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

Journal Article · Fri Jun 01 00:00:00 EDT 2007 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2006.12.021· OSTI ID:20951670

Viswanathan, Akila N ^[1]; Dimopoulos, Johannes ^[2]; Kirisits, Christian ^[2]; Berger, Daniel ^[2]; Poetter, Richard ^[2]

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1. Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Boston, MA (United States)
2. Department of Radiotherapy and Radiobiology, Medical University of Vienna, Vienna (Austria)

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 (D{sub 90}), the minimal target dose (D{sub 100}), 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 cm{sup 3}, 1 cm{sup 3}, and 2 cm{sup 3} for the OARs were evaluated. A standardized approach to contouring on CT (CT{sub Std}) was developed, implemented (HR- and IR-CTV{sub CTStd}), and compared with the MRI contours. Results: Tumor height, thickness, and total volume measurements, as determined by either CT or CT{sub Std} were not significantly different compared with the MRI volumes. In contrast, the width measurements differed in HR-CTV{sub CTStd} (p = 0.05) and IR-CTV{sub CTStd} (p = 0.01). For the HR-CTV{sub CTStd}, this resulted in statistically significant differences in the volume treated to the prescription dose or greater (MRI, 96% vs. CT{sub Std}, 86%, p = 0.01), D{sub 100} (MRI, 5.4 vs. CT{sub Std}, 3.4, p <0.01), and D{sub 90} (MRI, 8.7 vs. CT{sub Std}, 6.7, p <0.01). Correspondingly, the IR-CTV DVH values on MRI vs. CT{sub Std}, differed in the D{sub 100} (MRI, 3.0 vs. CT{sub Std}, 2.2, p = 0.01) and D{sub 90} (MRI, 5.6 vs. CT{sub Std}, 4.6, p = 0.02). The MRI and CT DVH values of the dose to 0.1 cm{sup 3}, 1 cm{sup 3}, and 2 cm{sup 3} 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 D{sub 90}, D{sub 100}, 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.

• OSTI ID: 20951670
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 68; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
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