Related Experiment Video
Updated: May 10, 2026
PET and MRI Guided Irradiation of a Glioblastoma Rat Model Using a Micro-irradiator
Published on: December 28, 2017
Treatment planning of intracranial targets on MRI derived substitute CT data
Joakim H Jonsson1, Adam Johansson, Karin Söderström
1Radiation Physics, Department of Radiation Sciences, Umeå University, Sweden. joakim.jonsson@radfys.umu.se
Background:
The use of magnetic resonance imaging (MRI) as a complement to computed tomography (CT) in the target definition procedure for radiotherapy is increasing. To eliminate systematic uncertainties due to image registration, a workflow based entirely on MRI may be preferable. In the present pilot study, we investigate dose calculation accuracy for automatically generated substitute CT (s-CT) images of the head based on MRI. We also produce digitally reconstructed radiographs (DRRs) from s-CT data to evaluate the feasibility of patient positioning based on MR images.
Methods And Materials:
Five patients were included in the study. The dose calculation was performed on CT, s-CT, s-CT data without inhomogeneity correction and bulk density assigned MRI images. Evaluation of the results was performed using point dose and dose volume histogram (DVH) comparisons, and gamma index evaluation.
Results:
The results demonstrate that the s-CT images improve the dose calculation accuracy compared to the method of non-inhomogeneity corrected dose calculations (mean improvement 2.0% points) and that it performs almost identically to the method of bulk density assignment. The s-CT based DRRs appear to be adequate for patient positioning of intra-cranial targets, although further investigation is needed on this subject.
Conclusion:
The s-CT method is very fast and yields data that can be used for treatment planning without sacrificing accuracy.
