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Quality Control (QC) Procedure for MR Guided Radiation Treatment Planning (MRgRTP) Using ACR Phantom
E Florez*, A Fatemi , University of Mississippi Med. Center, Jackson, MS
Presentations
SU-I-GPD-J-116 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: We commissioning 3T MRI scanner for brain fractionated radiotherapy (RT) and stereotactic radiosurgery (SRS). We defined our system geometrical distortion baseline using big phantom, QUASAR MRI3D, Modus Medical Devices Inc., during commissioning and repeated measurements bi-weekly. We also run our routine ACR QC tests using standard MRI ACR phantom. Using big phantom bi-weekly is time consuming, therefore, we propose to adopt our weekly ACR measurements for geometrical distortion evaluation.
Methods: We summarized ACR measurements during the initial seven weeks Figure 1. The results compared with big phantom results at two different diameter volume surface (DVS), 320 mm and 203 mm to match with ACR phantom Figure 2.
Results: We summarized big phantom measurements during commissioning, Table 1 and 2. For 320 mm DVS, (X Mean= 0.4 0.29 mm, X Max= 1.45 mm, YMean= 0.21 0.18 mm, YMax= 0.94 mm, ZMean = 0.35 0.23 mm, ZMax=0.93 mm, Absolute Mean = 0.66 0.25 mm, Absolute Max= 1.55 mm) and 203 mm DVS, (X Mean= 0.25 mm, XMax = 0.3 mm, YMean= 0.2 mm, YMax= 0.3 mm, ZMean= 0.5 mm, ZMax= 0.5 mm, Absolute Mean= 0.72 mm, Absolute Max= 0.75 mm). We compare ACR measurements with baseline to define our relative baseline (r-baseline), Table 2. We reported 54% on Mean and 65% on Max differences at X-direction (r-baseline Mean= 0.84 mm and r-baseline Max= 1.44 mm), 42% on Mean and 65% on Max differences on Y-direction (r-baseline Mean= 0.49 mm, r-balance Max= 1.44 mm) and 17% on Mean and 43% on Max difference on Absolute measurement (r-baselineMean= 1.02 mm, r-baselineMax= 1.9 mm).
Conclusion: We will continue our bi-weekly big phantom measures for the next 6 months to confirm ACR phantom measurements accuracy and reproducibility. Also, we are working on our new 3D analysis approach for proper comparison.
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