Yasuhiro Fukushima

Diagnostic reference level of computed tomography (CT) in japan

Optimisation of computed tomography (CT) parameters is important in avoiding excess radiation exposure. The aim of this study is to establish the diagnostic reference levels (DRL) of CT in Japan by using dose-length product (DLP). Datasheets were sent to all hospitals/clinics which had CT scanner(s) in Gunma prefecture. Data were obtained for all patients who underwent CT during a single month (June 2010), and the distributions of DLP were evaluated for eight anatomical regions and five patient age groups. The DRL was defined as the 25th and 75th percentiles of DLP. Datasheets were collected from 80 of 192 hospitals/clinics (26 090 patients). DLP for head CT of paediatric patients tended to be higher in Japan compared with DRLs of paediatric head CTs reported from the EU or Syria. Although this study was performed with limited samples, DLP for adult patients were at comparable levels for all anatomical regions.

Perfusion evaluation of lung cancer: assessment using dual-input perfusion computed tomography.

Purpose: The aim of this study was to investigate the feasibility of separately evaluating bronchial (BAP) and pulmonary arterial perfusion (PAP) of lung cancers using dual-input perfusion computed tomography. Materials and Methods: Twenty-nine lesions from 28 patients [19 men and 9 women; age, 65.8±11.3 y (mean±SD); range, 39 to 85 y] were included in this study (1 patient had 2 tumors). From computed tomography data, quantitative maps of PAP and BAP were created using the dual-input maximum-slope method. Total blood perfusion (TBP) was defined as the sum of PAP and BAP, and the percentage of PAP to TBP was defined as %PAP. Correlation of these values with tumor size, location, and pathologic type was statistically analyzed. Results: PAP ranged from 2.0 to 93.1 mL/min/100 mL (mean±SD, 26.8±26.4), BAP was 0 to 65.4 (25.1±19.12), TBP was 20.7 to 132.0 (52.0±29.0), and %PAP was 4% to 100% (48.8%±31.9%). PAP, TBP, and %PAP correlated negatively with tumor size (P<0.05). PAP and %PAP were higher in the peripheral zone than in the central zone (P<0.05). There was significant correlation between pathologic type and the respective perfusion parameters (P>0.05). Conclusions: We were successful in separating the dual vascular supply to assess dual-input perfusion of lung cancer. We found perfusion of lung cancers to depend on tumor size and location. Acknowledging and assessing the dual vascular supply in lung perfusion may have clinical implications in the management of lung cancer treatment.

Creation and application of three-dimensional computer-graphic animations for introduction to radiological physics and technology

Physics-related subjects are important in the educational fields of radiological physics and technology. However, conventional teaching tools, for example texts, equations, and two-dimensional figures, are not very effective in attracting the interest of students. Therefore, we have created several multimedia educational materials covering radiological physics and technology. Each educational presentation includes several segments of high-quality computer-graphic animations designed to attract students’ interest. We used personal computers (PCs) and commercial software to create and compile these. Undergraduate and graduate students and teachers and related professionals contributed to the design and creation of the educational materials as part of student research. The educational materials can be displayed on a PC monitor and manipulated with popular free software. Opinion surveys conducted in undergraduate courses at Kitasato University support the effectiveness of our educational tools in helping students gain a better understanding of the subjects offered and in raising their interest.

デュアルエナジーCT におけるスペクトラルHU 曲線の最適関数の推定

The purpose of this study was to reveal the optimal function for regression of spectral Hounsfield Unit (HU) curves. The optimization procedure consists of the following steps: 1) obtaining dual energy CT (DECT) images of the RMI 467 phantom, 2) obtaining virtual monochromatic images from DECT images, 3) mapping each region of interest (ROI) to a phantom rod on virtual monochromatic images, 4) obtaining spectral HU curves for all rods, 5) regression of spectral HU curves using various functions, including linear, quadratic polynomial, cubic polynomial, quartic polynomial, quintic polynomial, sextic polynomial, septic polynomial, exponential, corrected exponential, bi-exponential, and logarithm, and 6) calculating the coefficients and the Akaike Information Criterion (AIC) of the functions listed above. Results indicated that the quintic polynomial function is suitable for analyzing the regression of spectral HU curves. The coefficients generated by the quartic or higher order polynomial functions were significantly higher than those generated by other functions (p<0.05). The median AIC of the quintic polynomial was the lowest among all functions. Therefore, we conclude that the quintic polynomial is the best function to use for the regression of spectral HU curves.