Patient radiation dose management unit 3

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 =