Optimizing dual energy cone beam CT protocols for preclinical imaging and radiation research.
OBJECTIVE
The aim of this work was to investigate whether quantitative dual-energy CT (DECT) imaging is feasible for small animal irradiators with an integrated cone-beam CT (CBCT) system.


METHODS
The optimal imaging protocols were determined by analyzing different energy combinations and dose levels. The influence of beam hardening effects and the performance of a beam hardening correction (BHC) were investigated. In addition, two systems from different manufacturers were compared in terms of errors in the extracted effective atomic numbers (Zeff) and relative electron densities (ρe) for phantom inserts with known elemental compositions and relative electron densities.


RESULTS
The optimal energy combination was determined to be 50 and 90 kVp. For this combination, Zeffand ρecan be extracted with a mean error of 0.11 and 0.010, respectively, at a dose level of 60 cGy.


CONCLUSIONS
Quantitative DECT imaging is feasible for small animal irradiators with an integrated CBCT system. To obtain the best results, optimizing the imaging protocols is required. Well-separated X-ray spectra and a sufficient dose level should be used to minimize the error and noise for Zeffand ρe. When no BHC is applied in the image reconstruction, the size of the calibration phantom should match the size of the imaged object to limit the influence of beam hardening effects. No significant differences in Zeffand ρeerrors are observed between the two systems from different manufacturers. Advances in knowledge: This is the first study that investigates quantitative DECT imaging for small animal irradiators with an integrated CBCT system.
1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands.
Lotte E J R
LE
Schyns
1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands.
Isabel P
IP
Almeida
1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands.
Stefan J
SJ
van Hoof
2 iMinds Medical IT-IBiTech-MEDISIP-INFINITY, De Pintelaan 185, Ghent, Belgium.
Benedicte
B
Descamps
2 iMinds Medical IT-IBiTech-MEDISIP-INFINITY, De Pintelaan 185, Ghent, Belgium.
Christian
C
Vanhove
3 Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany.
Guillaume
G
Landry
1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands.
Patrick V
PV
Granton
1 Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, Netherlands.|4 Medical Physics Unit, Department of Oncology, McGill University, Montréal, QC, Canada.
Frank
F
Verhaegen
D015502:Absorptiometry, Photon; D000818:Animals; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003952:Diagnostic Imaging / Q000379:methods; D005069:Evaluation Studies as Topic; D007091:Image Processing, Computer-Assisted; D023421:Models, Animal; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity
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