Introduction: X-ray imaging of the pelvis is placed at the very top of the most frequent radiation-burdening investigations. According to a minority of previous studies, a reduction in doses should be concentrated in conjunction with the patient's positioning according to the position of the ionizing cells of the AEC digital radiography system. Purpose: The purpose is to determine how DAP, effective dose, doses to specific organs and image quality are changing according to cranially or caudally orientated position in the X-ray of the pelvis. Methods: The research was carried out in two parts. In the first part of the study we measured doses on the phantom, where 10 images were taken in HT and 10 in the HA layout. The second part of the study was expanded to 200 patiens, one hundred per each x-ray mashine. We measured DAP, field size, height and mass from which we calculated ITM. Then we calculated effective dose and absorbed dose for individual organs accordingly. The radiographs were independently evaluated by three radiologists. Results: The research on the phantom and patients on both x-ray machines did not show statistically significant differences in field size and ITM. DAP on Siemens Ysio shows a 9,5 % (p = 0.032) difference on the phantom and 37,3 % (p = 0.002) the difference in patients in favor of a cavalous setting. The Efective dose on Siemens Ysio is lower by 35,7 % in the HA position and is statistically significantly different (p = 0.002). In the measurement of effective doses on individual organs, the statistically significant difference was measured in patients imaging on Siemens Ysio: bladder (36.5 %), skin (35 %), lower colon (35 %), pelvis pelvis (33 %), the uterus (32,8 %), the ovaries (32,4 %) and the large intestine (28,8 %). We did not find significant differences at Siemens Luminus. Radiologists estimates were 5, 4% higher in caudally orientated position at Siemens Ysio, but otherwise statistically significant differences were not detected on the phantom or patients. Discussion: Due to the position of ionization cells, the results between Siemens Luminus and Ysio differ. Statistically significant differences in DAP, effective dose, absorbed dose to selected organs in the replacement of the patient's position can be found at Siemens Ysio.Conclusion: While preserving the image quality, using the caudally orientated position at Siemens Ysio reduced the DAP by 37,7 % and the average effective dose by 35,7 %. The mean absorbed dose to selective organs is 33,4 %. We conclude that positioning patiens caudally orientated according to ionizing cells is a method of selection.
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