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radiologic personnel
who is measured with an occupational radiation monitors (dosimeters)?
patients
who’s radiation dose is measured by simulated x-ray exams?
mGya
KERMA is expressed in?
-entrance skin exposure
-bone marrow dose
-gonadal dose
patient dose is expressed in 1 of 3 ways?
1%
ESE value, the exit skin dose will be approximately ____ of the ESE
4 cm
th half value layer of x-rays in soft tissue is approximately?
the ESE
What is easy to measure and reasonably accurate estimates?
nomograms
used for estimating output x-ray intensity and approximate ESE is called?
hematologic effects
What effect is rarely experienced in diagnostic radiography?
the mean marrow dose
the average radiation dose to the entire active bone marrow is?
measured directly
the bone marrow dose cannot be?
stochastic
radiation induced leukemia is what response?
mGyt/year
the mean marrow dose is approximately?
suspected genetic effects of radiation
measurements and estimates if gonad dose are important because of the?
the genetically significant dose
is the gonad dose that if received by every member of the population, would produce the total genetic effect on the population as the sum of the individual doses actually received ir a weighted average gonad dose is called?
GSD is 0.2 mSv/year
what is the gonaldal dose in the United States?
the unnecessary patient dose
any dose that is not required fir the patients well being ir fir proper management is called?
chest exams
what should not be done for routine hospital admissions?
chest and lumbar exams
what should not be apart of the pre-employment exam?
no precise medical indication
routine exams should not be preformed when there is?
analog film
what resulted in unnecessary patient radiation dose?
5%
repeats should be under ___ repeat rate
increase in patient dose
increasing kVp =
reduces patient dose
reception in mAs =
lower patient dose
digital radiography can be conducted at higher kVp resulting in?
high kVp and low mAs
digital =
increase patient dose
increase in mAs =
increase patient dose
increase in mAs, decreasing the kVp =
85%digital
DR uses approximately ____ less mAs than traditional film screen
contrast
in digital imaging, kVp is less important as a controlling factor of ?
subject contrast
kVp is still the primary controller of
image or radiographic contrast
digital imaging the LUT is the primary controller of?
increase in image quality and reduced patient dose
digital exam of specific anatomy is conducted, the kVp should start to be increased and a reduction in mAs this results in?
NO effect in patient dose
focal spot size has absolutely?
reduces dose to patient
beam restriction improves image quality and?
-reduces the volume of tissue directly irradiated
-reduces amount of scatter radiation
collimations reduces patient exposure by limiting the size and shape of the x-ray beam to only the area of interest, beam restriction reduces patient dose in two ways?
post-processing
allows radiographers to digitally mask an image to hide the lack of primary beam collimation is known as?
collimation/beam restriction
post processing should never replace proper?
-less scatter radiation
-less hazard or dose to the patient
-higher radiographic contrast
once again beam restriction/collimation results in?
-decreases patient dose
-improved image quality and contrast
-improved spatial resolution
what are the effects of the use of the compression band on image quality?
part thickness and decreasing OID
compression when possible can improve spatial resolution by reducing?
contrast resolution
additive vs. destructive pathologies, thicker body parts would produce more scatter, thus decreasing
OID and spatial resolution
a thinner part decreases the ____, thus giving less magnification and improves _______________
fixed kVp technique
use a higher kVp level and lower mAs resulting in reduction in patient entrance skin exposure is for what technique system?
variable kVp technique
use lower kVp level and higher mAs resulting in higher patient entrance skin exposure (higher dose) is for what technique system?
analog film/ screen system
what uses two different film/screen combination?
high resolution/ detail
extremities use a ________________ and therefore accounted for high patient dose
higher speed/ film screens
all other exams use a _______________ used to reduce patient dose when the higher resolution was needed
hardening of the beam
tube filtration =
tube filtration
elimination of undesirable low-energy x-ray photons by the intersection of absorbing materials in the primary beam =
reduce patient skin dose or ESE
what is the primary filtration is to?
increases the overall average anergy of the beam and decreases in the tube output
filtration =
AEC
what eliminates the need for the radiographer to set an exposure time
-ionization chamber
-phototimer/ photomultiplier
What are the 2 types of AEC?
ionization chamber
-just beneath the tabletop above the cassette
-located immediately under the x-ray table
phototimer/ photomultiplier
-small fluorescent screen is positioned beneath the cassette or image receptor
increase in patient dose
use of grid results in?
radiation protection
a grid is never a mean of?
image quality
grids can improve?
results in increased image contrast
analog film =
reduce patient dose
lower grid ratio while still maintaining exposure, one can significantly?
10 cm
it is recommended that a grid be used if a body park is thicker than?
the air gap technique
what is the alternative to using a grid?
reduce in patient dose
the air gap technique increase image contrast =
misses the IR
air gap puts the IR further away and basically scatter?
-magnification radiography
-lesser extent
-chest radiography
when is the primary application air gap technique?
15:1
a 10 inch air gap is silimar to?
reduce patient motion and repeats
patients having confidence in their radiographer are more likely to follow instructions which helps?
motion
what is the primary imaging problem?
children
who is most radiosensitive and the effects if radiation exposure will be carried longer?
fluoroscopy
what has much higher patient doses than conventional “overhead tube” radiography
-pulse progressive fluoroscopy
-GCF
what can reduce radiation dose during fluoroscopy?
ESE of 40 mGy/min
what is the average ESE for a fluoroscopic exam?
extended beam on time
Cath labs have higher patient doses due to?
15 Gyt
Center for devices and radiation health states that any dose exceeding ______ isa sentinel event and must be reported
pulse type fluoroscopic imaging
radiation pulses during?
predetermined value range
brightness is converted ti a digital value and compared ti an acceptable?
operator exposure to radiation
pulse control effectively reduces patient dosage and?
energy spectrum, shape and frequency semiautomatically
grid controlled fluoroscopy can modify the x-ray beams?
think
the beam can “______'“ for itself and adapt for each exam
children and potentially reproductive patients
gonadal shielding should be considered for all patients especially?
2 inches of the primary beam
gonadal shielding should be used when the gonads lie within the primary beam =
gonadal shielding is used
propers patient positioning and beam collimation should not be relaxed when?
50% females
90% males
properly placed gonadal shielding significantly reduces patient ___ for females and ___ males
-flat contact
-shadow contact
-shaped contact
what are the three types of gonadal shielding?
flat contact
used for simple recumbent exams (PA vs PA)
shadow contact
attaches to tube head and ideal for surgery to avoid contact with any sterile field
shaped contact
more efficient for exams in which must obtain oblique, lateral or erect positions and enclose male reproductive organs and remain in position
interrupted or impaired
effects on fertility =
congenital effects
irradiation on utero =
-gestation
-congenital
-neonatal
genetic effects =
gestation
the length of time from conception to birth
congenital
refers to a condition present at birth
neonatal
relates to the time immediately after birth
teratogenic effects
radiation exposure ti developing embryo or fetus after conception
mutagenic effects
radiation exposure to human gametes prior to conception
-spontaneous abortion
-congenital anomalies
-childhood malignancies
what are possible responses to the irradiation in utero?
100 mGy (0.1 Gyt) or 10 rad
the threshold dose for fetal damage is approximately?
a therapeutic abortion is not indicated unless other risk factors are involved
below 100 mGy =
the risk of latent injury may justify a therapeutic abortion
above 250 mGy =