Program Information
Meeting the ACR QC Requirements for Mechanically Scanned Transducers
A Blatnica , A Errico*, Boston University/Boston University Medical Center, Boston, MA
Presentations
SU-E-I-38 Sunday 3:00PM - 6:00PM Room: Exhibit HallPurpose: To investigate methods and phantoms, both commercially available and fabricated, that will comply with the Geometric Accuracy Quality Control test for mechanically scanned transducers.
Methods: A Gammex UTED was modified to enable caliper dimension measurements by insertion of polyester thread “pins†using needles and a locating jig that allowed placement of the thread at 14mm intervals. The modified phantom was evaluated on a Philips iU22 US system with a VL13-5 broadband linear array transducer with single sweep 3D volume acquisition. 2D (axial and lateral) caliper measurements were made on inserted pins. The transducer was rotated 90 degrees and a 3D sweep was acquired, with measurements taken on the reconstructed slices in the scanning direction. A CIRS model 054GS US phantom was then imaged using the same techniques and methods, with measurements being taken on the lateral resolution pins (3mm and 7mm spacing) at 3cm depth and the results were compared.
Results: 3D measurements in the lateral direction for the CIRS phantom showed an average difference (over multiple scanning techniques) of 9.7% at 4mm spacing and 7.9% at 7mm spacing. The modified UTED produced an average difference of 6.7% at 14mm spacing. Corresponding 2D caliper measurements resulted in a 3.0% difference for the CIRS and -3.7% for the UTED. Lateral resolution decreased from 2D to 3D scanning by 207% for the CIRS (0.53mm to 1.625mm) and 82% for the UTED (1.080mm to 1.970mm).
Conclusion: The modified UTED phantom compares favorably with the CIRS phantom. Issues with lateral resolution blurring in the 3D sweeps can cause inconsistencies in caliper measurements, therefore yearly consistency should be the standard, not an absolute measurement. It is possible for a facility to modify a less expensive phantom that will allow them to meet the QC requirements for Geometric Accuracy set forth by the ACR.
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