Program Information
Comparison of Image Quality Between RT CT Simulators
N Tomic*, P Papaconstadopoulos , J Seuntjens , F De Blois , S Devic , McGill University, Montreal, QC
Presentations
TU-C2-GePD-I-2 (Tuesday, August 1, 2017) 10:00 AM - 10:30 AM Room: Imaging ePoster Lounge
Purpose: In this work we compare image quality parameters derived from phantom images taken on two radiotherapy CT simulators. To make an unbiased comparison, we assured images were obtained with the same surface dose measured using XR-QA2 model GafChromic film placed at the phantom surface.
Methods: Radiotherapy CT simulators GE LS 16 (80 cm bore size) and Philips Brilliance Big Bore (85 cm bore size) were compared in terms of image quality using CATPHAN-504, scanned with Head and Pelvis protocol. Dose was measured at the phantom surface, with CT scans taken until doses on both scanners were within 5%. Dose profiles were sampled using XR-QA2 model GafChromicTM film stripes taped at four sides of the phantom. We performed image quality comparison using CATPHAN-504 modules for: spatial resolution, low contrast detectability, image uniformity, and contrast to noise ratio.
Results: In terms of spatial resolution and low contrast detectability, the GE scanner appears slightly better for both protocols. While the uniformity of the images for GE Head protocol is slightly better, the Philips has better characteristics for the Pelvis protocol. Also, Philips CT images show significantly less noise for both scanning protocols. The CNR results show that Philips CT images appear to be better, except for high Z material for GE Head protocol.
Conclusion: The GE CT-simulator provides slightly better image quality in terms of spatial resolution and low contrast detectability, due to its smaller bore size and lower impact of scattering on the image quality, while Philips CT images appear with better SNR. In terms of CNR, Philips provides superior image quality than GE Pelvis protocol. This could be explained by the use of harder beam quality (GE-7.4 mm Al vs, Philips-6.9 mm Al), indicating the influence of the beam energy spectrum on image quality parameters.
Contact Email: