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7&8 product&emission
Equipment. Chap 7&8, x-ray Production, and Emission
| Question | Answer |
|---|---|
| What generates most of the heat created in the anodes? | The constant excitation and return of outer shell e-. |
| Ejection of an inner shell electron is __________ radiation | characteristic |
| In characteristic radiation, the x-ray has energy equal to the .... | difference in the binding energies of the orbital e- involved. |
| Tungsten K shell # of e- and binding energy? L shell? | 2 e-, 69keV. 8 e-, 12 keV |
| __________ has very specific energies. __________ x-rays produced can have any energy up to 70keV. | characteristic, brems |
| In the dx range, most x-rays are __________. (charact or brems) | brems |
| at 65 kVp, no useful _______ x-rays are produced; therefore, the beam is all _________. | characteristic, brems |
| At 100 kVp, approx 15% of the beam is ___________, the rest is _______. | characteristic, brems. |
| A ______ spectrum contains only specific values. | discrete |
| A _________ spectrum contains all possible values. | continuous |
| The discrete energies of characteristic x-rays are characteristic of the differences between | electron binding energies in a particular element |
| Characteristic x-rays have fixed energies, and form a ____ emission spectrum. | discrete |
| Bremsstrahlung have a range of energies and form a _________ spectrum | continuous |
| Brems emission spectrum extends from 0- max projectile electron energy, with the highest number of x-rays having approx. _______________ | 1/3 the max energy |
| Factor: tube current. Effect: | amplitude of spectrum (up and down) ..........current is mA/mAs |
| Factor: Voltage. Effect: | Amplitude and position (up and down, left/right) |
| Factor: Added Filtration. Effect: (and when) | Amplitude (up/down), most effective at low energy |
| Factor: Target material. Effect: | Amplitude (up/down), position (left/right) |
| Factor: Voltage waveform. Effect: (and when) | Amplitude (up/down) most effective at high energy |
| The farther to the right a spectrum is..... | the higher the effective energy or quality of beam. |
| The larger the area under the curve.... | The higher the x-ray intensity or quantity. |
| A change in mA or mAs results in a proportional change in amplitude at ____________ across the spectrum. | all energies |
| Change in kVp results in an increase in the amplitude at all energies but a greater increase at ______ energies than _____. Therefore, the spectrum shifts to the _____/_____ side. | high, low. Right/high energy |
| The maximum energy of x-ray emission always remains numerically equal to the | kVp |
| A change in kVp has what effect on the position of the discrete spectrum? | none |
| Discrete emission spectrum shifts to the _____ with an increase in the atomic # of target material. What happens with the continuous spectrum? | right. Slight increase in amplitude. (more effect on characteristic/discrete) |
| Increasing target atomic # enhances the efficiency of x-ray production and the energy of what x-rays? | characteristic and brems |
| Difference between three-phase/6-pulse and three-phase/12-pulse power? | simply the reduced ripple obtained with 12 pulse generators. |
| ______ generators are based on fundamentally different electrical engineering. | High frequency generators |
| Because of reduced ripple, operation with 3-phase or high frequency is equivalent to an approx ______% increase in kVp, or almost doubling of mAs over single phase power. | 12% (..or 16%?) |
| What is "grays in air" measurement? | quantity, exposure, intensity |
| What does the standard x-ray machine produce? | 50 uGy/mAs at 70 kVp measured at 100 cm SID |
| intensity of the beam is measured in | milligray in air (mGya) (formerly milliroentgen (mR)) called x-ray quantity |
| mGya (mR) is a measure of the # of ____ ____ produced in air by a quantity of x-rays | ion pairs |
| x-ray quantity is proportional to the | kVp ^2 |
| inherent filtration for a machine is approx | .5 mm Al equivalent (total with added must be 2.5) |
| Added filtration for a machine is approx.? | 2 mm Al equivalent. (total with inherent must be 2.5) |
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Zoest35
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