Vikneswary Batumalai1,2,3, Siobhan Burke1, Dale Roach2,3, Karen Lim1,3, Glen Dinsdale1, Michael Jameson1,2,3,4, Cesar Ochoa1, Jacqueline Veera5, Lois Holloway1,2,3,4,6, Shalini Vinod1,2,3. 1. Department of Radiation Oncology, South Western Sydney Local Health District, New South Wales, Australia. 2. Ingham Institute for Applied Medical Research, New South Wales, Australia. 3. South Western Clinical School, University of New South Wales, New South Wales, Australia. 4. Centre for Medical Radiation Physics, University of Wollongong, New South Wales, Australia. 5. Peter MaCallum Cancer Centre, Victoria, Australia. 6. Institute of Medical Physics, School of Physics, University of Sydney, New South Wales, Australia.
Abstract
OBJECTIVES: The use of MRI is becoming more prevalent in cervical cancer external beam radiotherapy (RT). The aim of this study was to investigate the impact of dosimetric differences between CT and MRI-derived target volumes for cervical cancer external beam RT. METHODS: An automated planning technique for volumetric modulated arc therapy was developed. Two automated planning plans were generated for 18 cervical cancer patients where planning target volumes (PTVs) were generated based on CT or MRI data alone. Dose metrics for planning target volumes and organs at risk (OARs) were compared to analyse any differences based on imaging modality. RESULTS: All treatment plans were clinically acceptable. Bladder doses (V40) were lower in MRI-based plans (p = 0.04, 53.6 ± 17.2 % vs 60.3 ± 13.1 % for MRI vs CT, respectively). The maximum dose for left iliac crest showed lower doses in CT-based plans (p = 0.02, 47.8 ± 0.7 Gy vs 47.4 ± 0.4 Gy MRI vs CT, respectively). No significant differences were seen for other OARs. CONCLUSIONS: The dosimetric differences of CT- and MRI-based contouring variability for this study was small. CT remains the standard imaging modality for volume delineation for these patients. ADVANCES IN KNOWLEDGE: This is the first study to evaluate the dosimetric implications of imaging modality on target and OAR doses in cervical cancer external beam RT.
OBJECTIVES: The use of MRI is becoming more prevalent in cervical cancer external beam radiotherapy (RT). The aim of this study was to investigate the impact of dosimetric differences between CT and MRI-derived target volumes for cervical cancer external beam RT. METHODS: An automated planning technique for volumetric modulated arc therapy was developed. Two automated planning plans were generated for 18 cervical cancer patients where planning target volumes (PTVs) were generated based on CT or MRI data alone. Dose metrics for planning target volumes and organs at risk (OARs) were compared to analyse any differences based on imaging modality. RESULTS: All treatment plans were clinically acceptable. Bladder doses (V40) were lower in MRI-based plans (p = 0.04, 53.6 ± 17.2 % vs 60.3 ± 13.1 % for MRI vs CT, respectively). The maximum dose for left iliac crest showed lower doses in CT-based plans (p = 0.02, 47.8 ± 0.7 Gy vs 47.4 ± 0.4 Gy MRI vs CT, respectively). No significant differences were seen for other OARs. CONCLUSIONS: The dosimetric differences of CT- and MRI-based contouring variability for this study was small. CT remains the standard imaging modality for volume delineation for these patients. ADVANCES IN KNOWLEDGE: This is the first study to evaluate the dosimetric implications of imaging modality on target and OAR doses in cervical cancer external beam RT.
Authors: W Robert Lee; Mack Roach; Jeff Michalski; Brian Moran; David Beyer Journal: Int J Radiat Oncol Biol Phys Date: 2002-10-01 Impact factor: 7.038
Authors: X Allen Li; An Tai; Douglas W Arthur; Thomas A Buchholz; Shannon Macdonald; Lawrence B Marks; Jean M Moran; Lori J Pierce; Rachel Rabinovitch; Alphonse Taghian; Frank Vicini; Wendy Woodward; Julia R White Journal: Int J Radiat Oncol Biol Phys Date: 2009-03-01 Impact factor: 7.038