Computed tomography versus magnetic resonance imaging-based contouring in cervical cancer brachytherapy: results of a prospective trial and preliminary guidelines for standardized contours.

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(90)), the minimal target dose (D(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 cm3, 1 cm3, and 2 cm3 for the OARs were evaluated. A standardized approach to contouring on CT (CT(Std)) was developed, implemented (HR- and IR-CTV(CTStd)), and compared with the MRI contours. RESULTS Tumor height, thickness, and total volume measurements, as determined by either CT or CT(Std) were not significantly different compared with the MRI volumes. In contrast, the width measurements differed in HR-CTV(CTStd) (p = 0.05) and IR-CTV(CTStd) (p = 0.01). For the HR-CTV(CTStd), this resulted in statistically significant differences in the volume treated to the prescription dose or greater (MRI, 96% vs. CT(Std), 86%, p = 0.01), D(100) (MRI, 5.4 vs. CT(Std), 3.4, p <0.01), and D(90) (MRI, 8.7 vs. CT(Std), 6.7, p <0.01). Correspondingly, the IR-CTV DVH values on MRI vs. CT(Std), differed in the D(100) (MRI, 3.0 vs. CT(Std), 2.2, p = 0.01) and D(90) (MRI, 5.6 vs. CT(Std), 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 D(90), D(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.

[1]  P. Dottino,et al.  A comparative study of computerized tomography, magnetic resonance imaging, and clinical staging for the detection of early cervix cancer. , 1990, Gynecologic oncology.

[2]  A. Dixon,et al.  A CT based dosimetry system for intracavitary therapy in carcinoma of the cervix. , 1987, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[3]  Patricia J Eifel,et al.  Comparison between CT-based volumetric calculations and ICRU reference-point estimates of radiation doses delivered to bladder and rectum during intracavitary radiotherapy for cervical cancer. , 2005, International journal of radiation oncology, biology, physics.

[4]  Sasa Mutic,et al.  PET-guided three-dimensional treatment planning of intracavitary gynecologic implants. , 2002, International journal of radiation oncology, biology, physics.

[5]  A Wambersie,et al.  Comparison of radiography- and computed tomography-based treatment planning in cervix cancer in brachytherapy with specific attention to some quality assurance aspects. , 2001, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[6]  P. Pareek,et al.  Radiography-based treatment planning compared with computed tomography (CT)-based treatment planning for intracavitary brachytherapy in cancer of the cervix: analysis of dose-volume histograms. , 2003, Brachytherapy.

[7]  C W Vick,et al.  CT of the normal and abnormal parametria in cervical cancer. , 1984, AJR. American journal of roentgenology.

[8]  Richard Pötter,et al.  The impact of sectional imaging on dose escalation in endocavitary HDR-brachytherapy of cervical cancer: results of a prospective comparative trial. , 2003, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[9]  Xiaochuan Pan,et al.  Reduction of computed tomography metal artifacts due to the Fletcher-Suit applicator in gynecology patients receiving intracavitary brachytherapy. , 2003, Brachytherapy.

[10]  J. Dimopoulos,et al.  Recommendations for image-based intracavitary brachytherapy of cervix cancer: the GYN GEC ESTRO Working Group point of view: in regard to Nag et al. (Int J Radiat Oncol Biol Phys 2004;60:1160-1172). , 2005, International journal of radiation oncology, biology, physics.

[11]  G. Stuecklschweiger,et al.  Dosimetry of intracavitary placements for uterine and cervical carcinoma: results of orthogonal film, TLD, and CT-assisted techniques. , 1992, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[12]  P. Eifel,et al.  The relationship between brachytherapy dose and outcome in patients with bulky endocervical tumors treated with radiation alone. , 1994, International journal of radiation oncology, biology, physics.

[13]  Christian Kirisits,et al.  Intercomparison of treatment concepts for MR image assisted brachytherapy of cervical carcinoma based on GYN GEC-ESTRO recommendations. , 2006, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[14]  J. Dimopoulos,et al.  Systematic evaluation of MRI findings in different stages of treatment of cervical cancer: potential of MRI on delineation of target, pathoanatomic structures, and organs at risk. , 2006, International journal of radiation oncology, biology, physics.

[15]  B. I. Choi,et al.  Uterine cervical carcinoma: comparison of CT and MR findings. , 1990, Radiology.

[16]  A. Viswanathan,et al.  Current controversies in high‐dose‐rate versus low‐dose‐rate brachytherapy for cervical cancer , 2006, Cancer.

[17]  Christian Kirisits,et al.  Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (I): concepts and terms in 3D image based 3D treatment planning in cervix cancer brachytherapy with emphasis on MRI assessment of GTV and CTV. , 2005, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[18]  C C Ling,et al.  CT-assisted assessment of bladder and rectum dose in gynecological implants. , 1987, International journal of radiation oncology, biology, physics.

[19]  Richard Pötter,et al.  Aspects of MR Image Distortions in Radiotherapy Treatment Planning , 2001, Strahlentherapie und Onkologie.

[20]  D. McShan,et al.  A CT-compatible version of the Fletcher system intracavitary applicator: clinical application and 3-dimensional treatment planning. , 1989, International journal of radiation oncology, biology, physics.

[21]  K Albano,et al.  CT-guided interstitial implantation of gynecologic malignancies. , 1996, International journal of radiation oncology, biology, physics.

[22]  A. E. Saarnak,et al.  Inter-observer variation in delineation of bladder and rectum contours for brachytherapy of cervical cancer. , 2000, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[23]  S L Schoeppel,et al.  Magnetic resonance imaging during intracavitary gynecologic brachytherapy. , 1992, International journal of radiation oncology, biology, physics.

[24]  D. Petereit,et al.  Literature analysis of high dose rate brachytherapy fractionation schedules in the treatment of cervical cancer: is there an optimal fractionation schedule? , 1999, International journal of radiation oncology, biology, physics.

[25]  J. Walsh,et al.  CT anatomy of the female pelvis: a second look. , 1994, Radiographics : a review publication of the Radiological Society of North America, Inc.

[26]  W T Yuh,et al.  Cervical cancer: application of MR imaging in radiation therapy. , 1993, Radiology.

[27]  Christian Kirisits,et al.  Dose and volume parameters for MRI-based treatment planning in intracavitary brachytherapy for cervical cancer. , 2005, International journal of radiation oncology, biology, physics.

[28]  G E Hanks,et al.  Tumor and treatment factors improving outcome in stage III-B cervix cancer. , 1991, International journal of radiation oncology, biology, physics.

[29]  Correlation between the treated volume, the GTV and the CTV at the time of brachytherapy and the histopathologic findings in 33 patients with operable cervix carcinoma. , 2004, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[30]  S L Schoeppel,et al.  Three-dimensional treatment planning of intracavitary gynecologic implants: analysis of ten cases and implications for dose specification. , 1994, International journal of radiation oncology, biology, physics.