ESE
Patient skin dose can be measured indirectly by using a ?
nomogram
Entrance skin dose (ESE) is most often used to measure what?
patient dose in Dx x-rays
GSD for U.S. is?
0.20 mSv
the patient will move 16 cm with a CT pitch of what?
1
Since CT uses a cone-shaped x-ray beam, the contrast resolution will be _______________ because the scatter radiation is _________________
improved; reduced
simplest way to measure patient dose is?
to measure the ESE
most frequently used monitor that can be used to measure patient exposure is?
TLD
Why is the GSD important?
due to radiation risks to the gene pool of the population
Minimum source-to-skin distance for radiography is ___________ for fixed equipment and ___________ for mobile equipment.
12"; 15"
MMD for Dx exams avarage for entire population of U.S. is?
100 mrad/yr
what has happened to patients reported for angio-interventional exams?
acute radiation skin effects
What is DLP?
Dose length product: combination of output radiation intensity and volume of tissue imaged
average BMD in the U.S. is?
1 mGy/yr
in multislice helical CT, the dose profile tail is called what?
penumbra
SSDE needs which two dimensions to be measured?
AP and lateral
ESE, BMD, and gonadal can all be used for what?
to estimate patient dose
If a KUB calls for 30 mAs, what will be ESD when the output intensity is 0.065 mGy/mAs?
1.95 mGy
(ESD = output intensity x mAs)
ESD = .065 mGy x 30 mAs
calculated from an estimate from ESE
bone marrow dose (BMD)
lowest intensity of scatter radiation from the patient is located where?
at a 90 degree angle from the pateint
DRT utilizes how many exposures during an exam?
6-10
Average fluoro exam ESE?
40 mGy/min
NCRP 116: dose limit for occupational workers per year is?
50 mSv
most important variables in determining x-ray dose
X-ray production efficiency and receptor speed
___________ collimators further reject scatter radiation and _____________ collimators define the cone beam.
predetector; prepatient
NCRP 116: the dose limit for the entire fetus gestation is?
5 mSv
1. What is the symbol for noise in CT?
2. What is noise is CT?
3. In radiography, noise is known as what?
1. Sigma
2. random statistical variations in CT numbers
3. Quantum mottle
In CT, what is described as more tissue irradiated due to the overlapping of the beam as the patient moves through the aperature?
Overrranging
What is the relationship of higher multislice value and patient radiation dose?
Inverse: the higher the multislice value, the lower the patient radiation dose will be.
T or F: The CT technologist selects the kVp and mA for exams.
False: The CT console computer automatically selects the mA and kVp. The Tech selects the anatomical part to be x-rayed.
In CT, what serves as the AEC?
MTF