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DHYG Radiology
Radiology for National Board
| Question | Answer |
|---|---|
| The energy of photons produced in an x-ray machine is dependent upon? | KVP |
| The speed at which electrons move across an x-ray tube is regulated by? | Kilovoltage |
| Changing from 75kVp to 90kVp will? | decrease x-ray density |
| What allows for greater penetration of x-rays? | increased kVp |
| What describes radiographic film that has many gradation of gray from totally white to black? | low contrast or many shades of gray |
| Both milliampere setting and exposure time determine what? | the number of x-rays produced |
| A radiograph is taken with an exposure time of 30 impulses, what is the exposure time in seconds? 60 impulses= 1 sec | 1/2 second |
| What is the principal factor that controls x-ray penetration? | Wavelength |
| According to the inverse square law, if distance is doubled what happens to the exposure time? | X 4 |
| What happens to the intensity when you switch from an 8" to a 16" cone? | decreases by 4 |
| Radiation film fog may be caused by | secondary radiation |
| What is the direct effect of radiation when a photon contacts outer orbital electrons called? | Thomson scattering |
| What is the transfer of all energy; ionization of inner electron? | Direct effect: Photoelectric |
| What is the transfer of partial energy; ionization of outer shell electron and the production of scatter radiation. | Direct effect: Compton effect |
| Name the most sensitive tissue to the least sensitive to radiation? | Reproductive, lymphatic, young bone, circulatory, endocrine respiratory, digestive mature bone, nervous |
| What is the maximum permissible dose for occupational exposure | 5 rem/year .05 Sv or 50 mSv |
| What thickness is required for the patient's lead apron? | .25 mm |
| Regarding film speed, what is the rule for exposure time and film speed D-E? | decrease exposure time by 1/2 |
| Regarding film speed, what is the rule for exposure time and film speed E-F? | decrease exposure time by 20% |
| What is the purpose of the collimator/lead diaphragm? | to limit the size and shape of the beam to 2.75 |
| What PID reduces scatter rays? | Long cone/rectangular |
| What is the purpose of filtering an x-ray beam? | remove low energy photons |
| Which projection is required to aid localization of an impacted maxillary premolar after periapical radiographs? | Maxillary occlusal projection |
| What is the purpose of using intensifying screens? | reduction of exposure time |
| If the temperature of processing solutions is slightly above normal, radiographs of desired density may be best obtained by? | decreasing developing time |
| In developing radiographs, what does the fixer do? | remove unexposed silver halide and shrink and harden the emulsion |
| what is the major difference between automatic and manual processing of radiographs? | Auto requires special solutions at higher temps |
| Name the technical error with too much vertical angulation. | Foreshortening |
| Name the technical error for incorrect cone or film placement | cone cut |
| What is the effect on a radiograph if the film is placed backwards? | herringbone |
| If you fail to completely submerse film in the developer what processing error would you have? | clear area |
| If you fail to completely submerse your film in the fixer what processing error occurs | a black streak |
| Scatter radiation, improper safe light and light leak all cause what processing error? | Film fog |
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