The impact of imaging modality (CT vs MRI) and patient position (supine vs prone) on tangential whole breast radiation therapy planning

Kylie Dundas; Elise M Pogson; Vikneswary Batumalai; Geoff P Delaney; Miriam M Boxer; Mei Ling Yap; Verity Ahern; Christine Chan; Steven David; Marion Dimigen; Jennifer A Harvey; Eng-Siew Koh; Karen Lim; George Papadatos; Elizabeth Lazarus; Joseph Descellar; Peter Metcalfe; Lois Holloway

doi:10.1016/j.prro.2017.07.007

The impact of imaging modality (CT vs MRI) and patient position (supine vs prone) on tangential whole breast radiation therapy planning

Pract Radiat Oncol. 2018 May-Jun;8(3):e87-e97. doi: 10.1016/j.prro.2017.07.007. Epub 2017 Jul 14.

Authors

Kylie Dundas¹, Elise M Pogson², Vikneswary Batumalai³, Geoff P Delaney⁴, Miriam M Boxer⁵, Mei Ling Yap⁴, Verity Ahern⁶, Christine Chan⁷, Steven David⁸, Marion Dimigen⁷, Jennifer A Harvey⁹, Eng-Siew Koh³, Karen Lim⁵, George Papadatos¹⁰, Elizabeth Lazarus⁷, Joseph Descellar¹¹, Peter Metcalfe¹², Lois Holloway¹³

Affiliations

¹ Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia. Electronic address: Kylie.Dundas@swsahs.nsw.gov.au.
² Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia; Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia.
³ Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia.
⁴ Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia; School of Medicine, University of Western Sydney, Sydney, NSW, Australia.
⁵ Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia.
⁶ Crown Princess Mary Cancer Care Centre, Westmead Hospital, NSW, Australia.
⁷ Department of Radiology, Liverpool Hospital, NSW, Australia.
⁸ Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.
⁹ School of Medicine, University of Queensland, QLD, Australia; Princess Alexandra Hospital, QLD, Australia.
¹⁰ Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia.
¹¹ Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia.
¹² Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia.
¹³ Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, NSW, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW, Australia; Ingham Institute for Applied Medical Research, Liverpool Hospital, Sydney, NSW, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, NSW, Australia.

PMID: 28993138
DOI: 10.1016/j.prro.2017.07.007

Abstract

Purpose: The purpose of this study was to evaluate the impact of magnetic resonance imaging (MRI) versus computed tomography (CT)-derived planning target volumes (PTVs), in both supine and prone positions, for whole breast (WB) radiation therapy.

Methods and materials: Four WB radiation therapy plans were generated for 28 patients in which PTVs were generated based on CT or MRI data alone in both supine and prone positions. A 6-MV tangential intensity modulated radiation therapy technique was used, with plans designated as ideal, acceptable, or noncompliant. Dose metrics for PTVs and organs at risk were compared to analyze any differences based on imaging modality (CT vs MRI) or patient position (supine vs prone).

Results: With respect to imaging modality 2/11 whole breast planning target volume (WB_PTV) dose metrics (percentage of PTV receiving 90% and 110% of prescribed dose) displayed statistically significant differences; however, these differences did not alter the average plan compliance rank. With respect to patient positioning, the odds of having an ideal plan versus a noncompliant plan were higher for the supine position compared with the prone position (P = .026). The minimum distance between the seroma cavity planning target volume (SC_PTV) and the chest wall was increased with prone positioning (P < .001, supine and prone values 1.1 mm and 8.7 mm, respectively). Heart volume was greater in the supine position (P = .005). Heart doses were lower in the supine position than prone (P < .01, mean doses 3.4 ± 1.55 Gy vs 4.4 ± 1.13 Gy for supine vs prone, respectively). Mean lung doses met ideal dose constraints in both positions, but were best spared in the prone position. The contralateral breast maximum dose to 1cc (D1cc) showed significantly lower doses in the supine position (P < .001, 4.64 Gy vs 9.51 Gy).

Conclusions: Planning with PTVs generated from MRI data showed no clinically significant differences from planning with PTVs generated from CT with respect to PTV and doses to organs at risk. Prone positioning within this study reduced mean lung dose and whole heart volumes but increased mean heart and contralateral breast doses compared with supine.

MeSH terms

Adult
Aged
Breast Neoplasms / diagnostic imaging
Breast Neoplasms / radiotherapy*
Female
Humans
Magnetic Resonance Imaging / methods*
Middle Aged
Patient Positioning / methods*
Tomography, X-Ray Computed / methods*