ABSTRACT
ABSTRACT: An iterative back projection method (i-BP) has been developed to improve the resolution of reconstructed images produced by electrical resistance tomography (ERT). This solution is based on an iterative calculation of the electrical fields and it is possible to reconstruct clearer images than those reconstructed by the conventional back projection method without divergence. However, it does take several minutes to finish the iteration process, and therefore this solution can be applied to flow fields that require high spatial resolution rather than short processing times, such as the accumulation of noble metals in glass melters. Numerical simulations and experiments using a simple model are performed in this study. The numerical simulations show that clear images are reconstructed both near the wall and at the center by i-BP. The conductivity correlation coefficient between the genuine distribution and the reconstructed image is improved from 0.4 to 0.9. The validity of the i-BP method is also confirmed by the experimental results. As a result, it is confirmed that ERT and i-BP are capable of reconstructing acceptable images and have potential for use in the visualization of the accumulation of noble metals in a glass melter.
ABSTRACT
OBJECTIVE: To date, numerous studies have been conducted on the diagnostic capabilities of positron emission tomography using [(18)F]-fluorodeoxyglucose (FDG-PET). However, no studies designed to evaluate the influence of FDG-PET on the selection of patient management strategies within the Japanese healthcare system have been reported to date. The aim of the present study was to investigate prospectively the proportion of patients whose management strategies were modified based on FDG-PET findings (strategy modification rate). METHODS: The strategy modification rate was calculated by comparing the patient management strategy (test and treatment plans) after FDG-PET with the strategy before FDG-PET for 560 cancer patients with nine types of cancer (lung cancer, breast cancer, colorectal cancer, head/neck cancer, brain tumor, pancreas cancer, malignant lymphoma, cancer of unknown origin, and melanoma). In addition, the details of the modifications to the patient management strategies were analyzed. RESULTS: The strategy modification rate for patients with lung cancer was 71.6% (149 of 208 patients, 95% confidence interval 65.0-77.7%), which was higher than previously reported strategy modification rates for lung cancer before and after FDG-PET (25.6%). The strategy modification rates for patients with cancers other than lung cancer were as follows: breast, 44.4% (56/126); colorectal, 75.6% (62/82); head and neck, 65.2% (15/23); malignant lymphoma, 70.0% (35/50); pancreas, 85.0% (17/20); and cancer of unknown origin, 78.0% (32/41). The mean modification rate (major and minor modifications) of the treatment plans after FDG-PET, relative to the plans before FDG-PET, was 55.4% (range 44.0-69.2%), with major modifications pertaining to the treatment plan made in 43.3-68.2% of the patients based on the objectives of the FDG-PET examination. CONCLUSIONS: The results from this study indicate that FDG-PET can contribute to the modification of management strategies (particularly treatment plans), especially for lung cancer patients but also for patients with other types of cancer.
