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Iterative reconstruction in CT: by how much can we divide the doses delivered to children and young adults?

English title Iterative reconstruction in CT: by how much can we divide the doses delivered to children and young adults?
Applicant Verdun Francis
Number 140995
Funding scheme Project funding (Div. I-III)
Research institution Institut de Radiophysique Département de Radiologie Université de Lausanne/CHUV
Institution of higher education University of Lausanne - LA
Main discipline Paediatrics
Start/End 01.01.2013 - 31.12.2015
Approved amount 288'852.00
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Keywords (5)

radiation exposure optimization; iterative reconstruction CT; image quality; pediatric CT; patient exposure

Lay Summary (English)

Lead
Lay summary
As in most Western countries,  CT is responsible for more than two third of the dose delivered to the population in Switzerland and this in spite of the fact that many efforts have been made by radiologists, medical physicists and manufacturers to optimize the examinations protocols.  Among the latest developments aiming at dose reductions one can mention the introduction of iterative image reconstructions, IR, and a better use of the X-ray beam energy.  The commercially available IRs (that tend to replace the standard filtered back projection, FBP) allow a modest dose reduction (about 30-40%) but require the acceptance of a change of the images’ texture.  More sophisticated IR’s are being developed where standard dose might be divided by factors as high as 8. Readable images are even obtained while reducing the dose by much higher factors.  In such a context it is essential to ensure that the diagnostic value of the examination remains sufficient. This project aims at determining up to what level patient dose can be reduced by taking FBP examinations as a gold standard and comparing them to follow up studies performed at very low dose levels together with IR. 
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Image quality in CT: From physical measurements to model observers.
Verdun FR Racine D Ott JG Tapiovaara MJ Toroi P Bochud FO Veldkamp WJ Schegerer A Bouwman RW (2015), Image quality in CT: From physical measurements to model observers., in Phys Med, 823.
Objective assessment of low contrast detectability in computed tomography with Channelized Hotelling Observer.
Racine D Ba AH Ott JG Bochud FO Verdun FR. (2015), Objective assessment of low contrast detectability in computed tomography with Channelized Hotelling Observer., in Phys Med., 1120.
Optimization of Radiation Dose and Image Quality in Musculoskeletal CT: Emphasis on Iterative Reconstruction Techniques (Part 1).
Omoumi P Becce F Ott JG Racine D Verdun FR (2015), Optimization of Radiation Dose and Image Quality in Musculoskeletal CT: Emphasis on Iterative Reconstruction Techniques (Part 1)., in Semin Musculoskelet Radiol. , 415.
Low-dose multidetector computed tomography of the cervical spine: optimization of iterative reconstruction strength levels
Omoumi P Verdun FR Ben Salah Y Vande Berg BC Lecouvet FE Malghem J Ott JG Meuli R Becce F. (2014), Low-dose multidetector computed tomography of the cervical spine: optimization of iterative reconstruction strength levels, in Acta Radiol. , 335.
MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction.
Tobalem F Dugert E Verdun FR Dunet V Ott JG Rudiger HA Cherix S Meuli R Becce F (2014), MDCT arthrography of the hip: value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction., in AJR Am J Roentgenol. , W665.
Update on the non-prewhitening model observer in computed tomography for the assessment of the adaptive statistical and model-based iterative reconstruction algorithms.
Ott JG Becce F Monnin P Schmidt S Bochud FO Verdun FR (2014), Update on the non-prewhitening model observer in computed tomography for the assessment of the adaptive statistical and model-based iterative reconstruction algorithms., in Phys Med Biol., 4047.

Datasets

Assessment of low contrast detection in CT using model observers: Developing a clinically-relevant tool for characterising adaptive statistical and model-based iterative reconstruction

Author Ott, Julien G.; Ba, Alexandre; Racine, Damien; Viry, Anais; Bochud, François O.; Verdun, Francis R.
Publication date 01.06.2017
Persistent Identifier (PID) 27156923
Repository Pubmed


Update on the non-prewhitening model observer in computed tomography for the assessment of the adaptive statistical and model-based iterative reconstruction algorithms

Author Ott, Julien G; Becce, Fabio; Monnin, Pascal; Schmidt, Sabine; Bochud, François O; Verdun, Francis R
Publication date 07.08.2014
Persistent Identifier (PID) 24990844
Repository Pubmed


Collaboration

Group / person Country
Types of collaboration
INSA (Institute of Applied Sciences) Lyon & CREATIS Medical research center France (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
CT Users Group 17th Meeting Talk given at a conference Mathematical observers for image quality optimisation: Results of a benchmark protocol with a channelized Hotelling observer 15.12.2015 Didcot, Great Britain and Northern Ireland Ryckx Nick; Verdun Francis; Ott Julien; Racine Damien;
SSRMP Annual Scientific Meeting 2015 Talk given at a conference Task-based assessment of a the novel ADMIRE algorithm 21.10.2015 Fribourg, Switzerland Verdun Francis; Racine Damien; Ryckx Nick; Ott Julien;
UKCR Liverpool Talk given at a conference Model observers – how can they help with iterative reconstruction image quality assessment? 30.06.2015 Liverpool, Great Britain and Northern Ireland Verdun Francis; Ryckx Nick; Racine Damien; Ott Julien;
SFPM, 54ème journées scientifique Talk given at a conference Modèles d'observateur pour l'évaluation de la qualité d'image en CT 09.06.2015 Lille, France Ott Julien; Racine Damien; Verdun Francis;
SFPM, 54ème journées scientifique Talk given at a conference Objective assessment of low contrast detectability for quality assurance in CT 09.06.2015 Lille, France Verdun Francis; Ott Julien; Racine Damien; Ryckx Nick;
Journées scientifiques de la Société Suisse de Radiologie, 102ème congrès annuel Talk given at a conference Towards an objective way to assess image quality in CT 04.06.2015 Basel, Switzerland Verdun Francis; Racine Damien; Ott Julien; Ryckx Nick;
Optimisation in X-ray and Molecular Imaging 2015 (OXMI 2015), Fourth Malmö Conference on, Medical Imaging Talk given at a conference Patient exposure optimisation through task-based assessment of a new iterative reconstruction technique: the ADMIRE algorithm 28.05.2015 Gothenburg, Sweden Verdun Francis; Ott Julien; Racine Damien; Ryckx Nick;
Optimisation in X-ray and Molecular Imaging 2015 (OXMI 2015), Fourth Malmö Conference on, Medical Imaging Talk given at a conference Objective task based assessment of low contrast detectability in iterative Reconstruction 28.05.2015 Gothenburg, Sweden Ryckx Nick; Verdun Francis; Ott Julien; Racine Damien;
Optimisation in X-ray and Molecular Imaging 2015 (OXMI 2015), Fourth Malmö Conference on, Medical Imaging Talk given at a conference Benchmarking of CT to patient exposure optimization 28.05.2015 Gothenburg, Sweden Racine Damien; Ryckx Nick; Ott Julien; Verdun Francis;
4th European IRPA Congress Talk given at a conference Towards a CT benchmarking in the framework of patient exposure optimization 23.06.2014 Genève, Switzerland Ott Julien; Verdun Francis;
Journées scientifiques de la Société Suisse de Radiologie, 101ème congrès annuel Poster Impact of iterative reconstruction techniques and multiplanar reformations on image quality: An ex vivo MDCT arthrography model 12.06.2014 Montreux, Switzerland Ott Julien; Verdun Francis;
Journées scientifiques de la Société Suisse de Radiologie, 101ème congrès annuel Talk given at a conference Reformations on image quality: An ex vivo MDCT arthrography model 12.06.2014 Montreux, Switzerland Ott Julien; Verdun Francis;
Journées scientifiques de la Société Suisse de Radiologie, 101ème congrès annuel Talk given at a conference MDCT arthrography of the hip: Value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction 12.06.2014 Montreux, Switzerland Verdun Francis; Ott Julien;
Journées scientifiques de la Société Suisse de Radiologie, 101ème congrès annuel Poster MDCT arthrography of the hip: Value of the adaptive statistical iterative reconstruction technique and potential for radiation dose reduction 12.06.2014 Montreux, Switzerland Alkadhi Hatem; Gudinchet François; Ott Julien; Verdun Francis;
53es Journées Scientifiques de la SFPM Talk given at a conference Impact du plan de reconstruction des images tomodensitométriques sur la qualité d'image 04.06.2014 Deauville, France Ott Julien; Verdun Francis;


Associated projects

Number Title Start Funding scheme
163344 Mathematical model observers to objectively optimize CT radiation exposure with respect to the clinical question 01.02.2016 Project funding (Div. I-III)
120382 Dose en CT cardiaque chez l'enfants et les jeunes adultes: un optimum entre qualité d'image et dose de radiations 01.12.2008 Project funding (Div. I-III)

Abstract

Scientific context:As in most Western countries, CT is responsible for more than two third of the dose delivered to the population in Switzerland and this in spite of the fact that many efforts have been made by radiologists, medical physicists and manufacturers to optimize the examinations protocols. Among the latest developments aiming at dose reductions one can mention the introduction of iterative image reconstructions, IR, and a better use of the X-ray beam energy. The commercially available IRs (that tend to replace the standard filtered back projection, FBP) allow a modest dose reduction (about 30-40%) but require the acceptance of a change of the images’ texture. More sophisticated IR’s are being developed where standard dose might be divided by factors as high as 8. Readable images are even obtained while reducing the dose by much higher factors. In such a context it is essential to ensure that the diagnostic value of the examination remains sufficient. Image quality should always be balanced with radiological risk which requires the assessment of organs dose. At the moment, only a few centers are able to accurately estimate individual patient doses in CT, but none are located in Switzerland. This requires Monte-Carlo simulations where programming in basic languages such as C++ represents a strong limitation in clinical routine. At the European level the “GATE” project aims to providing medical physicists with toolboxes to assess organ dose in radiology and nuclear medicine in a simpler and more efficient way. As CT protocols optimization needs to be done on the individual organ dose basis rather the on the effective dose basis, the use of GATE in CT dose estimation looks promising.Aims of the project:This project aims at investigating the balance between image quality and patient dose in CT. We first propose to assess the benefits and limits of IR’s with standardized phantoms by measuring image quality parameters (such as spatial resolution and image noise). We will also study the effect of the presence of movement during data acquisition since this might represent a challenge for IR’s. In parallel our goal is to characterize the changes of image texture IR’s might introduce and understand the potential effect this might have on clinical images. Different phantoms leading to images where various textures are produced will be studied with standard methodologies used to describe texture in objective ways. On a more clinical related level, we aim at determining up to what level patient dose can be reduced by taking FBP examinations as a gold standard and comparing them to follow up studies performed at very low dose levels together with IR. We also propose to investigate if the change of the reconstruction plan (sagittal or coronal instead of transverse) allows recovering more diagnostic information. In collaboration with a French laboratory we aim at developing the tools required by GATE to estimate patient dose at the organ level delivered by a state-of-the-art CT unit. Within this project we wish to assess the actual benefit tube voltage modulation during the acquisition might provide.Expected results:This project will concentrate on three common examinations (cardiac: follow up of congenital diseases; lung: follow up of patient suffering from cystic fibrosis (CF); abdomen: follow up of testicular tumors, sarcoma, lymphoma or Hodgkin’s disease) performed on children and young adults where it has been shown that 30% of that population might have at least 3 scans, 4% at least 9 scans. At the end of the project we would like to have a clear answer concerning the way CT protocols have to be modified to fully benefit from the IR approach for that particular population where dose reduction should have a full priority. Concerning the dose estimation aspect this project should demonstrate if for the population studied tube voltage modulation allows a further radiological risk reduction.Finally, this project aims to strengthen national and international scientific collaborations in the field of medical imaging.
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