RADT_153_Unit_7_Exam - RADT 153 Image Analysis Unit 7 Unit...

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Unformatted text preview: RADT 153 Image Analysis Unit 7 Unit Exam The Effect of Focal Spot Size on Radiographic Quality 2 7.0 The Effect of Focal Spot Size on Radiographic Quality Unit Exam Directions: 1. Write your name and the date on your Scantron form. Identify the subject as the course number (for example, RADT 101) along with the test number (for example, Unit 1). 2. For each of the questions below, select the best answer to the question. 3. Using a No. 2 pencil, fill in the appropriate answer on the answer sheet. 4. Erase unwanted answers completely. Questions with two or more filled in answer spaces are graded as incorrect. 5. Answer all questions. 6. You have a maximum 15 minutes to complete the following 25 questions. (Note this time factor approximates the amount of time you would be allowed to answer the same number of questions on the Registry examination in radiography) ------------------------------------------------------------------------------------------------1. The focal spot of the x-ray tube is an important radiographic tool for the radiographer in the control of recorded definition of image details. A. B. 2. True False Selecting the correct focal spot size on dual focused x-ray tubes gives the radiographer the capacity for creating images with minimal _____________. A. B. C. D. E. voltage kVp expense geometric unsharpness umbra 3 3. When steeper anode angles are used, the emerging x-ray beam becomes more non-uniform because the beam must pass through additional anode target material. A. B. 4. Regardless of the anode angle, a non-uniformity of x-ray intensity exists within the diverging x-ray beam (the area of greatest x-ray intensity emerging from the tube port is under the cathode portion) This is known as the ____________. A. B. C. D. E. 5. tungsten alpha particle heel effect focal spot thermionic emission The __________ focal spot is the actual area of bombardment by the cathode electrons on the target. (also called actual focal spot) A. B. C. D. E. 7. non-uniformity effect cathode phenomenon inverse square law law of conservation of mass heel effect _____________ refers to the target area on the anode upon which the cathode electrons fall and from which x-rays emerge. A. B. C. D. E. 6. True False object contact electronic optical principle The ___________ focal spot is the projected area of the electronic focal spot, which is at right angles to the electronic beam. (also called effective focal spot) A. B. C. D. E. object contact electronic optical principle 4 8. The optical focal spot, which is projected onto the film, is smaller than the electronic focal spot size of a given x-ray tube.This is known as _________________. A. B. C. D. E. 9. Periodic measurement of the focal spot is not necessary in medical radiography. A. B. 10. check the autotransformer measure SID monitor patient dose measure focal spot size detect and measure Compton scatter The optical focal spot is controlled by... A. B. C. D. E. 13. True False The pin-hole method, star-test pattern, and focal spot resolution test tool are three tools used to... A. B. C. D. E. 12. True False If the focal spot is larger than the manufacturer’s limits, it can cause problems with respect to the recorded definition of image details. A. B. 11. The heel effect The line focus principle Inverse square law Square law relative focal spot principle distance exposure time electronic focal spot size filament wire selection both C and D The focusing cup provides a compressed electron stream, which in turn provides a smaller focal spot. A. B. True False 5 14. The focusing cup is positively charged. A. B. 15. The correct application of _______ and use of the corresponding focal spot size affect the geometric quality of the radiographic image. A. B. C. D. E. 16. True False Radiographic contrast is directly related to focal spot size. A. B. 20. True False Radiographic density is directly related to focal spot size. A. B. 19. True False If mA and focal spot restriction were not built into the design of xray tubes, a high mA requirement from a small filament wire would quickly result in rapid heat exhaustion. A. B. 18. distance shielding mA kVp heat The use of low mA results in a small focal spot A. B. 17. True False True False Radiographers who place thicker anatomy parts under the cathode end of the x-ray tube are taking advantage of ___________. A. B. C. D. E. patient size the inverse square law the blooming affect the heel effect nothing 6 21. A smaller filament wire causes a smaller penumbral effect because the x-ray photons are in a more vertical relationship to the anatomy being radiographed. A. B. 22. A condition called ___________ occurs in which higher mA settings generate larger focal spots compared to lower mA settings. A. B. C. D. E. 23. True False Changing the focal spot size form small to large will cause severe size distortion of the image details. A. B. 25. heel umbra blooming fog artifact Magnification radiography is a special radiographic technique employing the use of a special “fractional” focal spot setting so that the penumbra effect is optimally minimized. A. B. 24. True False True False Shape distortion is caused by target, object, and film misalignment, and therefor is not affected by focal spot size. A. B. True False ...
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