VERIDIC first deliverable: Standards for digital dose reporting

In interventional cardiology (IC), patients may be exposed to high doses to the skin resulting in tissue reactions (e.g. skin burns) following single or multiple procedures. Assessing the maximum skin dose (MSD) to the patient together with the dose distribution during (or after) these procedures is, as recommended by the ICRP Committee 3, essential from patient radiation protection point of view. Several software tools (online or offline) have been developed to help medical physicists in assessing the MSD during or after the procedure; they are either commercialised by major X-ray equipment manufacturers or produced by independent companies (e.g. dose management software companies). The capabilities and accuracy of such skin dose calculation (SDC) software markedly differ among vendors; and the reporting of the MSD estimate as well as the related accuracy in the Radiation Dose Structured Report (RDSR) is neither systematic nor harmonised. The VERIDIC project focuses on the harmonization of RDSR and on the validation of SDC software products, which will optimise radiation protection of patients. Among the overall project objectives, the Work Package 1 (WP1) dealt with the SDC harmonization issue in the view of proposing a possible standardisation of the digital dose reporting. Two different sub-tasks were carried out: (i) The review of existing software and (ii) the harmonization of dose reporting and tracking. In the first subtask (i), 19 software tools claiming SDC capacities were identified in the literature and reviewed according to their SDC algorithms and their capabilities. Special attention was dedicated to their main features and limitations of interest for the clinical user. In the second subtask (ii), RDSRs from recent systems of the four main manufacturers (Philips, Siemens, GE and Canon) were compared with a view to identifying the availability and the completeness of the data necessary for the calculation. The ability of two dose management systems to extract RDSR data was also investigated by comparing their output with the original RDSR. Although most SDC software tools use a comparable approach to estimate the skin dose, considerable differences in the implementation exist. While the accuracy of the 10 SDC products which were experimentally validated with measurements on phantoms, was acceptable (within ±25%); the agreement was poor for the two products which were also validated on patients (within ±43% and ±76%, respectively). In addition, no software has been validated on angiographic units from all manufacturers, though several software developer claimed vendor-independent transportability Strong heterogeneities in examination related technical parameters encoded in RDSR by the manufacturers were found, especially important for all dose calculation related data; even more heterogeneities were pointed out when considering the DICOM fields exports through two dose management software products. This highlighted the need for harmonizing both RDSRs and their exports in order to be able to calculate MSD from these data in an easy and straightforward way. Essential parameters for MSD calculation and dose mapping were listed and should be included in both RDSRs and exports. A public DICOM field to store MSD was suggested, as well as the use of the existing field to store final dose maps. To enhance harmonization, a flat representation of the skin dose map in addition the possible 3D representation was also suggested, in order that skin dose maps of multiple procedures on the same patient could easily be overlaid and the resulting MSD could be better estimated.