Abstract
Aims: This study compares the volumetric and spatial relationships of gross tumour volume (GTV) derived from CT (CT-GTV) and GTV derived from MRI (-) to determine the utility of multi-modality imaging for radiotherapy treatment planning in rectal cancer.Methods and Materials: Fifteen patients with T3 rectal cancer were accrued over 18 months. The male-:-female ratio was 2:1. The average age was 60.3 years (range 38-79). All patients underwent a diagnostic MRI and CT and MRI simulation. Data sets were co-registered. A site specialised diagnostic radiologist contoured all volumes in consultation with a radiation oncologist. CT-GTV was contoured while blinded to MR data sets. - was contoured independently 2-4 weeks later whilst blinded to its respective CT-GTV data. Tumour volumes were analysed for three anatomical subregions (sigmoid, rectal and anal). Reference points on tumour volumes were used for spatial comparison and analysis.Results: The mean CT-GTV/- ratio was 1.2 (range 0.5-2.9). The tumour volume ratios for the rectal subregion were well correlated. CT-GTV provided adequate spatial coverage of tumour in reference to - with the average mean discrepancy of 0.12 (range -0.08-0.38) or a maximum discrepancy of <0.4-cm (1.54 standard deviation). CT-GTV coverage was inadequate for tumours with MRI evidence of anal and sigmoid invasion.Conclusions: Conventional simulation CT imaging provided a reasonable estimate of the GTV. - imaging with staging MRI can assist target volume definition where there is involvement of the sigmoid and anorectal region and avoid geographic misses. The role of a simulation MRI may aid in this process but remains investigational.
Original language | English |
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Pages (from-to) | 562-568 |
Number of pages | 7 |
Journal | Journal of Medical Imaging and Radiation Oncology |
Volume | 54 |
Issue number | 6 |
DOIs | |
Publication status | Published - Dec 2010 |
Externally published | Yes |
Keywords
- CT
- GTV
- MRI
- Radiotherapy
- Rectal cancer
- Target volume
- Treatment planning