GXMO Test Questions with Complete
Solutions
ionization the ability to remove electrons; foundation of x-ray interaction with tissue
making them valuable for image creation but damages the tissue
PE effect x-ray photon ejects an inner shell electron becoming fully absorbed in the
process--causes secondary photons and increasing patient dose. Absorbed dose is dependent on
the amount of ionizing radiation
sources of radiation natural materials, solar radiation, and medical radiation
images formation non-interacting transmitting radiation which attenuates differently
according to the anatomy it travels through
scatter radiation type of radiation that interacts with tissues but weakens and changes
direction before exiting
,protective tube housing encloses the x-ray tube and constructed with lead lining; prevents
electric shock to the tube and facilitates cooling; can be made of glass or metal; the metal tubes
extend the life; creates vacuum for x-ray production
cathode side of the tube that produces the electrons and forces them toward the anode;
negatively charged
focusing cup surrounds the cathode to force the electrons into a controlled beam and
prevents direction which means less scatter
filament wire coil of tungsten wire at the cathode; source of electrons via thermionic
emission
anode side of the tube that is a positively charged target for electrons to convert to x-rays;
composed of molybdenum copper and tungsten; consists of a target, stator, and rotor
anodes can be stationary or rotating (rotating disperse heat and reduce wear)
,window sheet of glass in the tube housing where x-rays are directed to exit; acts as partial
filtration of the beam
filtration reduction of low energy photons to reduce patient dose
two types of filtration added and inherent filtration
what must the min mmAl be for tubes above 70 kVp? 2.5 mmAl
added filtration filtration added to the part of the tube to absorb low energy photons and
reduce patient dose
compensating filters added to primary beam to alter intensity often used in nonuniform
anatomic regions; commonly a step wedge or trough filter
collimator/collimation shutters; most common beam restricting device; set of 2-3 sets of
lead shutters immediately below the tube window and limit the field of the beam; allows for
variable field size
, fixed aperture flat piece of lead with a hole in it below the tube window
cones and cylinders a fixed aperture with extended flange and slide into the tube directly
below the window; decrease unsharpness
PBL (positive beam limitation) automatic collimator; limits size and shape of the beam to
make the IR in the bucky; used to reduce patient exposure
thermionic emission refers to the process of boiling off electrons from the filament during
x-ray production; occurs when the tungsten filament gains enough heat so the outer shell
electrons are emitted and form a cloud around the filament creating the space charge effec
kilovoltage determines the speed at which the electrons travel across the tube which
determines the x-ray energy and quality
as kVp increases... beam penetrability increases
milliamperage/tube current the number of electrons flowing per unit of time; controls the
heat of the filament and thus the number of electrons boiled off
Solutions
ionization the ability to remove electrons; foundation of x-ray interaction with tissue
making them valuable for image creation but damages the tissue
PE effect x-ray photon ejects an inner shell electron becoming fully absorbed in the
process--causes secondary photons and increasing patient dose. Absorbed dose is dependent on
the amount of ionizing radiation
sources of radiation natural materials, solar radiation, and medical radiation
images formation non-interacting transmitting radiation which attenuates differently
according to the anatomy it travels through
scatter radiation type of radiation that interacts with tissues but weakens and changes
direction before exiting
,protective tube housing encloses the x-ray tube and constructed with lead lining; prevents
electric shock to the tube and facilitates cooling; can be made of glass or metal; the metal tubes
extend the life; creates vacuum for x-ray production
cathode side of the tube that produces the electrons and forces them toward the anode;
negatively charged
focusing cup surrounds the cathode to force the electrons into a controlled beam and
prevents direction which means less scatter
filament wire coil of tungsten wire at the cathode; source of electrons via thermionic
emission
anode side of the tube that is a positively charged target for electrons to convert to x-rays;
composed of molybdenum copper and tungsten; consists of a target, stator, and rotor
anodes can be stationary or rotating (rotating disperse heat and reduce wear)
,window sheet of glass in the tube housing where x-rays are directed to exit; acts as partial
filtration of the beam
filtration reduction of low energy photons to reduce patient dose
two types of filtration added and inherent filtration
what must the min mmAl be for tubes above 70 kVp? 2.5 mmAl
added filtration filtration added to the part of the tube to absorb low energy photons and
reduce patient dose
compensating filters added to primary beam to alter intensity often used in nonuniform
anatomic regions; commonly a step wedge or trough filter
collimator/collimation shutters; most common beam restricting device; set of 2-3 sets of
lead shutters immediately below the tube window and limit the field of the beam; allows for
variable field size
, fixed aperture flat piece of lead with a hole in it below the tube window
cones and cylinders a fixed aperture with extended flange and slide into the tube directly
below the window; decrease unsharpness
PBL (positive beam limitation) automatic collimator; limits size and shape of the beam to
make the IR in the bucky; used to reduce patient exposure
thermionic emission refers to the process of boiling off electrons from the filament during
x-ray production; occurs when the tungsten filament gains enough heat so the outer shell
electrons are emitted and form a cloud around the filament creating the space charge effec
kilovoltage determines the speed at which the electrons travel across the tube which
determines the x-ray energy and quality
as kVp increases... beam penetrability increases
milliamperage/tube current the number of electrons flowing per unit of time; controls the
heat of the filament and thus the number of electrons boiled off
