Project

Discipline

paediatric; cardiac; image quality; radiation exposure optimization; Computed tomography; paediatric radiology; cardiac CT; signal detection; observe performance

Lead
Lay summary
Computed Tomography, CT, is certainly a fantastic tool that runs the risk of becoming a victim of its own success due to the public health concerns it may elicit. Already on Jan 23rd 2001, USA Today published a particularly alarming paper (titled: “Radiologists agree CT scans harm kids”) where it was mentioned that 1,500 patients from the 1.6 million children (under the age of fifteen) scanned might eventually die from cancer caused by excess radiation; this, without any emphasis on the fact that CT actually saves lives. More recently, the June 19th, 2007 edition of The New York Times highlighted once again the impact of CT on the population’s exposure level. It mentioned in particular that the 62 million CT scans performed in the US in 2006 were responsible for more than half of the population’s total exposure from radiological investigations. Since one or two years, cardiac CT acquisition is becoming more and more popular. This might pose an additional problem concerning population’s exposure since relatively high doses (from 12 to 40 mSv per examination) are typically delivered to patients over 45 - 50 years old. If this situation is already problematic for an adult population, it is even more so for young children investigated for cardiac malformations which are then followed-up by many CTs over their entire life. Knowing that such a population is particularly sensitive to ionising radiation, it becomes an ethical imperative to make every effort to reduce its exposure as much as possible. At the moment, data acquisition protocols have not been optimized along the lines of a sound methodology. The aim of this project is to address this problem by answering the following questions:1) What is the situation concerning data acquisition of cardiac CT (for children and the follow-up of a young population surgically treated for heart malformations)? 2) How to objectively balance patient dose and image quality of static and moving structures? 3) Are the optimal set of parameters using the methodology presented just above (point 2 of the project) adequate in clinical applications? - When dealing with very young children (up to 10 years old)? - When dealing with follow-up studies for young adults? This study will assure that cardiac CT examinations performed on children and young adults in Switzerland are optimized using a state-of-the-art methodology. This study will also provide the scientific community with a methodology allowing an objective way to reconcile image quality and patient dose by means of the very latest concepts from a dose and image quality point of view (introduction of new dosimetric concepts such as equilibrium dose, dose line integral … and use of objective image quality descriptors such as NEQ and DQE, parameters that are being adapted for the particular case of CT). Finally, the development of scientific competences in this field in Switzerland will help future international collaborations.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

Title	Year

Number	Title	Start	Funding scheme

Computed Tomography, CT, is certainly a fantastic tool that runs the risk of becoming a victim of its own success due to the public health concerns it may elicit. Already on Jan 23rd 2001, USA Today published a particularly alarming paper (titled: “Radiologists agree CT scans harm kids”) where it was mentioned that 1,500 patients from the 1.6 million children (under the age of fifteen) scanned might eventually die from cancer caused by excess radiation; this, without any emphasis on the fact that CT actually saves lives. More recently, the June 19th, 2007 edition of The New York Times highlighted once again the impact of CT on the population’s exposure level. It mentioned in particular that the 62 million CT scans performed in the US in 2006 were responsible for more than half of the population’s total exposure from radiological investigations. Since one or two years, cardiac CT acquisition is becoming more and more popular. This might pose an additional problem concerning population’s exposure since relatively high doses (from 12 to 40 mSv per examination) are typically delivered to patients over 45 - 50 years old. If this situation is already problematic for an adult population, it is even more so for young children investigated for cardiac malformations which are then followed-up by many CTs over their entire life. Knowing that such a population is particularly sensitive to ionising radiation, it becomes an ethical imperative to make every effort to reduce its exposure as much as possible. At the moment, data acquisition protocols have not been optimized along the lines of a sound methodology. The aim of this project is to address this problem by answering the following questions:1) What is the situation concerning data acquisition of cardiac CT (for children and the follow-up of a young population surgically treated for heart malformations)? 2) How to objectively balance patient dose and image quality of static and moving structures? - How valid is the CTDIvol (volume Computed Tomography Dose Index) concept in assessing patient dose? - What are the benefits and limits of the NEQ (Noise Equivalent Quanta) and DQE (Detective Quantum Efficiency) metrics when applied to CT? - In the patient dose-image quality space (expressed in terms of CTDIvol or a more appropriate quantity and NEQ) how fast image quality is reduced when changing acquisition parameters such as kV, mAs, pitch values, X-ray tube rotation time…?- Where is located the present state of the practice (obtained from point 1 of this project) situated and which parameters could be proposed to improve the situation? - What gain in dose can be expected from iterative image reconstruction algorithms recently introduced for CT? 3) Are the optimal set of parameters using the methodology presented just above (point 2 of the project) adequate in clinical applications? - When dealing with very young children (up to 10 years old)? - When dealing with follow-up studies for young adults? This study will assure that cardiac CT examinations performed on children and young adults in Switzerland are optimized using a state-of-the-art methodology. This study will also provide the scientific community with a methodology allowing an objective way to reconcile image quality and patient dose by means of the very latest concepts from a dose and image quality point of view (introduction of new dosimetric concepts such as equilibrium dose, dose line integral … and use of objective image quality descriptors such as NEQ and DQE, parameters that are being adapted for the particular case of CT). Finally, the development of scientific competences in this field in Switzerland will help future international collaborations.