Aims and objectives
The main goal of this research was to evaluate the effectiveness of a protocol for dose reduction in paediatric CT examinations,
in which it is suggested a reduction factor depending on the thickness and age of the patient,
and to evaluate the effect on image quality.
Methods and materials
Target Population:
Paediatric head,
chest and abdomen CT examinations,
performed in a radiology department from a public hospital.
Study Type
1.
Retrospective study (probabilistic sample);
2.
Quantitative study (experimental method using two phantoms)
Variables:
Independent variables: Baseline current-time product (mAs) and protocol parameters: tube voltage (kVp),
current-time product (mAs),
pitch.
.
Dependent variables: CTDIvol values (Volume Computed Tomography Dose Index),
DLP values (Dose-length product),
CT image quality parameters (noise,
low contrast resolution,
high contrast resolution),
reduction factor and appropriate paediatric mAs.
Instruments
Protocol for dose...
Results
It was possible to verify,
despite the relation between the contrast-to-noise ratio (CNR) and the current-time product isn´t absolutely linear,
there is a CNR increasing/decreasing when current-time product increase/decrease,
respectively (Fig.7).
It is also known that there are limits below which the CNR (0.7 for paediatric head and 0.4 for paediatric abdomen) is no longer acceptable,
so reducing the current-time product must be done in a thoughtful way.
The dose reduction achieved was 25,9% for head CT examinations in newborn patients,
13,8% for patients until...
Conclusion
This protocol proved to be efficient,
it was possible to reduce the dose to 25.9% for paediatric head CT examinations and maintain acceptable the image quality.
The radiographers should adopt it into their daily routine,
considering the optimal dose reduction,
and such practice is essential to minimize potential risks to paediatric patients during CT examinations,
attending the ALARA (As Low As Reasonably Achievable).
Personal information
João Pinheiro (MSc),
Professor in the Medical Imaging and Radiotherapy Department,
Health School - University of Algarve,
Portugal.
E-mail:
[email protected]; Tel: +351289800100
Bárbara Morgado (BSc),
Collaborator in the Medical Imaging and Radiotherapy Department,
Health School - University of Algarve,
Portugal.
E-mail:
[email protected]
António Abrantes (PhD),
Professor in the Medical Imaging and Radiotherapy Department,
Health School - University of Algarve,
Portugal.
Researcher in CICS.NOVA (Universidade Nova de Lisboa – Pólo de Évora) and Member of Studies Center in Healthcare (CES-ESSUALG).
E-mail:
[email protected]
Luís Ribeiro (PhD),
Professor...
References
1.
Society for Pediatric Radiology (2007).
How to Develop CT Protocols for Children.
CT Protocol Alliance Final 12-11-07.
http://www.pedrad.org/Portals/6/Procedures/Protocols.pdf
2.
Pro-Project.
(1991).
Pro-CT Dose.
http://www.pro-project.pl/en/computed-tomography/item/1066-pro-ct-dose.html
3.
American College of Radiology.
(2013).
CT Accreditation Phantom Instructions.
http://www.acr.org/~/media/ACR/Documents/Accreditation/CT/PhantomTestingInstruction.pdf
4.
CNEN (2014).
Norma CNEN NN 3.01.
Resolução 164/14,
Março de 2014
5.
American College of Radiology (2014) ACR–AAPM PRACTICE PARAMETER FOR DIAGNOSTIC REFERENCE LEVELS AND ACHIEVABLE DOSES IN MEDICAL X-RAY IMAGING.
PRACTICE GUIDELINE - Reference Levels. ACR Council,
Resolution 39.
6.
Dalmazo,
J.,
Júnior,
J.,
Brocchi,
M.
Costa,...