title: Energy dependence and angular dependence of an optically stimulated luminescence dosimeter in the mammography energy range.
abstract: This study aimed to investigate the energy dependence and the angular dependence of commercially available optically stimulated luminescence (OSL) point dosimeters in the mammography energy range. The energy dependence was evaluated to calculate calibration factors (CFs). The half-value layer range was 0.31-0.60 mmAl (Mo/Mo 22-28 kV, Mo/Rh 28-32 kV, and W/Rh 30-34 kV at 2-kV intervals). Mo/Rh 28 kV was the reference condition. Angular dependence was tested by rotating the X-ray tube from -90° to 90° in 30° increments, and signal counts from angled nanoDots were normalized to the 0° signal counts. Angular dependence was compared with three tube voltage and target/filter combinations (Mo/Mo 26 kV, Mo/Rh 28 kV and W/Rh 32 kV). The CFs of energy dependence were 0.94-1.06. In Mo/Mo 26-28 kV and Mo/Rh 28-32 kV, the range of CF was 0.99-1.01, which was very similar. For angular dependence, the most deteriorated normalized values (Mo/Mo, 0.37; Mo/Rh, 0.43; and W/Rh, 0.58) were observed when the X-ray tube was rotated at a 90° angle, compared to 0°. The most angular dependences of ± 30°, 60°, and 90° decreased by approximately 4%, 14%, and 63% respectively. The mean deteriorated measurement 30° intervals from 0° to ± 30° was 2%, from ± 30° to ± 60° was 8%, and from ± 60° to ± 90° was 40%. The range of energy dependence in typical mammography energy range was not as much as that in general radiography and computed tomography. For accurate measurement using nanoDot, the tilt needs to be under 30°.
authors.affiliation: Department of Radiological Technology, Graduate School of Medicine, Tohoku University, Sendai, Japan.|Department of Radiology, TOYOTA Memorial Hospital, Toyota, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Kawaguchi
authors.affiliation: Department of Imaging, Nagoya Kyoritsu Hospital, Nagoya, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Matsunaga
authors.affiliation: School of Health Sciences, Fujita Health University, Toyoake, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Department of Radiological Technology, Graduate School of Medicine, Tohoku University, Sendai, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Chida
mesh_terms: D006801:Humans; D049449:Luminescence; D008327:Mammography / Q000379:methods*; D036103:Nanotechnology; D011829:Radiation Dosage; D000072232:Radiation Dosimeters; D011874:Radiometry / Q000295:instrumentation* / Q000592:standards; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: angular dependence; energy dependence; mammography; optically stimulated luminescence dosimetry; point-based dosimeter