X-Ray Attenuation Comparison for Four Head Phantoms at the Circle of Willis
T Harten1*, S Rosenbaum2, C Ionita3, D Bednarek4, S Rudin5, (1) Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, (2) Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY, (3) SUNY at Buffalo, Buffalo, NY, (4) SUNY Buffalo School of Medicine, Buffalo, NY, (5) Univ. at Buffalo (SUNY) School of Med., Buffalo, NYSU-E-I-23 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To compare the x-ray attenuation of three commercial anthropomorphic head phantoms with a uniform head-equivalent phantom and a cadaver for both lateral and frontal views.
Methods: We compared the attenuation of various phantoms used for evaluating angiographic equipment used in neurovascular interventions. These include three commercial anthropomorphic phantoms, (RS-240T, SK150, and PBU-50), with uniform solid phantoms, and a cadaver head using the same fluoroscopy technique parameters at 80 kVp for four different fields of view (FOV) centering on the Circle of Willis: 8, 7, 6, and 5 inches. The uniform phantom for the frontal plane was 13 mm of aluminum and 15 cm of acrylic and the AAPM head equivalent was for the lateral plane. A 5-cm diameter ionization chamber placed at the source of x-rays and a 20-cm diameter placed at the flat-panel-detector were used for exposure measurements enabling average attenuation determination.
Results: The percent differences of exposure rates were calculated relative to those of the uniform phantoms. The results for the lateral plane show that the PBU-50 is similar to the AAPM phantom. For the smallest FOV, the attenuation percent differences are 64.5% (RS-240T), 47.6% (SK150), 22.8% (PBU-50), and 59.3% (cadaver), with the average being 48.5%±16.1. For the frontal plane, the SK150 is closest to the uniform head-equivalent phantom. For the smallest FOV, the attenuation percent differences were 36.9% (RS-240T), 12.3% (SK150), 39.1% (PBU-50), and 41.0% (cadaver), with the average as 32.3%±11.7. Results for the other FOVs were similar.
Conclusion: This study identifies a general similarity between commercial anthropomorphic phantom and cadaver heads with some differences for one phantom in each view as well as a substantial difference between commercial anthropomorphic phantoms and standardized uniform phantoms. This study indicates that caution is required when selecting the appropriate phantom for evaluating angiographic imaging equipment. (Support: NIH Grant 2R01EB002873)
Funding Support, Disclosures, and Conflict of Interest: Support: NIH Grant 2R01EB002873
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