» Does the kV value that I select for fluoroscopy have an effect on the absorbed dose to tissues in the patient? Yes, in general, increasing the kV reduces the exposure of the patient and especially to the skin exposed by the beam. This is because the higher kV produces radiation beams with increased penetration through the patient’s body and less radiation is required at the entrance surface (*) to produce the necessary exposure to the image receptor. The other factor that must be considered in selecting the appropriate kV value is the effect on image contrast. In general, lower kV values produce increased image contrast. This can be especially significant in fluoroscopy when using iodine contrast media. (*) The number of photons and the total energy carried by these photons per unit area. For a more rigorous definition and detailed discussion (energy fluence) see Conversion Coefficients for use in Radiological Protection against External Radiation and Dosimetry in Diagnostic Radiology: An International Code of Practice. » Does using the automatic brightness control (ABC) ensure that I am delivering the lowest exposure to my patients? Not in all cases. While the ABC is useful for adjusting the exposure to produce a good image for different patient thicknesses and densities, the actual exposure depends on the exposure level that has been set by the manufacturer or the engineer who maintains the equipment. The optimum setting of the ABC exposure level is one that delivers only the exposure to the image receptor that is required to produce the necessary image quality in terms of the visual noise. » Does changing the field of view, or magnification mode, have an effect on the exposure to the patient? Yes with regard to the absorbed dose and no with regards to the energy imparted. Changing from a large field of view to an increased magnification increases the exposure required by the image intensifier tube. Therefore, the absorbed dose to tissues within the beam is also increased. Decreasing the field of view by a factor of two increases the dose rate by a factor of four. Attention has to be paid to magnification. Example: Field of view, diameter 25 cm Dose rate= 0.3 mGy/s However, since the X ray beam is covering a smaller area, the total energy imparted is about the same as with the larger field of view that produces a lower dose rate. » Does moving the X ray beam to different areas of the patient’s body during a procedure have an effect on the exposure to the patient? Yes. Since the absorbed dose to a specific tissue is influenced by the number of photons impinging on the same area of the skin, moving the beam spreads the radiation over more of the patient’s body and reduces the absorbed dose to any one area of the skin. The highest absorbed dose to a specific tissue occurs when the X ray beam is not moved but remains at the same location on the patient’s body during a procedure. Special attention should be paid to avoiding overlapping image areas combined with projections through the body at relatively low angles of the X ray beam (obliquity, e.g. cranio caudal or caudio cranial projections). In summary, moving the beam can help avoid radiation injuries to the skin. The PKA, and the total energy imparted, is not changed by moving the beam during a procedure. The total energy imparted to a given region of the body is related to the probability of radiation induced cancer. 1 Patient dose increases as fluoroscopic A 2  Referring to the nomogram in Figure 3–3, what is the approximate patient ESE from an AP projection of the abdomen made at 105 cm using 70 kVp, 300 mA, 200 ms, and 2.5 mm Al total filtration? A 3 Which of the following statements is (are) true with respect to radiation safety in fluoroscopy? Tabletop radiation intensity must not exceed 2.1 R/min/mA. A 4 Which of the following most effectively minimizes radiation exposure to the patient? A D High-speed intensifying screens 5 When an image intensifier's magnification mode is used, A 6 Which of the dose–response curves shown in Figure 3–7 is representative of radiation-induced skin erythema? Dose–response curve A A B C D 7 If the exposure rate to an individual standing 2.0 m from a source of radiation is 15 R/min, what will be the dose received after 2 minutes at a distance of 5 m from the source? A 8 Which one of the following is (are) used to control the production of scattered radiation? Collimators A 9 Moving the image intensifier closer to the patient during traditional fluoroscopy decreases the SID A 10 At least how many HVLs are required to reduce the intensity of a beam of monoenergetic photons to less than 10% of its original value? A 2 B 3 C 4 D 5 11 Which of the following is (are) characteristic(s) of a 16:1 grid? It absorbs more useful radiation than an 8:1 grid. A 12 How does the use of rare earth intensifying screens contribute to lowering the patient dose? It permits the use of lower milliampere-seconds A 13 What is the approximate ESE for the average upright PA chest radiograph using 115 kVp and a grid? A 14 Which of the following will reduce patient dose during fluoroscopy? A 15 Which of the following is most likely to permit the greatest decrease in patient exposure? A D Changing from an 8:1 grid technique to nongrid 16 Which of the following projections is most likely to deliver the largest dose to the ovaries? A B AP lumbar spine, 14 × 17 in. cassette, 80 kVp 17 Which of the following tissues is (are) considered to be particularly radiosensitive? Intestinal mucous membrane A 18 Which one of the following is (are) used to control the production of scattered radiation? Collimators A 19 An increase in total filtration of the x-ray beam will increase A 20 What is the approximate ESE for the average AP lumbar spine radiograph? A 21 If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate? A 22 The source-to-table distance in fixed/stationary fluoroscopy must A 23 If a patient received 1,400 mrad during a 7-minute fluoroscopic examination, what was the dose rate? A 24 Which of the following factors will affect both the quality and the quantity of the primary beam? Half-value layer (HVL) A 25 The advantages of beam restriction include which of the following? Less scattered radiation is produced. A 26 The interaction illustrated in Figure 3–5 can pose a safety hazard to personnel A 27 What quantity of radiation exposure to the reproductive organs is required to cause temporary infertility? A 28 If a patient received 0.9 rad during a 3-minute fluoroscopic examination, what was the dose rate? A 29 What is the approximate entrance skin exposure (ESE) for the average AP supine lumbar spine radiograph? A 30 Which of the following radiation situations is potentially the most harmful? A C 31 How does filtration affect the primary beam? A A 32 Which of the following result(s) from restriction of the x-ray beam? Less scattered radiation production A 33 Which of the following has (have) an effect on the amount and type of radiation-induced tissue damage? Quality of radiation A 34 Filtration is added to the x-ray beam to A D produce an x-ray beam with higher average energy. 35 Which of the following will increase patient dose during fluoroscopy? Decreasing the SSD A 36 How many HVLs are required to reduce the intensity of a beam of monoenergetic photons to less than 15% of its original value? A 2 B 3 C 4 D 5 37 The focal spot-to-table distance in mobile fluoroscopy must A 38 Gonadal shielding should be provided for male patients in which of the following examinations? Femur A 39 Which of the following is (are) likely to improve image quality and decrease patient dose? Beam restriction A 40 Radiation safety requirements for fluoroscopic equipment include the following: A 41 To radiograph an infant for suspected free air within the abdominal cavity, which of the following projections of the abdomen will demonstrate the condition with the least patient exposure? A C 42 All the following have an effect on patient dose except A 43 Which of the following is (are) associated with Compton scattering? 1. High-energy incident photons A 44 The most efficient type of male gonadal shielding for use during fluoroscopy is A B 45 What is the approximate entrance skin exposure (ESE) for the average anteroposterior (AP) supine abdomen radiograph? A 46 Which of the following would be the safest interval of time for a fertile woman to undergo abdominal radiography without significant concern for irradiating a recently fertilized ovum? A B 47 An increase of 1.0 mm added aluminum filtration of the x-ray beam would have which of the following effects? Increase
in average energy of the beam A 48 The automatic exposure device that is located immediately under the x-ray table is the A 49 If the exposure rate to an individual standing 4.0 m from a source of radiation is 10 mR/h, what will be the dose received after 20 minutes at a distance of 6 m from the source? A 50 Which of the following terms is correctly used to describe x-ray beam quality? A 51 At least how many HVLs are required to reduce the intensity of a beam of monoenergetic photons to less than 10% of its original value? A 52 All of the following device(s) are generally used to help reduce patient dose, except grid A 53 If a patient received 4,500 mrad during a 6-minute fluoroscopic examination, what was the dose rate? A 54 Guidelines for the use of protective shielding state that gonadal shielding should be used if the patient has reasonable reproductive potential A 55 Which of the following groups of exposure factors will deliver the least patient dose? A 56 Which of the following methods can be used to reduce radiation exposure to a recently fertilized ovum? Elective booking A 57 All of the following have an effect on patient dose except A 58 Classify the following tissues in order of increasing radiosensitivity Liver cells A 59 Which of the following functions to protect the x-ray tube and the patient from overexposure in the event that the phototimer fails to terminate an exposure? A 60 Which of the following will produce the most significant increase in patient dose? A 61 Which of the following is most likely to result in the greatest increase in patient exposure? A D 62 Lateral deviation of the nasal septum may be best demonstrated in the A C 63 Reducing the number of repeat images is an important way to decrease patient exposure and can be accomplished by A 64 The principal function of filtration in the x-ray tube is to reduce A 65 Inherent and added filtration in the x-ray tube functions to A A 66 Patient dose during fluoroscopy is affected by the distance between the patient and the input phosphor A 67 From which of the following primary beam sizes, all other factors remaining constant, will the greatest radiation exposure result? A 68 Which of the following groups of exposure factors will deliver the least amount of exposure to the patient? A A 69 Which of the following safeguards is (are) taken to prevent inadvertent irradiation in early pregnancy? Patient postings A 70 A fluoroscopic examination requires 3 minutes of exposure on time. If the exposure rate for the examination is 250 mR/hr, what is the approximate exposure for the three minute procedure? A 71 The largest amount of diagnostic x-ray absorption is most likely to occur in which of the following tissues? A 72 The measure of the rate at which energy is transferred from ionizing radiation to soft tissue is termed A 73 The primary function of filtration is to reduce A 74 With milliamperes (mA) increased to maintain output intensity, how is the ESE affected as the source-to-skin distance (SSD) is increased? A 75 Which of the following is (are) important for patient protection during fluoroscopic procedures? A 76 Filters used in radiographic x-ray tubes generally are composed of A 77 Which of the following interactions between x-ray photons and matter involves a high-energy photon and the ejection of an outer shell electron? A 78 The primary function of filtration is to reduce A 79 A minimum total amount of aluminum filtration (inherent plus added) of 2.5 mm is required in equipment operated A 80 Which of the following would be most likely to cause the greatest skin dose (ESE)? A 81 In which of the following examinations would a cassette front with very low absorption properties be especially important? A 82 The recommendation of "elective booking" states that elective abdominal radiographic examinations on women of reproductive age should be limited to the A B 83 Methods of reducing radiation exposure to patients and/or personnel include A 84 The reduction in x-ray photon intensity as the photon passes through a material is termed A 85 When the collimated field must extend past the edge of the body, allowing primary radiation to strike the tabletop, as in a lateral lumbar spine radiograph, what may be done to prevent excessive radiographic density owing to undercutting? A D 86 All the following function to reduce patient dose except A 87 Types of structural damage to a DNA molecule by ionizing radiation include which of the following? single-side-rail scission A 88 It is necessary to question a female patient of childbearing age regarding her date of last menstrual period A 89 Replacing 200-speed intensifying screens with 400-speed screens will require the exposure to be cut in half. A 90 A test radiograph like the one pictured in Figure A would be made by the radiation safety officer (RSO) or equipment service person and is used to evaluate Figure A. Courtesy of Stamford Hospital, Department of Radiology A B C D 91 The SSD in mobile fluoroscopy must be A 92 The reduction in the intensity of an x-ray beam as it passes through material is termed A 93 The interaction between x-ray photons and tissue that is responsible for radiographic contrast but that also contributes significantly to patient dose is A A 94 Which of the following contributes most to patient dose? A A 95 For radiographic examinations of the skull, it is generally preferred that the skull be examined in the A 96 It is essential to question female patients of childbearing age regarding the date of their last menstrual period A 97 Aluminum filtration has its greatest effect on A A low-energy x-ray photons 98 The focal spot-to-table distance, in mobile fluoroscopy, must be A 99 If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate? A 100 Which of the following groups of exposure factors would deliver the lowest patient dose? A A 101 Patient exposure can be minimized by using which of the following? A 102 Types of gonadal shielding include which of the following? Flat contact A 103 If the entrance dose for a particular radiograph is 320 mR, the radiation exposure at 1 m from the patient will be approximately A What is entrance skin exposure?The entrance skin dose (or entrance surface dose), abbreviated as ESD, is the measure of the radiation dose that is absorbed (measured in milligray) by the skin as it reaches the patient. Entrance skin dose is a directly measurable quantity, often, measured using thermoluminescent dosimeters (TLD) 1.
Which of the following are the prime factors of exposure in radiography?The prime factors of exposure are milliamperage (mA), exposure time (S), kVp, and SID.
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Which of the following radiographic procedures delivers the lowest entrance skin exposure?
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