A. patient exposures Flashcards
________: Exposure factor in the diagnostic range that mainly controls beam quality or beam penetrability (beam energy)
Kilovolt peak (kVp)
KVP controls
radiographic contrast
As kVp is____, less x-rays are absorbed by the patient and less dose to the patient
increased
Higher kVp can increase ______, which contributes to patient dose
Compton scatter
_________ rule: Increasing the kVp by 15% is equal to doubling mAs This allows for the reduction of mAs and patient dose
Fifteen percent rule
Fifteen percent rule will affect the
contrast and the radiographic image
________= Exposure factor in diagnostic range that determines beam quantity
Milliampere seconds (mAs)
mAs combines
mA with seconds (exposure time)
As mA is increased, the quantity of x-rays produced is
increased proportionately
mAs controls patient dose more than
kVp
____is used to reduce the radiation exposure to the patient or radiation worker
Shielding
Shields are placed between the radiation source and the exposed person in forms of
protective apparel for diagnostic ranges
Protective apparel can be worn by the radiation worker or by the patient to protect sensitive body parts that will not be included in the
diagnostic image
Radiation workers wear lead aprons when performing ____
fluoroscopic exams
Protective aprons are made of
0.5 mm of lead
Patients can wear gonadal and thyroid shields when this does not affect the
quality of the image
protective aprons Reduces occupational exposure to
10%
____= the thickness of an absorber material that will reduce the beam to half of its original value
half-value layer (HVL)
____= the thickness of an absorber material that will reduce the beam to one-tenth of its original value
Tenth-value layer (TVL)
1 TVL= ____HVL
3.3
______will affect the radiation field size, which affects the exposed area
collimation
A ____field size will increase the exposed area and increase dose
larger
Collimation affects
scatter
As field size increases, scatter increases, and patient dose ___
increases
To reduce patient dose from scatter, collimate field sizes during imaging procedures. This includes
MV portal and KV imaging on treatment machines
Patient or part thickness will affect
scatter and patient dose
Thicker body parts will cause more
scatter
Thicker parts require an increase in technical factors to produce a
quality image
An increase in ____factors will increase patient dose
technical
The _____ included in the image will also determine the amount of scatter
type of tissue
Attenuation of the beam is determined by
muscle, bone, fat, air, etc.
Proper _____is necessary for patient compliance, which may reduce the number of repeat images needed
communication
Repeating images ___patient dose
increases
In certain instances, exposure time may need to be reduced to reduce patient motion . To compensate for the shorter exposure time,
mA may need to be increased, which Will increase patient dose
