Measurement of Neutron Dose Equivalent within and Outside of a LINAC Treatment Vault Using a Neutron Survey Meter

This work concerns neutron doses associated with the use of a Siemens Primus M5497 electron accelerator, which is operated in the photon mode at 15 MV. The conditions offer a situation within which a fraction of the bremsstrahlung emission energies exceed the photoneutron threshold. For different field sizes, an investigation has been made of neutron dose equivalent values at various measurement locations, including: (i) At the treatment table, at a source-surface distance of 100 cm; (ii) at the level of the floor directly adjacent to the treatment table; and (iii) in the control room and patient waiting area. The evaluated neutron dose equivalent was found to range from 0.0001 to 8.6 mSv/h, notably with the greatest value at the level of the floor directly adjacent to the treatment couch (8.6 mSv/h) exceeding the greatest value on the treatment table (5.5 mSv/h). Low values ranging from unobservable to between 0.0001 to 0.0002 mSv/h neutron dose were recorded around the control room and patient waiting area. For measurements on the floor, the study showed the dose equivalent to be greatest with the jaws closed. These data, most particularly concerning neutron distribution within the treatment room, are of great importance in making steps towards improving patient safety via the provision of protective measures.

Signal Control Method for through and Left-Turn Shared Lane by Setting Left-Turn Waiting Area at Signalized Intersections

This paper proposes a signal control method for the through and left-turn shared lanes at signalized intersections to solve traffic conflicts between left-turn vehicles and opposing through vehicles by setting left-turn waiting area (LWA). Delays and stops are weighted to form an integrated performance index (PI) in a vehicle-to-infrastructure cooperation system. The PI models pertaining to all vehicles are established based on the LWA intersection. In addition, an optimized method of signal timing parameters is constructed by minimizing the average PI. VISSIM simulation shows that the average PI decreases by 6.51% compared with the original layout and signal timing plan of the intersection, since the increased delay of the side-road left-turn vehicles is insufficient to offset the reduced delay of the side-road through vehicles after the improvement. The sensitivity analysis shows that the greater the traffic volume of the phase including the through and left-turn shared lanes, the higher the operation efficiency of the LWA intersection compared with the typical permitted phase intersection. When the left-turn vehicles of the shared lanes in each cycle are less than the stop spaces, the LWA intersection can effectively reduce the average PI of the shared lanes. Furthermore, the more the stop spaces in the LWA, the lower the average PI in the same traffic conditions.

Effect of the presence of an aquarium in the waiting area on the stress, anxiety and mood of adult dental patients: A controlled clinical trial

Background Interaction with fish is known to reduce stress and anxiety in humans. Objective This trial evaluated the effect of an aquarium present in a geriatric dental clinic waiting-area (WA) on blood pressure (BP), heart-rate (HR), anxiety, and mood of waiting patients. Methods Participants were recruited into three groups: control (CG): WA without aquarium; partially-stocked aquarium (PSA): aquarium without fish; fully-stocked aquarium (FSA): aquarium with fish. BP and HR of the participants were recorded upon arrival and after 20-minutes of waiting, along with anxiety [State trait anxiety inventory (STAI-6)] and mood [Feeling scale (FS), Felt arousal scale (FAS)] scores. A purpose-built questionnaire evaluated the subjective assessment of the participants’ experience in the WA. ANOVA with repeated measures and nonparametric tests were used for statistical analysis (p<0.05). Results 392 patients (mean age: 65.07±16.9y) completed this trial. There was an effect of time on the BP [systolic: F(1, 120) = 44.82, p<0.001; diastolic: F(1, 120) = 25.10, p<0.001] and HR [F(1, 120) = 40.94, p<0.001]. No effect of groups on BP [systolic: F(1, 120) = 1.01, p = 0.32; diastolic: F(1, 120) = 0.01, p = 0.92] was revealed, but a decrease of HR [F(1, 120) = 21.59, p<0.001]. No effect of time*group on BP [systolic: F(1, 120) = 0.89, p = 0.35; diastolic: F(1, 120) = 0.31, p = 0.58], or HR [F(1, 120) = 1.04, p-0.31]. WA groups had no effects on the participants’ anxiety [H(2) = 2.76, p = 0.25], or mood [FS: H(2) = 2.28, p = 0.32; FAS: H(2) = 1.54, p = 0.46]. Patients rated FSA higher than others [H(2) = 20.98, p<0.001). Conclusions There was no influence of the presence of an aquarium on the patients’ blood pressure, heart rate, anxiety, or mood.

Anti-microbial effect of filtered 222nm excimer lamps in a hospital waiting area

SummaryBackgroundHospital aquired infections is a considerable challenge for vulnerable patients. Ultraviolet light based on the excitation of mercury emit light at 254nm and has well established antimicrobial effects but the use hereof in populated areas is hindered by the carcinogenic properties of 254nm. This is in contrast to the recently developed excimer lamps based on krypton chloride (KrCl). These lamps emit light with a peak intensity at a wavelength of 222nm and have recently been demonstrated to have broad bactericidal and viricidal effects including efficient inactivation of SARS-CoV2. It is, however, unclear how efficiently 222nm lamps perform in a real-life setting such as a hospital waiting area. In this study we aimed to assess the antimicrobial efficacy of filtered 222nm excimer lamps in a real-world setting at an out-patient pulmonology clinic.MethodsFiltered KrCl 222nm excimer lamps (UV222 lamps) were installed in a densely populated waiting room at the out-patient waiting area at Department of Respiratory Diseases and Allergy at Aarhus University Hospital, Aarhus, Denmark. Furniture sufaces were sampled and analyzed for bacterial load in a single arm interventional longitudinal study with and without exposure to filtered 222nm UVC-light. Furthermore, bacterial species were identified using MALDI-ToF mass-spectrometry.FindingsThe exposure to filtered 222nm UVC-light significantly reduced the number of colony-forming-units, and patches with high desity of bacteria. Pathogenic bacteria such as Staphylococcus Aureus and Staphylococcus Epidermidis were detected only in the non-exposed areas suggesting that these species are highly sensitive to inactivation by 222nm UVC-light.ConclusionFiltered 222nm UVC-light is highly anti-microbial in a real-world clinical setting reducing bacterial load and eradicating clinically relevant bacteria species. Filtered 222nm UVC-light has the potential to become an important part of current and future anti-microbial prevention in the clinic.

Study of the Space Occupied by a Wheelchair User at Metro de Santiago Platforms by Laboratory Experiments

The objective is to study the space a wheelchair passenger would use in the preferential waiting areas of an urban railway platform. For this purpose, an analysis of the variables that interfere in the space occupied by a wheelchair user was carried out at Metro de Santiago platforms, to design a preferential prototype waiting area at the Human Dynamics Laboratory of the Universidad de los Andes (Chile). The prototype has a 3.0 m long and 2.5 m wide carriage, together with a preferential waiting area on the platform of the same length as the carriage, and 2.0 m wide. With this prototype defined, a detection method was developed using PeTrack software, to accurately identify the limits of the space occupied by a wheelchair user under two scenarios of different density levels in the preferential waiting area: medium-density (1.5 passengers/m2) and high-density (4.0 passengers/m2). It was observed that the space occupied by a wheelchair user decreased by 33% as the density increased from medium to high. On the other hand, for a high-density level, the space occupied by a wheelchair user was found to be 61% higher than that occupied by a passenger without reduced mobility. This variation occurred mainly because passengers increased their distance from the wheelchair user, which widened their area of influence. Further experiments are proposed as future research to extend this analysis using other density situations.