8: xray production

What happens when projectile electrons strike the x-ray tube target?

The kinetic energy is transferred to the tungsten atoms, producing x-rays and heat.

What are the two types of x-rays produced during electron target interactions?

Characteristic x-rays and Bremsstrahlung x-rays.

What percentage of projectile electron interactions results in x-ray production?

Approximately 1% at 60 kVp, increasing to 70% at 20 MV.

What is the primary outcome of projectile electron interactions in the anode?

99% of interactions result in the conversion to heat.

How does increasing tube current affect heat production in the anode?

Heat production increases directly with increasing tube current; doubling the current doubles the heat.

What is characteristic radiation?

It occurs when a projectile electron removes an inner shell electron from a target atom, resulting in ionization and the emission of an x-ray photon.

K characteristic X-rays have the energy of Aprox….

69 kvp

What percentage of X-rays consist of characteristic X-rays ?

15%

What is Bremsstrahlung radiation?

It is produced when a projectile electron is slowed by the electric field of a target atom nucleus, resulting in the emission of x-ray energy.

What is the atomic number of tungsten?

74.

What happens to an outer shell electron when an inner shell electron is removed in characteristic radiation?

An outer shell electron drops to fill the void, emitting an x-ray in the process.

What factors affect the x-ray emission spectrum?

Factors include mAs, kVp, added filtration, target material, and voltage ripple.

What is the relationship between kVp and x-ray production efficiency?

Efficiency increases with higher kVp; at 60 kVp, 0.5% of kinetic energy is converted to x-rays, while at 100 kVp, it is approximately 1%.

What type of x-rays are primarily produced in the diagnostic range?

Most x-rays produced are Bremsstrahlung x-rays.

What is the effect of increasing mAs on Bremsstrahlung radiation?

Increasing mAs leads to an increase in Bremsstrahlung radiation.

What is the significance of the binding energy in characteristic radiation?

The energy of the emitted x-ray is equal to the difference in binding energies of the orbital electrons involved.

What happens when a projectile electron is barely influenced by the nucleus?

It results in a low-energy Bremsstrahlung x-ray.

What happens when a projectile electron is greatly influenced by the nucleus?

It results in a high-energy Bremsstrahlung x-ray.

What is the primary source of heat generation in the x-ray tube target?

Most of the heat generated is due to outer-shell excitation of electrons.

What is the role of the anode in x-ray production?

The anode serves as the target for the projectile electrons, facilitating the production of x-rays and heat.

Useful characteristic X-rays from tungsten targets are _ X-rays

K shell

What type of x-rays are produced by slowing electrons at the target?

Bremsstrahlung x-rays

What are most X-rays brems or characteristic?

Brems

What are the types of target interactions

Characteristic and brems

Brems X-rays are produced by _ at the target

Slow electrons

How does increasing kVp affect the x-ray beam?

It increases both the quantity and quality of the x-ray beam.

What is the useful limit for kVp in x-ray production for bremsstrahlung?

Usually around 150 kVp.

What does the area under the curve in an x-ray emission spectrum represent?

The total number of x-rays emitted.

What happens to the x-ray emission spectrum when mA is increased?

The amplitude of the spectrum increases, but the shape remains the same.

What is the 15% Rule in x-ray exposure?

Increasing kVp by 15% has the same effect as doubling the mAs.

How does added filtration affect the x-ray beam?

It reduces intensity while increasing effective energy.

What is the effect of target material on x-ray emission?

It affects both the quantity and quality of x-rays produced.

Which type of waveform has the least voltage ripple?

High frequency

What is a characteristic x-ray emission spectrum based on?

The atomic number of the element.

What is the relationship between maximum x-ray energy and wavelength?

They are inversely proportional; shorter wavelengths correspond to higher energies.

How does increasing kVp affect the average x-ray energy?

It shifts the distribution to a higher average x-ray energy.

What effect does increasing kVp have on the amplitude of the x-ray emission spectrum?

It increases the area under the curve.

What does a shift to the right mean

Higher quality of beam (kvp)

What does a larger areas under the curve mean?

Quantity

What is the result of using a higher atomic number target material?

It increases both Bremsstrahlung and characteristic x-rays.

How does the x-ray emission spectrum change with increasing mAs?

The amplitude increases proportionally at all energies.

What is the effect of voltage waveform on x-ray intensity?

Higher frequency waveforms lead to increased x-ray intensity and effective energy.

What happens to low energy x-rays when added filtration is used?

They are absorbed, resulting in a 'hardening' of the x-ray beam.

What is the effect of increasing kVp by 15% on mAs?

It allows for a decrease in mAs while maintaining the same optical density.

What is the significance of the characteristic cascade in x-ray production?

It results in more intense K x-rays, which are part of the useful beam.

If kvp is changed will amplitude or position be affected

Both

What does a shift to the right in the x-ray emission spectrum indicate?

Higher quality of the x-ray beam.

What is the relationship between kVp and the quality of the x-ray beam?

Higher kVp results in higher quality x-rays.

What is the maximum x-ray energy associated with?

Minimum (shorter) x-ray wavelength.

What is the effect of increasing kVp beyond a certain point?

It diminishes the usefulness of the beam, leading to mostly bremsstrahlung x-rays.

What is the effect of increasing mA from 200 to 400?

It allows twice as many electrons to flow.

How does the shape of the x-ray emission spectrum change with different factors?

The shape generally remains the same, but the curve can shift.

What happens if current increases ?

Amplitude of spectrum changes but shape doesn't

Where are the strongest characteristic X-rays formed from ?

O shell dropping to k shell

What factors affect the xray emission spectrum?

Ma/ mas

Kvp

Filtration

Target materials

Voltage waveform