The main goal of this study is to characterize threshold contrast values and average glandular dose (AGD) in mammography exams, as well as their relationship with acceptable (minimum quality values) and achievable values (desirable quality values) from the fourth edition of the EUREF protocol. Therefore, data from 84 mammography units of 6 different manufactures and 15 different models was gathered across Portugal during 2020 and 2021. The contrast measurements were obtained with a CDMAM 4.0 phantom. Within the tested units, 6 failed to comply with the acceptable EUREF values for threshold contrast and 5% achieved all levels of desirable contrast. Only 3% of the units presented values above an AGD achievable level of 2.4 mGy, for an equivalent breast thickness of 60 mm. As these acceptable and achievable values are used as a guideline for the setup of dose and image quality of mammography units, the obtained results demonstrate that clinical images are being produced with an AGD much lower than the achievable dose values. As a result, contrast threshold values are close to the minimum quality values which could result in images with lower diagnostic data, compromising the justification of X-ray exams. Results proved that there is a possibility for an AGD increase, aiming achievable image standards. Greater levels of radiation dose correlated with better image quality and consequently higher diagnostic confidence could be consistent with the optimization principle for radiation protection.

In Portugal, Computed Tomography exposures for adult routine head, adult routine abdomen and paediatric abdomen (5 years old) were evaluated between 2019 and 2020 in 92 CT units. The third quartile value for CTDIvol was 63,2 mGy for adult head exams, 15,9 mGy for adult abdomen and 5,2 mGy for paediatric abdomen. However, the CTDIvol for head examination in 7,6% of units exceeded the suspension level proposed in EU report 162 while the number of units exceeding suspension levels for adult and paediatric abdomen were 3,2% and 0,0 %, respectively. The used acquisition parameters and the referred CT unit’s specifications were studied to understand how radiation dose relates with tube voltage, tube current, rotation time, detector width, slice width, pitch value and the use of automatic exposure control (AEC). The axial acquisition mode was predominant (67%) in the head exams. However, the helical scanning was commonly used in abdomen exams. Dose reduction from adult to paediatric exams was achieved using a lower tube current (a 60% average reduction). AEC is preferably used in abdomen protocols (84% in adult exams and 96% in paediatric exams). Nonetheless, in adult routine head protocols only 27% used this system. Data was gathered from clinics and hospitals covered by this study which allowed an estimate of an annual frequency of 206 CT examinations per thousand population in Portugal. The estimated dose index (CTDIvol) and frequency of CT examinations for the Portuguese population agreed with data from other countries.