X-Ray Physics Review part 2 Flashcards
What does the autotransformer do?
It provides precise voltage to the filament and high voltage transformer
Give another name for the high voltage transformer
step-up transfomer
Between autotransformers and high-voltage transformers which has a fixed turns ratio and which is adjustable
The autotransformer is adjustable and the high voltage is fixed (usuall 1000:1)
What does the rectifier do?
It converts AC to DC because the xray tube can only operate on DC current
Is the filament transformer high voltage or low voltage
low voltage
What is the relationship between current (amperage) and voltage (v)?
they are inversely proportional. If current is increased, voltage will be decreased.
What type of generator is commonly used in Xray equiptment today?
High Frequency
Is the negative side of the x-ray tube the anode or the cathode?
The cathode is the negative side
What part of the x-ray tube are the filaments and focusing cup located?
The cathode
What are the filaments made of that are inside of the focusing cup of an x-ray tube?
Thoriated Tungsten
What changes in the x-ray tube when you select large focal spot vs small focal spot?
The large vs small thoriated tungsten filaments
Is the positive side of the x-ray tube the anode or the cathode?
The anode is the positive side of the x-ray tube
What is the target for the electrons produced by the cathode?
The anode.
Is there actually oil in the x-ray tube?
Yes! dielectric oil is used as an insulator in the x-ray tube. It prevents sparking and is a thermal insulator
What x-ray tube component produces thermionic emission when heated?
The filament
What is it called when additional electrons cannot be emitted from the filament because too many electrons have already collected around the filament?
The Space Charge Effect
The greater the mA the (more or less) electrons form the cloud?
more
When the electrons strike the anode they either produce nothing but heat or produce x-rays. What is the probability of each?
99% heat - 1% x-rays
What are the two main mechanisms for x-ray production in the x-ray tube?
Bremsstrahlung Radiation (interactions) and Characteristic Radiation (interactions)
What common term is Bremsstrahlung radiation known as?
“breaking” radiation
Why is bremsstrahlung radiation called “breaking” radiation?
because x-rays are given off when the electron slows or “breaks” as it bends around the nucleus
Between bremsstrahlung and characteristic radiation (interactions) which is responsible for the majority of the x-rays produced in the x-ray tube?
Bremsstrahlung
Which type of x-ray production involves the ejecting of an electron on the target material?
Characteristic radiation
Which type of x-ray production involves the projectile electron bending around the nucleus of the target atom but not actually ejecting a target electron?
Bremsstrahlung Radiatioin
True or False - Characteristic radiation is only possible when the incident electron has more energy than the binding energy of the inner shell electron?
True
True or False - In characteristic radiation the x-rays are only actually produced when the outer shell electron fill an inner shell vacancy?
True
What is the primary technical factor set by the technologist that is responsible for the penetrating power or the QUALITY of the x-ray beam?
kVp
What is the 15% rule with reference to kVp and mAs?
That increasing the kVp by 15% is roughly equivalent to doubling the mAs when it comes to density
Does increasing mAs increase the number of x-rays produced or the quality of x-rays produced?
increasing mAs increases the number or quantity of x-rays produced
Does tube filtration remove low energy photons or high energy photons?
filtration removes the useless low-energy x-ray photons. This is known as beam hardening
Does CT use a lot of tube filtration or a little?
CT uses a lot of tube filtration because of the high energies needed
What is the benefit of reducing low energy photons by increasing filtration in an x-ray tube?
Increased filtration will remove low energy photons and thus reduce patient dose
Which generator will produce a spectrum with the highest average energy? (high frequency, 3 phase 12 pulse, 3 phase 6 pulse, or single phase)
High frequency
