Type of Document	Master's Thesis
Author	Robertson, Chad Joseph
Author's Email Address	crobe56@tigers.lsu.edu,crobe56@gmail.com
URN	etd-01142010-133415
Title	Prototype Electron Phantom for Radiographic and Radiochromic Film Dosimetry
Degree	Master of Science (M.S.)
Department	Physics & Astronomy
Advisory Committee	Advisor Name Title Price, Mich Committee Chair Hogstrom, Kenneth Committee Member Parker, Brent Committee Member Sajo, Erno Committee Member Stacy, Greg Committee Member
Keywords	solid water phantom film phantom radiochromic film electron dosimetry radiographic film
Date of Defense	2009-11-12
Availability	unrestricted
Abstract Robertson, Chad Joseph, B.S. Louisiana Tech University, 2006 Master of Science, Spring Commencement, 2006 Major: Medical Physics and Health Physics Prototype Electron Phantom for Radiographic and Radiochromic Film Dosimetry Thesis directed by Professor Kenneth R. Hogstrom Pages in thesis, 133. Words in abstract, 350 ABSTRACT Purpose: The purpose of this work is to develop a solid electron beam film phantom for use with radiographic film (RGF) and radiochromic film (RCF) to measure relative dose distributions in a principal plane containing the central axis for 6每20MeV electron beams. It was hypothesized that relative dose distributions measured using film will agree with corresponding diode measurements within ㊣2% of the central-axis maximum dose or ㊣1mm distance-to-agreement (DTA). Method and Materials: Three prototype film phantoms were designed at Mary Bird Perkins Cancer Center and constructed by Gammex-RMI, Inc. Relative dose measurements, planar (2D) dose distributions containing central-axis, were acquired in the phantom using both Kodak-XV RGF and GafChromic-EBT RCF. Correspondingly, diode measurements were acquired utilizing a Scanditronix-Wellhofer 2D-water phantom. For prototype 3, dose distributions were measured at 100-cm SSD using a 15x15-cm2 field-size at 6, 9, 12, 16, and 20 MeV, as well as 2x2-cm2 and 4x4-cm2 field-sizes at 9 and 16 MeV. Relative dose differences were evaluated with respect to regional criteria of acceptability: (1) high dose, low dose-gradient region (≒ 2 % dose), (2) high dose-gradient region (≒ 2 mm DTA), and (3) low-dose, low dose-gradient region (≒ 2 % dose). Results: RGF depth-dose measurements agreed with diode measurements within all criteria for all measurements conditions. 2D dose distributions were in agreement with over 98% of measured dose points agreeing within ㊣2% dose or ㊣1mm DTA for all energies (6每20MeV, 15x15-cm2). RCF depth-dose measurements agreed for all measurement conditions in all regions excluding the build-up region (<1每2cm depth), where measurements were approximately 3每4% low. 2D dose distributions reflected differences seen in the depth-doses with 90% of data points within criteria. Conclusion: With appropriate modifications, the prototype 3 phantom is capable of accurately measuring relative electron dose distributions using RGF sufficiently for clinical use. RCF measurements acquired in the same phantom consistently underestimated diode measurements by 3每4% at depths <2-cm. The cause of this systematic error, believed to be a combination of film-edge misalignment and RCF depth-dependency, must be resolved before prototype phantom 3 with appropriate modifications would be acceptable for clinical use.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    robertson_thesis.pdf 67.70 Mb 05:13:24 02:41:10 02:21:02 01:10:31 00:06:01

If you have questions or technical problems, please Contact LSU-ETD Support.