Establishing Dose Reference Levels for CT in a Chilean Hospital including technologist performance

Congress:

EuroSafe Imaging 2019

Poster Number:

ESI-0101

Type:

EuroSafe Imaging

Keywords:

Dosimetric comparison, Dosimetry, CT, Radioprotection / Radiation dose, Radiation physics, Action 4 - Dose management systems, Action 2 - Clinical diagnostic reference levels (DRLs), Quality assurance

Authors:

D. Fabri, P. Soffia, J. Sanguesa, R. Castillo

DOI:

10.26044/esi2019/ESI-0101

DOI-Link:

https://dx.doi.org/10.26044/esi2019/ESI-0101

Fig. 1: 25th, 50th and 75th percentil for DLP values for CT Chest protocol for each...

Fig. 2: 25th, 50th and 75th percentil for DLP values for CT Head protocol for each...

Table 2: DRL values for Clinica Alemana and those published in 2017 by Karl et al.,...

Table 1: DRL values for the 10 most frequent exams performed at Clinica Alemana on 2018....

Description of activity and work performed

Implementation of a radiation dose-monitoring program for patients undergoing CT exams and establishment of DRL values

The first step for implementing the program was the review of all CT protocols, deleting protocols that were duplicated, unused, and ambiguous. Then, all the remaining protocols were arranged on a set of Master Protocols on the Radiation Dose monitoring platform (Radimetrics®, Bayer). Master Protocols were also homologated to RadLex Playbook index (RPID, RSNA)). The use of RPID codes simplify the process of comparing typical or local calculated DRLs with National or Regional published values.

A process for sending dose index information from the CT unit in DICOM SR format to the RIS-PACS system was established. This information was then sent to the Radimetrics platform.

After gathering data for year 2018, DRLs were calculated for all protocols that were performed at least 30 times during the study period. The data correspond to exams performed in six different devices, located in three cities in Chile.Forty-four thousand and twenty (44,020) exams where included in this study. 46 Master Protocols meet the inclusion criteria. Typical DRL values were computed for both DLP and CTDI_vol.

We present the values for the 10 most frequent exams in our institution considering all patients, making no distinction between different patient sizes (Table 1).

Karl et al. published in 2017 the DRLs for the 10 most frequent exams perform in the US, only six of them can be related to protocols performed at our institution. Values for our institution and those published in 2017, taking into account all patients regarding their sizes are presented (Table 2).

There are many factors influencing dose delivered to the patient. It is hard to establish how much each of them affects the result. As a first approach of looking one of these parameters, we studied the for the two most frequent exam, the performance of the operators, by means of simply comparing de 25th, 50th and 75^th of DLP of the exams perform by each of them (Fig 1 and 2).