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Breathing-motion induced interplay effects for stereotactic body radiotherapy of liver tumours using flattening-filter free volumetric modulated arc therapy
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- Edvardsson, A. (author)
- Lund University,Lunds universitet,Radiotherapy Physics,Forskargrupper vid Lunds universitet,Lund University Research Groups
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- Scherman, J. (author)
- Skåne University Hospital
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- Nilsson, M. P. (author)
- Lund University,Lunds universitet,Tumörmikromiljö,Sektion I,Institutionen för kliniska vetenskaper, Lund,Medicinska fakulteten,Tumor microenvironment,Section I,Department of Clinical Sciences, Lund,Faculty of Medicine,Skåne University Hospital
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- Wennberg, B. (author)
- Karolinska University Hospital
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- Nordström, Fredrik, 1981 (author)
- University of Gothenburg,Gothenburg University,Göteborgs universitet,Institutionen för kliniska vetenskaper, Avdelningen för radiofysik,Institute of Clinical Sciences, Department of Radiation Physics,Sahlgrenska University Hospital
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- Ceberg, C. (author)
- Lund University,Lunds universitet,Radiotherapy Physics,Forskargrupper vid Lunds universitet,Lund University Research Groups
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Ceberg, S. (author)
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(creator_code:org_t)
- 2019-01-08
- 2019
- English.
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In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 64:2
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Abstract
Subject headings
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- The purpose of this study was to investigate breathing-motion induced interplay effects for stereotactic body radiotherapy (SBRT) of liver tumours treated with flattening-filter free (FFF) volumetric modulated arc therapy (VMAT). Ten patients previously treated with liver SBRT were included in this study. All patients had four-dimensional computed tomography (4DCT) scans acquired prior to treatment. The 4DCT was sorted into 8-10 phases covering an equal time interval. A FFF VMAT plan was created for one fraction in the mid-ventilation phase for each patient. To generate dose distributions including both interplay effects and dose blurring, a sub-plan was calculated for each phase. The total dose distributions were accumulated to the mid-ventilation phase using the deformed vector fields (DVF) from deformable image registration between the corresponding CT and the mid-ventilation phase CT. A blurred dose distribution, not including interplay effects, was also obtained by distributing the delivery of the whole plan uniformly on all phases, and was similarly accumulated to the mid-ventilation phase. To isolate interplay effects, this blurred dose distribution was subtracted from the total dose distribution with interplay effects. The near minimum dose (D-98%), mean dose (D-mean), heterogeneity index (HI), and the near minimum dose difference (Delta D-98%) between the accumulated dose distributions with and without interplay effects were calculated within the gross tumour volume (GTV) for each patient. Comparing the accumulated dose distributions with and without interplay effects, the D-98(%) decreased for nine of the ten patients and the HI increased for all patients. The median and minimum differences in D-98(%) were -2.1% and -5.0% (p = 0.006), respectively, and the median HI significantly increased from 6.2% to 12.2% (p = 0.002). The median Delta D-98% was -4.0% (range - 7% to - 1.5%). In conclusion, statistically significant breathing-induced interplay effects were observed for a single fraction of FFF VMAT liver SBRT, resulting in heterogeneous dose distributions within the GTV.
Subject headings
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
- NATURVETENSKAP -- Fysik -- Annan fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Other Physics Topics (hsv//eng)
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Cancer och onkologi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Cancer and Oncology (hsv//eng)
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Radiologi och bildbehandling (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Radiology, Nuclear Medicine and Medical Imaging (hsv//eng)
Keyword
- liver
- VMAT
- SBRT
- breathing motion
- interplay effects
- FFF
- radiotherapy
- respiratory motion
- radiation-therapy
- dosimetric impact
- free beams
- lung
- delivery
- registration
- rapidarc
- abdomen
- Engineering
- Radiology
- Nuclear Medicine & Medical Imaging
Publication and Content Type
- ref (subject category)
- art (subject category)
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