Radiation and X-ray equipment

Question 1

Bremsstrahlung is the most prevalent mechanism of?

Answer 1

X-ray production (85% at 100kVp)

Question 2

Bremsstrahlun gdoes NOT involve an electron striking another particle in the target- it involves…

Answer 2

interaction between the incident electron and the nucleus of a target atom

Question 3

“braking radiation” means?

Answer 3

it gets bent around the curve of the nucleus, deflected by the
magnetic pull of the nucleus.

Question 4

The closer to the nucleus an electron goes, the more severely its course is?

Answer 4

changed and the greater the energy released as it “brakes around the corner”

Question 5

Bremsstrahlung radiation represents a spectrum of

Answer 5

wavelengths (varying degrees of “braking” thus varying energies of resultant photons)

Question 6

Characteristic radiation represents only 15% of?

Answer 6

the origin of the Xray beam @ 100kVp

Question 7

o Characteristic radiation prevalence increases…

Answer 7

when you raise kVp higher

Question 8

Characteristic radiation is caused by?

Answer 8

ejection of an inner shell electron by collision between the incoming and the native electron

Question 9

This radiation has a specific wavelength because?

Answer 9

it happens when an L shell electron drops into the K shell when the K shell electron was knocked out in the collision.

Question 10

The change in energy from L shell to K shell is?

Answer 10

predictable and constant

Question 11

X-ray beam types:

Answer 11

o Primary radiation
o Secondary/scatter radiation
o Remnant radiation

Question 12

Primary radiation

Answer 12

• from the tube to the patient

Question 13

Secondary/scatter radiation

Answer 13

• created by the beam’s interaction with the patient and almost always has LESS energy than primary radiation

Question 14

Remnant radiation

Answer 14

• radiation that goes through the patient and creates the image we will see

Question 15

Anode charge

Answer 15

positive

Question 16

Anode has what kind of target?

Answer 16

tungsten

Question 17

Are x rays formed on the anode side?

Answer 17

yes

Question 18

Anodes focal spots

Answer 18

small focal spot is a central region within the larger focal spot

Question 19

Anodes have what kind of housing?

Answer 19

copper for target (heat management)

Question 20

Anodes rotor is?

Answer 20

motorized (hence the extra wire going into the anode side of the tube housing)

Question 21

rotating anode is for?

Answer 21

r heat management and increased durability of the anode

Question 22

Cathode have what kind of charge?

Answer 22

negative

Question 23

How many filaments does a cathode have?

Answer 23

2: small and large

Question 24

Cathode focusing cup used to?

Answer 24

focus electrons towards a point (instead of allowing them to
diverge from the filament)

Question 25

thermionic emission creates?

Answer 25

the space charge (electron cloud)

Question 26

mA and time determines the # of?

Answer 26

electrons

Question 27

Glass is Pyrex, housing is metal and there is oil within- all designed to manage?

Answer 27

heat and contain radiation produced that will not be useful beam

Question 28

Leakage radiation is?

Answer 28

X-rays that escape the tube housing

Question 29

Actual focal spot vs. effective focal spot is a function of?

Answer 29

anode angle and whether you are using large or small focal spot

Question 30

Anode angle is usually in the range of?

Answer 30

10-20 degree range; 12 degrees usually

Question 31

12 degrees reflects a balancing act:

Answer 31

 keeping the actual focal spot as large as possible (heat dissipation)
 keeping the effective focal spot size as small as possible (detail and
image sharpness)
 minimizing “heel effect” (lower anode angles = larger heel effect)

Question 32

Anode angle is calculated from?

Answer 32

from the vertical axis to the face of the anode

 larger angle = larger effective focal spot

Question 33

The anode side of the beam will be less or more intense than the cathode side of the beam?

Answer 33

less

Question 34

mAs:

Answer 34

 rate of flow of electrons- determines quantity of X-ray photons in the beam
 radiation exposure is a function of mA and time (s)
 film density varies proportionately (linear relationship, or “directly”) with mAs

Question 35

kVp:

Answer 35

• controls speed of electrons to the target from the cathode, hence responsible for the energy (wavelength) of photons and the resultant X-ray beam
• penetration ability of the beam is a function of kVp
• the radiographic scale of contrast is a function of kVp

Question 36

Electricity

Answer 36

we use fully rectified 60 cycle/second electricity resulting in 120 “pulses” of
electricity per second.