# Assessment of a Patient Dose Monitoring System for Average
## 1 Introduction  
Mammography has traditionally been the most suitable and effective technique for the screening and diagnosis of breast cancer. The use of ionizing radiation in this procedure introduces a non-negligible risk of cancer due to radiation exposure. Therefore, special attention has always been given to monitoring and optimizing breast-absorbed doses to ensure patient safety.  
In mammography, the radiation dose to the breast is estimated in terms of the average glandular dose (AGD). Since it is not possible to measure the dose absorbed by the breast directly, the AGD is only an estimate of the energy deposited per unit mass of glandular tissue, and as such, it provides an indication of the breast dose. The average glandular dose is calculated using conversion factors from air kerma to AGD derived from Monte Carlo simulations [1, 2, 3, 4, 5, 6, 7], and it depends on X-ray spectra, beam quality, breast thickness, andbreast density (glandularity). While most AGD estimates assume that the breast consists of 50% glandular tissue and 50% fatty tissue [1, 4, 5, 6, 7, 8], it is well known that breast composition has variable density. Therefore, the assumption of 50% glandularity leads to a rough estimate of the absorbed dose. Some authors have addressed this issue by developing a model to estimate breast glandularity based on the patient's age and compressed breast thickness (CBT) [2, 3]. However, even this approach has limitations, as glandularity is not assessed by considering the actual breast composition. This is a critical point in mammography, since the amount of fibroglandular tissue in the breast is closely related to the risk of radiation-induced breast cancer: women with dense breast tissue have a higher risk of breast cancer compared to women with less dense tissue [9, 10, 11, 12, 13, 14].  
All modern digital mammography units provide an indication of the AGD for each exposure, which is displayed on the screen and stored in the header of the DICOM image file. In the context of evaluating doses to the population and clinical audits, as outlined in the European Atomic Energy Community (EURATOM) directive [15] and in accordance with the International Commission on Radiological Protection (ICRP) recommendations on the use of diagnostic reference levels (DRLs) in medical imaging [16], acceptable and achievable dose levels--expressed as average glandular doses--are assessed in the European guidelines for quality assurance in breast screening and diagnosis [17, 18, 19] and international recommendations [16, 20, 21, 22].  
Given the large number of mammograms performed daily, the implementation of patient dose monitoring and optimization is facilitated through the use of online dose management systems. These systems store all relevant information for each exposure (e.g., patient data, study date, equipment model, exam parameters, dosimetric quantities), enabling easier collection of large datasets to optimize protocols, reduce radiation doses, and perform statistical analysis. However, the estimated average glandular dose provided by digital mammographic units needs to be verified using independent measurements and compared with other calculation models.  
The aim of this study was to assess and verify the reliability of a patient dose monitoring system as a tool for estimating the average glandular dose in mammography and to compare the dose values provided by the mammography systems with those calculated using independent models. Furthermore, we aimed to evaluate whether the integration of software for the estimation of real glandularity improves the accuracy of AGD calculations compared to traditional methods.