There is an increase in utilization of direct digital radiography systems (DR) in the Netherlands[1]. The transfer properties of DR differ from the conventional systems. It is unknown if the current protocols are optimal for the X-abdomen on DR[2]. There is a shortage of literature about the ratio between the effective patient dose and low-contrast detectability (LCD). The aim of this study is to optimize the LCD corrected for the effective patient dose for the X-abdomen.

204 x-ray images were made on direct digital radiography system with the using of the following parameters: Tube voltage (60-90 kV) Filtering (0,1/0,2 mm Cu + 1 mm Al, 2 mm Al and none) Patient volume (15cm (V15) - 30cm (V30)) All images were made with Anti-scatter grid and AEC S800. The IQ-X technical phantom was used to determine theLCD in µmAl. All images were repeated with a dosimeter in the setting to measure the entrance dose(mGy) which was used in the effective patient dose...

Figure 1.Effect of tube voltage and filtering The LCD normalized for effective patient dose is fairly constant for all tube voltages and the lowest using 0,2 mm + 1 mm Al filtering. Figure 2.Normalized LCD for different patient volumes The normalized LCD per patient decreases from 6,08 (V20) to 10,03µmAl (V30) using 0,2 mm + 1 mm Al filtering and using AEC S800. Figure 3.Recommended X-abdomen protocol The current protocol of the Martini Hospital uses tube voltage modulation and AEC S800. This protocol does not...

To achieve the lowest effective patient dose for the desired LCD a protocol with a constant high tube voltage, 0,2 mm Cu filtering can suffice for all patient volumes. To achieve a constant LCD for all image volumes hospital can switch from tube voltage modulation to tube current modulation, using AEC and density corrections. More research is needed about the clinical image quality and to determine if the current LCD is the most optimal LCD for the X-abdomen.

Authors: Vijfschagt, Natasja [email protected] Winter, Michelle [email protected] Supervisors: Borns, Chris [email protected] Talsma, Anne [email protected] Hanze University, Groningen, The Netherlands Martini Hospital, Groningen, The Netherlands

[1]I. de Waard en P. Stoop, „Resultaten enquête kwaliteitsaspecten,” RIVM, Bildhoven, 2010. [2] M. Körner, C. H. Weber, S. Wirth, K. J. Pfeifer, M. F. Reiser en M. Treill, „Advances in Digital radiography: physical prinicples and system overview,” Radiography, vol. 27, nr. 3, pp. 675-687, 2007. [3]N.D. Vijfschagt, M. Winter, 'Physics based optimization of image quality for the x-abdomen in direct digital radiography', 2017