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Spectral Comparison of the Xoft and Zeiss 50 KVp X-Ray Systems

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L Kelley

L Kelley1*, R Holt2 , T Rusch1 , (1) Xoft - a subsidiary of iCAD, San Jose, CA (2) Pacific Crest Medical Physics, Inc, Chico, CA


SU-E-T-301 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

To compare x-ray spectra of the 50 kVp Xoft Axxentâ„¢ and Zeiss INTRABEAMâ„¢ x-ray sources after filtration by saline-filled balloons applicators or spherical polymer applicators, respectively.

Measurements were made for 3.5, 4.0 and 5.0 cm diameter applicators using an AmpTek model XR-100T-CdTe cadmium telluride spectrometer with 100 μm diameter collimating aperture and model PX4 digital pulse processor. Spectra were then corrected for escape processes using AmpTek XRF-FP Escape software. Both Axxent and INTRABEAM sources were operated at 50 kV and 40 μA to eliminate pulse saturation. The balloon or spherical applicator was placed in a centering fixture in contact with the collimator cap. The distance through the collimator housing from the applicator surface to the spectrometer’s beryllium entrance window was nominally 52mm. Approximately 500,000 counts were collected for each spectrum.

Measured spectra in all cases had a broad Bremsstrahlung continuum with subtle differences in characteristic low energy x-rays lines from the different materials used for the anode thin films and substrates. After corrections for escape events average energies were calculated for spectra emerging from applicators. The average energies were 28.2 ±0.3 keV, 29.0±0.7 keV, and 31.7±0.9 keV for the 3.5, 4.0 and 5.0 cm diameter applicators, respectively. Differences in average energies ranged from 2.0 to 5.6% for these diameters. The mean energies of the spectra are more dependent on balloon size than on the delivery system used.

Energy spectra at the surfaces of 3.5, 4.0 and 5.0 cm diameter applicators were measured for the Axxent and INTRABEAM x-ray systems were using a Cd-Te spectrometer. The average energies of the two x-ray systems for comparable applicator sizes were within 5.6%, and as little as 0.6 keV difference for the smaller applicator size.

Funding Support, Disclosures, and Conflict of Interest: Research sponsored by Xoft, a subsidiary of ICAD

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