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Radiography
Radiation Protection II
| Question | Answer |
|---|---|
| ESE | entrance skin exposure |
| average AP supine lumbar spine radiograph delivers an ESE of about | 350 mrad (0.35 rad). |
| The average AP supine abdomen delivers about | 300 mrad |
| the average AP cervical spine is about | 80 mrad |
| Use factor | describes the percentage of time that the primary beam is directed toward a particular wall. |
| Workload | is determined by the number of x-ray exposures made per week. |
| Occupancy factor | is a reflection of who occupies particular areas (radiation workers or nonradiation workers) and is another factor used in determining radiation barrier thickness. |
| SSD | Source Skin Distance |
| A 0.25-mm lead equivalent apron will attenuate about | 97% of a 50-kVp x-ray beam, 66% of a 75-kVp beam, and 51% of a 100-kVp beam. |
| A 0.5-mm apron will attenuate about | 99% of a 50-kVp beam, 88% of a 75-kVp beam, and 75% of a 100-kVp beam. |
| The 1.0-mm lead equivalent apron will provide | close to 100% protection at most kVp levels, but it is rarely used because it weighs anywhere from 12 to 24 lb. |
| Lead aprons are available with what various lead equivalents | 0.25, 0.5, and 1.0 mm are the most common. |
| What will result at 200 and 500 rad | 200 rad temporary sterility, 500 rad sterility |
| Explain HVL reduction amounts | the first HVL would reduce the intensity to 50% of its original value, the second to 25%, the third to 12.5%, and the fourth to 6.25% of its original value. |
| The average high kVp chest with grid delivers an ESE of about | 20 mrad (0.020 rad). |
| he same chest done without grid at 80 kVp would deliver an ESE of about | 12 mrad (0.012 rad). |
| Remnant Radiation is | the radiation that emerges from the patient to form the radiographic image. |
| The interaction between x-ray photons and tissue that is responsible for radiographic contrast but that also contributes significantly to patient dose is | the photoelectric effect. |
| With mA increased to maintain output intensity, how is the ESE affected as the SSD is increased | The ESE decreases. |
| What is the intensity of scattered radiation perpendicular to and 1 m from the patient, compared to the useful beam at the patient's surface | 0.1% |
| Aluminum filtration has its greatest effect on | long wavelength radiation. |
| Patient dose increases as fluoroscopic | FOV decreases |
| Which contributes most to occupational exposure? | Compton scatter. |
| Which contributes most to patient dose? | Photoelectric effect |
| Personnel present in the x-ray room during fluoroscopic examinations wear lead aprons to protect them primarily from | Compton scatter |
| Stochastic effects of radiation are | nonthreshold & randomly occurring. The chance of occurrence of stochastic effects is directly related to the radiation dose; that is, as radiation dose increases, there is a greater likelihood of genetic alterations or development of cancer. |
| Examples of stochastic effects include | carcinogenesis and genetic effects. |
| Nonstochastic effects are | predictable, threshold responses; that is, a certain quantity of radiation must be received before the effect will occur, and the greater the dose, the more severe the effect. |
Created by:
Thevictory
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