PRINCIPLES OF IMAGING

As the kilovoltage is given to the X-ray tube, this will.

Projectile electrons speed up towards the other side of the tube.

Trisha, a radiologic technologist, employed a high kVp on a cervical spine examination. She noticed that his radiograph is too dark. What is the appropriate reason this resulted in a dark film?

She uses high frequencies of X-rays that enable them to pass through the patient.

Mary Grace initiates the rotor switch after positioning the patient. From the control console, she heard a noise coming from the x-ray tube. She knows that this happens because of:

Moving electrons begin to produce magnetic fields.

When an outer shell electron fills the void in an inner shell, electromagnetic energy is released. What principle explains the emission of electromagnetic energy?

Law of conservation of energy

Ms. Co, a radiologic technology intern, notices that the two images she produces have a different blackness. She notices the first one is much lighter in blackness compared to the other one. If she uses 400 mA on the first one and 800 mA on the next, what is the probable cause of the differentiation in blackness?

The radiation quantity is greater on the second exposure.

During X-ray production, electrons tend to accumulate at the center of the focusing cup once the electrons are emitted from the filament. Why?

The electric charge of the focusing cup repels the electrons.

There is a greater percentage of heat production than X-ray production during theemission of radiation in the X-ray tube. Why?

Because all interactions can produce excitation of outer shell electrons.

How will a grid help in improving the contrast of a radiograph?

It will absorb the scatter radiation before it reaches the IR.

A radiograph is taken using 88 kVp, 100 mA, 0.017 sec, and 40 inches SID. If

Andy Lim, a radiologic technologist-on-duty, wants to repeat it using 73 kVp, 100 mA, 0.017 sec, and 40 inches SID, what would be the most appropriate problem with the first radiograph?

The image appears to have more density because of overpenetration.

A projectile electron comes from the filament, bombards the nuclear field at a short distance, and emits radiation. What is the energy of the radiation emitted?

The radiation possesses a higher energy because of greater energy loss by the projectile electron.

Mr. Pikit, a radtech, used 400 mA, 1/16 sec, 78 kVp, and 160 cm SID as a technical factor for a chest X-ray exam. After processing, he noticed that the image displayed lower contrast. How would he amend this?

Use a grid that will absorb the scattered X-rays.

An X-ray of an orbit shows underexposure using 3 mAs, 70 kVp, and 100 cm SID. If you are the Radtech on duty, what is the appropriate solution for this problem?

Increase the kVp to 80 kVp.

Ms. Alex, a basketball athlete, injured her shoulder during a final game in a sport fest. If the radtech uses 200 mA and 0.06 sec in the exposure, which of the following factors will produce the same density as the shoulder exam?

400 mA and 0.03 sec

A 43-year-old male patient rushed into the emergency room complaining of epigastric pain. He rated the pain as 8/10. The emergency department doctor requested an abdominal X-ray. Nova, the RTOD, uses 84 kVp, 12 mAs, and a 12:1 grid. If she wanted to increase the contrast of the image, what variable must she use?

Nova may use a 16:1 grid ratio and 15 mAs

If the kilovoltage is supplied to the x-ray tube, this will:

The polyenergetic x-rays are emitted

The kVp affects the contrast of the radiograph because:

kVp controls the penetrability of X-rays

Which of the following statements below would BEST reverse a low subject contrast abdominal radiograph?

Increase the distance between object and detector

Which set of technical factors and accessories would produce the shortest scale of contrast?

10:1 grid, 60 mAs, 65 kv, 10x12-in field size, high-speed screens

What happens if the mAs is increased from 12 to 24?

The X-ray intensity is increased.

The beam centering device is composed of the mirror and the light, which must be placed at what angle to the focal spot?

45 degrees

When a film demonstrates long scale contrast because of overpenetration, the appropriate change to restore a shorter scale of contrast would be which of the following?

Decrease the amount of kVp used in the panel

Which of the following reasons is correct for why contrast media gives greater contrast?

The large difference in absorption between contrast material and bone tissue

A satisfactory abdominal radiograph was produced using an 8:1 grid, 25 mAs, and 90 kVp. Due to the long scale of contrast in the image, a second image was requested with a 12:1 grid. What will be the new mAs for the second image?

31.3 mAs

A radiograph of the shoulder in lateral projection is underexposed and must be repeated. The original technique used was 70 kV with 2.5 mAs. The technologist decides to keep the mAs at the same level but change the kV to increase radiographic density. How much of an increase is needed in kV to double the density?

80.5 kV, 2.5 mAs

A satisfactory radiograph of an abdomen is made in the supine position, using 14 in. x 17 in. collimation. If 8 in. x 10 in collimation is used to demonstrate the gallbladder without a technique compensation, the resultant film would demonstrate which of the following?

Less density

Which of the following radiographic techniques would compensate for a low-kvp technique?

200 mA & 0.75 sec

Which one of the following clinical indications requires a decrease in manual exposure factors?

Advanced osteoporosis

An anteroposterior (AP) projection of the femur was made using 300 mA, 0.03 seconds, 76 kV, 40-in. SID, 1.2-mm focal spot, and a 400-speed film-screen system. With all other factors remaining constant, which of the following exposure times would be required to maintain radiographic density/brightness at a 44-in. SID using 500 mA?

22 ms

Increasing the amount of filtration will have what impact on contrast and density?

Decrease contrast, decrease density

In a radiograph of a large abdomen, which of the following is (are) effective way (s) to minimize the amount of scattered produced from the patient?

I. Use of compression

II. Use of beam restriction

III. Use of a grid

I and II only

If a radiograph exposed using a 12:1 ratio grid exhibits increased brightness/loss of density at its  lateral edges, it is probably because the:

SID was too great

Decreasing field size from 14 x17 inches to 8 x 10 inches, with no other changes, will do which of the following?

Decreased amount of scattered radiation generated

Which of the following statements is true?

Patient dose would be greater when using a 12:1 grid than when using 8:1, assuming equal film densities.

The stationary grids are being used by a Level 2 Radiology Department for almost a year now. Alice, the chief R, uses the grid for trauma radiography and cleans it right away with mild soap and running water whenever spilled with patient’s blood. After months of using the same stationary grid, she noticed that the grid is slowly deteriorating and has become defective. What is the most likely cause of the problem?

The interspace material is made up of carbon fiber material.

Which of the following would NOT produce an increase in scattered radiation?

Employing an air-gap technique for use in cervical lateral projection

After taking an abdominal radiograph of a male geriatric patient with the use of a stationary linear-parallel grid, the resulting image turned out to have radiopaque longitudinal lines all throughout the 14x17-in radiograph. Which of the following statements below would provide a solution to the problem?

Utilize a moving grid/bucky tray

Which of the following groups of factors would produce the least radiographic density?

100 mA, 0.020 second, 80 kV, 200-speed screens

A satisfactory radiograph was made using a 36-in. SID, 6 mAs, and a 12: grid. If the examination will be repeated at a distance of 72 in, what should be the new milliampere-seconds value to maintain the original density?

24 mAs

A satisfactory radiograph of the lateral cervical spine is taken at an 80” distance at 10 milliampere-second received 187.5 mGy of x-ray intensity. If the distance is changed to 40” with all other factors remaining constant, what would be the new x-ray intensity?

750 mGy

Matteo, a RadTech intern, wanted to use the smallest possible field size in a lumbar examination. After carefully positioned the patient, he increases the collimation. This means:

The resultant image will display a high contrast

Using fixed milliampere-seconds and variable kilovoltage technical factors, each centimeter increase in patient thickness requires what adjustment in kilovoltage if the patient thickness is 14.5 cm and k is 40?

69 kV

Which of the following is the correct restriction of x-ray beam?

The x-ray field should always be smaller than image receptor size

HVL may be defined as the thickness of a designated absorber required to achieve which of the following?

Decrease the intensity of the primary beam by 50% of its initial value

Which of the following is NOT used as a filter material:

Magnesium

As specified in the manufacturing manual, the newly delivered mobile X-ray machine is already equipped with inherent filtration. Which of the following are examples of inherent filters?

Metal envelope, port window and dielectric oil bath

The conic filter is primarily used in:

Digital Fluoroscopy

Which of the following will reduce the production of scatter radiation?

I.Use of cones and cylinders

II.Utilization of a grid

III.Lower kVp settings

IV.Air gap technique

1 and 3

Which of the following is produced when an electron interacts near the nucleus of an atom?

Bremsstrahlung

Which of the following does NOT describe a low image contrast?

1. High kVp setting

2. Low kVp setting

3. Short scale of contrast

4. Long scale of contrast

5. Few gray tones

6. Many gray tones

2, 3, 5

Precisely fixed energies are representative of what type of photon?

Characteristic radiation

If a 60 kVp X-ray energy is changed to 120 kVp, this will:

Decrease patient dose

Which of the following is the effect of long-wavelength X-rays?

Low density

A radiograph that exhibits low contrast is one that has:

Many shades of gray with minimal difference in density between each shade

Advantages of using a Fixed kVp Technique Chart include less

I. Exposure latitude

II. Patient exposure

III. Scatter radiation production

2 only

These are emitted when a free electron interacts with the outer shell electron of an atom.

Anode Heat

A clavicle X-ray PA is performed with 5 mAs, 72 inches SID, and 80 kVp, the constant value of the machine is 40. What is the patient thickness?

8 in

How will radiographic density be affected when the SID is decreased by half?

Quadrupled

During the exposure of 80 kVp, what is the k-characteristic X-ray energy?

57 keV

The characteristic X-ray energy may be changed if which factor is changed?

Target atom

An exposure of a chest radiograph requires the use of 120 kVp, 40 mAs, and 72 in SID in digital radiography. The average energy is equivalent to:

40 keV

Which type of target interaction is responsible for most of the x-rays in the diagnostic beam?

Bremsstrahlung interaction

Grid ratio is defined as the ratio of the:

Height of the lead strip to the distance between them

Compared with parallel grids, focused grids:

Allow more transmitted photons to reach the image receptor

With which of the following grids would a convergent point be formed if imaginary lines from its grid lines were drawn in space above it:

Linear Focused

Off-focus grid cut-off occurs by using an SID that is not:

Equal to the focal range of the grid

A grid should be used whenever that anatomic part size exceeds:

10 cm

Grid cut off, regardless of the cause, is most recognizable radiographically as reduced:

Density

A radiograph of the abdomen requires 300 milliampere and 500 ms. The patient is unable to breathe-hold, which results in motion blur. Therefore, the exposure is made with a time of 250 ms. What is the required milliampere?

600 mA

A severe cut-off along the edge of the image when using a stationary grid is due to:

An upside-down placement of a focused grid

How many HVLs must elapse before the remaining X-ray intensity is less than 0. 1% of the original X-ray intensity?

10 HVL

Which of the following statements best describes the relationship of the primary controlling technical factor of density?

As mAs increases, density increases

A grid is constructed with 2.0 mm high, 0.2 mm thickness grid strips and 0.4 mm thickness of the interspace material. If 20 mAs is used on the first exposure and an 8:1 grid is employed on the next exposure, what would be the change in mAs?

40 mAs

Which of the following materials cannot

be used as grid interspace material:

I. Lead

II. Plastic

III. Aluminum

1 only

The number of lead strips per inch is termed as:

Grid Frequency

Which of the following has the purpose of blurring the grid lines?

Potter-Bucky diaphragm

The advantage of using aluminum rather than carbon fiber as an interspace material:

Non-hygroscopic and It does not absorb moisture

How does a 5:1 grid ratio, as compared to a 10:1 grid ratio, affect density? The 10:1 grid ratio will:

More scatter is removed; therefore, it decreases density

A particular grid measures 8 mm high, and its lead strips measure 0.8 mm separated from each other by 0.5 mm. The grid ratio is?

16:1

What is the best method of minimizing the amount of secondary radiation reaching the film in radiographing a large abdomen?

I. Use the smallest collimation

II. Use of compression device

III. Use of high grid ratio

1, 2 and 3

Of the following group of factors, which will produce the greatest radiographic contrast:

20 mAs, 50 kVp, 40” FFD

Which one of the following clinical indications is a constructive pathology?

Tuberculosis

It refers to the filtration provided by the X-ray tube structure, housing, and collimator (if attached):

Total filtration

The quantity of x-ray photons delivered to the patient in a given exposure is primarily regulated by:

mAs

Which of the following characteristics of tissue will contribute to a minimum attenuation of the X-ray beam, EXCEPT?

High mass density

The result of using the air-gap technique in a chest radiography is:

Increased distortion

SEQUENCING. Arrange the following anatomical structures from blackest to whitest.

I. Humerus

II. Left lung

III.Hepato

IV. Air in the stomach

V. Fatty tissues

4,2,5,3,1

Which of the following statements comparing ionization chamber AEC systems with phototimers is true?

Ionization chamber systems measure radiation before it interacts with the image receptor

Which of the following technique charts is used to produce a short scale of contrast?

Variable kVp and fixed mAs

The following are types of moving grid mechanisms, EXCEPT:

1. Oscillating

2. Reciprocating

3. Synchronous

3 only

A lateral chest technique uses 70 kVp, 20 mAs, which results in x-ray intensity of 320 uGy at the position of patient. If the kVp is increased to 140 kVp, what will the intensity be?

1280 uGy

A chest radiograph shows low contrast using 120 kVp and 10 mAs. If a repeat is requested to increase the contrast and maintain its denisty, what will be the new kVp and mAs to be used?

102 kVp, 20 mAs

The 15% kVp rule states that:

Density may be halved by decreasing kVp by 15%

The distance from the source of the radiation to the X-ray film affects the:

I. the wavelength of the X-ray beam

II. the scatter radiation production

III. the density of the radiograph

3 only

The atomic number of the air is:

7.6

A change of mAs in the exposure factors will change the:

I.Average photon wavelength

II.Number of radiations emitted

III.Ionizations in air

2 and 3

Which of the following requires a decrease in exposure factors?

Emphysema

An increase in FFD will result in: 

Low radiation exposure to the film

Secondary radiation has the greatest effect on which of the following radiographic qualities

I. Recorded detail

II. Contrast

III. Density

IV. Distortion

2 & 3 only