Connecting the missing piece: a retrospective evaluation of image quality and dose in respect to the parameters variability for a clinical CT protocol

Congress:

EuroSafe Imaging 2018

Poster Number:

ESI-0071

Type:

EuroSafe Imaging

Keywords:

Radioprotection / Radiation dose, CT, Abdomen, Action 13 - Stakeholder engagement and collaboration, Action 10 - EuroSafe Imaging Stars, Action 2 - Clinical diagnostic reference levels (DRLs), Action 10 - Improved communication and collaboration of health professionals in radiation protection, Action 8 - EuroSafe Imaging Stars network and data collection, Action 3 - Optimisation, diagnostic reference levels, image quality, Diagnostic procedure, Radiation safety, Kv imaging

Authors:

T. Viana Miranda Lima, S. Schindera, S. Scheidegger, G. Lutters

DOI:

10.1594/esi2018/ESI-0071

DOI-Link:

https://dx.doi.org/10.1594/esi2018/ESI-0071

Fig. 1: CTDIvol before and after change of protocol. Green represents patients below 90...

Fig. 2: In-house phantom with the DDC insert. The phantom has an effective diameter of...

Fig. 3: DDC insert, different colours represent HU concentration either in contrast...

Fig. 4: DDC curves for all series for the contract enhanced section of the phantom....

Background/introduction

The main aim of a CT examination is to accurate answer the clinical question. Recently, radiation dose management systems (DMS) have been introduced in different hospitals as they support continuous optimisation of patient care in respect to patient exposure [1]. Optimisation of patient exposure can only be complete if carried out alongside with an image quality (IQ) evaluation to ensure that the obtained result is clinical relevant. The aim of this work was to evaluate a proposed method for IQ assessment on an abdominal CT...

Description of activity and work performed

Difference detailed curves (DDC) were obtained from images acquired with an in-house purposely built phantom (5 series of different HU concentration of 6 lesions from 3 to 9 mm each) [2] to evaluate the impact on IQ by the changes found in the protocol exposure. DDCs are used to evaluate resolution and low contrast detectability in respect to dose parameters by a human observed method by fitting a logarithmic function to the detectable lesions series [2]. We found that the affected protocol parameter was the...

Conclusion and recommendations

Patient exposure changes were only observed for our abdominal protocol due to continuing use of DMS. At this work we connected protocol changes to the final observed IQ. As expected, the highest CTDIvol protocol produced the highest observed IQ. Most importantly, it can be seen from the DDC, that aside from the highest CTDIvol protocol, all other protocols showed no statistical difference from the lowest CTDIvol (series 1). This reduces the justification weight for the observed patient exposure increase after the software installation.

Personal/organisational information

Aarau Cantonal Hospital (KSA) is the largest hospital in the canton of Aargau and, next to the university hospitals, one of the largest center hospitals in Switzerland. As an inter-regional facility with a non-Cantonal charisma, the KSA has a first-class medical-technical infrastructure, is actively involved in research and is an important further education center for prospective specialists as well as an attractive employer for numerous occupational groups through the training of 31 specialist titles, 19 of them in A-status from care, therapy and operation. The...

References

[1] European Council Directive (2013) 2013/59/Euratom on basic safety standards for protection against the dangers arising from exposure to ionising radiation and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom. OJ of the EU. L13; 57: 1–73 (2014). [2] C. Sommer et al.: (2017) Evaluation of low contrast resolution and radiation dose in abdominal CT protocols by a difference detail curve (DDC) method. Current Directions in Biomedical Engineering, 3 (2), pp 517-519