rAD pROTECTIONMinimizing patient exposure

Which of the following projections is most likely to deliver the largest dose to the ovaries?



A
 
AP lumbar spine, 7 × 17 in. cassette, 80 kVp 


B
 
AP lumbar spine, 14 × 17 in. cassette, 80 kVp 


C
 
AP abdomen, 80 kVp 


D
 
AP abdomen, 70 kVp

Which of the following will reduce patient dose during fluoroscopy?

1.	Decreasing the source-skin distance (SSD)
2.	Using 2.5 mm Al filtration
3.	Restricting tabletop intensity to less than 10 R/min

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

Which of the following is (are) likely to improve image quality and decrease patient dose?

1. Beam restriction


2. Low kilovolt and high milliampere- second factors


3. Grids

A
 
1 only 


B
 
1 and 3 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

If a patient received 0.9 rad during a 3-minute fluoroscopic examination, what was the dose rate?



A
 
3 mrad/min 


B
 
30 mrad/min 


C
 
300 mrad/min 


D
 
3,000 mrad/min

The interaction illustrated in Figure 3–5

1. can pose a safety hazard to personnel


2. can have a negative impact on image quality


3. occurs with low-energy incident photons

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

Which of the following result(s) from restriction of the x-ray beam?

1. Less scattered radiation production


2. Less patient hazard


3. Less radiographic contrast

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

Classify the following tissues in order of increasing radiosensitivity

1. Liver cells


2. Intestinal crypt cells


3. Muscle cells

A
 
1, 3, 2 


B
 
2, 3, 1 


C
 
2, 1, 3 


D
 
3, 1, 2

Which one of the following is (are) used to control the production of scattered radiation?

1. Collimators


2. Optimal kV


3. Use of grids

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

It is essential to question female patients of childbearing age regarding the

1. date of their last menstrual period


2. possibility of their being pregnant


3. number of x-ray examinations they have had in the past 12 months

A
 
1 only 


B
 
1 and 2 only 


C
 
1 and 3 only 


D
 
1, 2, and 3

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
 
1.2 R 


B
 
2.4 R 


C
 
4.8 R 


D
 
9.6 R

From which of the following primary beam sizes, all other factors remaining constant, will the greatest radiation exposure result?



A
 
8 × 10 


B
 
10 × 12 


C
 
11 × 14 


D
 
14 × 17

Patient dose increases as fluoroscopic



A
 
FOV increases 


B
 
FOV decreases 


C
 
FSS increases 


D
 
FSS decreases

If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate?



A
 
0.2 rad/min 


B
 
2.0 rad/min 


C
 
5 rad/min 


D
 
200 rad/min

Which of the following methods can be used to reduce radiation exposure to a recently fertilized ovum?

1. Elective booking


2. Patient questionnaire


3. The 10-day rule

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

The interaction between x-ray photons and tissue that is responsible for radiographic contrast but that also contributes significantly to patient dose is



A
 
the photoelectric effect 


B
 
Compton scatter 


C
 
coherent scatter 


D
 
pair production

What is the approximate entrance skin exposure (ESE) for the average anteroposterior (AP) supine abdomen radiograph?



A
 
300 rad 


B
 
300 mrad 


C
 
35 rad 


D
 
35 mrad

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
 
83.3 R 


B
 
83.3 mR 


C
 
12.5 R 


D
 
12.5 mR

An increase of 1.0 mm added aluminum filtration of the x-ray beam would have which of the following effects?

1. Increase in average energy of the beam


2. Increase in patient skin dose


3. Increase in milliroentgen output

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

For radiographic examinations of the skull, it is generally preferred that the skull be examined in the



A
 
AP projection 


B
 
PA projection 


C
 
recumbent position 


D
 
supine position

B

Which of the following most effectively minimizes radiation exposure to the patient?



A
 
Small focal spot 


B
 
Low-ratio grids 


C
 
Increased SID 


D
 
High-speed intensifying screens

he focal spot-to-table distance, in mobile fluoroscopy, must be



A
 
a minimum of 15 inches. 


B
 
a maximum of 15 inches. 


C
 
a minimum of 12 inches. 


D
 
a maximum of 12 inches.

Filters used in radiographic x-ray tubes generally are composed of



A
 
aluminum 


B
 
copper 


C
 
tin 


D
 
lead

Which of the following terms is correctly used to describe x-ray beam quality?



A
 
mA 


B
 
HVL 


C
 
Intensity 


D
 
Dose rate

Patient exposure can be minimized by using which of the following?

1.	Accurate positioning
2.	High-kV, low-mAs factors
3.	Rare earth screens

A
 
1 only 


B
 
1 and 2 only 


C
 
1 and 3 only 


D
 
1, 2, and 3

If a patient received 1,400 mrad during a 7-minute fluoroscopic examination, what was the dose rate?



A
 
200 rad/min 


B
 
5 rad/min 


C
 
2.0 rad/min 


D
 
0.2 rad/min

All the following have an effect on patient dose except



A
 
kilovoltage 


B
 
milliampere-seconds 


C
 
focal spot size 


D
 
inherent filtration

Patient dose during fluoroscopy is affected by the

1. distance between the patient and the input phosphor


2. amount of magnification


3. tissue density

A
 
1 only 


B
 
3 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

Aluminum filtration has its greatest effect on



A
 
low-energy x-ray photons 


B
 
high-energy x-ray photons 


C
 
low-energy scattered photons 


D
 
high-energy scattered photons

Which of the following is (are) associated with Compton scattering?

1.	High-energy incident photons
2.	Outer-shell electrons
3.	Characteristic radiation

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

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
 
The first 10 days following the cessation of menstruation 


B
 
The first 10 days following the onset of menstruation 


C
 
The 10 days preceding the onset of menstruation 


D
 
About 14 days before menstruation

What is the approximate ESE for the average upright PA chest radiograph using 115 kVp and a grid?



A
 
20 rad 


B
 
20 mrad 


C
 
200 rad 


D
 
200 mrad

The advantages of beam restriction include which of the following?

1. Less scattered radiation is produced.


2. Less biologic material is irradiated.


3. Less total filtration will be necessary.

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

The SSD in mobile fluoroscopy must be



A
 
a minimum of 15 in. 


B
 
a maximum of 15 in. 


C
 
a minimum of 12 in. 


D
 
a maximum of 12 in.

Types of structural damage to a DNA molecule by ionizing radiation include which of the following?

1. single-side-rail scission


2. double-side-rail scission


3. cross-linking

A
 
1 only 


B
 
2 only 


C
 
1 and 2 only 


D
 
1, 2, and 3

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
 
Circuit breaker 


B
 
Fuse 


C
 
Backup timer 


D
 
Rheostat

Inherent and added filtration in the x-ray tube functions to



A
 
reduce patient skin dose. 


B
 
shorten the scale of contrast. 


C
 
reduce scattered radiation. 


D
 
soften the x-ray beam.

Which of the following would be most likely to cause the greatest skin dose (ESE)?



A
 
Short SID 


B
 
High kilovoltage 


C
 
Increased filtration 


D
 
Increased milliamperage

Which of the following groups of exposure factors would deliver the lowestpatient dose?



A
 
2.5 mAs, 100 kVp, 400-speed screens 


B
 
10 mAs, 90 kVp, 200-speed screens 


C
 
10 mAs, 70 kVp, 800-speed screens 


D
 
10 mAs, 80 kVp, 400-speed screens

When an image intensifier's magnification mode is used,

1.	output screen gain is increased.
2.	resolution increases.
3.	patient dose increases.

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

What quantity of radiation exposure to the reproductive organs is required to cause temporary infertility?



A
 
100 rad 


B
 
200 rad 


C
 
300 rad 


D
 
400 rad

Which of the following groups of exposure factors will deliver the least patient dose?



A
 
300 mA, 250 ms, 70 kVp 


B
 
300 mA, 125 ms, 80 kVp 


C
 
400 mA, 90 ms, 80 kVp 


D
 
600 mA, 30 ms, 90 kVp

The primary function of filtration is to reduce



A
 
patient skin dose 


B
 
operator dose 


C
 
image noise 


D
 
scattered radiation

A

If a patient received 2000 mrad during a 10-minute fluoroscopic examination, what was the dose rate?



A
 
0.02 rad/min 


B
 
0.2 rad/min 


C
 
2.0 rad/min 


D
 
20 rad/min

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

B

How does filtration affect the primary beam?



A
 
It increases the average energy of the primary beam. 


B
 
It decreases the average energy of the primary beam. 


C
 
It makes the primary beam more penetrating. 


D
 
It increases the intensity of the primary beam.

It is necessary to question a female patient of childbearing age regarding her

1. date of last menstrual period


2. possibility of being pregnant


3. age at her first pregnancy

A
 
1 only 


B
 
1 and 2 only 


C
 
1 and 3 only 


D
 
2 and 3 only

Which of the following will increase patient dose during fluoroscopy?

1. Decreasing the SSD


2. Using 2.5 mm Al filtration


3. Restricting tabletop intensity to less than 10 R/min

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

Which of the following is most likely to result in the greatest increase in patient exposure?



A
 
Changing from a 400 speed system to a 200 speed system 


B
 
Increasing kVp 15% and cutting mAs in half 


C
 
Using two tomographic cuts instead of two plain images 


D
 
From nongrid technique to 8:1 grid

Which of the following groups of exposure factors will deliver the leastamount of exposure to the patient?



A
 
400 mA, 0.25 second, 100 kVp 


B
 
600 mA, 0.33 second, 90 kVp 


C
 
800 mA, 0.5 second, 80 kVp 


D
 
800 mA, 1.0 second, 70 kVp

The measure of the rate at which energy is transferred from ionizing radiation to soft tissue is termed



A
 
the characteristic effect 


B
 
Compton scatter 


C
 
linear energy transfer 


D
 
the photoelectric effect

The most efficient type of male gonadal shielding for use during fluoroscopy is



A
 
flat contact 


B
 
shaped contact (contour) 


C
 
shadow 


D
 
cylindrical

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
 
focal spot size. 


B
 
linearity. 


C
 
collimator alignment. 


D
 
spatial resolution.

What is the approximate entrance skin exposure (ESE) for the average AP supine lumbar spine radiograph?



A
 
350 rad 


B
 
350 mrad 


C
 
35 rad 


D
 
35 mrad

With milliamperes (mA) increased to maintain output intensity, how is the ESE affected as the source-to-skin distance (SSD) is increased?



A
 
The ESE increases. 


B
 
The ESE decreases. 


C
 
The ESE remains unchanged. 


D
 
ESE is unrelated to SSD.

Which of the following is most likely to permit the greatest decrease in patient exposure?



A
 
Changing from a 200-speed system to a 400-speed system 


B
 
Increasing kilovoltage by 15% and cutting the milliampere-seconds value in half 


C
 
Changing collimation from 10 × 12 to 14 × 17 


D
 
Changing from an 8:1 grid technique to nongrid

Moving the image intensifier closer to the patient during traditional fluoroscopy

1. decreases the SID


2. decreases patient dose


3. improves image quality

A
 
1 only 


B
 
1 and 2 only 


C
 
1 and 3 only 


D
 
1, 2, and 3

Radiation safety requirements for fluoroscopic equipment include the following:

1.	SSD at least 38 cm on stationary (fixed) equipment.
2.	SSD at least 30 cm on mobile equipment.
3.	high level/boost mode must have continuous audible signal.

A
 
1 only 


B
 
1 and 2 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

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
 
22.5 mR 


B
 
7.5 mR 


C
 
4.44 mR 


D
 
1.48 mR

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
 
Reduce the milliampere-seconds. 


B
 
Reduce the kilovoltage. 


C
 
Use a shorter SID. 


D
 
Use lead rubber to absorb tabletop primary radiation.

Which of the following is (are) important for patient protection during fluoroscopic procedures?

1.	Intermittent fluoroscopy
2.	Fluoroscopic field size
3.	Focus-to-table distance

A
 
1 and 2 only 


B
 
1 and 3 only 


C
 
2 and 3 only 


D
 
1, 2, and 3

A minimum total amount of aluminum filtration (inherent plus added) of 2.5 mm is required in equipment operated



A
 
above 50 kVp 


B
 
above 60 kVp 


C
 
above 70 kVp 


D
 
above 80 kVp

The primary function of filtration is to reduce



A
 
patient skin dose. 


B
 
operator dose. 


C
 
image noise. 


D
 
scattered radiation.

Which of the following safeguards is (are) taken to prevent inadvertent irradiation in early pregnancy?

1. Patient postings


2. Patient questionnaire


3. Elective booking

A
 
1 and 2 only 


B
 
1 and 3 only 


C
 
2 and 3 only 


D
 
1, 2, and 3