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Rad Safety Mod 7
Final Exam
| Question | Answer |
|---|---|
| National Council of Radiation Protection and Measurements (NCRP) | group that reviews regulations formulated by the International Commission on Radiological Protection (ICRP) and decides how to include them in U.S. radiation protection criteria. |
| effective dose-equivalent (EDE) limiting system | method for assessing radiation exposure and associated risk of biologic damage to radiation workers and the general public; this method determines the various risks of cancer and genetic effects to tissue and organs exposed to radiation. |
| occupational exposure | Radiation exposures occurring in the workplace and in the course of an individual's employment. |
| Effective dose equivalent (EDE) limits | The upper boundary dose of ionizing radiation that will result in a negligible risk of bodily injury or genetic damage to the recipient. |
| EDE limits | whole-body annual total EDE limit at 50 millisieverts (5000 mrem). The cumulative whole-body EDE limit should not exceed the occupationally exposed person's age in years times 10 mSv (1000 mrem). |
| EDE limits during pregnancy | The EDE limit during pregnancy is 5 millisieverts (500 mrem), and the monthly dose should not exceed 0.5 millisieverts (50 mrem). |
| primary radiation | Radiation from the useful beam. |
| secondary radiation | The other two types of radiation, which also require protection, are leakage radiation from the x-ray tube housing and scatter radiation. |
| leakage radiation | from the x-ray tube housing |
| scatter radiation | Radiation that bounces off of matter and air. |
| primary protective barrier | Any wall toward which the primary beam may be directed. It is designed to prevent primary radiation from reaching personnel or other people on the other side of the barrier. |
| secondary protective barrier | Designed to protect areas from secondary radiation. Scatter and leakage radiation. |
| What is the most common primary protective barrier? | lead bonded to sheet rock or wood panelling |
| Four pounds per square foot of lead is equal to......? | a sheet of lead 1/16 of an inch thick. |
| What are alternative materials for primary radiation barriers? | concrete, concrete block, or bricks.As a general rule, 4 inches of concrete is equal to 1/16 of an inch of lead sheeting. |
| What is the the minimum height of a primary barrier? | 7 feet above the floor of the x-ray room when the x-ray tube is 5 to 7 feet from the wall. |
| What is the intensity of scatter radiation 1 meter from the patient? | It is 0.1% of the intensity of the useful beam directed at the patient. |
| What is the leakage radiation limit 1 meter from the x-ray tube? | must not exceed 100 milliroentgens per hour (2.58 x 10-5 C/kg/hr) when the tube is operated continuously at its highest current for its full potential. In most cases the leakage radiation is much less than this limit. |
| secondary protective barriers | lead sheets 1/32 of an inch thick, gypsum board, lead glass, or lead acrylic. Walls that are considered secondary protective barriers may be constructed with four layers of 5/8-inch gypsum board. |
| What is the control booth window usually made of? | 1.5-mm lead-equivalent glass. This equivalent is usually Lucite-Pb-equivalent barriers. This material contains 30% lead by weight and is made from an acrylic copolymer resin and an organic lead salt. |
| Where is the control booth located in the room? | The control booth barrier should be positioned such that no one can enter the radiographic examination room without being seen by the radiographer. |
| Can the radiographer operate the control switch outside the control booth? | The control panel exposure switch should be designed so that it can only be used from within the control booth. If the exposure switch is attached to a cord, the cord should not reach beyond the protective barrier. |
| How is the thickness of protective barriers calculated? | To calculate the thickness of protective barriers, designers must consider four factors: distance, occupancy, workload , and use. |
| workload | The radiation-output weighted time when an x-ray generator is actually delivering radiation; specified either in units of mA seconds per week or mA minutes per week. |
| inverse square law | Law stating that the intensity of radiation is inversely proportional to the square of the distance from the radiation source. the intensity, or quantity of radiation, at that greater distance decreases by a factor of 4. |
| Where is the best placement of the x-ray machine? | An x-ray machine is best positioned in the center of a room. Then all walls are equally exposed. |
| occupancy factor (T) | A factor used to modify the shielding requirements for a particular barrier by accounting for the percentage of time that the space beyond the barrier is occupied. |
| uncontrolled areas | areas occupied by members of the general public. include waiting rooms, hallways, stairways, even streets and parking lots,workspaces occupied by hospital employees not trained to work with radiation, employee restrooms, and storage areas. |
| Controlled areas | occupied by employees who have been trained in radiation protection procedures and who wear radiation monitoring devices. |
| What is the occupancy factor in controlled areas? | Full occupancy includes areas such as all work spaces routinely used by occupationally exposed personnel. In controlled areas, the occupancy is always considered to be 1. |
| What is the occupancy factor for a partial occupancy area? | occupancy factor of 1/4 |
| What is the occupancy factor for an occasional occupancy area? | may be assigned a factor of 1/16. |
| maximum weekly permitted dose equivalent to people in uncontrolled areas? | less than the maximum annual effective dose equivalent to the occasional exposure of the general public. 20 microsieverts (100 mR) per week. |
| effective dose equivalent for occupants of Controlled areas? | less than 1000 microsieverts per week. |
| Workload | is essentially the radiation output when the unit is actually delivering radiation. the average mAs of the x-ray generator and the number of x-ray examinations per week. |
| use factor | the fractional amount of time during which the x-ray beam is energized or directed toward a particular barrier. Also called the beam-direction factor. |
| What is the use factor for walls,floor and ceiling of the x-ray room that are routinely exposed to the primary beam? | Because floors are often exposed to primary beams during examinations on tables, they are always given a factor of 1. Doors, walls, and ceilings of radiation rooms exposed routinely to the primary beams are also given a use factor of 1. |
| What is the use factor of doors and walls not routinely exposed to the primary beam? | Doors and walls of radiation rooms not exposed routinely to the primary beam are given a use factor of 1/4. |
| What is the use factor for ceilings of x-ray rooms not exposed routinely to the primary beam? | Ceilings of radiation rooms not exposed routinely to the primary beam are given a use factor of 1/16. |
| What is the use factor for secondary barriers? | Secondary barriers, those at which the primary beam is not directed, are always given a use factor of 1. The reason for this is that scatter and leakage radiation are always present when the tube is energized. |
| lead apron | always be used when it is not possible to remain behind a protective barrier always be worn during mobile radiography and during all fluoroscopic examinations. lead equivalent thickness from 0.25 to 1 mm. |
| What is the most widely used apron lead equivalent thickness? | 0.5-mm thickness |
| What type of protective apparel should be used during mobile radiography or during fluoroscopic procedures? | protective apron |
| What is the minimum thickness of gloves worn by the radiographer? | a minimum thickness of 0.25 mm of lead equivalent should be worn whenever the hands must be protected from the x-ray beam |
| What type of shield should be used during fluoroscopy and other special radiographic procedures? | thyroid gland shields |
| What is the lead equivalent of the neck and thyroid gland shielding? | 0.5 mm lead equivalent. |
| What is the lead equivalent of the eyeglasses used for radiation protection? | optically clear lenses that contain lead with a 0.35- to 0.5-mm lead equivalent. |
| Who should immobilize the patient? | first choice should always be an older relative or friend who is beyond reproductive age. If a relative or friend is not present, hospital personnel other than those working with radiation. NEVER the technologist. |
| The Monthly effective dose equivalent (EDE) for a pregnant worker is....? | 0.5 millisieverts (0.05 rem) per month. |
| What is the equivalent dose limit for the embryo-fetus for the duration of pregnancy? | 5 millisieverts (500 mrem) |
| Radiologic personnel who are pregnant wear two personnel monitoring devices to measure their exposure. Where are they located? | One monitor should be worn at collar level outside the protective apron. The second personnel monitoring device is worn at waist level under the protective apron. |
| personnel monitoring | Procedures used to estimate the amount of radiation received by individuals who work in a radiation environment. |
| What amount of radiation gets through a protective apron? | monitor under the protective apron should show exposure values of less than 10% of those outside the apron. |
| What is the estimated dose to the embryo-fetus? | only 30% of the skin dose. |
| Do pregnant radiographers working in radiation oncology or nuclear medicine departments need to to take extra precations? | Yes, they should handle only small quantities of radioactive material. |
| 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. |
| additional protective measures found in fluoroscopy are....? | protective drape and Bucky slot cover |
| protective drape | A protective barrier used in fluoroscopy; consists of a sliding panel with a minimum of 0.25-mm lead equivalent attached to the front of the spot film device of a fluoroscopic x-ray unit. |
| Bucky slot cover | The gap for the Bucky tray leaves an opening approximately 5 cm wide at the side of the table at about gonadal level. The Bucky slot cover, consisting of a 0.25-mm lead equivalent, automatically covers this opening. |
| cumulative timer | A radiation protection device used during fluoroscopy that either sounds an alarm or interrupts the x-ray beam after the fluoroscope has been activated for 5 minutes to ensure that the operator is aware of the ON time of the beam. |
| How long is the exposure switch cord of a mobile x-ray unit? | It must be long enough to allow the radiologic technologist to stand at least 6 feet away from the patient to minimize the risk of scatter radiation. |
| Where is the best place for the radiographer to stand to receive the least amount of scatter radiation? | the best position for a radiographer to stand is at right angles to the x-ray beam and scattering-object line. |
| quality control (QC) | monitors radiology instruments and equipment. It ensures equipment is operating properly and that repeat radiographs are not required because of equipment errors or malfunctions. |
| three steps of quality control | acceptance testing of the equipment upon installation, routine performance evaluation of all equipment, and correction of any problems. |
| How often are evaluations of collimation usually done? | at least twice a year; all other evaluations are conducted at least annually |
Created by:
elaughery
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