The International Commission on Radiological Protection (ICRP) recommends that the exposure dosefrom radiological examinations should be as small as possible (as low as reasonably achievable, ALARA). ...However,some patients transported to the emergency center were subject to multiple radiological examinations such as mobileX-ray, computed tomography (CT) examination and digital subtraction angiography (DSA). Increased radiation exposure is a concern for patients. By inserting a thermoluminescent dosimeter (TLD) into a tissue-equivalent phantom, the equivalent dose and effective dose of each radiological examination were determined at each anatomical region. According to the total equivalent doses of radiological imaging (mobile X-ray, head-to-pelvis CT, head DSA), the head equivalent dose was 267.26 mGy. This value is lower than the threshold (3 Gy) for temporary hair loss proposed in ICRP Publication 59. The head dose was 0.05 mSv for head mobile X-ray, 60.43 mSv for head-to-pelvis CT, and 8.42 mSv for head DSA. The total effective dose was 68.9 mSv. To optimize ALARA measurements as well as the radiation dose, it is necessary to know the exposure dose of radiological examination. The dose data evaluated in this study will be useful for the estimation of radiation risks for patients of emergency centers who undergo multiple radiation examinations.
A lithium fluoride (LiF)-silicon (Si)-based neutron detector was developed for real-time measurement of neutron beams for boron neutron capture therapy (BNCT). Detection efficiencies for thermal ...neutrons were measured at the national standard neutron field in Japan and simulated using a Monte Carlo simulation code to evaluate the absolute BNCT neutron fluence rates. The simulation neutron detection efficiencies agreed excellently with the experimental results, within an experimental error of 3%. The simulation results reproduced well the peaks of tritons and alpha particles emitted from the 6Li(n,t)4He reaction, peak of the protons produced by the <inline-formula> <tex-math notation="LaTeX">^{14}\text{N} </tex-math></inline-formula>(n,p)<inline-formula> <tex-math notation="LaTeX">^{14}\text{C} </tex-math></inline-formula> reaction in air, and distribution of alpha particles produced by the neutron capture reactions of dopant boron. The active BNCT neutron detector was characterized based on the experimental and simulation results.
A back-illuminated thin Si diode was developed for fast neutron sensor in active personal neutron dosimeter for detecting fast neutrons below 1 MeV. Neutron response functions for the fast neutron ...sensor with the back-illuminated thin Si diode were evaluated based on measurements of monoenergetic neutron beams at the National Metrology Institute of Japan and Monte Carlo simulations using the Particle Heavy Ion Transport Code System in the neutron energy over 500 keV. The lower limit of neutron detection energy was decreased to 500 keV and neutron detection efficiencies were increased several times over other fast neutron sensors. It is possible to measure neutron doses in the neutron energy range of 500 keV–1 MeV using this novel fast neutron sensor, but the neutron doses were undetectable using other fast neutron sensors. The neutron detection efficiencies were closer to the personal dose equivalent conversion curve than those for other fast neutron sensors in this neutron energy range. Neutron doses of individuals employed at a nuclear facility were evaluated using the active personal neutron dosimeter, which consists of both the novel fast and slow neutron sensors.
Abstract
Average beat interval (BI) and beat interval variability (BIV) are primarily determined by mutual entrainment between the autonomic-nervous system (ANS) and intrinsic mechanisms that govern ...sinoatrial node (SAN) cell function. While basal heart rate is not affected by age in humans, age-dependent reductions in intrinsic heart rate have been documented even in so-called healthy individuals. The relative contributions of the ANS and intrinsic mechanisms to age-dependent deterioration of SAN function in humans are not clear. We recorded ECG on patients (n = 16 < 21 years and n = 23 41–78 years) in the basal state and after ANS blockade (propranolol and atropine) in the presence of propofol and dexmedetomidine anesthesia. Average BI and BIV were analyzed. A set of BIV features were tested to designated the “signatures” of the ANS and intrinsic mechanisms and also the anesthesia “signature”. In young patients, the intrinsic mechanisms and ANS mainly contributed to long- and short-term BIV, respectively. In adults, both ANS and intrinsic mechanisms contributed to short-term BIV, while the latter also contributed to long-term BIV. Furthermore, anesthesia affected ANS function in young patients and both mechanisms in adult. The work also showed that intrinsic mechanism features can be calculated from BIs, without intervention.
Background
The local impedance (LI) is an emerging technology that monitors tissue‐catheter coupling during radiofrequency (RF) ablation. The relationships between the LI, RF delivery time, and ...lesion formation remain unclear.
Methods
Using an LI‐enabled RF catheter in an ex vivo experimental model, RF lesions were created combined with various steps in the power (40 and 50 W), CF (10 g, 30 g, and 50 g), and time (10s, 20s, 30s, 40s, 50s, and 60s at 40 W and 5 s, 10s, 20s, 30s, 40s, 50s, and 60s at 50 W). The correlations between the LI drop, lesion size, and RF delivery time were evaluated. The rate of change in the time‐dependent gain in the LI, depth, and diameter and the time to reach 90% decay of the peak dY/dT (time to 90% decay) were assessed.
Results
The correlation between the LI drop and ablation time revealed non‐linear changes. The time to a 90% decay in the LI drop differed depending on the RF ablation setting and was always shorter with the 50 W setting than 40 W setting. The LI drop always correlated with the lesion formation under all ablation power settings. Deeper or wider lesions were predominantly created within the time to 90% decay of the LI drop.
Conclusion
The LI drop was useful for predicting lesion sizes. Deeper or wider lesions cannot be obtained with a longer ablation than the 90% decay time of the LI drop. A shorter ablation than the 90% decay time of the LI drop would be preferable for an effective ablation.
Takotsubo cardiomyopathy is a common disease, but Takotsubo cardiomyopathy complicated by ventricular septal perforation is very rare. We describe the case of a 92-year-old male who had Takotsubo ...cardiomyopathy complicated by ventricular septal perforation. We treated the patient medically without surgical or catheter interventions. In three weeks, his abnormal wall motion recovered completely, whereas the ventricular septal perforation remained open. He was ambulatory, subsequently discharged, and had been uneventful for one year. In this manuscript, we discuss the importance of non-invasive management for Takotsubo cardiomyopathy complicated by ventricular septal perforation.
A real-time neutron detector was developed to measure an intense neutron beam, based on both a thin silicon sensor and an extremely thin neutron converter for boron neutron capture therapy (BNCT). ...Neutron response function and detection efficiency were evaluated at the BNCT facility. The response function consists of neutron events, detecting both triton particles produced from the 6Li (n,t)4He reaction and alpha particles from the 10B (n,α)7Li reaction. The detector is able to clearly separate the BNCT neutron beam from coexisted gamma rays. A depth distribution of slow neutron flux in an acrylic block was experimentally obtained. While the relative depth distribution of over 20 mm in depth is in line with the results of the neutron activation measurements of gold, the absolute values are around 17% smaller than the corresponding neutron activation results, which was due to the incomplete evaluation of the neutron detection efficiency and angular-dependent response of the neutron detector.
•Real-time neutron detector to be able to measure intense neutron beam.•Neutron beam for boron neutron capture therapy can be followed in a real time.•Neutron response function consists of secondary particles produced both neutron-lithium and neutron-boron reactions.•The neutron detector is composed of thin Si pn diode and extremely thin LiF neutron converter.•Linearity of neutron detection was experimentally obtained.
Background
Recently, a novel contact force (CF) sensing catheter with mesh‐shaped irrigation tip (TactiFlex SE, Abbott) was invented and is expected to be useful for safe and effective radiofrequency ...ablation. However, this catheter's detailed characteristics of the lesion formation are unknown.
Methods
With an in vitro model, TactiFlex SE and its predecessor, FlexAbility SE, were used. A cross‐sectional analysis of 60 s lesions (combination of various energy power settings 30, 40, and 50 W, and CFs 10, 30, and 50 g) and longitudinal analysis (combination of various powers 40 or 50 W, CFs 10, 30, and 50 g and ablation times 10, 20, 30, 40, 50, and 60 s) of both catheters were analyzed and compared.
Results
One hundred eighty RF lesions were created in protocol 1 and 300 in protocol 2. The lesion formation, impedance changes, and steam pops characteristics were similar between the two catheters. Higher CFs were related to higher incidences of steam pops. A nonlinear, time‐dependent increase in the lesion depth and diameter was observed for all power and CF settings, and linear, positive correlations between the RF delivery time and lesion volume were observed for all power settings. Compared with 40 W, a 50 W ablation created greater lesions. Longer durations with higher CF settings had a higher steam pop incidence.
Conclusions
The lesion formation and incidence of steam pops with TactiFlex SE and FlexAbility SE were similar. A 40 or 50 W ablation with careful CF control not to exceed 30 g in addition to monitoring impedance drops was required to safely create transmural lesions.
Lesion formation using a TactiFlex catheter.
Objective
Postoperative pain is a major issue with subcutaneous implantable cardioverter defibrillators (S‐ICD). In 2020, we introduced intravenous patient‐controlled analgesia (IV‐PCA) in addition ...to the conventional, request‐based analgesia for postoperative pain control in S‐ICD. To determine the effect and safety, we quantitatively assessed the effect of IV‐PCA after S‐ICD surgery over conventional methods.
Methods
During the study period, a total of 113 consecutive patients (age, 50.1 ± 15.5 years: males, 101) underwent a de novo S‐ICD implantation under general anesthesia. While the postoperative pain was addressed with either request‐based analgesia (by nonsteroid anti‐inflammatory drugs, N = 68, dubbed as “PCA absent”) or fentanyl‐based IV‐PCA in addition to the standard care (N = 45, dubbed as “PCA present”). The degree of postoperative pain from immediately after surgery to 1 week were retrospectively investigated by the numerical rating scale (NRS) divided into four groups at rest and during activity (0: no pain, 1–3: mild pain, 4–6: moderate pain, 7–10: severe pain).
Results
Although IV‐PCA was removed on Day 1, it was associated with continued better pain control compared to PCA absent group. At rest, the proportion of patients expressing pain (mild or more) was significantly lower in the PCA present group from Day 0 to Day 4. In contrast to at rest, a better pain control continued through the entire study period of 7 days. No serious adverse events were observed. A few patients experienced nausea in both groups and the inter‐group difference was not found significant.
Conclusion
IV‐PCA suppresses postoperative pain in S‐ICD without major safety concerns.
Intravenous patient‐controlled analgesia (IV‐PCA) in addition to the standard treatment evidently mitigates postoperative pain following S‐ICD implantation without major safe concerns. Even though it was used for only 1 day, pain control seems better in the following days.
INTRODUCTIONIn percutaneous coronary intervention (PCI) to atherosclerotic lesions in the right coronary artery (RCA), coronary artery dissection in the ostium of the RCA is a rare but fatal ...complication. Stent implantation to the ostium of RCA may be selected for the prevention of aorto-ostial dissection. AIMTo find factors associated with aorto-ostial stent coverage to mild to moderate ostial stenosis during the treatment of severely narrowed non-ostial RCA lesions. MATERIAL AND METHODSThe primary interest was to find factors associated with ostial stent coverage using multivariate regression analysis. We included 236 patients who underwent intravascular ultrasound (IVUS)-guided PCI to severely narrowed RCA lesions with mild to moderate ostial stenosis, and divided those into the ostial-coverage group (n = 52) and the non-coverage group (n = 184). RESULTSThe prevalence of continuous ostial plaque detected by intravascular ultrasound (IVUS) was significantly greater in the ostial-coverage group (84.6%) than in the non-coverage group (52.9%) (p < 0.001). Multivariate logistic regression analysis revealed that continuous ostial plaque detected by IVUS (OR = 5.398, 95% CI: 2.322-12.553, p < 0.001) was significantly associated with ostial stent coverage after controlling confounding factors. Ischaemia-driven target vessel revascularization was less frequently observed in the ostial-coverage group than in the non-coverage group, without reaching statistical significance (p = 0.069). CONCLUSIONSContinuous ostial plaque detected by IVUS was significantly associated with ostial stent coverage to the mild to moderate stenosis when PCI to non-ostial, severely narrowed RCA lesions was performed. The use of IVUS may enhance the safety but may increase the total stent length in PCI to RCA.
PDF
