Synthetic MRI can provide proton density (PD), T₁ value, T₂ value for each pixel by only one data acquisition and can create various contrast-weighted images. The aim of this study is to evaluate the effect on the calculation of the T₁·T₂ value when changing the scan parameters for synthetic MRI. In the phantom study, when changing 1st TE/2nd TE/TR/TSE factor, the effect on the T₁·T₂ value calculated by synthetic MRI was examined. In the volunteer study, the brain was imaged and compared with known T₁·T₂ value. In phantom study, the effect on the T₂ value by the 1st TE/2nd TE/TSE factor was shown. In volunteer study, there was no problem in the calculated value of brain parenchyma. However, the T₂ value of cerebrospinal fluid had the error of known value. The results show that it is necessary to set appropriate scan parameters on synthetic MRI.

Background: ¹²³Iodine-labelled N-(3-fluoropropyl) -2β-carbomethoxy-3β-(4-iodophenyl) nortropane (¹²³I-FP-CIT) single photon emission computerized tomography (SPECT) images are used for differential diagnosis such as Parkinson’s disease (PD). Specific binding ratio (SBR) is affected by scattering and attenuation in SPECT imaging, because gender and age lead to changes in skull density. It is necessary to clarify and correct the influence of the phantom simulating the the skull. Purpose: The purpose of this study was to develop phantoms that can evaluate scattering and attenuation correction. Methods: Skull phantoms were prepared based on the measuring the results of the average computed tomography (CT) value, average skull thickness of 12 males and 16 females. ¹²³I-FP-CIT SPECT imaging of striatal phantom was performed with these skull phantoms, which reproduced normal and PD. SPECT images, were reconstructed with scattering and attenuation correction. SBR with partial volume effect corrected (SBR_act) and conventional SBR (SBR_Bolt) were measured and compared. Results: The striatum and the skull phantoms along with ¹²³I-FP-CIT were able to reproduce the normal accumulation and disease state of PD and further those reproduced the influence of skull density on SPECT imaging. The error rate with the true SBR, SBR_act was much smaller than SBR_Bolt. Conclusion: The effect on SBR could be corrected by scattering and attenuation correction even if the skull density changes with ¹²³I-FP-CIT on SPECT imaging. The combination of triple energy window method and CT-attenuation correction method would be the best correction method for SBR_act.

This study aims to establish optimal scan parameters by high temporal resolution computed tomography (CT) scan for emergency patients who cannot hold their breath. First, we investigated scan parameters that can reduce the effect of motion by evaluating motion artifacts from the moving phantom scan and the temporal sensitivity profile (TPS) measurement. Second, we confirmed the standard deviation (SD) of the CT values as well as the operating time and exposure dose. As the results, plan C [rotation time: 0.275 s, detector rows: 80, pitch factor (PF): 1.100] and plan E (rotation time: 0.275 s, detector rows: 100, PF: 0.880) demonstrated high temporal resolution. The difference between the two is PF. The noise of plan C increased because PF is higher than plan E. This is also evident from the results of SD measurement. Our study demonstrates that the optimal parameters for patients who cannot hold their breath in the emergency care are plan C and plan E. In conclusion, we clarified necessary optimal scan parameters to provide clinical image that has more diagnostic information by reducing the effect of breath motion for emergency patients.

Coronary computed tomography angiography (CCTA) was performed in 283 patients with atrial fibrillation (Af) using a prospective electocardiogeaphic gated scanning with a manual exposure-termination technique. When preparatory 5-beat scanning contained at least one RR interval longer than 800 ms, 5-beat diastolic scanning (R+800 ms protocol) was selected. When no RR interval longer than 800 ms was observed, 2-beat scanning starting at end-systolic phase (R+210 ms to R protocol) was chosen. In R+800 ms protocol, we manually terminated scanning when motion free real-time reconstruction image was confirmed. R+800 ms protocol was applied in 95% of the cases and required an average of 2 cardiac cycles, providing motion-free images in 91% of the patients. The mean exposure dose was less than that with R+210 ms to R protocol. Using the protocols above, 90% of the all patients with Af provided motion free images and 99% of them were evaluable.

¹H-MRS, which is a method of measuring fat and iron deposits in the liver, has a single voxel spectroscopy imaging method called high-speed T₂-corrected multiecho (HISTO) based on the STEAM method. If HISTO measurement accuracy is high, it will be one of the biomarkers, so the measurement accuracy was examined. We imaged a self-made phantom simulating a known amount of fat and iron deposition in the liver. A regression analysis of HISTO-measured values for hepatic fat phantom was performed. In addition, regression analysis was performed on the hepatic iron phantom for the R₂ values obtained from the T₂ values measurement and the actually measured value of the HISTO. From the regression analysis, the correlation coefficients were 0.999, 0.992 and 0.977, respectively. The measurement accuracy of HISTO is high, and the reliability of the obtained fat and iron deposit value is high.

We created the device, which can conduct a radiological technologist’s voice to a subject during CT scanning. For 149 lung cancer, dynamic respiratory CT were performed. 92 cases were performed using this device, the others were without this device. The respiratory cycle and respiratory amplitude were analyzed from the lung density. A stable respirating cycle was obtained by using the audio indicator system. The audio indicator system is useful for respiratory dynamic CT.

Portable radiography is available for the patient who is postoperative, severe condition and old. As they have weak immunity, it is important to prevent from hospital infection. Wrapping of 14×14 inch or 14×17 inch X-ray cassette by a plastic (polyethylene) bag a little bit bigger than the cassette was proposed for infection prevention in portable radiography. How to wrap the cassette easily was devised using the sheath of a polyester bag cutting at the bottom. In radiography with the grid, the plastic bag fastens the X-ray grid to the cassette substantially without any other means. In addition, the wrapped cassette, or the cassette with grid covered by the foamed plastic sheet alleviates patient’s discomfort.

Direct measurement of each patient organ dose from computed tomography (CT) is not possible. Most methods to estimate patient organ dose is using Monte Carlo simulation with dedicated software. However, the method and the relative differences between organ dose simulation and measurement is unclear. The purpose of this study was to compare organ doses evaluated by Monte Carlo simulation with doses evaluated by in-phantom dosimetry. The simulation software Radimetrics (Bayer) was used for the calculation of organ dose. Measurement was performed with radio-photoluminescence glass dosimeter (RPLD) set at various organ positions within RANDO phantom. To evaluate difference of CT scanner, two different CT scanners were used in this study. Angular dependence of RPLD and measurement of effective energy were performed for each scanner. The comparison of simulation and measurement was evaluated by relative differences. In the results, angular dependence of RPLD at two scanners was 31.6±0.45 mGy for SOMATOM Definition Flash and 29.2±0.18 mGy for LightSpeed VCT. The organ dose was 42.2 mGy (range, 29.9–52.7 mGy) by measurements and 37.7 mGy (range, 27.9–48.1 mGy) by simulations. The relative differences of organ dose between measurement and simulation were 13%, excluding of breast’s 42%. We found that organ dose by simulation was lower than by measurement. In conclusion, the results of relative differences will be useful for evaluating organ doses for individual patients by simulation software Radimetrics.