Abstract P5-01-02: Glandular dose in contrast-enhanced dual-energy mammography

Abstract INTRODUCTION Estimation of the Average Glandular Dose (AGD) absorbed by the breast during x-ray based examination is an established part of quality control procedures for breast imaging, both for standard mammography and new techniques as digital breast tomosynthesis (DBT) and contrast enhanced digital mammography (CEDM). It is however fundamental that every optimization program obtains an adequate imaging quality. In our study we evaluated the AGD absorbed by the breast, during CEDM examinations, performed with Dual Energy (DE) technique in our Department. MATERIALS AND METHODS We retrospectively evaluated 37 DE mammograms; we reported and analyzed AGD, Entrance Skin Exposure (ESE), anode/filter combinations, breast thickness, kV (kilovolt), mAs (milliAmpere per second), and compression in daN (decaNewton) values, for each mammography view obtained on high and low energy. In 10 Patients, it was possible to compare DE with a recent standard mammography performed on the same mammography unit. RESULTS AGD values for the entire DE study, in craniocaudal and mediolateral oblique views, resulted between 4.23 mGy and 13.44 mGy; based on the breast thickness (27-79 mm) and on the anod/filter combination. We found out a significantly lower AGD for small breast thicknesses and Mo/Rh and Mo/Cu combination compared to Rh/Rh and Rh/Cu. In the whole study evaluation, the AGD percentage report due to low and high energy acquisitions resulted between 76.8% and 81.6%, and between 18.4% and 23.2%, respectively. For the 10 Patients in which was possible a direct comparison with the data obtained with recent standard mammography, resulted a ratio between DE AGD and standard mammography AGD variable from 1.43 to 2.48 (mean value: 2.0), again with lower AGD values obtained with Mo/Rh - Mo/Cu combination and for small breast thicknesses. AGD ratio between low energy and standard mammography acquisition resulted between 1.23 and 3.31. DISCUSSION CEDM is proving to have all the potential to get a definite role in diagnosis and breast tumor staging, providing a direct correlation between morphologic and functional imaging. In our study we assessed the dosimetry to determine if an additional x-ray exposure will be a limit to DE use and, if that is the case, in which measure. Data in the literature on DE dosimetry are still spare and extremely heterogenous. In any case, the increase of delivered dose could be justifiable when compared to the great benefits given by this technique in breast cancer early diagnosis and staging, especially in dense breast tissue, in the follow-up of Patients with breast cancer history and in case of MRI incompatibility. Furthermore, when compared to MRI, CEDM is an easy-access, low-cost, fast and well accepted exam by the patient. CONCLUSIONS Although the risk of induced carcinogenesis associated with x-ray breast modalities is small, dosimetric aspects should be considered both for the risk evaluation and for optimization of acquisition systems; with the advance of the technologies we will be able to have a dose reduction by maintaining high quality standards. Results obtained from this preliminary study needs to be extended by a larger case study to get a complete evaluation and comprehension of the phenomenon. Citation Format: Cossu E, Castellani F, Fiaschetti V, Mariateresa M, Tiziana R, Angelo T. Glandular dose in contrast-enhanced dual-energy mammography [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-01-02.