The effect of CT-MR image registration on target volume delineation and dose distribution in radiotherapy planning of brain tumors [Beyin tu;mo;rlerinin radyoterapi planlamasi{dotless}nda, bt ve mrg go;ru;ntu; eş leştirilmesinin hedef volu;m belirlenmesine vedoz dagi{dotless}li{dotless}mi{dotless}na etkisi]

OBJECTIVES To determine the accuracy of computed tomography (CT)/ magnetic resonance imaging (MRI) image registration performed using tomography system and software present in our department and discover the magnitude of error during the process. METHODS First, calibration data of the CT was reviewed. Following image registration, done using four anatomic landmarks, deliniation of eyeballs and target volume took place. RESULTS The registration score was 9.51±0.11 out of 10 and mean distance was 1.92±0.51 mm. Center coordinates of the eyeballs, contoured using MRI and CT images were compared. Maximum difference was 2.25 mm for the right eye and 2.11 mm for the left eye. Volumes of tumor contours produced from registered images were bigger (75.37 cmsup3/sup vs. 44.81 cmsup3/sup). But in the treatment plans without image registration, the tumor volume received 95-107% of presicribed dose. CONCLUSION Image registration process found to be applicable and repro-ducable for our clinic. It has seen that image registration improves target volume delineation. © 2011 Association of Oncology.