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CT > Cttutor > Flashcards

Cttutor Flashcards

1
Q

During CT examinations, gonadal shielding of the female patient can be applied for which of the following exams?

  1. Brain
  2. Chest
  3. Abdomen
A

All
1,2,3

Gonadal shielding may be used whenever the gonads do not lie within the region of interest. In the female patient gonadal shielding is most difficult during CT scanning of the pelvis.

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2
Q

When speaking of x-ray radiation, which of the following is true?

1 rem = 1 rad
1 rad = 1 Sv
1 rad = 1 Gy
1 rem = 1 Gy
A

1 rem = 1 rad

When measuring the radiation dose from x-rays, rads and rems are equivalent. The units of Sv and rem are used to measure any kind of ionizing radiation where 1 Sv =100rem. The units of rad and Gy are used to measure specifically x-ray radiation where 1 Gy = 100 rads.

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3
Q

There is a universal standard set of forms required by law, in all states, which must be signed by a patient before the CT scan can be performed.

True
False
A

False

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4
Q

A patient with a chest tube is brought to the CT department for a CT examination, the suction unit used on the patient should remain…

Level with the patient
18 inches above the patient
Below the patient
None of the above
A

BELOW THE PT

To properly drain the chest tube a suction unit must remain below the level of the patient.

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5
Q

The blood urea nitrogen level would be considered outside the normal range at ______ mg/dl.

10 mg/dl
16 mg/dl
20 mg/dl
32 mg/dl
A

32mg/do

The BUN is considered within normal limits in the range of 5 to 25 mg/dl.

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6
Q

A CT examination requiring IV contrast media may NOT be indicated with which of the following conditions?

  1. Allergy to iodine
  2. Renal impairment
  3. Previous serious reaction to contrast media used during a prior diagnostic procedure
A

1,2,3

Indications that a patient will not be able to tolerate IV contrast include previous reactions to contrast media, allergies to iodine, and renal impairment.

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7
Q

Which of the following tests is an indication of renal function?

  1. Creatinine
  2. BUN
  3. PTT
A

1 & 2

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8
Q

Which of the following values for prothrombin time are considered outside the normal range?

  1. 10 seconds
  2. 25 seconds
  3. 30 seconds
A

2 & 3

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9
Q

All of the following vital signs are considered normal EXCEPT?

  1. An oral temperature of 97 degrees
  2. 110 BPM for a pediatric patient
  3. Adult pulse of 75 BPM
  4. Adult blood pressure of 160/100
A

4 only

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10
Q

An elevation of which of the following lab tests would impact the decision to administer IV contrast media?

  1. BUN
  2. PT
  3. Creatinine
A

1,2,3
N) and creatinine both test a patient’s renal function. Prothrombin time (PT) measures a patient’s blood coagulation. It is important to know that the patient’s kidneys will be able to clear the contrast solution from the body. Also important is the patient’s ability to stop bleeding after the removal of an IV.

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11
Q

Which of the following technical factors should be used during dynamic CT scanning?

  1. Patient continuously moving through the gantry during data acquisition.
  2. Rapid scanning with minimal interscan delays.
  3. Intravenous bolus administration of iodinated contrast media.
A

2 and 3 only
Dynamic scanning is a technique used during imaging of the chest and abdomen. After the bolus injection of contrast media the scanning follows rapidly through the area of interest. Interscan delays are kept to the minimum amount allowed by the tube cooling requirements of the scanner.

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12
Q

Which factor(s) has no measurable effect on spatial resolution?

  1. kVp
  2. Focal spot size
  3. Detector sampling frequency
  4. Matrix size
A

Answer: KVP
The following factors affect spatial resolution of a CT image: focal spot size, detector size, spacing, field of view, pixel dimension, matrix size and detector sampling rate. The kVp does not have an effect on spatial resolution.

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13
Q

A CT examination calls for the use of a stereotactic unit, this specialized equipment is required with which of the following exams?

A

CT-guided biopsy of the brain

Stereotactic biopsy units are specialized localization devices designed specifically for CT-guided biopsies. Due to the need for precision and accuracy they are commonly used for inter-cranial lesions.

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14
Q

When performing a high-resolution chest CT which of the following protocols should be used?

1) 1-mm sections, bone algorithm
2) 3-mm sections, standard algorithm
3) 10-mm sections, standard algorithm
4) 10-mm sections, bone algorithm

A

ANSWER: 1
High-resolution CT of the chest is used to examine diffuse pulmonary disease. HRCT uses narrow slices (1-3mm) and a high-resolution algorithm(bone).

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15
Q

A CT scan of the abdomen is performed for the differentiation of renal cysts. Which of the following statements is true regarding renal cyst protocol?

  1. Region of interest measurements of the cyst should be made to help determine its composition.
  2. Scans should be done through the kidneys before and after intravenous contrast administration.
  3. The patient should refrain from urination for 2 hours before the examination.
A

1and 2

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16
Q

A complication following CT-guided needle biopsy of the lung is…

A

Pneumothorax

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17
Q

CT guided percutaneous drainage for aspiration would be used for which pathological processes?

A

A: abdominal abscess

It is common to employ the use of CT during percutaneous aspiration and drainage procedures. Ct - guided aspiration of abdominal abscesses is a nonsurgical therapeutic technique.

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18
Q

When performing a CT scan of the neck which of the following will produce the best scout or localizer projection?

Posteroanterior
Anteroposterior
Oblique
Lateral
A

Lateral

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19
Q

The portions of the brain that enhance during a CT examination of the brain with iodinated contrast media are the posterior horn of the lateral ventricle and the cranial blood vessels.

True
False
A

false

Cerebrospinal fluid contained in the posterior horn of the lateral ventricle does not enhance with the administration of contrast material. A good blood supply as found in the cranial blood vessels, choroid plexus, and dura mater enhance well during a contrast study of the brain.

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20
Q

The average density in Hounsfield units of a renal cyst should be between -20 to +20 Hounsfield units.

A

TRUE

The average density of a renal cyst should be near or equal to that of water: -20 to + 20 Hounsfield units.

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21
Q

The molecular composition of the tissues through which the x-ray photons pass will affect the total quantity of x-ray photons completely penetrating the patient body.

A

TRUE

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22
Q

The system component responsible for converting the projection attenuation data into the proper form for the array processor is the analog-to-digital converter.

True
False
A

TRUE

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23
Q

Which generation of scanners employ multi-row detector technology?

A

3rd generation scanner

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24
Q

Which factor(s) has no measurable effect on spatial resolution?

  1. kVp
  2. Focal spot size
  3. Detector sampling frequency
  4. Matrix size
A

KVP

The following factors affect spatial resolution of a CT image: focal spot size, detector size, spacing, field of view, pixel dimension, matrix size and detector sampling rate. The kVp does not have an effect on spatial resolution.

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25
Q

Xenon is an ideal gas for CT due to its low atomic number and low solubility.
True
False

A

Xenon has a high atomic number and has a high-fat solubility.
False

26
Q

The advantages of using an automatic power injector versus the manual bolus method of intravenous contrast administration include…

  1. Uniform contrast administration through the entire length of the study.
  2. Increased tissue enhancement due to the fast injection rates.
3. Decrease in the volume of contrast needed.
	1 only
	3 only
	1 and 2 only
	1 and 3 only
A

1 and 2

27
Q

When placing a butterfly needle into a vein for intravenous contrast administration, the correct angle of insertion is…

A

Properly stabilize the vein and insert the needle at a 15 degree angle with the bevel facing upward.

28
Q

Quality control tests that should be performed daily on a CT scanner include…

  1. The accuracy of the laser-localization device should be tested.
  2. The CT number calibration should be checked.
3. The noise levels (standard deviation) of a water phantom should be examined.
	1 only
	2 only
	1 and 2 only
	2 and 3 only
A

2 and 3

29
Q

CTDI and MSAD can be used to calculate dose in spiral CT.
True
False

A

FALSE

CTDI and MSAD are accepted dose descriptors for spiral CT

30
Q

The average density of a solitary pulmonary nodule indicates it is benign when it falls within the following ranges…

15-30 Hounsfield units
50-80 Hounsfield units
125-145 Hounsfield units
175-200 Hounsfield units
A

175-200 Hounsfield units

Researchers feel pulmonary nodules appearing on CT examinations of the lungs can be considered benign if their average density is more than +164 Hounsfield units. The closer to +200 Hounsfield units the more certain the benign diagnosis is acurate.

31
Q

Of the following, which are included in the rights of the patient?

  1. Considerate and respectful care is the right of the patient.
  2. A copy of the diagnostic procedure performed should be given to the patient.
3. The refusal of medical treatment is the patient's right.
	1 only
	1 and 2 only
	1 and 3 only
	1, 2, and 3
A

According to The American Hospital “Patient’s Bill of Rights” written in 1973, the patient has the right to considerate and respectful care and the right to refuse treatment. The release of the patient’s exam is not an inherent right and is left to the discretion of the physicians involved.

32
Q

Give the voxel dimension for an image that was produced with a 1.0 mm aperture size and was displayed using a 512 2 matrix and a 15cm DFOV.

0.29mm X 0.29mm X 1.0 cm
0.29mm X 0.29mm X 1.0mm
2.9mm X 2.9mm X 1.0mm
.029mm X .029mm X 1.0cm
A

To calculate the pixel dimension divide the DFOV by the matrix size, then multiply by the length of the voxel.

33
Q

Several names are commonly used to describe high spatial frequency algorithms used for imaging sharp density changes occurring in bone tissue. These include bone, edge, and detail.

True
False
A

True

34
Q

Allergies to shellfish are ALWAYS considered an absolute contraindication to the use of intravenous iodinated contrast media during CT examinations.

True
False
A

False

35
Q

Instructions for a patient just completing an intrathecal injection of iodinated contrast media for a post-myelograpic CT study of the lumbar spine should include…

1) Take home cleansing enema.
2) No instructions resume normal activity.
3) Rest for 8 to 24 hours with the head slightly elevated.
4) Rest for 8 to 24 hours in the Trendelenburg position.
A

Rest for 8 to 24 hours in the Trendelenburg position.

The patient should be instructed to rest with head slightly elevated (35-45 degrees) to reduce the risk of headaches.

36
Q

The convolution method is not related to the filtered back projection.
True
False

A

False

37
Q

The binary language computer term for the smallest unit of information is the…

Byte The bit is derived from the binary digit and can be represented by 1 or 0. A sequence of eight bits constitutes a byte.
Bit
Chip
A

P

38
Q

Place the following radiographic examinations in the order in which they should be performed on a single patient.

CT of the abdomen, gastrointestinal series, barium enema
CT of the abdomen, barium enema, gastrointestinal series
barium enema, gastrointestinal series, CT of the abdomen
Gastrointestinal series, CT of the abdomen, barium enema
A

The radiographic exams should be in the following order: CT study first (barium being dense can cause streak artifacts on the CT image), barium enema (the barium given during the gastrointestinal series can interfere with the interpretation of a diagnostic enema study), and the gastrointestinal series last.

39
Q

A voxel with an attenuation coefficient less than water is assigned a pixel value with a(n) _____________ CT number.

Negative
Positive
Extremely large
None of the above
A

Net

40
Q

To best demonstrate the bony details of a shoulder joint a ___________________ algorithm should be used.

High spatial frequency
Soft tissue
Standard
Low spatial frequency
A

High

41
Q

Which of the following technical factors should be used during dynamic CT scanning?

  1. Patient continuously moving through the gantry during data acquisition.
  2. Rapid scanning with minimal interscan delays.
  3. Intravenous bolus administration of iodinated contrast media.
    1 only
    1 and 3 only
    2 and 3 only
    1, 2, and 3
    Dynamic scanning is a technique used during imaging of the chest and abdomen. After the bolus injection of contrast media the scanning follows rapidly through the area of interest. Interscan delays are kept to the minimum amount allowed by the tube cooling requirements of the scanner.
A

P

42
Q

Retrospective reconstruction uses scan data (raw data) to reconstruct a second image with an adjustment in a technical factor.

True
False
A

True

43
Q

The greatest factor affecting contrast resolution of a CT scanner is…

	Beam hardening
Noise appears as graininess that obscures the outline and delineation of structures. This limits the ability of the scanner to separate them, degrading the resulting CT image.
	Patient motion
	Noise
	Hardware malfunction
A

P

44
Q

Which formula may be used to calculate the dimensions of a pixel?

	Pixel size = DFOV/matrix size
	Pixel size = DFOV X matrix size
	Pixel size = slice thickness/matrix
The formula for pixel size is DFOV X matrix size. Each pixel is a square with four equal sides usually given in millimeters. The area of the pixel is calculated by squaring the dimension and then adjusting to millimeters squared.
	Pixel size = matrix size/DFOV
A

P

45
Q

1 and 3 only
Diatrizoate, iothalamate and metrizoate are the generic names for the commonly used types of iodinated contrast media known by their trade names Hypoaque, Conray, and Isopaque, respectively.

A

P

46
Q

Which of the following will increase the average photon energy of the x-ray beam ?

	Increase filtration
	Increase mAs
Filtration stops the weaker photons thus improving the overall average photon energy.
	Increase collimation
	Increase mAs and increase filtration
A

P

47
Q

Of the following types of contrast material which may be used during a CT examination of the chest?

	Iopamidol
Iopamidol is a non-ionic contrast media. Diatrizoate meglumine is an ionic contrast media. Barium sulfate contrast in the form of a paste is used to outline the esophagus.
	barium sulfate
	Diatrizoate meglumine
	All of the above
A

P

48
Q

To magnify the CT image on the display monitor, which of the following should be used?

	Increased SFOV
The DFOV controls the amount of scanned information to be displayed on the monitor. Displaying a small portion of the scan information on the matrix results in the appearance of a larger image.
	Decreased matrix size
	Decreased DFOV
	Increased DFOV
A

P

49
Q

Which of the following statements is correct concerning a CT image displayed in a window with a level of 0 and a width of 500?

Pixels with values between -250 and +250 Hounsfield units are assigned shades of gray.
Pixels with values between 0 and 500 Hounsfield units appear white.
Pixels with values greater than +500 Hounsfiel units are black.
Pixels with negative values appear white.
A

A

50
Q

The best method to enlarge an area of a CT image for closer examination (such as the sacrum from a CT image of the pelvis) would be to use targeting rather than magnification.

True
False
A

True

51
Q

The term ____________ describes a contrast material that does not dissociate into charged particles within a solution.

	Neutral
	Non-ionic
	Osmolar
The term Non-ionic pertains to contrast materials that do not dissociatee into charged particles (ions) when placed in solution. Ionic contrast materials on the other hand contain salts that form independent particles in aqueous solutions.
	Ionic
A

P

52
Q

The scan geometrics of a third-generation CT scanner has which of the following relationships?

Translate - axial
Translate - rotate
Rotate - rotate
Rotate - stationary
A

Rotate

53
Q

Systemic hypotension causes a condition of cerebral ischemia, the term used to describe this is…

Myocardial infarction
Transient ischemic attack
Hydrocephalus
Vasovagal reaction
A

Vado

54
Q

When performing a CT examination of the thoracic spine of a patient whose thorax measures 38 cm which of the following display fields of view (DFOV) should be used?

	42 cm DFOV
When displaying the spine on the monitor the goal is to choose a DFOV that will enlarge the spine. This is referred to as targeting, a technique that provides an enlarged image with no loss of detail compared to magnification mode. 15 cm DFOV is sufficient to target the spine and enlarge the image on the monitor.
	32 cm DFOV
	25 cm DFOV
	15 cm DFOV
A

P

55
Q

Which of the following CT procedures require written consent from the patient in the form of a signature to perform?

Three-dimensional reconstruction procedure.
Abdomen scan with intravenous contrast.
Noncontrast chest examination.
Radiation therapy planning of the breast. The administration of contrast media involves an invasive procedure, requiring the consent of the patient.
A

P

56
Q

After completion of a CT exam of the pelvis the radiologist requests a closer view of the sacrum. This can best be accomplished by which of the following?

  1. Magnify the image by two times.
  2. Rescan the patient using a smaller Scan field of view (SFOV).
  3. Use retrospective reconstruction of the image using a smaller display field of view (DFOV).
    1 only
    2 only
    3 only
A

3 only
1 and 3 only
Targeting the area of interest places the region of interest over the entire display matrix. This is accomplished by a decrease in the DFOV size. This increases resolution and detail over the other alternative of magnifying which allows a closer enlarged look at a specific area on the CT image.

57
Q

A nonmalignant enlargement of the prostate gland that is common in older men is referred to as…

Prostatic abcess
Prostatic hypertrophy
Extraprostatic extension
Prostatic carcinoma
A

Pro hypo

58
Q

Of the following, which would not be considered an absolute contraindication to the use of intravenous iodinated contrast media during a CT examination of the kidneys?

Acute sickle cell anemia
Pheochromocytoma
Prior acute reaction to contrast media
Allergies to shellfish
A 
Acute sickle cell anemia
A history of an allergic reaction to shellfish is not always a definite contraindication to iodinated contrast material. Non-ionic contrast material may be use depending on the severity of the allergic reaction. The patient may also be premedicated with corticosteroids, antihistamines or both.
	Pheochromocytoma
	Prior acute reaction to contrast media
	Allergies to shellfish
59
Q

The amount of contrast volume recommended for an intravenous iodinated contrast injection for imaging the neck is between 100-150mL.

True
False A volume of 100 to 150 is sufficient for imaging the neck. Exact volume and administration varies among institutions. M
A

P

60
Q

The largest occupational exposure results from the interaction between x-ray and matter in which of the following?

Compton effect
Characteristic effect
Bremsstrahlung effect
Photoelectric effect
A

Compton effect
Characteristic effect
Bremsstrahlung effect
A CT technologist is never exposed to primary radiation. A Compton reaction results in an x-ray photon striking an outer shell orbital electron of an atom of tissue. The orbit electron is ejected and is termed a recoil electron. The resulting incident x-ray photon retains part of its original energy and continues on in a different path as a scatter photon.

61
Q 
Of the following types of image noise which does the CT technologist have the ability to most easily reduce?
       Artifactual noise
	Quantum noise
	Electronic noise
	Detector noise
A

Quantum noise also called statistical noise of a CT image is reduced by increasing mAs and/or increasing the pixel and voxel dimension. This increases the number of x-ray photons abosorbed by the detectors for each voxel to tissue.

CT (2 decks)

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