Computed tomography (CT) is a very powerful tool in the field of the diagnostic imaging and the evaluation of different clinical conditions [1].Although the use of CT in diagnostic radiology has increased over the last few years, much effort has been made to help improvement of radiation protection of both the patients and the staff during CT examinations. The aim of this study is to investigate the influence of the CT gantry rotation time (trot) on the patient exposure.

The survey is performed with two different CT systems: 320-slice and 16-slice (Figure 1 and Figure 2).[Fig 1][Fig 2] Head and cardiac CT examinations are involved in the current study. In order to evaluate the patient exposure - volume computed tomography dose index (CTDIvol) and dose length product (DLP) are used. For additional analyses, the values for the tube voltage, tube current, pitch, beam width (NxT), slice thickness, number of slices and some patient data - sex, age and weight are also recorded. The survey...

The patient data presented in Table 1 is collected on the 320-slice CT system between 2018 and 2020. The total number of the patients is 91 (55% - women and 45% - men). The analyses show that the median CTDIvol and DLP values (and the standard deviation), per phase, for the contrast cardiac CT phase, 320-slice CT system and trot=0.375 s are: 46.5(21.4) mGy and 740.6(342.8) mGy.cm. For the same CT system and faster trot=0.35 s, the median CTDIvol and DLP values are 1.4 times...

Faster CT gantry trot does have an impact on the patient exposure. А reduction of the trot leads to 1.2-2.0 times lower patient exposure, depending on the CT system and the type of examination. However, faster trot may result in an increased image noise, artifacts and decreased image quality [4]. Therefore, a team of physicist, radiologist and radiographer will always find the best compromise between the diagnostic image quality and the radiation exposure. Lowering the CT trot has to be implemented in the everyday routine...

[1] Daniel Ginat & Rajiv Gupta, “Advances in Computed Tomography Imaging Technology“, Annual review of biomedical engineering 2014, 16. 431-53. 10.1146/annurev-bioeng-121813-113601; [2] Nikolaos V. Tsekos, “Review: Basics of Imaging”, 2019, http://www2.cs.uh.edu/~cs6370/; [3] Anna Romanyukha, Les Folio, Stephanie Lamart, Steven L. Simon and Choonsik Lee, "Body size specific effective dose conversion coefficients for CT scans", Radiation Protection Dosimetry 2016 Dec, 172(4): 428-437; [4] Martin Beeres, Julian Wichmann, Jijo Paul, Emmanuel Mbalisike, Mohamed Elsabaie, Thomas Vogl, Nour-Eldin Nour-Eldin, “CT chest and gantry rotation time: does the rotation...

D. P. Ivanova: Nothing to disclose M. Nedevska: Nothing to disclose D. Kostova-Lefterova: Nothing to disclose V. V. Groudeva: Nothing to disclose K. Romanova: Nothing to disclose