Computed Tomography Versus Magnetic Resonance Imaging-Based Contouring in Cervical Cancer Brachytherapy: Results of a Prospective Trial and Preliminary Guidelines for Standardized Contours

Akila N. Viswanathan, Johannes Dimopoulos, Christian Kirisits, Daniel Berger, Richard Pötter

Research output: Contribution to journalArticle

Abstract

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. Methods and Materials: Ten patients underwent both MRI and CT after applicator insertion. The dose received by at least 90% of the volume (D90), the minimal target dose (D100), the volume treated to the prescription dose or greater for tumor for the high-risk (HR) and intermediate-risk (IR) clinical target volume (CTV) and the dose to 0.1 cm3, 1 cm3, and 2 cm3 for the OARs were evaluated. A standardized approach to contouring on CT (CTStd) was developed, implemented (HR- and IR-CTVCTStd), and compared with the MRI contours. Results: Tumor height, thickness, and total volume measurements, as determined by either CT or CTStd were not significantly different compared with the MRI volumes. In contrast, the width measurements differed in HR-CTVCTStd (p = 0.05) and IR-CTVCTStd (p = 0.01). For the HR-CTVCTStd, this resulted in statistically significant differences in the volume treated to the prescription dose or greater (MRI, 96% vs. CTStd, 86%, p = 0.01), D100 (MRI, 5.4 vs. CTStd, 3.4, p <0.01), and D90 (MRI, 8.7 vs. CTStd, 6.7, p <0.01). Correspondingly, the IR-CTV DVH values on MRI vs. CTStd, differed in the D100 (MRI, 3.0 vs. CTStd, 2.2, p = 0.01) and D90 (MRI, 5.6 vs. CTStd, 4.6, p = 0.02). The MRI and CT DVH values of the dose to 0.1 cm3, 1 cm3, and 2 cm3 for the OARs were similar. Conclusion: Computed tomography-based or MRI-based scans at brachytherapy are adequate for OAR DVH analysis. However, CT tumor contours can significantly overestimate the tumor width, resulting in significant differences in the D90, D100, and volume treated to the prescription dose or greater for the HR-CTV compared with that using MRI. MRI remains the standard for CTV definition.

Original languageEnglish (US)
Pages (from-to)491-498
Number of pages8
JournalInternational Journal of Radiation Oncology Biology Physics
Volume68
Issue number2
DOIs
StatePublished - Jun 1 2007

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Keywords

  • Brachytherapy
  • Cervical cancer
  • Computed tomography
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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