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1. Increasing kV (tube voltage): increases the effective photon energy + increases the total number of photons. This shifts the spectrum up + to the right.

2. Increasing mA (tube current): proportional to the number of electrons flowing from the cathode to the anode per unit time. The quantity of x-rays is thus directly proportional to tube current * exposure time (mAs); increases the output of both bremsstrahlung + characteristic radiation. This shifts the spectrum up.

3. Changing the target atomic number: changes the amount of bremsstrahlung radiation + the photon energy of the characteristic radiation.

4. Generator waveform: affects the quality & quantity of the emitted x-ray spectrum. For the same kV, a single-phase generator provides a lower average potential difference than does a high-frequency generator.

5. Beam filtration.


1. Bushberg, J. T. (2012). The essential physics of medical imaging. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. Find it at Amazon
2. Heggie, J. C., Liddell, N. A., & Maher, K. P. (1997). Applied imaging technology. Melbourne: St. Vincents Hospital.

Ⓒ A. Manickam 2018

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