Targeting accuracy of single-isocenter intensity-modulated radiosurgery for multiple lesions
| Autor: | J. Casals, J.F. Calvo-Ortega, Miquel Pozo, Sandra Moragues |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Film Dosimetry
medicine.medical_treatment Dose distribution Radiosurgery Sensitivity and Specificity Linear particle accelerator Imaging phantom 030218 nuclear medicine & medical imaging Neoplasms Multiple Primary 03 medical and health sciences 0302 clinical medicine medicine Humans Scattering Radiation Dosimetry Radiology Nuclear Medicine and imaging Physics Radiological and Ultrasound Technology Phantoms Imaging business.industry Radiotherapy Planning Computer-Assisted Reproducibility of Results Isocenter Radiotherapy Dosage Intensity (physics) Treatment Outcome Oncology 030220 oncology & carcinogenesis Coronal plane Radiotherapy Intensity-Modulated Tomography X-Ray Computed Nuclear medicine business Radiotherapy Image-Guided |
| Zdroj: | Medical Dosimetry. 42:104-110 |
| ISSN: | 0958-3947 |
| Popis: | To investigate the targeting accuracy of intensity-modulated SRS (IMRS) plans designed to simultaneously treat multiple brain metastases with a single isocenter. A home-made acrylic phantom able to support a film (EBT3) in its coronal plane was used. The phantom was CT scanned and three coplanar small targets (a central and two peripheral) were outlined in the Eclipse system. Peripheral targets were 6 cm apart from the central one. A reference IMRS plan was designed to simultaneously treat the three targets, but only a single isocenter located at the center of the central target was used. After positioning the phantom on the linac using the room lasers, a CBCT scan was acquired and the reference plan were mapped on it, by placing the planned isocenter at the intersection of the landmarks used in the film showing the linac isocenter. The mapped plan was then recalculated and delivered. The film dose distribution was derived using a cloud computing application (www.radiochromic.com) that uses a triple-channel dosimetry algorithm. Comparison of dose distributions using the gamma index (5%/1 mm) were performed over a 5 × 5 cm2 region centered over each target. 2D shifts required to get the best gamma passing rates on the peripheral target regions were compared with the reported ones for the central target. The experiment was repeated ten times in different sessions. Average 2D shifts required to achieve optimal gamma passing rates (99%, 97%, 99%) were 0.7 mm (SD: 0.3 mm), 0.8 mm (SD: 0.4 mm) and 0.8 mm (SD: 0.3 mm), for the central and the two peripheral targets, respectively. No statistical differences (p > 0.05) were found for targeting accuracy between the central and the two peripheral targets. The study revealed a targeting accuracy within 1 mm for off-isocenter targets within 6 cm of the linac isocenter, when a single-isocenter IMRS plan is designed. |
| Databáze: | OpenAIRE |
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