Quantifying motion for pancreatic radiotherapy margin calculation
| Autor: | Christopher J Moore, Julia Stratford, Pooja Jain, Patricia M Price, Gillian A Whitfield, A Henry, Thomas E Marchant, Gillian R Watkins, Ali M Amer, Melanie M Green |
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| Rok vydání: | 2012 |
| Předmět: |
Male
medicine.medical_specialty Movement medicine.medical_treatment Planning target volume Motion (geometry) Radiotherapy Setup Errors Organ Motion Fiducial Markers Margin (machine learning) Humans Medicine Fluoroscopy Radiology Nuclear Medicine and imaging Conformal radiation Aged medicine.diagnostic_test business.industry Radiotherapy Dosage Hematology Cone-Beam Computed Tomography Middle Aged Pancreatic Neoplasms Radiation therapy Oncology Female Radiology Radiotherapy Conformal business Fiducial marker Nuclear medicine |
| Zdroj: | Radiotherapy and Oncology. 103:360-366 |
| ISSN: | 0167-8140 |
| Popis: | Background and purpose Pancreatic radiotherapy (RT) is limited by uncertain target motion. We quantified 3D patient/organ motion during pancreatic RT and calculated required treatment margins. Materials and methods Cone-beam computed tomography (CBCT) and orthogonal fluoroscopy images were acquired post-RT delivery from 13 patients with locally advanced pancreatic cancer. Bony setup errors were calculated from CBCT. Inter- and intra-fraction fiducial (clip/seed/stent) motion was determined from CBCT projections and orthogonal fluoroscopy. Results Using an off-line CBCT correction protocol, systematic (random) setup errors were 2.4 (3.2), 2.0 (1.7) and 3.2 (3.6)mm laterally (left–right), vertically (anterior–posterior) and longitudinally (cranio-caudal), respectively. Fiducial motion varied substantially. Random inter-fractional changes in mean fiducial position were 2.0, 1.6 and 2.6mm; 95% of intra-fractional peak-to-peak fiducial motion was up to 6.7, 10.1 and 20.6mm, respectively. Calculated clinical to planning target volume (CTV–PTV) margins were 1.4cm laterally, 1.4cm vertically and 3.0cm longitudinally for 3D conformal RT, reduced to 0.9, 1.0 and 1.8cm, respectively, if using 4D planning and online setup correction. Conclusions Commonly used CTV–PTV margins may inadequately account for target motion during pancreatic RT. Our results indicate better immobilisation, individualised allowance for respiratory motion, online setup error correction and 4D planning would improve targeting. |
| Databáze: | OpenAIRE |
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