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Rad Saftey Mod 6
Final Exam
Question | Answer |
---|---|
Entrance skin exposure | The simplest and most frequently used method for reporting patient skin dose, usually measured with a thermoluminescent dosimeter (TLD). |
mean marrow dose | The average radiation dose to the entire active bone marrow. |
genetically significant dose (GSD) | The dose equivalent to the reproductive organs for the entire gene pool; if received by every human, this dose would be expected to cause gross genetic injury to the total population. |
genetic effects | The effects of ionizing radiation on future generations. |
leukemia | Literally, white blood; a neoplastic overproduction of white blood cells. |
"elective booking." | This requires that the referring physician or radiologist determine the time of the patient's previous menstrual cycle. |
At what fetal dose level must a complete dosimetric evaluation be conducted? | If the examination involved a fetal dose exceeding 10 mGy (1 rad) or more. |
What is the suggested dose level where an abortion could be considered? | Evidence suggests a line somewhere between 100 and 250 mGy (10 and 25 rad). |
Exposure Factors | area examined. The effective atomic numbers and densities of the tissue involved.The IR exposure requirements. The (SID). filtration being used. The balance of radiographic density and contrast required. |
C-arm fluoroscopy units | Portable multiposition device often used in the operating room for orthopedic procedures; produces real-time (motion) images of a patient. |
Beam-limitation devices | Device that limits a patient's exposure to unnecessary x-rays by confining the primary beam to the area of clinical interest, thereby limiting the amount of body tissue irradiated. |
aperture diaphragms | A simple beam limitation device consisting of a flat piece of lead with a hole of a designated size and shape cut through it. |
cones | A type of beam-limitation device that confines the radiographic beam to a certain area; consists of a circular metal tube that attaches to the x-ray tube housing or collimator to limit the x-ray beam to a predetermined size and shape. |
collimators | An adjustable devise used to restrict x-ray beam size and shape. |
positive beam limitation (PBL) | A feature of some collimators that automatically calculates the aperture (based on the distance from the film and the film size) so that the radiation field size matches the film size. |
Filtration | Elements that are part of, or added to, the x-ray tube to reduce exposure to the patient's skin and superficial tissues. |
"added filtration." | Filters added outside the glass window of the x-ray tube housing above the collimator shutters. |
"inherent filtration" | The filtration caused by the glass envelope of the x-ray tube and the insulating oil surrounding the tube. It amounts to approximately 0.5 mm aluminum equivalent. |
Wedge filters | Specialized filter that compensates for varying thickness densities of an area such as the foot; the thick portion of the wedge is positioned over the toes and the thin portion over the heel. |
shields | Device used to protect an area, such as the reproductive organs, from ionizing radiation. |
flat contact shields | Uncontoured protective shield constructed of lead strips or lead-impregnated materials placed over a patient to protect areas of the body that do not need to be examined; available in a number of shapes. |
shaped contact shields | Protection device made of radiopaque material and contoured to enclose the male reproductive organs. |
shadow shields | Shield made of radiopaque material that is suspended over the patient to cast a shadow in the primary beam over areas to be protected, such as a patient's gonads. |
Lucite-Pb-equivalent shields | Shield (often used for breast and gonad shielding) made from a transparent plastic material containing 30% lead by weight; also called "clear-lead" shield. |