ch. 2 anatomy of machine

Question 1

what controls the # of electrons produced by the filament

Answer 1

cathode

Question 2

process of changing alternating current to a direct current

Answer 2

recitification

Question 3

what reduces the x-ray machine input voltage from 110-220V to 10 V to prevent burnout of the cathode filament

Answer 3

step-down transformer

Question 4

what controls the length of exposure

Answer 4

timer switch

Question 5

AKA self-rectifiers

Answer 5

valve tubes

Question 6

what allows the flow of electrons in one direction only

Answer 6

valve tubes

Question 7

what is the peak energy of the x-rays that determines the quality called

Answer 7

kilovoltage (kVp)

Question 8

what part of the x-ray tube consists of a coiled wire tungsten filament that emits electrons when heated

Answer 8

actual focal spot

Question 9

what is the small area of the target were electrons collide on the anode

Answer 9

focal spot

Question 10

the ____ is made up of molybdenum because it has a high melting point and is a poor heat conductor

Answer 10

focusing cup

Question 11

___ acts as a conductor of heat and draws the heat away from the tungsten target

Answer 11

oil

Question 12

what type of anode is found in dental and small portable radio graphic units

Answer 12

stationary

Question 13

what type of anode continually provides a cooler surface for the electron stream to hit

Answer 13

rotating

Question 14

restricting device used to control the size of the primary x-ray beam

Answer 14

collimator

Question 15

what are the 4 factors that an x-ray tube rating is based upon

Answer 15

focal spot size, target angle, anode speed, electrical current

Question 16

what unit is the x-ray tubing rating expressed in

Answer 16

kilowatts

Question 17

stationary anode focal spot size

Answer 17

small

Question 18

using a high kVp and a low mAs helps prevent

Answer 18

damage to anode

Question 19

what noise happens when anode bearing fails

Answer 19

grinding metal/ no noise

Question 20

how far away should the radiographer be from the machine

Answer 20

6 feet

Question 21

what increases the incoming voltage of 110-220 V to 1000 V

Answer 21

step up transformer

Question 22

a decrease of intensity on the anode side of x-ray beam due to angle

Answer 22

heel effect

Question 23

creates a partial shadow of the object being imaged

Answer 23

halo effect

Question 24

what size focal spot is ideal and why

Answer 24

small; greater detail

Question 25

what is the #1 cause of x-ray tube failure

Answer 25

cathode failure

Question 26

how can cathode failure be avoided

Answer 26

let the machine heat up

Question 27

what is gassy tube

Answer 27

glass envelope damage; occurs when air gets into glass tube

Question 28

the line-voltage compensator is associated with the ___ and is automatic in most new machines

Answer 28

autotransformer

Question 29

what is the maximum electrical and thermal rating for portable x-ray units

Answer 29

60-90 kVp

Question 30

what is the maximum electrical and thermal rating for table top x-ray units

Answer 30

40-120 kVp

Question 31

coning aka

Answer 31

collimation

Question 32

due to heel effect, what part of the animal should be placed toward the cathode

Answer 32

large size

Question 33

what occurs during 1st phase of the exposure button

Answer 33

filament heats and anode spins

Question 34

what occurs during 2nd phase of the exposure button

Answer 34

radiograph is created

Question 35

__ kVp and __mAs techniques should be used as often as possible to prevent anode damage

Answer 35

high;low

Question 36

what is the glass vacuum tube that contains the cathode and the anode of the x-ray tube

Answer 36

glass envelope

Question 37

metal deposits on the inner wall of the envelope that attract electrons from the cathode

Answer 37

arcing

Question 38

control panel of the machine

Answer 38

console

Question 39

low energy circuit, when heated, releases electrons from their orbits

Answer 39

filiment

Question 40

amount of electical energy being applied

Answer 40

milliamperage

Question 41

creates constant electrical potential across the tube

Answer 41

full wave rectification

Question 42

converts alternating to direct current

Answer 42

half wave rectification

Question 43

what is used to focus the beam

Answer 43

lead shutters

Question 44

recessed area where the filament lies, directing the electrons toward the anode

Answer 44

focusing cup

Question 45

effect of making the focal spot appear smaller when viewed from the position of the film

Answer 45

line focus principle