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RAD107 Review
Radiographic Exposure
Question | Answer |
---|---|
You are instructed to cut an aperture diaphragm which would allow the radiation field to cover an 8x10" cassette. The SID is 40 inches and the target to diaphragm distance is 5 inches. Compute the aperture opening. | 1"x1.25 |
A room to be used exclusively to produce 14x17" chest radiographs is being installed. The SID is 180 cm, the source to diaphragm distance is 10 cm. What size would the opening of the diaphragm be to cover the film? | .77x.944 |
A radiograph is taken with a High Speed Screen, 8:1 grid, at 60 mAs and 76 kVp. What would the new mAs be to maintain density if a 16:1 grid was employed? | 120 |
As the ratio of the grid increases, causing the appropriate change in technique, what affect on patient exposure can be expected? | Increase due to the increase in mAs to compensate for the higher grid ratio. |
A radiograph is taken with medium (100) speed screens, non-Bucky, using 15 mAs at 80 kvp. If a RE (300) screen is used instead, what new mAs should be used to maintain the same radiographic density? | 5 mAs |
A radiograph is taken with Regular (400) speed screens, non-grid, using 100 mAs at 80 kVp 40” SID. If an image is desired using a Slow (100) speed screen, what new mAs should be used to maintain the same radiographic density? | 400 mAs |
A radiograph is taken with Regular (400) speed screens, non-grid, using 100 mAs at 80 kVp 40” SID. If an image is desired using a Slow (100) speed screen. How would this change affect contrast? | Longer scale, decrease contrast, more latitude. |
A radiograph is taken with Regular (400) speed screens, non-grid, using 100 mAs at 80 kVp 40” SID. If an image is desired using a Slow (100) speed screen. If you made no adjustments to the technic, what affect would it have on image density? | Decrease, due to slower screen. |
A radiograph is taken with Regular (400) speed screens, non-grid, using 100 mAs at 80 kVp 40” SID. If an image is desired using a Slow (100) speed screen, what affect would this have on image resolution? | Increased image resolution. |
A radiograph is taken with Regular (400) speed screens, non-grid, using 10 mAs at 80 kVp 40” SID. If an image is desired using a 10:1 grid, what new mAs should be used to maintain the same radiographic density? | 40 |
A radiograph is taken with Regular (400) speed screens, non-grid, using 10 mAs at 80 kVp 40” SID. If an image is desired at 72”, what new mAs should be used to maintain the same radiographic density? | 32.4 |
What scenario could be used to reduce the intensity of scattered radiation produced in a patient measuring 38 cm? | To decrease scatter production; use a compression band to decrease patient size,collimate, or by turning the patient from supine to prone.Lower the kVp, increase the mAs. |
What scenario could be used to reduce the intensity of scattered radiation produced in a patient measuring 38 cm? | Use a compression band.Collimation.Turning the patient from supine to prone.Lower the kVp, increase the mAs. |
As the kVp increases, what happens to the latitude for demonstrating subject contrast? | Increases. |
When you need to penetrate many different types of body tissues (ie, chest) in producing a radiograph, the proper combinations of exposure factors would be? | Increased kVp and decreased mAs. |
An exposure is taken at 30 mAs and 78 kVp. The radiograph has high contrast and adequate recorded detail, but lacks sufficient density. | Double the mAs |
The xray absorption characteristics of tissues are often variable. Which patient factors may effect the degree of radiation attenuation? | Patient's AgeMuscle DevelopmentPathological ConditionsEmaciation |
Changing kVp, we will have an effect on which image qualities? | DensityContrast |
You are reviewing a portable radiograph. The technologist tells you to repeat the film and decrease your penetration as well as your density. When you review the film you note the radiograph to be gray and the density to be excessive. What do you do? | Decrease your kVp by 15%. Do not adjust any other factor. Remember kVp affects density and contrast. |
A transthoracic humerus is taken at 50 mA, 0.8 seconds, and 80 kVp. The resultant image possesses acceptable penetration but insufficient density. However, the patient was sent upstairs before you saw the film. You now have to do the study portable. To | 80 mAs at 80 kVp |