Slide 1

Slide 2 The long-awaited, much-anticipated X-ray Quiz #2 from Seattle, WA---March 2001. Youll quake in your shoes when you take this one! (48 slides!) Brought to you by Washington State X- ray Control, PO Box 47827, Olympia, WA 98504--tel: 360 236 3237--e-mail: mike.odlaug@doh. wa.gov Go into Slide Show mode in PowerPoint, and left click to move through the slides; right click to go back. Slide 3 What does PACS stand for? Posterior Anterior Chest System Positive Action Collimation System Picture Archiving and Communications System Parts and Charts System Slide 4 C. A term commonly used in digital imaging to describe the system used for sending, viewing, & storing images Slide 5 True or False? Digital imaging always means lower exposure to the patient than for conventional film radiography. Digital imaging means that you cannot produce a hard copy image. Slide 6 False and false. Digital does not necessarily guarantee a lower dose since computer image manipulation is so forgiving with respect to dose. Slide 7 The annual whole body occupational dose limit is 5 REM. What is the limit for the eye? A. 5 REM B. 10 REM C. 15 REM D. 25 REM E. 50 REM Slide 8 E. 15 REM Skin is 50. Slide 9 What is the equivalent number of SI units for 200 millirem? 20 microSieverts 20 milliSieverts 2 microSieverts 200 milliSieverts 2 milliSieverts Slide 10 One of those is correct. These SI units are certainly difficult to get a hold of, arent they? Do a little research and calculation and figure it out. (Hint: 100 rem = 1 Sv) Slide 11 What is the usual range for patient dose rate during fluoroscopy? A. 20 - 40 R/minute B. 20 40 mR/minute C. 2 9 R/minute D. 1 10 mR/minute E. 2 - 9 R/hour Slide 12 C. 2 -9 Roentgens per minute Of course, it can be lower and higher in some cases. FDA and state rules allow a maximum of 10 R/min and HLC can go up to 20 R/min Slide 13 Switching to magnification mode in fluoroscopy A. uses a smaller portion of the input phosphor screen. B. increases the dose rate to the patient, if ABC is operating C. requires the use of pulsed HLC. Slide 14 A and B. Pulsed mode fluoroscopy and High Level Control are not related to magnification. Slide 15 Regarding the differences between MRI and CT, which of the following is true? A. MRI is used strictly for brain imaging. B. MRI provides biochemical info, and gives better contrast. C. MRI is equal in image quality to CT. D. MRI uses more radiation to obtain the same information. Slide 16 B. Additional note: the MRI machine is more expensive than a CT system and each exam costs more and takes longer. Slide 17 True or False: A. Magnetic Resonance Imaging uses no ionizing radiation B. MRI uses only magnetic fields and RF pulses C. Lead must not be used in the walls of an MRI room. Slide 18 A. True, B. True, C. False Lead wouldnt be necessary and anyway, it is non-ferrous and thus not subject to magnetic fields. Slide 19 Skin entrance patient exposures are higher for low kVp techniques, because A. You have to use more photons to get through the patient B. The energy of the beam is lower and thus it penetrates less C. You have to use a different film speed. D. You have to use more mAs. Slide 20 A, B and D Sometimes, facilities use latitude film and then try to regain contrast by using lower kVp but then they have to increase the mAs. Slide 21 Collimation is: A. A common misspelling of the word columnation. B. Proper alignment of the column upon which the X-ray tube is mounted. C. of benefit to patient, operator and interpretation of the resultant film. D. Not necessary in dental X-ray exams. Slide 22 C. Proper collimation provides a better radiograph with decreased scatter to the operator, and of course less area of the patient exposed. Slide 23 A high ESE for a lumbar spine exam could be due to: A. Lousy processing B. Low kVp techniques C. Slow film/screen speed D. A preference for dark images by the film reader E. A high ratio grid. Slide 24 All of the above. Dont you just love answers like this? Slide 25 The unaided human eye can resolve how many line pairs per millimeter? A. 1 lp/mm B. 5 lp/mm C. 10 lp/mm D. 15 lp/mm E. 20 lp/mm Slide 26 C. 10 lp/mm We have sharp eyes, dont we? Slide 27 Intensifying screens can resolve about how many lp/mm? A. 1 lp/mm B. 1-5 lp/mm C. 7-15 lp/mm D. 15-20 lp/mm Slide 28 C. 7-15 lp/mm The old calcium tungstate par speed screens are smack in the middle at 10 lp/mm. Slide 29 Why dont automatic film processors have a stop-bath step? A. Because the rollers squeeze the developer out of the film. B. Because the fixer already contains some acetic acid. C. Because the transit time is too fast. D. Because X-ray film is too sensitive. Slide 30 A and B are correct. Besides, the processor would have to be that much larger to accommodate another compartment and roller set. Slide 31 What is the latent image? A. The ghostly penumbra around the image. B. The part of the image that will never show up on film. C. The invisible change induced in silver halide crystals. Slide 32 C is correct I thought ghostly penumbra sounds like a pretty good answer, though! Slide 33 True or False: A. Compton scattering contributes to film fogging. B. The photoelectric effect is a photon absorption interaction resulting in an ejected electron. C. Pair production cannot occur in diagnostic X-ray energies. Slide 34 All are correct. Compton scattering is the source of most of the scatter. Pair production, by the way, is not a dating service. Slide 35 For extra credit: What is the minimum photon energy that will permit the production of an electron and a positron (pair production) when an X-ray interacts with the nucleus of a target atom? Slide 36 1.02 MeV Slide 37 True or False: The radiation intensity coming from the cathode side of the X-ray beam field is higher than that from the anode side (Heel effect). Slide 38 True The anode sort of self-attenuates or blocks the heel portion of the X-rays generated Slide 39 True or False A.) Dental intra-oral X-ray tubes have rotating anodes B.) Fluoroscopic tubes can operate continuously because the milliAmperage is low. C.) The oil in an X-ray tube is designed to lubricate the rotating anode. Slide 40 No, Yes and No. Intraoral tubes have stationary anodes. The oil in a tube housing acts as a coolant and heat distributor. Slide 41 Ripple in a voltage waveform is: A.) the same as fudge in certain ice creams B.) is 100% for single phase power. C.) is 1% for high frequency waveforms D.) not measurable at all. Slide 42 B and C are correct. Although fudge ripple does sound good. Slide 43 X-ray milli-amperage is: A. The amount of current delivered to the filament of the X-ray tube cathode B. the number of electrons flowing per second from anode to cathode C. the number of electrons flowing per second from cathode to anode. Slide 44 C is correct. Some current is, of course, sent to the filament to make it glow, but thats another story. Slide 45 Dust, dandruff and cookie crumbs on an intensifying screen: A. will not show up on the resulting films because they are radiolucent B. will show up as black specks on the film C. will show up as white specks on the film Slide 46 C. Other possible artifacts include static, processor marks and fog from light leaks. Slide 47 The grid moves during a radiographic exposure so that A. it can automatically get into position for the next shot B. it smooshes the grid lines and makes them disappear. C. it increases the resultant clean-up of scattered X-rays Slide 48 B. I just made up the other two. Smooshes is a recognized scientific term used by President Bush. Slide 49 What does the German word Bremsstrahlung mean? A. broken straight line B. breaking radiation C. literally, bratwurst inhaled D. braking radiation Slide 50 Ja, wohl, the answer is D. Braking, meaning slowing down, rather than breaking, meaning coming apart. Slide 51 Congratulations. You have earned 1 credit of Continuing Education. I would appreciate corrections and comments to make this quiz better. And you can send your complaints about anything else to Gary. Robertson@doh.wa.gov