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Fukuda A.,Shiga Medical Center for Children
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2010

Kilovoltage cone beam computed tomography (CBCT) imaging may be useful in verifying patient position in stereotactic radiosurgery (SRS). To evaluate its efficacy, we investigated isocenter differences in the radiation beam and CBCT with respect to the achievable setup of a conventional frame-based SRS system. A verification phantom constructed from two plastic boards and Gafchromic-EBT film (4 × 4 cm2) pricked with a pin, was scanned by simulation CT. An isocenter at the tip of pin was planned in the treatment planning system and positioned using stereotactic coordinates. Star-shot irradiation was performed to evaluate the difference between the radiation isocenter and the target (pinhole). CBCT rotation of 200° with a micro multileaf collimator (m3) was performed and measured the isocenter difference between CBCT and the target (tip of pin) by comparing relative coordinates. Data acquisition was performed 13 times on different days and differences were analyzed by calculating mean and standard deviation. The mean difference between the radiation beam and the target (pinhole) and between radiation beam and CBCT isocenter, were 0.6 ± 0.2 mm and 0.8 ± 0.1 mm, respectively. The setup accuracy of conventional stereotactic coordinates and the isocenter accuracy of CBCT complied with AAPM Report No. 54. Source


Fukuda A.,Shiga Medical Center for Children
Journal of Applied Clinical Medical Physics | Year: 2010

Kilovoltage cone beam computed tomography (CBCT) imaging may be useful in verifying patient position in stereotactic radiosurgery (SRS). To evaluate its efficacy, we investigated isocenter differences in the radiation beam and CBCT with respect to the achievable setup of a conventional frame-based SRS system. A verification phantom constructed from two plastic boards and Gafchromic-EBT film (4 × 4 cm2) pricked with a pin, was scanned by simulation CT. An isocenter at the tip of pin was planned in the treatment planning system and positioned using stereotactic coordinates. Star-shot irradiation was performed to evaluatethe difference between the radiation isocenter and the target (pinhole). CBCT rotation of 200° with a micro multileaf collimator (m3) was performed and measured the isocenter difference between CBCT and the target (tip of pin) by comparing relative coordinates. Data acquisitionwas performed 13 times on different days and differences were analyzed by calculating mean andstandard deviation. The mean difference between the radiation beam and the target (pinhole) and between radiation beam and CBCT isocenter, were 0.6 ± 0.2 mm and 0.8 ± 0.1 mm,respectively. The setup accuracy of conventional stereotactic coordinates and the isocenter accuracy of CBCT complied with AAPM Report No. 54. Source


Fukuda A.,Shiga Medical Center for Children | Fukuda A.,Kanazawa University | Lin P.-J.P.,Virginia Commonwealth University | Matsubara K.,Kanazawa University | Miyati T.,Kanazawa University
Journal of Applied Clinical Medical Physics | Year: 2014

The purpose of this study was to develop and evaluate a noninvasive method to assess table feed speed (mm/s) in modern commercial computed tomography (CT) systems. The table feed (mm/rotation) was measured at selected nominal table feed speeds, given as low (26.67 mm/s), intermediate (48.00 mm/s), and high (64.00mm/s), by utilizing a computed radiography (CR) cassette installed with a photostimulable phosphor plate. The cassette was placed on the examination table to travel through the isocenter longitudinally, with a total scan length of over 430mm. The distance travelled was employed to determine the total table feed length. To calculate the table feed speed, gantry rotation time was measured concurrently at a preselected nominal rotation time of 750 ms. Upon completion of data acquisition, the table feed and gantry rotation time were analyzed and used to calculate the actual table feed speed (mm/s). Under the low table feed speed setting, the table feed speed was found to be 26.67 mm/s. Similarly, under the intermediate and high table feed speed settings, the table feed speed was found to be 48.10 and 64.07mm/s, respectively. Measurements of the table feed speed can be accomplished with a CR system and solid-state detector, and the table feed speed results were in excellent agreement with the nominal preset values. Source


Yamada S.,Shiga Medical Center for Adults | Saiki M.,Shiga Medical Center for Adults | Satow T.,Shiga Medical Center for Adults | Fukuda A.,Shiga Medical Center for Children | And 3 more authors.
European Journal of Neurology | Year: 2012

Background: Taking an advantage of the high sensitivity of 3D T2*-weighted gradient-recalled-echo (GRE) imaging to cerebral microbleeds, we investigated the relationship between cerebral microbleeds and leukoaraiosis. Methods: Participants aged 40years or more have been evaluated for the presence of cerebral microbleeds using 3D T2*-GRE sequence since 2006. The severity of periventricular hyperintensity (PVH) and deep white matter hyperintensity (DWMH) on fluid attenuated inversion recovery images was assessed using Fazekas rating scales. Multivariate logistic regression analyses were conducted after adjustment for stroke subtype, age, PVH, DWMH, hypertension, dementia, and use of platelet aggregation inhibitors. Additionally, we examined the association between cerebral microbleeds and other covariates using a Pearson's correlation analysis. Results: Amongst 389 patients, 67 patients had a single microbleed and 93 had multiple microbleeds. The prevalence of microbleeds was 83% amongst 53 patients with intracerebral hemorrhage (ICH), 49% amongst 173 with infarction, and 20% amongst 163 without any type of stroke. In the multivariate analyses, the odds ratio (95% CIs) of microbleed detection was 10.1, (4.12-24.8) for ICH, 2.33 (1.12-4.85) for atherosclerotic infarction, 1.66 (1.10-2.48) for PVH, and 1.49 (1.02-2.19) for DWMH. In the Pearson's correlation analysis, cerebral microbleeds were closely related to PVH (Pearson's correlation coefficient; 0.48) and DWMH (0.37), compared with age (0.16). Conclusions: High-grade PVH, high-grade DWMH, ICH, and atherosclerotic infarction were significantly independent predictors for cerebral microbleeds. In addition, we found that the grades of PVH and DWMH have a closer association with the number of cerebral microbleeds than age. Click to view the accompanying paper in this issue. © 2011 The Author(s). European Journal of Neurology © 2011 EFNS. Source


Fukuda A.,Shiga Medical Center for Children | Fukuda A.,Kanazawa University | Miyati T.,Kanazawa University | Matsubara K.,Kanazawa University
Radiological Physics and Technology | Year: 2013

In Japan, the entrance air kerma rate (EAKR) to a patient cannot exceed 50 mGy/min in conventional fluoroscopy. However, it is unclear where the EAKR should be measured. We obtained the tube potential and tube current as a function of polymethylmethacrylate (PMMA) thickness, and the EAKR at the interventional reference point (IRP) was measured from the trajectory. The EAKR at the point established by the U.S. Food and Drug Administration (FDA) was calculated from EAKR at the IRP. The EAKR at the IRP exceeded the limit at a PMMA thickness of 22-28 cm. However, the EAKR did not exceed the limit at the FDA point. If the EAKR to a patient is being verified to meet the recent Japanese ruling, the EAKR should be measured at the FDA point, and if the EAKR is being evaluated for determination of the skin dose, it should be monitored at the IRP. © 2013 Japanese Society of Radiological Technology and Japan Society of Medical Physics. Source

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