Purpose: To compare the contours and dose-volume histograms (DVH) of the tumor and organs at risk (OAR) with computed tomography (CT) vs. magnetic resonance imaging (MRI) in cervical cancer brachytherapy – prospective single institutional study.

Materials & Methods: A total of 79 histologically proven cervical cancer patients of Stage IIB to IIIB, completed concurrent Chemoradiation were enrolled in a prospective Institutional Board approved brachytherapy protocol between March 2017 and May 2018. All of them underwent brachytherapy using a MRI-compatible tandom and ovoids applicator. Planning is done using both CT and MRI for the first fraction. The tumour and organs at risk (bladder, rectum and sigmoid) were contoured separately on CT and on MRI using clinical findings combined with GEC-ESTRO guidelines. The Dose Volume (DVH) parameters of Tumor and OARs were analysed using paired t test. P values < 0.05 were considered significant.

As per our Departmental protocol, all patients received 7Gy x 3fractions.

Results: The mean V100 is higher for CT based planning compared to MRI and D90 is higher for MRI based planning with statistically significant difference (p -). D2cc of bladder, rectum is same in both. D2cc for sigmoid is higher in MRI based planning.

Conclusion: Both CT and MRI based planning can be done. MRI gives better tissue delineation hence of HRCTV, resulting in lesser V100 and higher D90, so dose to actual tumor can be escalated in bulky disease with respect bladder and rectum.

Keywords: Carcinoma cervix, Brachytherapy, Computed tomography, Magnetic resonance imaging, Dosimetric Parameters.

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