title: A dosimetric study of small photon fields using polymer gel and Gafchromic EBT films.
abstract: The use of small field sizes is increasingly becoming important in radiotherapy particularly since the introduction of stereotactic radiosurgery and intensity-modulated radiation therapy techniques. The reliable measurement of delivered dose from such ﬁelds with conventional dosimeters, such as ionization chambers, is a challenging task. In this work, methacrylic and ascorbic acid in gelatin initiated by copper polymer gel dosimeters are employed to measure dose in 3 dimensions. Field sizes of 5 × 5mm(2), 10 × 10mm(2), 20 × 20mm(2), and 30 × 30mm(2) are investigated for a 6-MV x-rays. The results show an agreement with Gafchromic film, with some variation in measured doses near the edge of the ﬁelds, where the film data decrease more rapidly than the other methods. Dose penumbra widths obtained with gel dosimeters and Gafchormic film were generally in agreement with each other. The results of this work indicate that polymer gel dosimetry could be invaluable for the quantification of the 3-dimensional dose distribution in small field size.
authors.affiliation: Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Hassani
authors.affiliation: Cancer Research Center, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: Nedaieha@sina.tums.ac.ir.
authors.forename: Hassan Ali
authors.initials: HA
authors.lastname: Nedaie
authors.affiliation: Department of Medical Physics, Shahid Beheshti university of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Hassan
authors.initials: MH
authors.lastname: Zahmatkesh
authors.affiliation: Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Kaveh
authors.initials: K
authors.lastname: Shirani
mesh_terms: D004307:Dose-Response Relationship, Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005373:Film Dosimetry / Q000295:instrumentation*; D005782:Gels / Q000528:radiation effects; D011108:Polymers / Q000528:radiation effects; D061766:Proton Therapy; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods
chemical_list: D005782:Gels; D011108:Polymers
keywords: Dosimetry; Gafchromic EBT film; Polymer gel dosimeter; Small field dosimetry