Safety Flashcards
The quantity of radiation dose received by the patient from a series of CT scans is referred to as the:
MSAD
Which of the following technical characteristics of a CT system does NOT directly affect patient dose?
A. Source-to-detector distance
B. Filtration
C. Detector efficiency
D. Filament size
D
Which of the following statements most accurately describes the relationship between slice sensitivity profile (SSP) and dose profile?
The dose profile is always wider than the SSP
The approximate radiation dose measured during a scan of a 100-mm-long pencil ionization chamber is termed the:
CTDI 100
The calculation of the average cumulative dose to each section within an acquisition of multiple sections is termed the:
MSAD
The multiple-scan average dose (MSAD) is used to describe the:
average dose to a single section within a scan of multiple sections.
Which of the following units is used to quantify effective dose?
Sievert (Sv)
If you increase detector pitch you will ——- pt dose
Decrease pt dose
The interaction between x-radiation and tissue that results in the complete loss of all x-ray photon energy is called:
photoelectric absorption
If you decrease pitch you will —— pt dose
Increase pt dose
A best practice for the use of in-plane bismuth shielding requires the:
placement of shield after the acquisition of scout (localizer) images.
Which of the following is the unit of radiation exposure?
Roentgen (R)
A dose check system features which of the following?
- Dose notification
- Dose alert
- Dose report
1 and 2
Current CT systems employ which of the following image reconstruction methods to reduce patient radiation dose?
Iterative reconstruction
As a patient size decreases, noise ———
Image noise is directly related to patient size. As a patient size decreases, noise decreases
Which of the following describes the system that adjusts the mA setting according to part size variations along the z-axis?
Longitudinal tube current modulation
Which of the following descriptors accounts for the dose effects of image spacing during axial acquisition?
MSAD
Because of the bow-tie filter employed in the CT x-ray system, positioning the patient at isocenter is critical to avoid:
increased patient exposure
The CT dose index (CTDI) is calculated for the central slice in a series that is surrounded by ______ slices on each side.
7
Which of the following technical factor adjustments would result in a decrease in the CTDIvol for a given acquisition?
Increased pitch
Side note to remember
As the pitch increases, the dose per section (CTDIvol) decreases.
A CT system may employ a focal spot tracking system to precisely direct the x-ray beam toward the detector array in an effort to reduce:
overbeaming
During helical CT acquisition, there is a small amount of x-ray exposure just before and immediately following the anatomical volume of interest. This may be referred to as:
overranging
When employing ECG-triggered tube current modulation during a cardiac CT, as the patient heart rate increases, the radiation dose savings:
Decreases
