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Purpose: This work has two related objectives. The first is to estimate the relative biological effectiveness of two radioactive heavy ion beams based on experimental measurements, and compare these to the relative biological effectiveness of corresponding stable isotopes to determine whether they are therapeutically equivalent. The second aim is to quantitatively compare the quality of images acquired postirradiation using an in‐beam whole‐body positron emission tomography scanner for range verification quality assurance. Methods: The energy deposited by monoenergetic beams of 11C at 350 MeV/u, 15O at 250 MeV/u, 12C at 350 MeV/u, and 16O at 430 MeV/u was measured using a cruciform transmission ionization chamber in a water phantom at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. Dose‐mean lineal energy was measured at various depths along the path of each beam in a water phantom using a silicon‐on‐insulator mushroom microdosimeter. Using the modified microdosimetric kinetic model, the relative biological effectiveness at 10% survival fraction of the radioactive ion beams was evaluated and compared to that of the corresponding stable ions along the path of the beam. Finally, the postirradiation distributions of positron annihilations resulting from the decay of positron‐emitting nuclei were measured for each beam in a gelatin phantom using the in‐beam whole‐body positron emission tomography scanner at HIMAC. The depth of maximum positron‐annihilation density was compared with the depth of maximum dose deposition and the signal‐to‐background ratios were calculated and compared for images acquired over 5 and 20 min postirradiation of the phantom. Results: In the entrance region, the hboxRBE10 was 1.2 ± 0.1 for both 11C and 12C beams, while for 15O and 16O it was 1.4 ± 0.1 and 1.3 ± 0.1, respectively. At the Bragg peak, the RBE10 was 2.7 ± 0.4 for 11C and 2.9 ± 0.4 for 12C, while for 15O and 16O it was 2.7 ± 0.4 and 2.8 ± 0.4, respectively. In the tail region, RBE10 could only be evaluated for carbon; the RBE10 was 1.6 ± 0.2 and 1.5 ± 0.1 for 11C and 12C, respectively. Positron emission tomography images obtained from gelatin targets irradiated by radioactive ion beams exhibit markedly improved signal‐to‐background ratios compared to those obtained from targets irradiated by nonradioactive ion beams, with 5‐fold and 11‐fold increases in the ratios calculated for the 15O and 11C images compared with the values obtained for 16O and 12C, respectively. The difference between the depth of maximum dose and the depth of maximum positron annihilation density is 2.4 ± 0.8 mm for 11C, compared to −5.6 ± 0.8 mm for 12C and 0.9 ± 0.8 mm for 15O vs −6.6 ± 0.8 mm for 16O. Conclusions: The RBE10 values for 11C and 15O were found to be within the 95% confidence interval of the RBEs estimated for their corresponding stable isotopes across each of the regions in which it was evaluated. Furthermore, for a given dose, 11C and 15O beams produce much better quality images for range verification compared with 12C and 16O, in particular with regard to estimating the location of the Bragg peak. [ABSTRACT FROM AUTHOR]

This study investigated the effects of the presence of a familiar pet dog on brain activity and psychophysiology in human volunteers. Fourteen participants (2 men, 12 women; mean age ± SD = 43.0 ± 10.8 years) were enrolled in the study. Uptake of 18F-2-fluoro-2-deoxyglucose ([18F]FDG) on whole-brain positron emission tomography (PET) scans in the presence (but without interaction) and absence of their own pet dog was analyzed. In addition, an electrocardiograph was recorded to assess heart rate variability. Psychological condition was determined using the Stress Response Scale-18 (SRS-18). PET brain images were analyzed and compared between the two conditions (f-tests; p < 0.001) using a statistical parametric mapping program (SPM-5). Deactivated brain areas were detected in the left middle frontal gyrus (Brodmann area: BA 8), the right fusiform gyrus (BA 20), the left putamen, and the thalamus in the presence of the pet dog, indicating reduced regional brain activities associated with stress perception and sympathetic arousal. Similarly, SRS-18 scores were significantly lower ip < 0.05) in the presence of the pet dog, indicating a lowered stress response. However, autonomic function was not found to differ significantly between the two conditions. Overall, these results suggest that the participants were "relaxed" In the psychological sense. PET with [18F]FDG appears to be a useful tool for examining the brain mechanisms underlying the psychophysiological well-being associated with the human-animal bond in terms of regional brain responses. [ABSTRACT FROM AUTHOR]

Abstract: We report on the development of a front-end ASIC for high spatial resolution PET detectors with time-of-flight capability based on LYSO scintillator arrays coupled with position-sensitive avalanche photodiode (APD) arrays. The ASIC is designed based on the open-IP LSI project led by JAXA and realized in TSMC CMOS technology. It consists of an 8-channel charge-sensitive amplifier, band-pass filters, differentiators, pulse-height and timing discriminators, and two-channel time-to-amplitude converters. As a result, energy resolution of 9.7% (FWHM) is obtained at 511keV, with a time resolution below 970ps . We will also report on the current status of developing a second-version ASIC designed to have 32-channel analog circuits with improved time resolution. [Copyright &y& Elsevier]

Background: Incorporating mediastinoscopy (MS) into the PET-based strategy for non-small cell lung carcinoma (NSCLC) patients might be cost-effective because MS can allow unnecessary thoracotomies to be avoided. The objective of our study was to assess the cost-effectiveness of incorporating MS into a PET strategy for NSCLC patients.Methods: To determine life expectancy (LE), quality adjusted life years (QALY), and the incremental cost-effectiveness ratio (ICER), a decision-tree sensitivity analysis was designed for histopathologically confirmed NSCLC patients with M0 disease, based on the three competing strategies of chest CT only vs. PET + CT vs. PET + CT + MS. A simulation of 1000 NSCLC patients was created using baselines of other relevant variables in regard to sensitivity, specificity, mortality, LE, utilities and cost from published data. One-way sensitivity analyses were performed to determine the influences of mediastinal metastasis prevalence on LE, QALY and ICER.Results: The LE and QALY per patient in the CT only strategy, PET + CT strategy and PET + CT + MS strategy were 4.79 and 4.35, 5.33 and 4.93 and 5.68 and 5.33 years, respectively, with a 20% prevalence of mediastinal metastasis. The ICERs were 906.6 yen x 10(3) (7555 US dollars)/QALY/patient at a 20% mediastinal metastasis prevalence, and 2194 yen x 10(3) (18,282 US dollars)/QALY/patient at a 50% prevalence, but exceeded 5280 yen x 10(3) (44,000 US dollars)/QALY/ patient at 80%.Conclusions: Our study quantitatively showed the CT + PET + MS strategy in place of the PET + CT strategy in managing NSCLC patients to be cost-effective. MS should be incorporated into the PET + CT strategy for NSCLC patients except in those highly suspected of having mediastinal disease on chest CT or PET. [ABSTRACT FROM AUTHOR]

A thermophilic and cyanide ion-tolerant bacterium, Bacillus stearothermophilus CN3 isolated from a hot spring in Japan, was found to produce thermostable β-cyano-l-alanine synthase. The enzyme catalyzes the synthesis of β-cyano-L-alanine from O-acetyl-l-serine and cyanide ions. The purified enzyme has a molecular mass of approximately 70 kDa and consists of two identical subunits. It was stable in the pH range of 6.0 to 10.0 and up to 70°C. The enzyme also catalyzes the synthesis of various β-substituted-l-alanine derivatives from O-acetyl-l-serine and nucleophilic reagents. The gene encoding the β-cyano-l-alanine synthase was isolated from B. stearothermophilus CN3. Sequence homology analysis revealed that the β-cyano-l-alanine synthase of the bacterium is O-acetyl-l-serine sulfhydrylase. A recombinant plasmid, constructed by ligation of the cloned gene and an expression vector, pKK223-3, was introduced into E. coli JM109. The transformed E. coli cells overexpressed β-cyano-l-alanine synthase. Heat stable β-cyano-l-alanine synthase can be applied to the synthesis of [4-11C]l-2,4-diaminobutyric acid as a tracer for positron emission tomography. [Copyright &y& Elsevier]

ABSTRACTIn Japan, 4.6 million people are living with dementia and the number is expected to rise to 7 million by 2025. Amyloid-β (Aβ) positron emission tomography (PET) is used for cognitively normal Japanese people with or without subjective cognitive decline (SCD) for the purpose of clinical trials or diagnosis. Nevertheless, no empirical studies have been conducted on the safety of disclosing amyloid status to such populations. We conducted amyloid PET imaging on 42 participants (Aβ positive (n = 10) and negative (n = 32)). State anxiety and depression were measured at pre- and post-disclosure, and test-related distress at post-disclosure. Mean state anxiety and depression scores were below the cut-off through pre- and post-disclosure in the Aβ positive and negative groups. State anxiety and depression did not change over time and were not different between groups. Mean test-related distress scores were within normal limits at post-disclosure in both groups. No significant difference was found between groups. Disclosing Aβ positive results did not cause greater mood disturbance than negative results in a short period of time. The short-term psychological safety of disclosing Aβ PET results to asymptomatic Japanese adults with SCD was indicated.

Purpose: The AI-300 automated infusion device (Sumitomo Heavy Industries, Ltd., Tokyo, Japan) is subject to administration error as a function of smaller volumes of 18 F-FDG dispensed via a three-way cock supplied with a disposable kit. The present study aimed to validate the administration accuracy of the AI-300 using an improved disposable kit for quantitative positron emission tomography (PET) assessment., Methods: We determined administration accuracy between the improved and previous disposable kits by measuring variations in dispensed volumes and radioactive concentrations of 18 F-FDG according to the criteria of the Japanese Society of Nuclear Medicine. A reference value was generated by measuring radioactivity using a standard dose calibrator., Results: The values obtained using the previous kit deviated from the reference values by a maximum of -10.6%, and the deviation depended on dispensed volumes of 18 F-FDG<0.25 mL. In contrast, the values were relatively stable when using the improved kit with dispensed 18 F-FDG volumes < 0.25 mL. Variations in radioactive concentrations were relatively stable using the improved kit, whereas that of the previous kit was slightly unstable at high radioactive concentrations., Conclusion: The administration accuracy of the AI-300 using the previous kit varied considerably according to smaller dispensed volumes, but the improved kit might alleviate this problem. The present results indicated that the improved disposal kit should be immediately implemented to eliminate uncertainty surrounding quantitative PET findings.