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

Published online by Cambridge University Press:  24 August 2015

S. A. Syam Kumar ,
P. Aparna ,
P. T. Anjana ,
C. P. Aswathi  and
G. P. Sitha
S. A. Syam Kumar*
Affiliation:
Department of Radiation Oncology, Division of Radiation Physics, Malabar Cancer Centre, Thalassery, Kerala, India
P. Aparna
Affiliation:
Department of Physics, University of Calicut, Thenhippalam, Kerala, India
P. T. Anjana
Affiliation:
Department of Physics, University of Calicut, Thenhippalam, Kerala, India
C. P. Aswathi
Affiliation:
Department of Physics, University of Calicut, Thenhippalam, Kerala, India
G. P. Sitha
Affiliation:
Department of Physics, University of Calicut, Thenhippalam, Kerala, India
*
Correspondence to: Dr Surendran Nair Ambika Devi Syam Kumar, Department of Radiation Oncology, Malabar Cancer Centre, Thalasseri, Kerala, India. Tel: +91 9961443954; E-mail: [email protected]
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Abstract

The 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.

Keywords

dose profileenhanced dynamic wedgesolid water phantomtreatment planning systemwedge factor2D array
Type
Original Articles
Information
Journal of Radiotherapy in Practice , Volume 14 , Issue 4 , December 2015 , pp. 394 - 402
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Copyright
© Cambridge University Press 2015 

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References

1.Ahmad, M, Hussain, A, Muhammad, W, Abbas, S Q, Matiullah, R. Studying wedge factors and beam profiles for physical and enhanced dynamic wedges. JMP 2009; 35: 35–40.Google Scholar
2.Kijewski, P Ket al. Wedge-shaped dose distribution by computer controlled collimator motion. Med Phys 1978; 5: 426–429.CrossRefGoogle ScholarPubMed
3.Leavitt, D D, Martin, M, Moeller, J H, Lee, W L. Dynamic wedge field techniques through computer controlled collimator motion and dose delivery. Med Phys 1990; 17: 87–91.CrossRefGoogle ScholarPubMed
4.Rutonjski, L, Kuzmanović, Z, Baucal, M, Petrović, B L, Teodorović, M. The quality assurance of Varian enhanced dynamic wedges using Daily QA Check 2. Arch Oncol 2008; 16: 7–9.CrossRefGoogle Scholar
5.Chang, S X, Gibbons, J P. Clinical implementation of non-physical wedges. AAPM 1999; 1–13.Google Scholar
6.Salk, J, Blank, P, Machold, U, Rau, E, Schneider, E, Röttinger, E M. Department of Radiotherapy, University of Ulm, Germany. Physical aspects in the clinical implementation of the enhanced dynamic wedge (EDW). http://www.uni-ulm.de/~jsalk/edw/edw.pdfGoogle Scholar
7.Allahverdi, M, Mohammadkarim, A, Esfehani, M, Nedaie, H, Shirazi, A, Geraily, G. Evaluation of off-axis wedge correction factor using diode dosimeters for estimation of delivered dose in external radiotherapy. JMP 2011; 37: 32–39.Google Scholar
8.Robertson, T H, Webb, C T. Analysis of off-axis enhanced dynamic wedge dosimetry using a 2D array. http://cms.bsu.edu/academics/collegesanddepartments/physicsandastronomy/researchcommunity/studentresearchprojects (student research thesis from ball state university). 2008; 1–4.Google Scholar
9.Buzdar, S A, Khan, M A, Nazir, A, Gadhi, M A, Nizamani, A H, Saleem, H. Effect of change in orientation of enhanced dynamic wedges on radiotherapy treatment dose. IJART 2013; 2: 496–500.Google Scholar
10.Prado, K Let al. Enhanced dynamic wedge factors at off-axis points in asymmetric fields. J App Clin Med Phys 2003; 4: 75–84.Google ScholarPubMed
11.Popescu, A, Lai, K, Singer, K, Phillips, M. Wedge factor dependence with depth, field size, and nominal distances: a general computational rule. Med Phys 1999; 26: 541–549.CrossRefGoogle ScholarPubMed
12.Tailor, R C, Followill, D S, Hanson, W F. A first order approximation of field-size and depth dependence of wedge transmission. Med Phys 1998; 25: 241–244.CrossRefGoogle ScholarPubMed
13.Liu, C, Li, Z, Palta, J R. Characterizing output for the Varian enhanced dynamic wedge field. Med Phys 1998; 25: 64–70.CrossRefGoogle ScholarPubMed
14.Zhu, X R, Gillin, M T, Jursinic, P A, Lopez, F, Grimm, D F, Rownd, J J. Comparison of dosimetric characteristics of siemens virtual and physical wedges. Med Phys 2000; 26: 2267–2277.CrossRefGoogle Scholar
15.Palta, J R, Daftari, I, Suntharalingam, N. Field size dependence of wedge factors. Med Phys 1998; 15: 624–626.CrossRefGoogle Scholar
16.Gibbons, J P. Calculation of enhanced dynamic wedge factors for symmetric and asymmetric photon fields. Med Phys 1998; 25: 1411–1418.CrossRefGoogle ScholarPubMed
17.Sehti, A, Leybovich, L B, Dogan, N, Glasgow, G P. Elimination of field size dependence of enhanced dynamic wedge factors. Phys Med Biol 2000; 45: 3359–3365.Google Scholar
18.Leavitt, D D, Lee, W L, Gaffney, D K, Moeller, J H, O’Rear, J H. Dosimetric parameters of enhanced dynamic wedge for treatment planning and verification. Med Dosim 1997; 22: 177–183.CrossRefGoogle ScholarPubMed
19.McCullough, E C, Gortney, J, Blackwell, R C. A depth dependence determination of wedge transmission factor for 4-10 MV photon beams. Med Phys 1998; 15: 621–623.CrossRefGoogle Scholar