Introduction: X-rays are electromagnetic waves of high frequency and short wavelength.
The beam of X-ray photons coming out of the X-ray tube has a broad energy spectrum -
polychromatic radiation. When the radiation passes through an object, most of the low-energy photons are absorbed in the first few centimetres of tissue, leaving only the high-energy photons to pass through the object and reach the imaging receiver. The examination
involves a trade-off between the minimum dose that radiological engineers can deliver to
produce a radiograph and the optimum quality of the radiograph - the ALARA principle.
Purpose: The purpose of this thesis is to determine the effect of additional filtration and
accelerating voltage on the dose received by the patient during pelvic imaging. Methods. We
have investigated the effect of additional filtration and accelerating voltage on the patient
dose when imaging the pelvis in AP projection. First, we performed the imaging with self-filtration, and then we gradually added additional filters made of aluminium and copper. We
measured the DAP, the object focal distance, from which we then calculated the VKD. We
also calculated the effective dose and the dose to specific organs, using the PCXMC 2.0
software. This programme uses Monte Carlo simulation. The method is based on the
calculation of photon transport, which depends on stochastic mathematical simulations of
the interactions between photons and matter. Results. This can be related to the fact that the
average energy of the X-ray photons increases with increasing anodic voltage. Also, the mAs
increases with increasing thickness of the additional Al and Cu filters. We have also shown
that the effective dose does not decrease with increasing thickness of the additional filters.
We were interested to see if, as DAP decreases, the dose to the organs also decreases. From
the measurement data obtained, it can be said that as the thickness of the filters increases,
the DAP decreases, but the dose to the organs increases. The final finding was that when
using larger filter thicknesses, the DAP decreases. Discussion and conclusion: We
concluded that in practice it makes sense to use additional filtration as it reduces the dose to
the patient. It is the task of the radiological engineer to keep the dose as low as possible and
to optimise the quality of the radiograph.
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