Radiotherapy treatment planning: benefits of CT-MR image registration and fusion in tumor volume delineation.
OBJECTIVE
Development of imaging techniques, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), made great impact on radiotherapy treatment planning by improving the localization of target volumes. Improved localization allows better local control of tumor volumes, but also minimizes geographical misses. Mutual information is obtained by registration and fusion of images achieved manually or automatically. The aim of this study was to validate the CT-MRI image fusion method and compare delineation obtained by CT versus CT-MRI image fusion.


METHODS
The image fusion software (XIO CMS 4.50.0) was applied to delineate 16 patients. The patients were scanned on CT and MRI in the treatment position within an immobilization device before the initial treatment. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated on CT alone and on CT+MRI images consecutively and image fusion was obtained.


RESULTS
Image fusion showed that CTV delineated on a CT image study set is mainly inadequate for treatment planning, in comparison with CTV delineated on CT-MRI fused image study set. Fusion of different modalities enables the most accurate target volume delineation.


CONCLUSIONS
This study shows that registration and image fusion allows precise target localization in terms of GTV and CTV and local disease control.
Department of Radiotherapy, Institute of Oncology of Vojvodina, Sremska Kamenica, Serbia. djanigor@yahoo.com
Igor
I
Djan
Borislava
B
Petrović
Marko
M
Erak
Ivan
I
Nikolić
Silvija
S
Lucić
D001932:Brain Neoplasms / Q000473:pathology / Q000532:radiotherapy; D057186:Comparative Effectiveness Research; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods; D011878:Radiotherapy / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D047368:Tumor Burden