Final test cont 12,14-16 Flashcards
Any image that must be repeated because of human or mechanical error during the production of the initial image is considered to be a repeat image. What effect does a repeat image have on the radiation dose received by the patient?
The patient’s skin and possibly the gonads, if they were in the included imaged area, receive a double radiation dose.
During a radiographic examination, which of the following combinations of technical exposure factors reduce patient radiation dose?
Higher kVp, lower mAs
When a pregnant patient must undergo a radiographic procedure, which of the following practices will minimize radiation exposure?
Selecting technical exposure factors that are appropriate for the part of the body to be imaged and precisely collimating the radiographic beam to include only the anatomic area of interest while shielding the lower abdomen and pelvis when this area does not need to be included in the area to be imaged.
According to the American College of Radiology (ACR), abdominal radiologic examinations that have been requested after full consideration of the clinical status of a patient, including the possibility of pregnancy, need
not be postponed or selectively scheduled.
The reason for discontinuing patient gonadal shielding and fetal shielding in diagnostic radiology is based on research that the use of such shielding may jeopardize the benefits of the radiologic examination because
an incorrectly placed shield within the collimated x-ray beam when an automatic collimator is used, can result in the lead in the shield obscuring anatomic information or interfering with the AEC system.
Specific area shielding may be selectively used during some x-ray procedures to protect which of the following?
1. Lens of the eye
2. Breast
3. Upper extremities
4. Lower extremities
1 and 2
________________________ are the sensing devices most often used to measure skin dose directly.
Thermoluminescent dosimeters
Which of the following procedures results in the lowest radiation effective dose to the patient?
Dual energy X-ray absorptiometry
According to the U.S. Public Health Service, the genetically significant dose (GSD) for the population of the United States is approximately
0.20 mSv.
Which of the following must always be the first step in protection of the reproductive organs?
Adequate and precise collimation of the radiographic beam to include only the anatomy of interest
Motion controlled by will is classified as voluntary motion. Lack of such control may be attributed to which of the following?
1. The patient’s age
2. Breathing patterns or problems
3. Physical discomfort
4. Fear of the examination
5. Mental instability
1, 2, 3, 4, 5
When a properly calibrated automatic exposure control (AEC) is not employed to obtain a uniform selection of technical x-ray exposure factors, well-managed imaging departments?
Make use of standardized technique charts that have been established for each x-ray unit in that facility.
Neglecting to use standardized technique charts necessitates estimating the technical exposure factors, which may result in
1. poor-quality images.
2. repeat examinations.
3. additional and unnecessary exposure of the patient.
All of the options
Reducing the field size to the anatomic features of interest not only reduces patient exposure but also
increases completed image quality by decreasing scatter
Because multiple bony areas span the entire body, the radiation dose absorbed by the organ called bone marrow
cannot be measured by a direct method; it can only be estimated.
Which of the following are reasons for unacceptable images?
1. Patient mispositioning
2. Incorrect centering of the radiographic beam
3. Patient motion during the radiographic exposure
4. Incorrect collimation of the radiographic beam
All of the options
After some decades of experience with modern digital x-ray equipment and as a result of improvements in dosimetry estimates of the efficacy of shielding with modern equipment and techniques, professional and scientific societies are
modifying shielding practices in diagnostic radiology to discourage the use of patient gonadal shielding and fetal shielding.
A blotchy radiographic image that results when an insufficient quantity of x-ray photons reaches the image receptor is called
quantum noise, or mottle.
Which of the following are involuntary motions that cannot be willingly controlled?
1. Chills
2. Tremors
3. Muscle spasms
4. Pain
5. Active withdrawal
All of the options.
Which of the following is frequently a problem in diagnostic pediatric radiography?
Patient motion
In the event that a pregnant patient is inadvertently irradiated
the radiation safety officer or the medical physicist should perform the calculations necessary to determine fetal dose.
Studies of groups such as the atomic bomb survivors of Hiroshima have shown that damage to the newborn is unlikely for doses below
0.2 Gy.
Essentially all diagnostic medical procedures result in fetal exposures ______________, so that _______________________.
of less than 0.01 Gy; the risk of abnormality is very small
Of the following radiologic procedures, which is (are) considered nonessential?
1. A chest x-ray examination automatically scheduled on admission to the hospital
2. Lumbar spine x-ray examination as part of a pre-employment physical
3. Whole-body computed tomography (CT) screening
All of the options
Analysis of an imaging department’s repeat rate
1. provides valuable information for process improvement.
2. helps minimize patient exposure.
3. improves overall performance of the department.
All of the options
Which of the following x-ray procedures increases the radiographer’s risk of exposure to ionizing radiation compared to general diagnostic radiography performed in an x-ray room?
1. Mobile C-arm fluoroscopy
2. Interventional procedures that use high level control fluoroscopy
3. Mobile radiographic examinations
All of the options
Occupational exposure of the radiographer can be kept as low as reasonably achievable (ALARA) through individual monitoring and other protective measures and the use of protective devices. Therefore, because exposure from radiation-related jobs will not alter the ______________________, radiation workers may receive a larger equivalent dose than members of the general population.
genetically significant dose
Which of the following are radiation-shielding design considerations?
1. The mean energy of the x-rays that will strike the barrier
2. Whether the barrier is of a primary or secondary nature
3. The workload of the unit
4. The use factor of the unit
5. The occupancy factor behind the barrier
All of the options
Whenever scattered radiation decreases, the radiographer’s exposure
decreases
Which of the following adjustments in technical exposure factors decreases the production of scattered radiation during routine radiographic procedures?
Increase kVp and decrease mAs in compensation
During which of the following x-ray examinations should a radiographer always wear a thyroid shield?
Fluoroscopy and x-ray special procedures
While standing behind the control-booth barrier, a radiographer makes a radiographic exposure. The x-rays scattered from the patient’s body should ____________________.
scatter a minimum of 2 times before reaching any area behind the control-booth barrier.
Which of the following is another term for use factor (U)?
Beam direction factor
The annual effective dose limit for individual members of the general population not occupationally exposed is ___________ for continuous or frequent exposures from artificial sources other than medical irradiation and natural background and ____________ for infrequent annual exposure.
1 mSv; 5 mSv
A protective curtain, or sliding panel, with a minimum of 0.25-mm lead equivalent, should normally be positioned between the fluoroscopist and the patient to intercept which of the following types of radiation?
Scattered radiation above the tabletop
f the intensity of the x-ray beam is inversely proportional to the square of the distance from the source, how does the intensity of the x-ray beam change when the distance from the source of radiation and a measurement point is tripled?
It decreases by a factor of 9 at the new distance.
For primary radiation, what is the term that represents a portion of beam-on time that the x-ray beam is directed at a primary barrier during the week?
Use factor
The maximum weekly permitted equivalent dose for a controlled area must not exceed
1 mSv.
When a radiologic technologist declares her pregnancy to her employer, which of the following is appropriate?
She continues to perform her duties without interruption of employment, provided that she has received radiation safety counseling and follows established radiation safety practices.
Which part(s) of a diagnostic x-ray unit should not be touched while a radiographic exposure is in progress?
Tube housing, collimator, and high-tension cables
When doors to radiographic and fluoroscopic rooms are closed during radiation exposures, a substantial degree of protection is provided for persons in areas adjacent to the room door. This is because in most facilities room doors have attenuation for diagnostic energy x-ray equivalent to that provided by _______ mm of lead.
0.8
When the time spent in a higher radiation area is reduced or limited, occupational exposure
is also reduced.
Compared to general diagnostic radiography performed in an x-ray room, imaging personnel receive the highest occupational exposure during which of the following procedures?
Fluoroscopy
Mobile radiography
X-ray special radiographic procedures
All of the options.
If the peak energy of the x-ray beam is 100 kVp, a protective lead apron must be the equivalent to at least which of the following measures?
0.25-mm thickness of lead
For C-arm devices with similar fields of view, the dose rate to personnel located within a meter of the patient is ____________ the dose rate to personnel from ______________.
comparable to; routine fluoroscopy.
Scattered radiation to the lens of the eyes of diagnostic imaging personnel can be substantially reduced by the use of protective eyeglasses fitted with optically clear lenses that contain a minimal lead equivalent protection level of
0.35 mm.
_______________ is essentially the radiation output weighted time that the unit is actually delivering radiation during the week.
Workload
To ensure that the lifetime risk of occupationally exposed persons remains acceptable, an additional recommendation is that the lifetime effective dose in mSv should not exceed
10 times the occupationally exposed person’s age in years.
Secondary radiation includes
1. leakage radiation.
2. primary radiation.
3. scatter radiation.
1 and 3 only
Who should determine the exact shielding requirements for a particular imaging facility?
Medical physicist
The isotopes used in brachytherapy are characterized by
relatively long half-lives that are measured in terms of multiple days, months, or years and, except for a few of them, by relatively high energy emissions.
Iodine-125 (125I53) has been used quite extensively since 2000 in the form of titanium-encapsulated cylindrical seeds to give a tumoricidal radiation equivalent dose to
cancers that are confined within the prostate gland
Tellurium-125 (125Te52) has
52 protons and 73 neutrons.
What is the half-life of Technetium-99m?
6 hours
In __________, a neutron transforms itself into a combination of a proton and an energetic electron.
beta decay
Considering the design of the medical imaging suites listed below, which suite requires shielding for the highest energy photons?
PET-CT imaging suite
While a patient receiving Iodine-131 (131I53) therapy is hospitalized, a large, _________, movable lead shield can be positioned between the patient and any attending personnel for protection.
up to 25-mm or 1-inch-thick
Diagnostic techniques in nuclear medicine typically make use of ___________ radioisotopes as radioactive tracers.
short-lived
Each Fluorine-18 (18F) nuclear transformation by positron decay yields two highly penetrating _________ photons.
511 keV
Of the following four choices, the design of a _______________ imaging suite will usually require the most lead shielding?
PET-CT
Any radioactive material that is attached to or associated with dust particles or in liquid form and is found on various surfaces is referred to as
radioactive contamination.
The actual long-term health effects of a “dirty bomb” are likely to be
minimal.
During a radiation emergency, the dose limit for individuals engaging in lifesaving activities is
250 mSv per event.
During a radiation emergency, if the dose rate exceeds ____________, emergency personnel should await specific instructions from radiation experts on how to proceed.
0.1 Sv/hr
If enough explosives are used to spread radioactive material over a broad area, then radioactivity is
diluted and may not be much higher than background levels.
Gamma rays differ from x-rays
only in the method of how they are produced.
A solid encapsulated radioactive source
is never to be touched directly with the hands; instead long tongs which add distance should be used.
At the conclusion of a brachytherapy or diagnostic radionuclide procedure, any residual isotope
is to be returned to its shielded container.
Radioiodide tablets that dissolve in the bloodstream permit an escape of some radioactivity through
1. the pores of the skin.
2. urination.
3. vomiting in some special cases.
All of the options
The National Library of Medicine and the National Institute of Health maintain a website that contains a wealth of information on dealing with radiation emergencies. It contains which of the following?
1. Both basic and advanced methods for decontamination
2. Methods to reduce exposure
3. Specific medical emergency procedures for various situations
All of the options
A becquerel (Bq) is defined as
1 disintegration per second.
Monoclonal antibodies (MAB) are antibodies that preferentially bind always to a specific
part of an antigen that is recognized by the antibody.
The success of radioimmunotherapy depends on the selective accumulation of
cytotoxic radioisotopes at affected areas.
If surface contamination from radioactive material is suspected, personnel, when working with patients, should wear
1. gowns.
2. masks.
3. gloves.
All of the options
Potassium iodide can be administered to block further uptake of radioactive iodine in the
thyroid gland.
