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Title: Targeting accuracy of single-isocenter intensity-modulated radiosurgery for multiple lesions

Abstract

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 cm{sup 2} region centered over each target. 2D shifts required to get the best gamma passing rates onmore » 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.« less

Authors:
; ; ;
Publication Date:
OSTI Identifier:
22685190
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Dosimetry; Journal Volume: 42; Journal Issue: 2; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; ALGORITHMS; BRAIN; COMPARATIVE EVALUATIONS; COMPUTERIZED TOMOGRAPHY; DOSIMETRY; LASERS; LINEAR ACCELERATORS; METASTASES; PHANTOMS; POSITIONING; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY; SURGERY

Citation Formats

Calvo-Ortega, J.F., E-mail: jfcdrr@yahoo.es, Pozo, M., Moragues, S., and Casals, J. Targeting accuracy of single-isocenter intensity-modulated radiosurgery for multiple lesions. United States: N. p., 2017. Web. doi:10.1016/J.MEDDOS.2017.01.006.
Calvo-Ortega, J.F., E-mail: jfcdrr@yahoo.es, Pozo, M., Moragues, S., & Casals, J. Targeting accuracy of single-isocenter intensity-modulated radiosurgery for multiple lesions. United States. doi:10.1016/J.MEDDOS.2017.01.006.
Calvo-Ortega, J.F., E-mail: jfcdrr@yahoo.es, Pozo, M., Moragues, S., and Casals, J. Sat . "Targeting accuracy of single-isocenter intensity-modulated radiosurgery for multiple lesions". United States. doi:10.1016/J.MEDDOS.2017.01.006.
@article{osti_22685190,
title = {Targeting accuracy of single-isocenter intensity-modulated radiosurgery for multiple lesions},
author = {Calvo-Ortega, J.F., E-mail: jfcdrr@yahoo.es and Pozo, M. and Moragues, S. and Casals, J.},
abstractNote = {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 cm{sup 2} 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.},
doi = {10.1016/J.MEDDOS.2017.01.006},
journal = {Medical Dosimetry},
number = 2,
volume = 42,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}