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A study of enhanced dynamic wedge dosimetry using a 2D ion chamber array detector

A study of enhanced dynamic wedge dosimetry using a 2D ion chamber array detector AbstractThe purpose of this work was to study the dosimetric properties of the enhanced dynamic wedge using a Seven29 ion chamber array. The PTW Seven29 ion chamber array and solid water phantoms were used for the study. Primarily, the solid water phantoms with the two-dimensional (2D) array were scanned using a computed tomography scanner at different depths. Using these scanned images, planning was performed for different wedge angles at 6 and 15 MV. A dose of 100 CGy was delivered in each case. For each delivery, the required monitoring units (MUs) were calculated. Using the same setup with a Varian Clinac iX, the calculated MU was delivered for different wedge angles. Subsequently, the different wedged dose distributions that had been obtained were analysed using Verisoft software. A shoulder-like region was observed in the profile; this region reduced as depth increased. The percentage deviation between the planned and measured doses at the shoulder region fell within the range of 0·9–4·3%. The standard deviation between planned and measured doses at shoulder region in the profile fell within 0·08±0·02 at different depths. The standard deviations between planned and measured wedge factors for different depths (2·5, 5, 10 and 15 cm) were 0·0021, 0·0007, 0·0050 and 0·0001 for 6 MV and 0·0024, 0·0191, 0·0013 and 0·0005 for 15 MV, respectively. On the basis of the studies that we performed, it can be concluded that the 2D ion chamber array is a good tool for enhanced dynamic wedge dosimetry. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Radiotherapy in Practice Cambridge University Press

A study of enhanced dynamic wedge dosimetry using a 2D ion chamber array detector

Journal of Radiotherapy in Practice , Volume 14 (4): 9 – Aug 24, 2015
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Publisher
Cambridge University Press
Copyright
© Cambridge University Press 2015 
ISSN
1467-1131
eISSN
1460-3969
DOI
10.1017/S1460396915000370
Publisher site
See Article on Publisher Site

Abstract

AbstractThe purpose of this work was to study the dosimetric properties of the enhanced dynamic wedge using a Seven29 ion chamber array. The PTW Seven29 ion chamber array and solid water phantoms were used for the study. Primarily, the solid water phantoms with the two-dimensional (2D) array were scanned using a computed tomography scanner at different depths. Using these scanned images, planning was performed for different wedge angles at 6 and 15 MV. A dose of 100 CGy was delivered in each case. For each delivery, the required monitoring units (MUs) were calculated. Using the same setup with a Varian Clinac iX, the calculated MU was delivered for different wedge angles. Subsequently, the different wedged dose distributions that had been obtained were analysed using Verisoft software. A shoulder-like region was observed in the profile; this region reduced as depth increased. The percentage deviation between the planned and measured doses at the shoulder region fell within the range of 0·9–4·3%. The standard deviation between planned and measured doses at shoulder region in the profile fell within 0·08±0·02 at different depths. The standard deviations between planned and measured wedge factors for different depths (2·5, 5, 10 and 15 cm) were 0·0021, 0·0007, 0·0050 and 0·0001 for 6 MV and 0·0024, 0·0191, 0·0013 and 0·0005 for 15 MV, respectively. On the basis of the studies that we performed, it can be concluded that the 2D ion chamber array is a good tool for enhanced dynamic wedge dosimetry.

Journal

Journal of Radiotherapy in Practice – Cambridge University Press

Published: Aug 24, 2015

Keywords: dose profile; enhanced dynamic wedge; solid water phantom; treatment planning system; wedge factor; 2D array

References

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