Performance tests of two portable mini gamma cameras for medical applications
The sentinel node gamma camera prototype.
SNGC prototype. (a) Image obtained with the lead calibration mask by direct application of Anger’s equations. No spatial calibration of the signals has been done. (b) Corrected image after application of the two-dimensional polynomial fit reconstruction position procedure. Best fit is achieved for and [Eqs. (1) and (2)].
(a) Measured SNGC prototype energy spectrum for a single location of the calibration mask. (b) Raw pulse height (channels) and (c) energy FWHM (in%) variation over the SNGC prototype surface area. (d) Measured energy spectrum for all the UFOV events after pulse height correction. These plots were obtained by using a source together with the calibration mask.
Uniform flood field image obtained for determination of the SNGC prototype spatial uniformity correction matrix. Only events within a 20% energy window were considered.
(a) Image obtained for the direction with the lead mask slit aperture placed on top of the gamma camera head covering the UFOV of the SNGC. (b) Line spread functions across the SNGC field of view for the direction.
(a) Extrinsic resolution using (SNGC) and (MFGC) diameter pinhole collimator. (b) Planar sensitivity as a function of the source to collimator distance for the SNGC ( diameter pinhole) and MFGC ( diameter pinhole).
(a) Image of two sentinel lymph nodes from a melanoma patient obtained with a conventional gamma camera for a distance lymph node-collimator of . The delivered dose to the patient was . (b) The same nodes taken with our SNGC prototype at a distance lymph node-collimator of .
The multi-flat-panel gamma camera prototype.
MFGC prototype. (a) Image obtained with the lead calibration mask by direct application of Anger’s equations. No spatial calibration of the signals has been done. (b) Corrected image after application of the reconstruction position procedure. Best fit is achieved for and [Eqs. (1) and (2)].
Uniform flood field image obtained for determination of the MFGC prototype spatial uniformity correction matrix. The image shown has been corrected in energy and position, but has not yet been corrected by uniformity.
Thyroid gland phantom images (only the region around the object of interest is shown) acquired with the MFGC prototype when equipped with a diameter pinhole collimator. The images were taken by placing the MFGC prototype at two different distances from the thyroid gland phantom: (left) and (right). Only events within the 20% energy window were considered. The distance between the “hot” nodules simulating thyroid lesions was . The magnification factor introduced by the pinhole collimator-source distance has been taken into account.
Reduced and mean deviation (in mm) for different degrees of the 2D polynomial fit [ and , Eqs. (1) and (2)]. Deviation for hole is calculated as , where and are the hole “reconstructed” (“real”) position.
Physical characteristics and main performances comparison among SNGC, MFGC prototypes, and the previous gamma camera.
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