SU‐FF‐T‐389: Prototype Electron Phantom for Radiographic and Radiochromic Film Dosimetry

Purpose: To develop a practical electron beam phantom for use with radiographic and radiochromic film to measure relative dose in a plane containing the central axis. Method and Materials: A prototype Solid Water® film phantom was used to measure 2D dose distributions in a principal plane containing the central axis for 6–20 MeV electron beams. Relative depth‐dose and 2‐D dose distributions were measured in the phantom using both Kodak XV radiographic and GafChromic EBT radiochromic films. To evaluate the dosimetric accuracy of the film‐phantom system, film measurements were compared to equivalent measurements acquired using a scanning diode and water phantom. 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: Radiochromic film depth‐dose measurements (9 and 16 MeV) agreed with diode measurements within criteria in all regions. Radiographic film depth‐dose measurements also agreed well in all regions excluding the build‐up region (<10 mm depth) where measurements were approximately 3% low. For both types of film, 2D dose distributions agreed with diode measurements in all regions of the curve with the maximum error (≈3%) near the surface (95% dose contour). Conclusion: The prototype phantom is capable of measuring relative electron dose distributions using radiographic and radiochromic film that are consistent with measurements taken using a scanning diode in a water phantom. Conflict of Interest: Gammex‐RMI, Inc. provided the prototype phantoms for this study.