical of rapidly dividing tissues with high alpha-beta ratios.
- Palliative radiation protocol
- A regimen using few large fractions to relieve signs and reduce hospital visits, accepting higher risk of late normal tissue injury.
- Tumor control probability
- The probability that all clonogenic tumor cells are eradicated by a given dose; it increases with total dose and decreases with tumor volume.
- Radiosensitizer
- An agent that increases the effect of radiation on tumor cells, often by mimicking oxygen or altering DNA repair, with potential normal tissue toxicity.
- Repopulation
- Proliferation of surviving cells during a course of radiotherapy; accelerated repopulation in tumors can reduce treatment efficacy if overall time is prolonged.
- Reoxygenation
- Improved oxygenation of previously hypoxic tumor cells after each fraction, increasing their radiosensitivity and improving overall tumor kill.
- Navicular syndrome radiography
- Radiographic changes include enlarged synovial invaginations, navicular bone sclerosis, and irregularity of the flexor cortex on the distal border.
- Laminitis rotation measurement
- On a lateromedial radiograph, the angle between the dorsal hoof wall and the dorsal cortex of the distal phalanx estimates phalangeal rotation.
- Cervical vertebral stenosis
- Equine cervical vertebral malformation diagnosed on lateral radiographs using minimum sagittal diameter and intravertebral ratios to detect spinal cord compression.
- Palmar osteochondral disease
- A metacarpophalangeal injury of racehorses seen radiographically as subchondral lucency or flattening of the palmar condyles of the third metacarpal bone.
- Equine thoracic ultrasound
- Preferred over radiography in adult horses because patient size limits x-ray penetration; it detects pleural effusion and peripheral pulmonary lesions.
- Equine stress fracture
- Incomplete cortical fractures of the third metacarpal or metatarsal bone that may be radiographically occult early and are detected by nuclear scintigraphy.
- Nuclear scintigraphy
- A nuclear medicine imaging technique using radiopharmaceutical uptake to detect regions of increased bone turnover before radiographic changes appear.
- Equine head CT
- Computed tomography provides detailed cross-sectional anatomy of dental roots, paranasal sinuses, and guttural pouches beyond survey radiography.
- Dorsal osteochondral fragment
- A fragment at the dorsal aspect of the metacarpophalangeal joint, often at the sagittal ridge, detected on flexed or skyline radiographic views.
- Sesamoid fracture
- A fracture of the proximal sesamoid bones of the fetlock, diagnosed radiographically and a common cause of acute severe equine lameness.
- Suspensory desmitis
- Inflammation or tearing of the suspensory ligament; radiography may show enthesophytes while ultrasound confirms ligament fiber disruption.