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Author Rodriguez, M. ♦ Bartolac, S. ♦ Rezaee, M. ♦ Bissonnette, J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION PROTECTION AND DOSIMETRY ♦ ABSORBED RADIATION DOSES ♦ ALGORITHMS ♦ COMPUTERIZED TOMOGRAPHY ♦ CORRECTIONS ♦ FILM DOSIMETRY ♦ IONIZATION CHAMBERS ♦ IRRADIATION ♦ LUNGS ♦ PHANTOMS ♦ PHOTON BEAMS ♦ PHOTONS ♦ PLANNING ♦ TOLERANCE
Abstract Purpose: To examine the agreement between absorbed doses calculated by RayStation treatment planning algorithm to those measured with gafchromic film and ion chamber when the photon beam is perturbed by attenuation or lateral scatter of lung material. Methods: A gafchromic EBT2 film was placed in the center of a 30×30×20 cm{sup 3} solid water phantom with a 5 cm lung slab placed at 10 cm depth. The film was irradiated at SSD = 100 cm with a 6 MV photon beam, 10×10 and 5×5 cm{sup 2} field sizes and with the beam parallel to the film and lung slab. A CT was performed to the phantom arrangement for RayStation dose calculation. The films were scanned in an Epson 10000X flatbed scanner and analyzed using the red channel, 16 bits, 76 dpi. PDD curves at the central axis and profiles at dmax were also measured in water using a CC13 (0.13 CC) ion chamber. Measurements and calculation of PDD curves at the central axis and profiles at dmax and 20 cm depth were compared using the criteria suggested by the AAPM Task Group # 53. Results: The PDD curves measured with gafchromic film and those measured in water with ion chamber agree with the ones calculated by RayStation within the uncertainty of the measurements which is within 3%. The passing rate values of the measured and calculated profiles for the 2 field sizes are within 94% for both at dmax and at 20 cm depth. Conclusion: Raystation dose calculation engine models inhomogeneity corrections. Differences between the calculated PDD curves and profiles and those measured with gafchromic film are within the uncertainty of the measurements and inside of the agreement tolerance suggested by TG53. Therefore, RayStation treatment planning has an acceptable algorithm to correct dose delivered by photon beams perturbed by lung tissue.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-06-15
Publisher Place United States
Journal Medical Physics
Volume Number 42
Issue Number 6


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