DI 1- Midterm Flashcards
Name the body planes and what they divide.
sagittal: left & right.
coronal: anterior & posterior
Horizontal (transverse): superior & inferior
Define the terms position, projection and view.
- Position = side of body nearest film; should be marked as such (ie RAO)
- Projection = path of the x-ray beam AP/PA/oblique
- View = side of anatomy best visualized, usually side nearest film.
Which body substance has the least subject density? The greatest? How would they appear radiographically?
Denser tissues show up more opaque on radiographs. In increasing density: air, fat, water and muscle, bone, metal
What is attenuation? How does pathology affect it? How are attenuation and radiographic blackness related? Which body substance attenuates most? Least?
Attenuation is the rate of absorption of x-rays as they go through tissue. The more a tissue attenuates, the more radiopaque it is. Radiographic blackness is how much blackness is on a film. The less attenuation, the more radiographic blackness on a film. In order of increasing attenuation: air, fat, water and muscle, bone, metal. Pathologies can affect the way a tissue attenuates, ex Breast CA decreases, an prostate CA increases attenuation.
What is radiographic density? What what x-ray factor controls it?
• Radiographic Density = radiographic blackness = amount of blackness on film. mAs controls it (milliamps X seconds = mAs)
- Increasing either current or exposure time will increase the x-ray dosage, thus increasing radiographic blackness
When you double or halve mA and leave everything else as is, what happens to your film? What happens to your patient?
The image increases in radiographic blackness
The patient receives double the radiation.
What x-ray factor is primarily responsible for controlling contrast?
Contrast is how many different shade of gray will show up on an image. It is controlled by kVp, kilovolt peak. Improving contrast means lowering kVp so more shades show up
What is beam restriction? What is scatter? Good? Bad? Scatter is Bad. How is scatter minimized?
Beam restriction reduces scatter for a clearer image by blocking some of the rays. Scatter is the result of some x-rays bouncing off tissue in oddball directions and it is bad always. Minimize with appropriate kVp, grid, and beam restriction.
What is the purpose of a radiographic grid? When should it be used? Where is the grid placed? What is the visible effect of using a grid? Does its use require more or less radiation?
aluminum casing with lead lines that are aligned to catch scatter, but straight beams go straight through. Placed between pt and film (remove scatter once it exits body). This greatly improves image contrast and sharpness. Using a grid increases the amount of radiation needed to get a good image.
What is shape distortion? How can they be minimized? What is size distortion? How can they be minimized?
Shape distortion is when something is elongated or foreshortened from improper placement of film, tube, or body part. Size distortion is when the shadow of an object is magnified as the object moves further from the film. It can be minimized by putting the object of interest as close to the film as possible.
Are children more sensitive to radiation than adults? What are the most sensitive body cells to radiation? The least sensitive?
Children are more sensitive to radiation because they have more mitotic cells and metabolically active cells. The most sensitive cells are: bone marrow, gonadal, Eye lens, GI tract. Least sensitive are muscle, nerve, chondrocyte.
What is a ROENTGEN?
Ionization produced by a specific amount of radiation in the AIR. SI = C/kg
Which is more dangerous, having a chest x-ray or being an unmarried male who eats Twinkies and drinks soda pop while driving his Ford Pinto?
The later. Alcohol use, being unmarried, smoking, MVA, pedestrian accident all greater risk than x-ray. Owning small car, long drive, consuming desert/sod, not fastening seatbelt all less than risk of x-ray
Which joint space(s) are seen well on routine shoulder (internal & external rotation) views? Which joint space is not seen well on those views? Which view(s) will demonstrate what is not seen on routine views?
Glenohumeral joint is not seen well on routine should rotation views, and requires a special study, Grashey method to visualize it. The A/C joint is often overexposed and may require a filter
When to order PA/lateral chest exam?
Order a PA chest exam when you want to see what’s going on in the chest, duh. Soft tissue dx and respiratory complaints NOT thoracic spine stuff.