front 1 Repeat protocols: | back 1 1. Kept to a minimum 2. Repeat analysis performed 3. Reasons for repeats should be documented 4. In-service training for frequent repeat exams |
front 2 Repeats result in ____________ the radiation to the patient and the technologist. | back 2 twice |
front 3 Repeats range from about _______ % of exams performed | back 3 5%-15% |
front 4 What is the purpose of immobilizing a patient? | back 4 to reduce patient motion and motion unsharpness |
front 5 When is scattered radiation produced? | back 5 During compton interaction |
front 6 What happens during compton interaction? | back 6 photon interacts with outer shell and electron and changes direction |
front 7 Scattered beam intensity is about ________th the intensity of the primary beam at a _______ degree angle at a distance of ____ meter from the patient. | back 7 1/1000th 90 degree angle 1 meter |
front 8 Types of Beam Limiting Devices: | back 8 1. Diaphragms 2. Cones 3. Collimators |
front 9 What is the most commonly used collimator? | back 9 variable-aperture collimator |
front 10 Accuracy within ____% of the SID is required with automatic collimation. | back 10 2% |
front 11 Inherent filtration | back 11 limits x-ray beam by use of glass window in the tube |
front 12 Added filtration | back 12 limits x-ray beam by use of piece of aluminum outside glass window of tube housing |
front 13 Total filtration | back 13 maximum amount of x-ray beam through the use of added and inherent filtration |
front 14 which type of filtration can be changed by a radiographer? | back 14 wedge filter |
front 15 What is the minimum total filtration for mobile diagnostic and/or fluoroscopy units? | back 15 2.5 mm Al equivalent |
front 16 Half-Value Layer (HVL) | back 16 thickness of material that will reduce x-ray intensity to half of its original value |
front 17 For lead aprons, if there is overlap on the front how much does protection increase? | back 17 1.0 mm |
front 18 What is the gonadal shielding requirements? | back 18 shield reproductive organs when they are in or near 5 cm of a properly collimated beam |
front 19 Gonadal shielding should be used: | back 19 reproductive age children pregnant patients front and back |
front 20 Types of Gonadal shielding | back 20 Flat Contact Shields Shadow Shields Shaped Contact Shields |
front 21 Shaped contact shields are worn by ________- and reduce exposure by ____%. | back 21 Males 90% |
front 22 Flat Contact Shields absorb how much of the primary beam? | back 22 95%-99% |
front 23 Lead equivalent for flat contact shields | back 23 1mm Pb |
front 24 Flat contact shields are used by ______ and reduce exposure by _____%. | back 24 Females 75% |
front 25 Where are shadow shields attached? | back 25 To collimator and is placed between x-ray tube and patient |
front 26 When is exposure latitude wide? | back 26 Computed Radiography Digital Radiography |
front 27 Air Gap | back 27 reduced need for grid and will decrease exposure as much as 5 times |
front 28 What are causes of repeat radiographs? | back 28 Dirty screens Artifact Incorrect projections Positioning errors Grid errors Poor communication skills |
front 29 ASRT supports gonadal and fetal shielding when shielding: | back 29 is safe and appropriate reduces excess radiation exposure increases patient comfort and confidence |
front 30 Why have shielding recommendations changed? | back 30 risks of genetic effects are lower shielding can interfere with AEC it is difficult to shield gonads during certain exams gonadal shielding may obscure important findings improvements in technology have reduced absorbed dose to pelvic organs a significant portion of dose to the ovaries is delivered by internally scattered x-rays that can't be blocked by shielding |
front 31 NCRP No. 13 reevaluates | back 31 the effectiveness of gonadal shielding considering technical advancements in medical imaging and current scientific evidence and provides updated recommendations regarding gonadal shielding for the medical imaging community |
front 32 aperature diaphragm | back 32 piece of flat lead with a hole in the center that attaches to the x-ray tube to confine the area of the beam |
front 33 cones | back 33 circular metal structure attached to the x-ray tube housing to restrict the x-ray beam to a predetermined size |
front 34 source-tabletop distance for fixed fluoroscopes | back 34 15 inches (38 cm) |
front 35 source-table top mobile fluoroscope | back 35 12 inches (30 cm) |