Title page for ETD etd-01142010-133415

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
  • solid water phantom
  • film phantom
  • radiochromic film
  • electron dosimetry
  • radiographic film
Date of Defense 2009-11-12
Availability unrestricted
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


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


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.

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