Radiation Production and X-Ray Equipment Flashcards
What is the most prevelant mechanism of Xray Production?
Bremsstrahlung “Braking radiation”
Bremsstrahlung “Braking Radiation” comes from what?
the incident electrons vector is bent by gravitationAL PULL OF THE TUNGSTUN TARGET NUCLEUS. THE RESULTANT LOSS OF ENERGY IAS THE INDECENT ELECTRON BENT AROUND THE NUCLEUS IS EMITTED AS A PHOTON
What happens as the electron goes closer to the nucleus
the more severely its course is changed and the greater the energy released as it brakes around the corner
True or False: Bremsstrahlung “Braking Radiation” involves an electron striking another particle in the target
False: it involves interaction between the incident electron and the nucleus of a target atom
Bremsstrahlung “Braking Radiation” Percentages
85% of Bremsstrahlung “Braking Radiation” are formed via Bremsstrahlung at 100kVp
The % increases as kVp goes down
The % decreases as kVp increases beyond 100kVp
Characteristic radiation comprises only 15% of the Xray beam @ 100kVp but its % rises as kVp rises and
Diminishes from that 15% as kVp diminishes below 100
What causes Characteristic radiation?
It is caused by collision of the incident electron with an inner shell electron, resulting in ejection of the inner shell electron
When is a characteristic radiation photon produced
produced when an electron from a shell other than the K shell drops into the vacated K shell spot.
the change in energy from the Lshell to the K shell is the energy of the photon
what is the energy of characteristic radiation produced at the tungston target
69KeV
what are the X-ray beam types
Primary radiation- from tube to patient
Secondary/ scatter radiation- created by the beams interaction with patient tissue
Remnant radiation- radiation that goes through the patient participates in creating the image we will see
The Anode
Positive charge. The magnitude of the positive charge applied to the anode causes electrons to be accelerated towards the anode- the flow is the electmotive force and is measured in kilovolts
Rotating anode maximizes heat managment and increases durability of the anode
Tungston target absorbs and distributes heat
Xrays are formed within the anode target
Rotor is motorized (hence the extra wire going into the anode side of the tube housing)
The Cathode
Negative charge
two filaments small and large
Focusing cup is negatively charged to focus the direction of electrons causes them to focus towards a point as they reach the tungston target
The negatively charged focusing cup bends the electrons course from a divergent a more convergent pattern towards the anode
Thermionic emission creates the space charge
mA and time mAs determines the # of electrons which determines the number of photons created which then determines density
True or False: the relationship between image density and mAs is linear and proportional
True if you double the mAs you double the image density
what is Leakage radiation
Is X-rays that escape he tube housing in any location other than the port
Actual focal spot vs effective focal spot
is a function of anode and whether you are using large or small focal spot- the larger focal spot will always produce a larger effective focal spot then a small focal spot if the anode angle is the same
What is the anode angle
its between 10-20 degrees; 12-15 degrees is most common for general radiography applications
12 degrees is the minimum for chiropractic applications it reflects a balancing act
