To Assess the Feasibility and Impact of Computed Tomotherapy (CT) and Magnetic Resonance Imaging (MRI) Fusion on Radiation Treatment Planning for Ten Patients With Cancer of the Cervix

Rationale/Background:

For a long time diagnostic imaging has been used in planning radiation treatment for the carcinoma of the cervix, although it is not the essential part of FIGO staging work up. In the past, treatment planning was based on examination under anesthesia (EUA) findings and standard portals were used. Various studies have shown high risks of geographical miss and/or inappropriate tumor coverage (up to >70%) with the use of standard portals, which was related to poor local control. Increasingly, diagnostic/planning CT and MRI imaging are used to plan radiation treatment.

Most patients with invasive carcinoma of the cervix, who are not candidates for radical hysterectomy, are treated by radiotherapy, often with concomitant chemotherapy with a curative intent. Amongst those patients, where cure is not achieved, there are a significant proportion who fail first or only in the pelvis. Higher doses of radiation would be expected to reduce this risk. With conventional radiotherapy, higher doses of radiation result in a higher rate of complications. New technology available at the Cross Cancer Institute (tomotherapy + intensity modulated radiation therapy [IMRT]) would be expected to permit higher doses of radiation to be delivered but avoid the increased risk of complications. Accurate definition of clinical target volume, composed of the cervix, uterus, gross primary tumor and the regional lymphatic drainage is required for accurate treatment planning. The MRI imaging is expected to be valuable in this regard. Demonstrating this is the immediate aim of this study. The investigators' long term aim will be to replace conventional external beam radiotherapy with helical tomotherapy. They expect to be able to apply increasing doses of radiation to the GTV + CTV and monitor short-term treatment effects with biological imaging, principally magnetic resonance spectroscopy (MRS). Eventually the investigators hope to be able to individualize radiation doses based in part on biological imaging, before and during treatment.

In their center the investigators routinely perform diagnostic and planning CT scans of almost all Ca. cervix patients before radiation treatment planning. This study will involve one additional MRI scan of the pelvis, which will take about 30 minutes to perform; this process has potential benefit in the treatment planning.

Studies comparing imaging modalities for diagnostic accuracy: