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.
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.
Authors: Shangjie Ren; Wendy Hara; Lei Wang; Mark K Buyyounouski; Quynh-Thu Le; Lei Xing; Ruijiang Li Journal: Int J Radiat Oncol Biol Phys Date: 2016-12-14 Impact factor: 7.038
Authors: B Zeinali-Rafsanjani; R Faghihi; M A Mosleh-Shirazi; M Saeedi-Moghadam; R Jalli; S Sina Journal: Br J Radiol Date: 2017-11-09 Impact factor: 3.039
Authors: Shu-Hui Hsu; Yue Cao; Theodore S Lawrence; Christina Tsien; Mary Feng; David M Grodzki; James M Balter Journal: Phys Med Biol Date: 2015-03-17 Impact factor: 3.609
Authors: Eric Paradis; Yue Cao; Theodore S Lawrence; Christina Tsien; Mary Feng; Karen Vineberg; James M Balter Journal: Int J Radiat Oncol Biol Phys Date: 2015-09-04 Impact factor: 7.038