Radiography Examination Questions with Correct Answers

How thick is the proper filtration for greater than 70 kVp machine setting? - 2.5 mm Do we ever hold film for a patient? - No! (duhhh) Definition of "latent period" - From time of exposure to noticeable effect Radiation injury to cells is affected by what 3 things? - Cell sensitivity, total dose, and dose rate Difference between radiosensitive and radioresistant? - Radiosensitive: more sensitive to UV (WBC, RBC, reproductive cells) Radioresistant: more resistant to UV (Bone, Nerve, Brain, Muscle) What is a "pointed cone" and why are they no longer used? - The "pointed cone" is the conical PID that appears as a closed, pointed plastic cone. It is no longer used because the x-rays penetrate the plastic and produce scatter radiation. Which length PID reduces radiation to patients, long or short? - Long Why do we put a protective lead apron on a patient during exposure? Why a thyroid collar and is it worm on a panoramic exposure? - -Protects the thyroid from scatter radiation -Prevents radiation from reaching the gland and protects the highly radiosensitive tissues of the thyroid -Thyroid collor is NOT recommended with extraoral films (panoramic) What shape PID reduces radiation to the patient the most? - Of the three types of PID, the RECTANGULAR TYPE is most effective in reducing patient exposure. What is the difference between genetic and somatic cells? - All of the cells in the body can be classified as either somatic or genetic. Somatic cells are all the cells in the body except the reproductive cells. The reproductive cells are termed genetic. rad is the acronym for? - Radiation Absorbed Dose Every patient should be evaluated individually for dental radiographs. - True. (end of ch. 5 questions) The 8-inch PID is more effective in reducing radiation exposure to the patient than the 16-inch PID. - False. (end of ch. 5 questions) Why? Because the LONG PID is more effective in reducing patient radiation. Pointed cones should not be used because of increased scatter radiation. - True (end of ch. 5 questions) **remember: Rectangular is best. :) The thyroid collar must be worn for all intraoral and extraoral films? - False (end of ch. 5 questions) Thyroid collar NOT worn for extraoral films If necessary, the dental radiographer may hold a film in the patient's mouth to ensure a diagnostic image? - False. (end of ch. 5 questions) *NEVER hold film in a patient's mouth What is the use of a filter in a dental x-ray tubehead? - A filter removes LOW-energy x-rays. What is NOT a component of inherent filtration? - a leaded cone What is the most effective method of reducing patient exposure to radiation? - fast film What PID is most effective in reducing patient exposure? - Rectangular PID (I think we get the picture..) What device restricts the size and shape of the x-ray beam? - Collimator What is used as a collimator? - Lead plate What is the function of filtration? - Reduces LOW-energy waves What is the recommended size of the beam at the patient's face? - 2.75 inches What describes the dose of radiation that the body can endure with little or no chance of injury? - Maximum permissible dose What is true of film badges? - Film badges should be worn at waist level when exposing x-ray films. Machines operating at 70 kVp or LOWER require ___ mm aluminum. - 1.5 Machines operating ABOVE 70 kVp require ___ mm aluminum. - 2.5 State the angle that the dental radiographer should stand to the primary beam: ___ - 90-135 degrees State the formula for maximum accumulated dose: - MAD = (N-18) x 5 rems/year MAD = (N-18) x 0.05 Sv/year What is "fast" film? - Fast film responds more quickly and requires less radiation exposure because the silver halide crystals in the emulsion are larger. **The larger the crystals, the faster is the film speed.** What is the cassette? - A special device that is used to hold the extraoral film and the intensifying screens. Cassettes are availabel in a variety of sizes that correspond to film and screen sizes. What is the screen? - The majority of extraoral films are screen films. It is a film that requries the use of a screen for exposure; is sensitive to fluorescent light rather than direct exposure to x-radiation. How does duplicating film differ from regular film? - Unlike intraoral and extraoral films, duplicating film is used only in a darkroom setting and is not exposed to x-rays.