CT REGISTRY- Revised Questions and Answers /
Guaranteed Pass
A patient has a severe vagal reaction to iodinated contrast material that includes bradycardia should be
given a treatment of - *treatment includes increasing blood pressure with IV fluids
*intravenous administration of atropine to block vagal stimulation of the heart
All of the following are synonyms for helical scanning EXCEPT:
a. volumetric scanning.
b. spiral scanning.
c. continuous acquisition scanning.
d. dynamic scanning. - Answer— d. Dynamic scanning refers to repeating data acquisitions in the
same location. Hence, it is also called nonincremental scanning. This is most frequently done to watch
how a structure fills with an iodinated contrast agent. Dynamic scans are most often done using a helical
scan method, but they can also be performed with axial scans. (Comprehensive Text Chapter 5 ; Heading:
Helical Scanning)
An enterovesical fistula is an abnormal communication between the bowel and the - bladder
-Typically results from inflammatory processes of the colon such as diverticulitis
An MDCT image is reconstructed using a 512x512 matrix and a display field of view of 44 cm. If the
detector collimation is set to a section width of 2.5 mm what is the volume of each voxel - How to
solve: The linear dimension of the pixel must first be calculated by dividing the DFOV, in mm, by the
matrix. This linear pixel dimension is squared to yield the pixel area in mm^2. The volume of the voxel
may be calculated by multiplying the pixel area by the section width
step 1. 44 cm/ 512 =0.0859
step 2. 0.0859*2.5 mm = 0.2148
step 3. move the decimal point =2.15 mm^3
ANATOMY COVERED CALC for MDCT: How much anatomy (lengthwise) will be covered in a helical scan
when the following parameters are selected: 15 seconds total acquisition time, .5 seconds gantry
, rotation time, 2mm slice thickness, 4 slices per rotation , pitch of 1.5? - Answer— d. To calculate
scan coverage use the formula: Pitch × total acquisition time × 1/rotation time × (slice thickness × slices
per rotation). Therefore, 1.5 × 15 × 1/0.5 s × (2 mm × 4) = 360 mm. (Comprehensive Text Chapter 5 ;
Heading: Helical Scanning/Fundamentals of Helical Technology/Helical Scan Coverage/MDCT Scan
Coverage/ Distance Covered in an MDCT Helical Scan Sequence)
ANATOMY COVERED CALC for MDCT: In an MDCT situation, programming a pitch of 1.2 and 4 slices per
rotation while acquiring images for 20 seconds using a 2.5 mm slice, and 0.5 second rotation speed will
result in how much anatomy coverage? - First use the formula : Pitch x total acquisition time x
1/rotation time x (slice thickness x slices per rotation) Therefore 1.2 x 20 x 1/0.5 x (2.5 x 4) =
Annual limits for Body, Eyes, and Skin - body: 5 rem (.05 sV, 50 mSv)
eyes: 15 rem (0.15 sV, 150 mSv)
skin: 50 rem (.5 sV, 500 mSv)
At the range of photon energies employed during most CT examinations, water exhibits an approximate
attenuation coefficient value of - 0.206
Cardiac output - the volume of blood pumped per minute by each ventricle. This is the product of
stroke volume and heart rate
normal is 4.0 - 8.0 L/min
CTDI-vol - Describes amount of E absorbed locally during the exposure
- does not reflect entire area or mass exposed or type of tissue irradiated
The dosimetry index used to approximate the radiation dose for CT sections acquired during a helical
scan
CTDIw is a weighted index that Approximate's radiation dose on the basis of variations that occur across
the field of view because of what? - Beam Hardening
Guaranteed Pass
A patient has a severe vagal reaction to iodinated contrast material that includes bradycardia should be
given a treatment of - *treatment includes increasing blood pressure with IV fluids
*intravenous administration of atropine to block vagal stimulation of the heart
All of the following are synonyms for helical scanning EXCEPT:
a. volumetric scanning.
b. spiral scanning.
c. continuous acquisition scanning.
d. dynamic scanning. - Answer— d. Dynamic scanning refers to repeating data acquisitions in the
same location. Hence, it is also called nonincremental scanning. This is most frequently done to watch
how a structure fills with an iodinated contrast agent. Dynamic scans are most often done using a helical
scan method, but they can also be performed with axial scans. (Comprehensive Text Chapter 5 ; Heading:
Helical Scanning)
An enterovesical fistula is an abnormal communication between the bowel and the - bladder
-Typically results from inflammatory processes of the colon such as diverticulitis
An MDCT image is reconstructed using a 512x512 matrix and a display field of view of 44 cm. If the
detector collimation is set to a section width of 2.5 mm what is the volume of each voxel - How to
solve: The linear dimension of the pixel must first be calculated by dividing the DFOV, in mm, by the
matrix. This linear pixel dimension is squared to yield the pixel area in mm^2. The volume of the voxel
may be calculated by multiplying the pixel area by the section width
step 1. 44 cm/ 512 =0.0859
step 2. 0.0859*2.5 mm = 0.2148
step 3. move the decimal point =2.15 mm^3
ANATOMY COVERED CALC for MDCT: How much anatomy (lengthwise) will be covered in a helical scan
when the following parameters are selected: 15 seconds total acquisition time, .5 seconds gantry
, rotation time, 2mm slice thickness, 4 slices per rotation , pitch of 1.5? - Answer— d. To calculate
scan coverage use the formula: Pitch × total acquisition time × 1/rotation time × (slice thickness × slices
per rotation). Therefore, 1.5 × 15 × 1/0.5 s × (2 mm × 4) = 360 mm. (Comprehensive Text Chapter 5 ;
Heading: Helical Scanning/Fundamentals of Helical Technology/Helical Scan Coverage/MDCT Scan
Coverage/ Distance Covered in an MDCT Helical Scan Sequence)
ANATOMY COVERED CALC for MDCT: In an MDCT situation, programming a pitch of 1.2 and 4 slices per
rotation while acquiring images for 20 seconds using a 2.5 mm slice, and 0.5 second rotation speed will
result in how much anatomy coverage? - First use the formula : Pitch x total acquisition time x
1/rotation time x (slice thickness x slices per rotation) Therefore 1.2 x 20 x 1/0.5 x (2.5 x 4) =
Annual limits for Body, Eyes, and Skin - body: 5 rem (.05 sV, 50 mSv)
eyes: 15 rem (0.15 sV, 150 mSv)
skin: 50 rem (.5 sV, 500 mSv)
At the range of photon energies employed during most CT examinations, water exhibits an approximate
attenuation coefficient value of - 0.206
Cardiac output - the volume of blood pumped per minute by each ventricle. This is the product of
stroke volume and heart rate
normal is 4.0 - 8.0 L/min
CTDI-vol - Describes amount of E absorbed locally during the exposure
- does not reflect entire area or mass exposed or type of tissue irradiated
The dosimetry index used to approximate the radiation dose for CT sections acquired during a helical
scan
CTDIw is a weighted index that Approximate's radiation dose on the basis of variations that occur across
the field of view because of what? - Beam Hardening
