Safety: Radiation Protection Flashcards

Question

143 - A modification in SID triggers an adjustment in the fluoroscopic automatic brightness control (ABC) feature. Which of these statements is true as SID decreases? A. As SID decreases, intensity of the x-ray photons at the image intensifier's input phosphor increases B. The ABC would decrease milliamperage to compensate for an increase in X-ray photon intensity at the image intensifier C. The ABC ensures constant brightness and corrects for variations in X-ray beam attenuation D. B and C E. A, B, and C

Answer 1

Correct Answer: E. A, B, and C As SID is decreased, the intensity of the x-ray photons at the image intensifier's input phosphor increases, stimulating the automatic brightness control (ABC) to decrease the milliamperage and thereby decreasing patient dose. The ABC ensures constant brightness and contrast of the output screen image by correcting for variations in x-ray beam attenuation with adjustments in kilovoltage and/or milliamperage.

Answer 2

E. B and C Throughout the examination, automatic exposure rate control keeps the radiation dose per frame at a preset level, according to the patient’s anatomy’s attenuation characteristics and maintaining a constant degree of image quality

Answer 3

A. Image intensifier An electronic device known as the X-ray image intensifier, also called the image receptor, transforms the X-ray beam intensity pattern (remnant beam) into a visible image that may be recorded by a video camera and shown on a video display monitor. An output phosphor, electron optics, photocathode, and an input phosphor layer are the essential parts of an X-ray image intensifier.

Answer 4

B. Patient dose is increased while using magnification mode A few strategies to reduce the amount of radiation that a patient receives during a fluoroscopic examination are shortening the fluoroscopic exposure time, using last image hold, positioning the patient as close to the image intensifier as feasible, utilizing an automatic brightness control (ABC) setting with the highest kVp and lowest mAs combination, limiting the use of boost and magnification modes, using collimation and the smallest field of view, using the lowest acceptable pulse rate, and adjusting the tube angle or patient position to distribute the dose over a greater anatomic area.

Answer 5

D. Total air kerma Presently, all fluoroscopes sold in the United States are mandated by the Food and Drug Administration (FDA) to be able to display the total air kerma at the interventional reference point. The International Electrotechnical Commission refers to this quantity as reference air kerma (RAK). Most fluoroscopes also have the ability to show the kerma-area product (KAP). Peak skin dose (PSD) estimation is a valuable tool that can be performed with RAK or KAP. There is a predilection for RAK in the United States.

Answer 6

A. Last image hold The most recent fluoroscopic image can be saved on the monitor using a function called "last image hold," which eliminates the requirement for continuous x-ray exposure during a fluoroscopic examination.

Answer 7

A. 3 Quantity of radiation in the X-ray beam and rate at which radiation is administered to the patient are directly impacted by milliampere-seconds (mAs). Patient exposure increases by a factor of two if mAs is increased from 5 to 10. The radiation exposure to the patient increases by a factor of three when mAs is raised from 10 to 30.

Answer 8

E. A and B Perhaps the best method for limiting the amount of radiation that patients are exposed to is to limit the irradiated field size using beam restriction techniques like collimation. Other strategies that help limit patient dose include patient positional adjustments and effective communication with the patient to minimize the need for repeat exposures. For instance, if less exposure to anterior organs is desired, PA projections are favored over AP projections.

Answer 9

B. Deep dose equivalent The external whole-body exposure equivalent at a tissue depth of 1 centimeter is known as the deep dose equivalent (DDE). The shallow dose equivalent (SDE) is the external skin or extremity exposure measured as the dose equivalent at a tissue depth of 0.007 cm, averaged across a 1 square centimeter area. The eye dose equivalent, committed dosage equivalent, committed effective dose equivalent, and total effective dose equivalent are additional metrics that can be used to evaluate personnel exposure monitoring.

Answer 10

B. 15 inches For fixed fluoroscopic systems, the minimum distance from source to skin is 15 inches. A minimum of 12 inches for source-to-skin distance is recommended when using mobile fluoroscopic equipment.

Answer 11

B. Half-value layer The thickness of material needed to cut an X-ray or gamma-ray beam’s intensity to one-half of its original value is known as half-value layer (HVL).

Answer 12

Correct Answer: B. Dose area product (DAP) The radiation dose exiting the X-ray tube multiplied by the area of the X-ray field is expressed as the Dose Area Product (DAP). DAP meters calculate the product of the X-ray field's area and in-air radiation. To determine the maximum radiation skin exposure, a DAP meter should be utilized.

Answer 13

C. Dose decreases by a factor of four The idea of dose reduction with increasing distance from the source is explained by the inverse square law. According to this law, radiation intensity is inversely proportional to the square of the distance from the source of radiation. Given an area (A) and a sphere radius (r), the region over which a radiation dose is spread rises in accordance with the formula A = 4πr². The dose is relative to the inverse of the square of the radius. Therefore, the dose will be reduced by a factor of four by doubling the distance. The amount of radiation to which the body is exposed can be decreased by applying this technique.

Answer 14

D. A and C The primary X-ray beam, secondary radiation exposure, and the patient themselves are all potential sources of radiation exposure. It is important that the primary X-ray beam only penetrate the part that is being examined. If necessary, only a non-occupationally exposed person wearing a lead apron should hold the patient. This lowers the radiographer's inadvertent exposure to the primary beam and minimizes their cumulative occupational exposure. Secondary radiation exposure is a result of both scatter and leakage radiation. Secondary radiation exposure is influenced by Compton effect and classical scattering. Particularly during fluoroscopic exams, the patient may serve as a source of scatter radiation. By using appropriate shielding and keeping a safe distance from the patient, occupational exposure to side scatter radiation from portable and fluoroscopic procedures can be reduced. Leakage radiation is any radiation that leaves the X-ray tube through an opening other than the window port. When the tube is working at its maximum kVp and mA, leakage should be controlled at or below 100 mR/hour (0.001 Sv) at 1 meter.

Answer 15

B. 100 mR/hr at 1 meter The primary X-ray beam, secondary radiation exposure, and the patient themselves are all potential sources of radiation exposure. It is important that the primary X-ray beam only penetrate the part that is being examined. If necessary, only a non-occupationally exposed person wearing a lead apron should hold the patient. This lowers the radiographer's inadvertent exposure to the primary beam and minimizes their cumulative occupational exposure. Secondary radiation exposure is a result of both scatter and leakage radiation. Secondary radiation exposure is influenced by Compton effect and classical scattering. Particularly during fluoroscopic exams, the patient may serve as a source of scatter radiation. By using appropriate shielding and keeping a safe distance from the patient, occupational exposure to side scatter radiation from portable and fluoroscopic procedures can be reduced. Leakage radiation is any radiation that leaves the X-ray tube through an opening other than the window port. When the tube is working at its maximum kVp and mA, leakage should be controlled at or below 100 mR/hour (0.001 Sv) at 1 meter.

Answer 16

Correct Answer: D. A and C Time, distance, and shielding are three fundamentals of radiation protection. This means that the radiographer should reduce the amount of time they spend near a source of radiation, increase the distance between themselves and the source, and employ a barrier or shielding device between themselves and the source to minimize their amount of radiation exposure. For example, healthcare organizations may rotate technologists through fluoroscopic examinations to decrease individual occupational dose.

Answer 17

B. Lead apron Shielding and aprons are examples of protective devices that serve to protect patients and healthcare professionals from exposure to ionizing radiation. To minimize radiation exposure, primary and secondary protective barriers exist. The NCRP #102 specifies a minimum lead equivalent for a range of protective devices. Lead aprons, thyroid shields, and the transparent lead-plastic overhead protective barrier are examples of protective devices having a minimum lead equivalent of 0.5 mm Pb. Gloves, a protective curtain for spot film devices, and bucky slot covers are examples of protective equipment with a minimum lead equivalent of 0.25 mm Pb. Protective glasses have a minimum lead equivalent of 0.35 mm Pb.

Answer 18

E. A and B For fluoroscopic and portable units, the maximum exposure at the tabletop of a fluoroscopic device is 10 R/minute (100 mGy/minute), or it cannot exceed 2.1 R/minute (21 mGy/minute) for each mA of operation at 80 kVp, as per NCRP #102 and Code of Federal Regulation-21 standards. Conventional (non-digital) fluoroscopic equipment typically functions in the 2 to 5 mA range.

Answer 19

Correct Answer: B. 40.32 R 2.1 R/minute (21 mGy/min) x 6 mA = 12.6 R/minute (126 mGy/min). Given that the fluoroscopy examination time was 3.2 minutes, the total exposure is equal to 12.6 R/minute (126 mGy/minute) x 3.2 minutes = 40.32 R (403.2 mGy). For fluoroscopic and portable units, the maximum exposure at the tabletop of a fluoroscopic device is 10 R/minute (100 mGy/minute), or it cannot exceed 2.1 R/minute (21 mGy/minute) for each mA of operation at 80 kVp, as per NCRP #102 and Code of Federal Regulation-21 standards

Answer 20

C. Thermoluminescent dosimeter Dosimeters come in a variety of forms and employ various methods for measuring radiation. These consist of a proportional counter, a film badge, a thermoluminescent dosimeter, a gas ionization chamber instrument, a pocket dosimeter, and an optically stimulated luminescent dosimeter. The functional element of a thermoluminescent dosimeter (TLD) is lithium fluoride. The light spectrum that the chip produces varies according to the energy levels that it absorbs. While TLDs are more costly than film badges, they are less prone to reading errors or artifacts. One drawback of using a TLD is that, after the chip is heated, it is destroyed and no archival record is kept aside from a written report of findings. A permanent or archival record of radiation exposure is provided by a film badge. It depends on ionizing radiation’s capacity to alter the film emulsion’s density. The degree of film blackening on the film emulsion surfaces under various types of attenuating filters, such as copper or tin, determines how much of the dose that the badge receives. Film badges have the advantage of being reliable and cost-effective. Long-term radiation monitoring can be successfully accomplished using film badges. A pocket dosimeter works by using ionization to modify the charge of an electrode, which discharges the electrode, by ionizing a gas inside a sealed chamber. Although a pocket dosimeter can be recharged and used again, it does not provide a permanent record of dosage. Using an aluminum oxide detector, optically stimulated luminescence dosimeters (OSLD) enable the distinction of radiation energy levels and between deep, shallow, and ocular exposure. After being read by a laser light, the sensing material illuminates in direct proportion to the amount of exposure it received. This type of radiation dosimeter is worn by radiographers at many medical facilities. For area surveys, a device known as the "cutie pie" is a gas ionization chamber instrument that monitors exposure rate. Although it can measure a wide range of exposures in a short amount of time, this instrument is not suitable for measuring radiation doses from brief exposure times. In the context of diagnostic medical imaging, a proportional counter is not employed. Alpha radiation, beta radiation, and other trace levels of radioactivity are detectable with a proportional counter.

Answer 21

C. 0.5 rem (5 mSv) Embryonic exposure must not exceed NCRP standards of 0.5 rem (5 mSv) for the duration of the gestational period and 0.05 rem (0.05 mSv) in any month after the pregnancy is confirmed.

Answer 22

C. The duration of the individual's employment For the duration that the employee works in medical imaging, occupational exposure records must be maintained.

Answer 23

A. 5 rem Under NCRP #116, ionizing radiation exposure at work is limited to the following annual exposure levels: 5 rem (50 mSv) for the whole body, 15 rem (150 mSv) for the lens of the eye, and 50 rem (500 mSv) for all other areas, including the breast, lung, gonadal, dermal tissues, extremities, and red bone marrow.

Safety: Radiation Protection Flashcards

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