Dosimetry of micro-computed tomography (µCT)

SCK•CEN Mentor

Dabin Jérémie, jdabin@sckcen.be, +32 (0)14 33 27 67

Expert group

Research in Dosimetric Applications

SCK•CEN Co-mentor

De Saint-Hubert Marijke , mdsainth@sckcen.be , +32 (0)14 33 21 40

Introduction

Micro-CT (µCT) imaging provides high-resolution anatomic information without being invasive. In addition, when used in combination with other imaging modalities such as positron emission tomography (µPET) and single-photon emission computed tomography (µSPECT), µCT also provides precious anatomical information. For all those reasons, µCT has become a common modality to image rodents in a large variety of preclinical studies. To cite only a few applications,  µCT has been used in rodents: to study the effects of stem cell treatment in bone healing; to follow the evolution of emphysema regions in the lungs; to monitor the cardiac function recovery after heart surgery; and to determine tumour volume.

However, one of the main limitations of µCT is the high radiation dose delivered to the animal. Indeed, due to the small dimensions of the anatomical structures to be imaged, relatively high photon fluence is used to achieve sufficient image quality. Exposure from a single examination might not be of concern, but the radiation dose cumulated over several examinations, as it is the case in longitudinal studies, may be as high as a few Gy. This is of concern since such exposure level may induce various physiological changes in the imaged rodents, and thus might influence the experimental outcomes of the preclinical studies.

Whereas considerable work has been dedicated to the characterisation of the dose delivered to patients during CT examinations, little has been done for the dosimetry of µCT examinations. In fact, there are currently no dosimetric indicators common to all µCT manufacturers, in contrast with the CT dose index (CTDI) and the dose-length product (DLP) available on clinical CT machines. Neither is there a standardised dosimetric approach to assess organ doses.

The dosimetric indicators and their relation with organ dose estimates in µCT would allow an easier comparison of imaging systems and practices, and a better characterisation of the confounding effect of radiation exposure in preclinical studies.

Objective

This project aims at (1) reviewing the existing literature on dosimetry in µCT, (2) comparing different dosimeter systems for measurements in µCT, (3) assessing the organ doses by means of measurements (3a) and Monte Carlo simulations (3b) and, ultimately, (4) developing a method to estimate organ doses in routine practice, based on Monte Carlo simulations and dosimetric indicators or examination settings. Some work was already accomplished during a previous internship.

The project will be performed in collaboration with the MoSAIC (Molecular Small Animal Imaging Center) and Laboratory of Experimental Radiotherapy of the KU Leuven and the University Hospital of Leuven (Universitair Ziekenhuis Leuven). SCK•CEN has wide experience in dosimetric measurements and Monte Carlo simulations, whereas MoSAIC laboratory has access to µCT facilities.

Good command of the English language is required.
Experience with Monte Carlo simulation software is an asset.

The minimum diploma level of the candidate needs to be

Academic bachelor

The candidate needs to have a background in

Physics , engineering

Estimated duration

Five to six months