RESUMEN
PURPOSE: Nuclear medicine quality control programs require daily evaluation for the presence of potential non-uniformities by commonly utilizing a traditional pixel value-based assessment (Integral CFOVUniformity). While this method effectively captures regional non- uniformities in the image, it does not adequately reflect subtle periodic structures that are visually apparent and clinically unacceptable, therefore requiring the need for additional visual inspection of the image. The goal of this project was to develop a new uniformity assessment metric by targetingstructural patterns and more closely correlating with visual inspection. METHODS: The new quantitative uniformity assessment metric is based on the 2D Noise Power Spectrum (NPS). A full 2D NPS was performed on each image. The NPS was thresholded to remove quantum noise and further filtered by the visual response function. A score, the Structure Noise Index (SNI), was then applied to each based on the average magnitude of the structured noise in the processed image. To verify the validity of the new metric, 50 daily uniformity images with varying degrees of visual structured and non-structured non-uniformity were scored by 5 expert nuclear medicine physicists. The correlation between the visual score and SNI were assessed. The Integral CFOV was also compared against the visual score. RESULTS: Our new SNI assessment metric compared to the Integral CFOV showed in increase in sensitivity from 67% to 100% in correctly identifying structured non-uniformities. The overall positive predictive value also increased from 55% to 72%. CONCLUSIONS: Our new uniformity metric correlates much more closely with visual assessment of structured non- uniform NM images than the traditional pixel-based method. Using this new metric in conjunction with the traditional pixel value-based assessment will allow a more accurate quantitative assessment of nuclear medicineuniformity.
RESUMEN
Public concern over radiation from medical imaging is now higher than ever before and hospitals are being placed under increased scrutiny to ensure that their patients do not receive radiation overdoses. California already requires that there is a record of a dose estimate for every CT examination. In response, there has been a renewed interest in research and commercial ventures for the best method to monitor radiation dose for medical imaging procedures. The goal of this session is to highlight some tools that are currently available for dose monitoring, to illustrate how using these tools can improve the quality of care at an institution, and to provide a sample of the future developments in radiation dose monitoring. LEARNING OBJECTIVES: 1. To provide an understanding of the basic science behind dose monitoring 2. To demonstrate few clinical implementation of dose monitoring systems 3. To discuss the advanced concepts currently under investigation (eg, patient size tracking) 4. To demonstrate how dose monitoring systems can be used for improved quality initiatives.