IJMPCERO  Vol.3 No.3 , August 2014
Principal Component Analysis of EBT2 Radiochromic Film for Multichannel Film Dosimetry
ABSTRACT

Radiochromic film with a dye incorporated into the radiation sensitive layer [Gafchromic EBT2, Ashland, Inc.] may be digitized by a color transparency scanner, digitally processed, and calibrated so that a digital image in units of radiation absorbed dose is obtained. A transformation from raw scanner values to dose values was developed based upon a principal component analysis of the optical densities of the red, green and blue channels of the color image of a dose of 0.942 Gy delivered by a Sr-90/Y-90 disk-shaped source. In the order of increasing eigenvalue, the three eigenimages of the principal component analysis contained, by visual inspection, 1) mainly noise; 2) mainly a pattern of irregular streaks; and 3) most of the expected dose information along with some of the same background streaking that predominated in the second eigenimage. The combination of the second and third eigenimages that minimized the background streaking was converted into a transformation of the red, green and blue channels optical densities and applied to films with a range of doses from 0 to 63.7 Gy. The curve of dose vs. processed optical density was fit by a two-phase association curve. This processing was applied to a film exposed from its edge by a different Y-90 source in a configuration that was modeled by Monte Carlo simulation. The depth-dose curves of the measurement and simulation agree closely, suggesting that this approach is a valid method of processing EBT2 radiochromic film into maps of radiation absorbed dose.


Cite this paper
Wendt III, R. (2014) Principal Component Analysis of EBT2 Radiochromic Film for Multichannel Film Dosimetry. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 3, 156-166. doi: 10.4236/ijmpcero.2014.33021.
References
[1]   Micke, A., Lewis, D.F. and Yu, X. (2011) Multichannel Film Dosimetry with Nonuniformity Correction. Medical Physics, 38, 2523-2534.
http://dx.doi.org/10.1118/1.3576105

[2]   Lewis, D., Micke, A., Yu, X. and Chan, M.F. (2012) An Efficient Protocol for Radiochromic Film Dosimetry Combining Calibration and Measurement in a Single Scan. Medical Physics, 39, 6339-6350.
http://dx.doi.org/10.1118/1.4754797

[3]   Sim, G.S., Wong, J.H.D. and Ng, K.H. (2013) The Use of Radiochromic EBT2 Film for the Quality Assurance and Dosimetric Verification of 3D Conformal Radiotherapy Using Microtek Scan Maker 9800XL Flatbed Scanner. Journal of Applied Clinical Medical Physics, 14, 85-95.
http://dx.doi.org/10.1120/jacmp.v14i4.4182

[4]   Hotelling, H. (1933) Analysis of a Complex of Statistical Variables into Principal Components, Part 1. Journal of Educational Psychology, 24, 417-441.
http://dx.doi.org/10.1037/h0071325

[5]   Hotelling, H. (1933) Analysis of a Complex of Statistical Variables into Principal Components, Part 2. Journal of Educational Psychology, 24, 498-520.
http://dx.doi.org/10.1037/h0070888

[6]   Wintz, P.A. (1972) Transform Picture Coding. Proceedings of the IEEE, 60, 809-820.
http://dx.doi.org/10.1109/PROC.1972.8780

[7]   Gonzalez, R.C. and Woods, R.E. (2008) Digital Image Processing. 3rd Edition, Pearson Prentice Hall, Upper Saddle River.

[8]   Schneider, C.A., Rasband, W.S. and Eliceiri, K.W. (2012) NIH Image to ImageJ: 25 Years of Image Analysis. Nature Methods, 9, 671-675.
http://dx.doi.org/10.1038/nmeth.2089

[9]   Butson, M.J., Yu, P.K., Cheung, T. and Metcalfe, P. (2003) Radiochromic Film for Medical Radiation Dosimetry. Materials Science and Engineering: R: Reports, 41, 61-120.
http://dx.doi.org/10.1016/S0927-796X(03)00034-2

[10]   International Specialty Products (2010) Gafchromic EBT2 Self-Developing Film for Radiotherapy Dosimetry, Revision 3. International Specialty Products, Wayne.
http://www.filmqapro.com/Documents/GafChromic_EBT-2_20101007.pdf

[11]   Jan, S., Santin, G., Strut, D., et al. (2004) GATE: A Simulation Toolkit for PET and SPECT. Physics in Medicine and Biology, 49, 4543-4561.
http://dx.doi.org/10.1088/0031-9155/49/19/007

[12]   Mendez, I., Peterlin, P., Hudej, R., Strojnik, A. and Casar, B. (2014) On Multichannel Film Dosimetry with Channel-Independent Perturbations. Medical Physics, 41, Article ID: 011705.
http://dx.doi.org/10.1118/1.4845095

[13]   Devic, S., Tomic, N., Soares, C.G. and Podgorsak, E.B. (2009) Optimizing the Dynamic Range Extension of a Radiochromic Film Dosimetry System. Medical Physics, 36, 429-437.
http://dx.doi.org/10.1118/1.3049597

[14]   Devic, S., Tomic, N., Pang, Z., et al. (2007) Absorption Spectroscopy of EBT Model GAFCHROMICTM Film. Medical Physics, 34, 112-118.
http://dx.doi.org/10.1118/1.2400615

[15]   Del Moral, F., Vazquez, J.A., Ferrero, J.J., et al. (2009) From the Limits of the Classical Model of Sensitometric Curves to a Realistic Model Based on the Percolation Theory for GafChromic EBT Films. Medical Physics, 36, 4015-4026.
http://dx.doi.org/10.1118/1.3187226

[16]   Arjomandy, B., Tailor, R., Anand, A., et al. (2010) Energy Dependence and Dose Response of Gafchromic EBT2 Film over a Wide Range of Photon, Electron and Proton Beam Energies. Medical Physics, 37, 1942-1947.
http://dx.doi.org/10.1118/1.3373523

[17]   Bruyant, P.P., Sau, J. and Mallet, J.-J. (1999) Noise Removal Using Factor Analysis of Dynamic Structures: Application to Cardiac Gated Studies. Journal of Nuclear Medicine, 40, 1676-1682.

[18]   Wendt III, R.E., Erwin, W.D. and Groch, M.W. (2000) Principal Component Analysis of Multigated Cardiac Bloodpool Studies and Correction of Count-deficient Frames. Proceedings of the 13th IEEE Symposium on Computer-Based Medical Systems, IEEE Computer Society, Houston, 195-200.
http://dx.doi.org/10.1109/CBMS.2000.856899.

 
 
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