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ARRT Review
Radiation Safety Part 2 - Minimizing Patient Exposure
| Question | Answer |
|---|---|
| What combination of kV and mAs is recommended to decrease patient exposure? | low mAs and high kV |
| List at least 3 types of patient shields | Flat contact, shaped, shadow, and breast shields |
| What type of shield would be best for a sterile field? | Shadow |
| What is the single most important way to reduce patient exposure? | restriction/collimation of the useful beam |
| List three types of beam restrictors. | Collimators, cones, and aperture diaphragms |
| Which size and length of cone attachment would reduce patient dose? | long and narrow ( vs. wide and short) |
| The x-ray glass envelope and its insulating oil function as what kind of filter? | inherent filtration |
| How much total filtration is required for equipment operating above 70 kVp? | 2.5 mm AL equivalent |
| What is the primary purpose of filtration of the useful x-ray beam? | To reduce patient dose |
| How does added filtration affect the average energy of the x-ray beam? | The average energy is increased |
| How does the added filtration affect the minimum wavelength of the x-ray beam? | Added filtration has no effect on the "minimum" wavelength of the x-ray beam |
| What are the two ways used to express x-ray beam quality? | kV and HVL |
| Because the primary x-ray beam is polyenergetic the entrance dose is often significantly ________ than the exit dose? | greater |
| To reduce exposure to the lens, the reproductive organs, and the breasts, it helpful to perform scoliosis exams in which projection? | PA |
| What is the concept employed every day, with every exam, in order to achieve optimal radiation protection? | ALARA or optimization |
| Who of the following is likely to be the most radiosensitive: 1 year old child, 20 year adult, or 50 year old adult? | 1 year old child |
| What is the feature of most imaging systems that terminates the x-ray exposure once adequate exposure reaches the image receptor? | AEC |
| How is imaging system speed related to patient exposure? | faster speed systems reduce required exposure (but lowers detail) |
| Is a 40 year old adult or 70 year old adult more radiosensitive? | 70 year old (slower repair processes with protein enzymes) |
| Changing from a nongrid to a grid procedure will require a/an _______ in patient exposure. | Increase |
| A/an _____ technique can function similar to, or in place of, a low ratio grid when distance is introduced between the patient/part and the IR. | Air gap |
| When used correctly, digital imaging can significantly ___ patient dose. | reduce |
| What is the principal reason that fluoroscopy potentially delivers a significantly higher patient dose than general radiography? | because the source of x-ray photons is much closer to the patient in fluoroscopy |
| Grids improve the radiographic image by reducing the amount of scattered radiation fog, but require a/an ____ exposure | increase |
| During C-arm fluoroscopy procedures, the patient-to-image intensifier distance should be as ______ as possible to reduce patient entrance dose. | short |
| How dose fluoroscopic magnification mode affect patient dose? | Magnification mode increases patient dose (and increases as you increase the magnification mode) |
| According to CFR, Title 21, for continued awareness of patient exposure during fluoroscopic procedures, cumulative Air Kerma is displayed in what unit? | mGy a |
| What are the two features of digital fluoroscopy that function to reduce patient dose? | Pulsed fluoroscopy and last image hold |
| The exposure switch on mobile x-ray equipment must allow the operator to be at least what distance from the x-ray tube during exposure? | 2 m or 6 feet |
| The SSD in mobile fluoroscopy must be at least _____. | 30 cm ( 12") |
| The SSD in fixed fluoroscopy must be at least _____. | 38 cm (15") |
| What type of mobile x-ray equipment does the kV decrease during the exposure? | Capacitor/condenser discharge mobile units |
| How is the patient entrance exposure (EDE) affected as fluoroscopic SSD is decreased? | patient ESE increases as the SSD decreases |
| What must the lead equivalent be of the fluoroscopic image receptor assembly? | 2.0 mm pb equiv |
| Fluoroscopic total filtration must be at least ________ | 2.5 mm Al equv |
| The fluoroscopic timer must provide signal after how my exposure time has passed? | 5 min |
| Fluoroscopic tabletop intensity "should not" exceed ____ per minute operated at 80kV. | 21 mgya/min (2.1 R/min) |
| High--level control fluoroscopic tabletop exposure "must" not exceed ____. | 200 mgya/min (20 R/min) |
| Automatic adjustment of the kV and/or mAs for adequate visualization during fluoroscopic exams, according to thickness, is termed _____ | Automatic brightness control (ABC) |
| Non -High--level control fluoroscopic tabletop exposure "must" not exceed ____. | 100 mgya/min (10 R/min) |
| Radiation that emerges from the leaded tube housing in directions other than that of the port or useful beam | Leakage |
| Leakage radiation must be less than ___ mgy/hr at a distance of ___ meter from the protective housing | 1 ; 1 |
| The SID indicator must be accurate to within ___% of the indicated SID | 2 |
| The variation in x-ray intensity should not exceed ___% | 5 |
| A C-arm should be placed with the fluoroscopic tube ___ the patient and the image intensifier ___ the patient | below; above |
| List 3 ways to reduce patient dose | Increase the SID ; higher kVp and decrease mAs; Increase filtration |
| When SID or SOD is increased, patient ESE ___ | decreases |
| If kVp increased with a decrease in mAs then patient dose is ___ | decreases |
| The ______________ is a measure of both the absorbed radiation dose and the area exposed | DAP - Dose Area Product |
| During fluoroscopic exams, the patient dose ________ as the field-of-view decreases. | increases |
| What is Field of View (FOV) | Also called magnification mode |
| Which of the following would not decrease patient exposure: grids, collimator, or gonadal shields | Grids |
| Which of the following will not contribute to patient dose? kVp, focal spot, mAs, inherent filtration | focal spot |
| Patient dose increases as the FOV ___________________- | decreases (magnification) |
| The largest amount of absorption will occur in what type of patient tissue? | bone |
Created by:
rcberger06
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