Tube Failure and Ratings

Question 1

Number 1 cause of x-ray tube failure

Answer 1

high heat

Question 2

most common malfunction in x-ray tube

Answer 2

electron arcing

Question 3

causes of filament burnout

Answer 3

excessive prep, high mA on cold filament, frequent overheating

Question 4

clues to filament burnout

Answer 4

no exposure ready light, exposure made on different filament

Question 5

prevention to filament burnout

Answer 5

avoid excessive prep, allow filament to cool, use lower mA station

Question 6

causes of cracked anode

Answer 6

high kV on cold anode, no equipment warm up procedure

Question 7

prevention of cracked anode

Answer 7

proper warm up procedure

Question 8

what is arcing

Answer 8

spark occurring with high potential difference

Question 9

causes of pitting of anode

Answer 9

excessive overheating, high mA exposures on warm anode, failed rotating anode

Question 10

clues to pitting of anode

Answer 10

dramatic decrease in radiation output, uneven densities

Question 11

prevention of pitting of anode

Answer 11

allow tube to cool, use cooling charts, lower mA when possible

Question 12

causes of surface melting “grazing”

Answer 12

non adherence to tube rating charts, frequent overheating

Question 13

surface melting (grazing)

Answer 13

small cracks in target track

Question 14

clues to surface melting

Answer 14

lower radiation output

Question 15

prevention of surface melting

Answer 15

allow tube to cool, adhere to tube rating charts, proper warm up procedure

Question 16

causes of imbalanced anode

Answer 16

cracked anode, bearing damage, anode warping

Question 17

clue to imbalanced anode

Answer 17

thumping, tube movement / vibration

Question 18

prevention of imbalanced anode

Answer 18

cooling time, warm up procedure, don’t use high kV on cold anode

Question 19

malfunctions that can cause arcing

Answer 19

imbalanced anode, gassy tube (tanning effect)

Question 20

causes of gassy tube of “suntan effect”

Answer 20

excessive prep time, electrons boiled off with no exposure, overheating, long periods of normal use

Question 21

clues to gassy tube or “tanning effect”

Answer 21

slow decrease in radiation output, increased filtering effect due to electron buildup

Question 22

prevention of gassy tube

Answer 22

proper cooling, 1-4 sec prep time

Question 23

why do we not change factors after prepping

Answer 23

it can cause arcing

Question 24

heat unit formula for half wave rectification

Answer 24

kV x mA x time (sec) x 1.35

Question 25

heat unit formula for full wave rectification

Answer 25

kV x mA x time (sec) x 1.41

Question 26

heat unit formula for single energy tube

Answer 26

kV x mA x time (sec)