Deck 23: Computed Tomography Simulation

Question 1

What are the internal components in the CT gantry?

A) couch movement controls
B) emergency off buttons
C) detector array and x-ray tube
D) simulation workstation

Answer 1

C
The x-ray tube and detector array rotate around the patient,while many x-ray transmissions pass through the patient and are recorded by the detectors.

Question 2

The first CT system used what type of machine movement to obtain image information?

A) translation
B) helical
C) spiral
D) fixed

Answer 2

A
The x-ray tube and detector assembly moved across the patient in a straight line.

Question 3

What is a maximum intensity projection,or MIP?

A) measurement of table translation
B) result of noise on an image
C) relationship between the matrix size and the pixel size on an image
D) fused scan that shows the maximum amount of tumor movement during the respiratory cycle

Answer 3

D
MIP takes scans at full inhalation and full exhalation and fuses together the images.Planning is then based on the amount of tumor motion.

Question 4

The reconstructed field of view that is displayed on the computer monitor should be large enough to display: I.the entire contour
II)the immobilization device
III)pertinent anatomy only

A) I
B) II
C) III
D) I and II

Question 5

The aperture or bore size of a CT scanner should be large to allow for patients to be scanned in treatment planning position.

Question 6

Window level is the range of numbers displayed or the contrast on a CT image.

Question 7

What are the varying electron densities displayed as pixels in shades of gray on the imaging screen?

A) incrementations
B) interpolations
C) Hounsfield units
D) translations

Question 8

Using a higher osmolality substance such as ionic iodine can greatly reduce adverse reactions with intravenous contrast agents.

Question 9

Of the four methods by which contrast media may be introduced into the body,which are the most common in CT simulation?
I)oral
II)intrathecal
III)intravascular
IV)intra-articular

A) I and II
B) I and III
C) II,III,and IV
D) I,II,and IV

Question 10

Which of the following are benefits of CT simulation?
I)the ability to outline critical structures and view these structures in three dimensions
II)machine setup parameters and treatment accessories unable to be verified on the CT scanner
III)virtual simulation allows for construction of DRRs without patient present

A) I and II
B) I and III
C) II and III
D) I,II,and III

Question 11

Of the following list of contrast agents,which is not water soluble and therefore should not be used in the gastrointestinal tract if there is an increased risk of perforation?

A) high-osmolality contrast
B) low-osmolality contrast
C) Gastrograffin
D) barium sulfate

Question 12

Of the four desired qualities of a CT image,which refers to the ability to see shades of gray in tissue?

A) spatial resolution
B) image contrast
C) low noise
D) low dose

Question 13

What are the rows and columns of cells on an image screen known as?

A) projection
B) artifacts
C) pitch
D) matrix

Question 14

Forward planning uses all of the following techniques except:

A) The planner selects the number of the beams.
B) It begins the plan with the end in mind.
C) The planner selects the direction and shape of the beams.
D) It uses conventional and conformal treatments.

Question 15

What does spatial resolution measure?

A) shades of gray on an image
B) detail in a CT image
C) couch pitch
D) speed of tube rotation

Question 16

The term pitch refers to:

A) the image displayed on the computer monitor
B) the rows and columns of cells on an image screen
C) the distance traveled by the couch during an x-ray tube rotation
D) spatial resolution

Question 17

A CT scanner specifically designed for use in the radiation therapy department should have which characteristics?
I)high performance scanner
II)laser and patient marking system
III)virtual simulation capabilities

A) I and II
B) I and III
C) II and III
D) I,II,and III

Question 18

Prior to the use of computed tomography (CT)in the simulation process,contouring was performed by use of solder wire or plaster.

Question 19

Which of the following are common artifacts in CT scanning?
I)partial volume artifacts
II)ring and star artifacts
III)motion artifacts

A) I and II
B) I and III
C) II and III
D) I,II,and III

Question 20

CT was developed in 1973 by:

A) Godfrey Hounsfield
B) Raymond Damadian
C) Wilhelm Roentgen
D) Garfield Hindenburg

Question 21

Mechanical and image quality checks should be evaluated by using the guidelines set by the:

A) nuclear regulatory agency
B) AAPM Radiation Therapy Committee Task Group No.66
C) AAPM Radiation Therapy Committee Task Group No.40
D) individual state guidelines

Question 22

The window level on a CT image is:

A) the range of numbers displayed on a CT image
B) the number of columns and rows of pixels demonstrated on an image
C) an unwanted image characteristic
D) the central Hounsfield unit of all the CT numbers displayed on an image

Question 23

The quality of the beam must be checked:

A) daily
B) weekly
C) yearly
D) biannually

Question 24

Monthly quality assurance check for a CT simulator should include: I.spatial resolution
II)Hounsfield number/electron density verification
III)reconstruction slice location
IV)image transfer protocols
V)left/right registration and distance between known points check

A) I and II
B) I,III,and V
C) II and III
D) II,III,IV,and V

Question 25

Image registration or fusion has all of the following characteristics except:

A) It ensures that the patient is in the same position for all scans.
B) It identifies preoperative volume.
C) It is useful in determining the extent of the tumor.
D) It uses two sets of images that are similar.

Question 26

The level of noise on a CT image is affected by which of the following factors?
I)mAs and kVp
II)filtration
III)pixel size
IV)slice thickness

A) I and II
B) I and III
C) I,II,III,and IV
D) I,II,and IV

Question 27

The window width on a CT image is:

A) the range of numbers displayed on a CT image
B) the number of columns and rows of pixels demonstrated on an image
C) an unwanted image characteristic
D) the central Hounsfield unit of all the CT numbers displayed on an image

Question 28

Artifacts seen on a CT image are caused by:

A) the relationship between the matrix size and the pixel size on an image
B) patient motion,anatomy,design of the scanner,or system failure
C) lack of a treatment planning system
D) large aperture or bore size

Question 29

The dose to the skin surface from a single CT slice is in the range of:

A) 1 to 6 cGy
B) minimal to less than 1 cGy
C) 1 to 6 Gy
D) 10 to 12 cGy

Question 30

Daily warmup procedures for the CT simulator should include: I.checking for laser alignment
II)checking noise levels by using a water phantom
LII)warming up the simulator according to the manufacturer's guidelines

A) I and II
B) II and III
C) I,II,and III
D) I and III