The effect of tomosynthesis X-ray pulse width on measured beam quality

Abstract

Tomosynthesis acquisition typically consists of a set of short x-ray pulses from an x-ray tube moved to different locations relative to the object being imaged. The pulsed x-rays used in the acquisition exhibit a "pulsing effect" on the beam quality results that is different from conventional mammography. We found that the measured exposure rates in term of mR per mAs are notably dependent on the width of x-ray pulse, while the half-value layer is weakly dependent on the pulse width. This phenomenon is due to the finite rise and fall time of kV and mA of the generator, and becomes significant for very short x-ray pulses. The pulsing effect, if ignored, gives incorrect tomosynthesis beam quality results and introduces errors in dose calculation. In this study, the phenomenon is fully characterized and two practical methods are introduced to account for the effect, which could also help to reduce the beam quality test time for tomosynthesis. © 2008 Springer-Verlag Berlin Heidelberg.