Walls Of Room Research Articles

Optimization of an active device for global control of low-frequency wall reflections in a semi-anechoic room

An active device has been designed and built at LMA to control low-frequency reflections on the absorbing walls of a semi-anechoic room: the sound pressure reflected by the walls in the presence of an unknown source is estimated by linear filtering of the total sound pressure near the walls, then neutralized using acoustic sources placed on the walls. Here, we present 2D numerical simulations, involving monopole sources and series of damped analytic modes, which have enabled us to optimize the active device, in particular to (i) deal with resonance frequencies at which cancelling the diffracted pressure near the walls is not sufficient to cancel it inside the room, (ii) minimize the number of the total pressure measurement points required to estimate the pressure diffracted by the walls at each location, and (iii) select the strategy for minimizing the virtual signals corresponding to the diffracted pressure. Simulations show that with the optimized device, the control remains efficient up to frequencies corresponding to one wall source per wavelength and a little less than two pressure sensors per wavelength. Experiments are underway to compare measurements with simulations.

“You don’t have to say much; paint it then!”: A Thematic Analysis of Mural Arts in Iraq (Mosul and Erbil as a Case)

People find themselves in need of adding some inspiration indoors; interior designers likely let their customers immerse in the charm of some wall art decor with sweet family room wall quotes like “Love begins at home”. The art of filling walls exceeds the interior spaces for decoration, including outdoor spaces where different forms of artistic expression are used. This wall art matters among populations globally as it conveys different messages to the public and the decision-makers as well. The current article investigates Mural Arts (MAs) in Mosul and Erbil, Iraq. The researchers aim to (1) interpret the variety of themes that Mosuli Artists (MoAs) and Erbili Artists (ErAs) communicate via painting and (2) figure out the shared and distinctive theme in MoAs and ErAs’ artwork. This study employed a qualitative approach to grasp the themes of MAs in both Mosul and Erbil. The researchers gathered 60 Mixed Mural Arts MMA samples (verbal and visual); 38 in Mosul and 22 in Erbil in four months (from 8 August to 20 November 2023). They purposefully covered a broad range of sites including street walls, building facades, government institution walls, school walls, and bridge side walls in both cities. The researchers employed the Thematic Analysis Approach (TAA)by Braun and Clarke (2006) benefiting from NVivo 11(1999-2017) software to induce themes in Mosul and Erbil. This study revealed a total of 13 themes in both Mosul and Erbil in Mosul and 5 in Erbil. 2 themes, viz. ‘Environmental Sustainability’ and ‘Patriotism’ were shared. Other 6 themes viz, ‘The Transformative Power of Knowledge’, ‘The Horse as a Symbol of Nobility’, ‘Reviving the City of Mosul’, ‘Women Abuse’, ‘Unity for Iraq’, and ‘Martyrdom’ were said to be distinctive in Mosul whereas 3 other themes, viz. ‘The Role of Women in Society’, ‘Music Therapy’, and ‘Motivation in Learning’ were interpreted in Erbil.

Optimum configuration of internal walls in intermittently conditioned rooms with different ventilation-behavior during off-periods and air conditioner operation durations

Investigations focus on optimizing insulation placement and thickness within internal walls of rooms equipped with intermittently operated air conditioners (AC), specifically targeting buildings located in China's Hot Summer and Cold Winter region. To achieve this objective, cooling and heating transmission loads for internal walls with varying insulation thicknesses, both internally and externally insulated, are calculated using EnergyPlus. Calculations are repeated across different air change rate (ACH) during AC off-periods and for varying AC operation durations. Subsequently, these transmission loads facilitate the determination of the optimal insulation position and thickness. The findings demonstrate that the internal walls with inside insulation (Wall-2) achieves an energy-saving rate of approximately 16–20 % during the cooling season and 30–60 % throughout the heating season when compared to that with outside insulation (Wall-1). Moreover, Wall-2's energy-saving advantage over Wall-1 is further accentuated with heightened ACH during off-periods and reduced durations of AC operation. Additionally, the optimal insulation thickness for Wall-2 was determined to be 0.06 m, 0.08 m, and 0.098 m for AC operation durations of 4 h, 7 h, and 10 h, respectively, with ACH having no impact on this optimal thickness. Life cycle savings varied between 254.56 and 552.31 ¥/m2/year, while payback periods varied between 1.76 and 2.33 years. These two indexes are both influenced by AC operation durations and ACH. Finally, the total energy consumption for cooling and heating is reduced by 40–50 %, when the internal wall is insulated to the optimal thickness internally.

De-implementation strategy to reduce unnecessary antibiotic prescriptions for ambulatory HIV-infected patients with upper respiratory tract infections in Mozambique: a study protocol of a cluster randomized controlled trial

BackgroundAntibiotics are globally overprescribed for the treatment of upper respiratory tract infections (URTI), especially in persons living with HIV. However, most URTIs are caused by viruses, and antibiotics are not indicated. De-implementation is perceived as an important area of research that can lead to reductions in unnecessary, wasteful, or harmful practices, such as excessive or inappropriate antibiotic use for URTI, through the employment of evidence-based interventions to reduce these practices. Research into strategies that lead to successful de-implementation of unnecessary antibiotic prescriptions within the primary health care setting is limited in Mozambique. In this study, we propose a protocol designed to evaluate the use of a clinical decision support algorithm (CDSA) for promoting the de-implementation of unnecessary antibiotic prescriptions for URTI among ambulatory HIV-infected adult patients in primary healthcare settings.MethodsThis study is a multicenter, two-arm, cluster randomized controlled trial, involving six primary health care facilities in Maputo and Matola municipalities in Mozambique, guided by an innovative implementation science framework, the Dynamic Adaption Process. In total, 380 HIV-infected patients with URTI symptoms will be enrolled, with 190 patients assigned to both the intervention and control arms. For intervention sites, the CDSAs will be posted on either the exam room wall or on the clinician´s exam room desk for ease of reference during clinical visits. Our sample size is powered to detect a reduction in antibiotic use by 15%. We will evaluate the effectiveness and implementation outcomes and examine the effect of multi-level (sites and patients) factors in promoting the de-implementation of unnecessary antibiotic prescriptions. The effectiveness and implementation of our antibiotic de-implementation strategy are the primary outcomes, whereas the clinical endpoints are the secondary outcomes.DiscussionThis research will provide evidence on the effectiveness of the use of the CDSA in promoting the de-implementation of unnecessary antibiotic prescribing in treating acute URTI, among ambulatory HIV-infected patients. Findings will bring evidence for the need to scale up strategies for the de-implementation of unnecessary antibiotic prescription practices in additional healthcare sites within the country.Trial registrationISRCTN, ISRCTN88272350. Registered 16 May 2024, https://www.isrctn.com/ISRCTN88272350

Sound isolation and speech privacy observations of modular wall construction in healthcare environments

A recent trend in healthcare spaces is emerging where exam room walls are stopping at or just above the ceiling. There are a number of reasons for doing this, including cost, large floor-to-floor heights, desire for prefabricated constructions, and the need for plenum flexibility for building services. The speech privacy at these locations is critically dependent on the noise reduction of the wall, door, and ceiling constructions as well as the sound masking system. Sound masking systems, long delivered directly from manufacturers or their representatives, are now being repackaged and sold by furniture vendors. Measurements and observations from the field will be presented. Locations where sound masking is not recommended and where upgraded construction is required will be discussed.

Justification of fire protection measures in the NPP control room using CFD fire modeling

Introduction. The present paper provides justification of fire safety measures to protect systems of the main control room of NPP using computational fluid dynamics fire modeling.Aim. To develop fire protection measures for systems of the NPP control room using computational fluid dynamics model.Materials and methods. The study involved analysis into purpose and application scope of various methods for modeling dynamics of development and spread of fire hazards. The application of the computational fluid dynamics fire modeling for multifunctional premises was considered.Results. Following the analysis of different methods for modeling the dynamics of development and spread of fire hazards, the present paper introduces the potential of using various methods of fire modeling in the evaluation of fire hazards for main control room. The obtained computations show that the temperature at the reinforcement site remains below the critical value in the most dangerous fire development scenarios like ventilation controlled fire. Moreover, fire hazards fail to spread through the walls of an uninsulated room within three hours at any value of fire load in main control room.Conclusions. The study revealed a potential for using computational fluid dynamics fire modeling for evaluating fire hazards in various buildings and premises, as well as for justifying the sufficiency of fire resistance requirements established for building structures. This regularity is obtained under conditions of preventing the spread of fire beyond the fire zone within the estimated burnout time of the entire fire load. The results received for this particular type of premises (cable floor) indicate that the designed fire resistance of the barriers separating safety system premises and normal operation premises guarantees non-proliferation of fire. The obtained regularities can be used in the development/revision of regulatory documents on fire safety at operating NPPs and NPPs under construction

Enhancing flame retardant wood’s versatility and adjustable properties through multi-scale micro-coating strategy

Wood, a naturally renewable material with a porous structure and breathability, rendering it a green construction material that can absorb sound, isolate heat and regulate moisture. Efforts to enhance wood’s resistance to combustion while maintaining its porous nature are hindered by the potential impact of physical and chemical treatments on its porous structure, posing a challenge in achieving flame-retardant wood that retains its breathability. Inspired by the multi-layer coating decoration method used on walls of various rooms in frame structure buildings, the study applies multi-scale micro-coating strategy to the multi-scale microstructure of wood. This strategy applied polyamino polyether methylene phosphonate (PAP), metal ions (Al3+/ Mg2+/ Ca2+), and alkali solutions to create a persistent multifunctional protective coating for the multi-scale wood structure. This coating effectively preserved the wood’s vessel, ray tissue, cell cavity, and pit structure, protecting its permeability. The modified wood demonstrated an increased limited oxygen value from 19.7 % to 38.4 % and a 55.9 % decrease in the total smoke release compared to natural wood, obtaining high fire safety. Furthermore, the modified wood exhibited adjustable antibacterial, photoaging-resistant and corrosion resistance properties depends on the type of metal. This strategy demonstrated proven reliability, versatility, and durability in the treatment of various metal ions, enabling the production of functional wood with tailored properties.

Investigation of the influence of different room geometries and wall thermal transmittances on the heat transfer in rooms with floor heating

Heat transfer analysis is crucial for precise energy performance estimates in buildings with floor heating systems. However, existing models for predicting heat transfer at wall surfaces often lack accuracy, overlooking realistic room conditions such as corners, edges, thermal bridges, and inhomogeneous wall temperatures, thus compromising energy performance prediction. This research develops more comprehensive correlation models for heat transfer coefficients that incorporate a broader range of realistic room configurations, including room volume, floor aspect ratio, and thermal transmittance of exterior walls—factors rarely explored collectively. This study conducts computational fluid dynamics simulations to analyse the radiative and convective heat transfer and applies thermal boundary layer theory to enhance the understanding of the convective heat transfer at room edges. Results indicate that the convective heat transfer is heavily influenced by changes in thermal boundary layer structures at room edges and depends greatly on the hydraulic diameter assumed for the walls. For the radiative heat transfer, the floor aspect ratio proved crucial. The newly developed models reveal deviations up to 96.5 % from existing ones, highlighting the limited applicability of the existing models. The developed models can enhance the accuracy in predicting the energy performance of buildings with floor heating systems.

Numerical-experimental investigation of a wind tower-room sustainable system: A parametric analysis of the mixed convection with humidification

The wind tower is a sustainable architectural solution designed to improve natural ventilation and thermal comfort in buildings while reducing energy consumption. This study examines thermal comfort, natural ventilation, and heat transfer in a wind tower-room system with air humidification, such that the interaction of mixed convection with these parameters can be linked. The performance of the system is evaluated considering both natural and forced convection, influenced by differential heating and air inlet through the tower, respectively. A parametric analysis explores various parameters like outside air temperature, humidity, and velocity, along with room wall temperatures. Reynolds and Grashof numbers range from 8.57 × 103-1.99 × 105 and 2.20 × 109-1.31 × 1010, respectively. Simulations are validated against experimental data, with deviations under 5.0 %, 10.0 %, and 19.6 % for dry-bulb temperature, wet-bulb temperature, and air velocity. The system shows improved heat extraction efficiency under dominant forced convection conditions. Humidification yields PPD values between 10.0 % and 46.0 % and PMV values below 0 at air temperatures range 25.0–30.0 °C. At air temperatures of 35.0 °C with air humidity below 40.0 %, PPD values remain below 20.0 %. However, above 40 % humidity, humidification is less effective. The air exchange effectiveness reduction due to humidification is minimal at 0.61 %. These results illustrate the combination of parameters necessary for the optimal performance of the tower-room system, this study provides a valuable guide for integrating wind towers with humidification systems in building design and contributing to reduced electricity use and CO2 emissions.

Radiation exposure in therapeutic endoscopic retrograde cholangiopancreatography with two types of fluoroscopy systems

AbstractFluoroscopy is necessary for endoscopic retrograde cholangiopancreatography (ERCP). Occupational radiation exposure of staff (endoscopists, nurses, or assistants) is inevitable. Fluoroscopes with a tube over‐couch (OC) rather than under‐couch (UC) may have more radiation reflection dosage on the staff's upper body theoretically, where the most vital organs are. In the study, we assessed the radiation exposure on staff by two different types of fluoroscopes in real‐world practice. Using a radiation dosimeter to measure the radiation dosage on endoscopists and assistants in each ERCP procedure under two different fluoroscopic systems (UC vs. OC). Forty‐one ERCP procedures were enrolled. Dosimeters were used NanoDots for the measurement of personal radiation exposure. Those dosimeters were attached to the left forearm and chest of the endoscopist and only the chest of two assistants, the wall of the ERCP room, and the controlling room in every procedure. Nine‐teen ERCPs were performed under the OC unit, and the other 22 ERCPs were UC method. Fluoroscopic time and output of radiation dose showed no significant difference between the two groups. Radiation exposure in endoscopist were 0.0911[0.1041–0.3974] mGy (OC) versus 0.0276 [0.0080–0.2924] mGy (UC), p < .01 for the forearm; and 0.0318 [0.0070–0.2628] mGy (OC) versus 0.0182 [0.0088–0.1628] mGy (UC), p = .04 for the endoscopist's body. There was no difference in radiation exposure from assistants in both groups. For all the ERCP procedures, the measurement of radiation exposure from high to low is endoscopist's hand, endoscopist's body, assistant 1, assistant 2, and ERCP room (p < .01). Radiation detection from ERCP room is slightly higher but close to controlling room (p = .06). For the safety of occupational radiation protection, tube of fluoroscope UC is better than OC for the endoscopists more than assistants. Besides, the assistant 1 took higher radiation exposure than assistant 2 for each ERCP procedure.

Mine Fires, Experiences in Extinguishing Large Underground Mine Fires

Mine fires are common the underground exploitation of mineral raw materials. With the development of mining science and practice, the methods of extinguishing mine fires using new methods and materials were also developed. Today, in mining practice, direct fire extinguishing with water or fire extinguishers, isolation of oxidation zones with insulating walls, installation of torket concrete on the walls of the pit room or use of special foams are most often used. Methods based on ventilation methods or the use of inert gases can also be encountered. All these methods are used to extinguish local oxidation processes, fires are localized in a part of the pit, ventilation department or goafs. This paper presents methods of extinguishing a mine fire where the fire zone covered a larger area and it was not possible to localize it in one part of the underground mine, the pit is completely closed and isolated until the oxidation process subsides due to lack of oxygen. At the time of the complete closure and isolation of the pit, several gas detectors remained in operation in the pit, through which the change in the composition of the pit air could be monitored during the still active pit fire. At the same time, samples of the pit atmosphere behind the isolation walls were regularly taken, their analysis was performed and they were compared with the data obtained using active gas detectors. The key question was when to reopen the pit, conduct an inspection and try to reactivate the pit operations. Although it is an underground brown coal mine, some experiences and knowledge can be applied and used in underground mines of other mineral resources threatened by pit fires. Experiences can also be applied in case of fire, where it is possible to control the fire zone only through insulating walls. It was established that changes in the activity of the pit fire were manifested both on the insulation walls and on the active gas detectors.

Indoor Radon Surveying and Mitigation in the Case-Study of Celleno Town (Central Italy) Located in a Medium Geogenic Radon Potential Area

Indoor radon surveying and remediation were implemented in a single-family home affected by high levels of indoor radon in the Celleno municipality (central Italy) with the aim of identifying the contribution of radon sources, evaluating the factors affecting radon entry into the building, and reducing radon risk. Average radon levels were relatively low at the ground floor (286 ± 202 Bq m−3) and first floor (167 ± 84 Bq m−3) in autumn when the temperature was still warm and the windows were open, but increased up to 2776 ± 1768 Bq m−3 and 970 ± 202 Bq m−3 in the first half of December, when the heating system was on and the windows were closed. The inner walls of the pilot room at the ground floor, semi buried on one side, were then treated with a waterproof product (a silane terminated polymer) and the average radon was halved (1475 ± 1092 Bq m−3) in the following month, which was still characterised by winter conditions. Radon entry in the room was identified and sealed with the same product, and a radon accumulation space behind a NE-SW oriented wall was naturally ventilated, reducing radon below the reference level in April with northerly winds conditions.

A Note on the Architectural Layout of the Early Islamic Church on Sir Bani Yas Island, UAE

It has been suggested that the church on Sir Bani Yas island, dated to the seventh–eighth century, originally had a tower rising over its south-eastern room. This would be a unique feature as other hitherto known churches in the Gulf dated to the early Islamic period did not have towers. One of the arguments for the existence of the tower has been the increased thickness of the northern wall of the south-eastern room. However, close examination of the remains reveals that the increased thickness of this wall is in fact related to the rectangular apse of the chancel. Other arguments used previously to support the claim that the church had a tower are critically assessed in this paper, which concludes that the Sir Bani Yas church had no tower and that its chancel had a rectangular apse, yet another architectural feature it shares with other early Islamic Gulf churches.

Radiation protection aspects in the design of a Boron Neutron Capture Therapy irradiation room

Boron Neutron Capture Therapy (BNCT) is a radiotherapy whose effect is due to the combination of low-energy neutron irradiation prior chemical targeting of tumour tissues with boron-10. The context of this work is the design of a clinical BNCT facility based on a Radio-Frequency Quadrupole proton accelerator, manufactured by the Italian National Institute of Nuclear Physics (INFN). Such a machine can provide a neutron beam suitable for the treatment of deep-seated tumours when coupled to a beryllium target and a Beam Shaping Assembly whose main constituent is densified lithiated aluminium fluoride. This paper refines the design of the facility, already addressed in preliminary studies, from the point of view of dosimetric quantities in the room and in the patient. The presented calculations have been performed with different Monte Carlo codes, and assess the time evolution of the dose due to the neutron activation of the irradiated materials. A comprehensive evaluation of the dose absorbed in the healthy organs of the patient is provided, with focus on the residual radioactivity of the patient urine, for three different treatment positions. Borated concrete is confirmed to be the best material for constructing the walls of the treatment room. A lead shielding at the beam-port is proposed to reduce the gamma dose at the irradiation position due to the activation of the Beam Shaping Assembly.

Using Gradiometric Technique to Prospect Archaeological Features in Tell Al-Deylam, South of Babylon City, Middle of Iraq

An extensive vertical magnetic gradiometry survey was carried out over an area spanning 1,188 square meters in the northwestern section of Dilbat; a recently discovered archaeological city within Tell Al-Deylam located approximately 20 km south of Babylon city, so as to reveal the real image of the archaeological features hidden beneath the earth’s surface. The vertical gradiometric survey was done by the Geometrics-G-858 Cesium magnetometer. The gradiometric results showed three clear longitudinal magnetic anomalies in different places on the magnetic contour map. The main anomaly is located on the edge of the northern part of the study area and extends longitudinally in the northwest and southeast direction. This may indicate the presence of the main outer wall, as it extends lengthwise about 30 m, with a width of 3-4 m, and a depth of about 1 m below the surface of the ground, and may contain the main northern gate of the Dilbat Temple. Besides that, this anomaly displayed approximately a high magnetic value of about + 60 nT, which indicates that the wall was built from baked brick composed of clay minerals rich in iron oxides. Furthermore, the magnetic contour map showed two other magnetic anomalies. The first one is located in the western part of the study area and appears perpendicular to the main magnetic anomaly. Meanwhile, the second anomaly occupied the southern part of the study area and is parallel to the main anomaly. The two anomalies showed approximately lower magnetic strength than the outer wall. So, they may represent the remains of the inner room walls built from mud bricks. The thickness of the two supposed walls is about 2.5 m and they are at a depth one meter from the ground. The findings of this method have been a good guide for new excavation, which led to finding the main wall built from fired bricks.

Radiation dose in radiologist from cerebral angiography using optically stimulated luminescence dosimeter

Background: The number of cerebral angiography procedures is increasing, resulting in higher X-ray radiation doses received by radiologists. Consequently, understanding the radiation doses received by radiologists and the accumulation of radiation in control rooms is crucial for guiding prevention strategies against radiation hazards. Objectives: This study aimed to measure and evaluate radiation doses to the hands, lenses of the eyes, and thyroids of radiologists performing cerebral angiography procedures, as well as to measure the accumulated radiation dose in the control room. Materials and methods: OSL dosimeters were placed on the eyeglass frames, thyroids, hands, and legs of radiologists performing 20 cerebral angiography procedures, as well as on the wall and window of the control room. Results: Radiologists’ average radiation doses were measured at specific body parts as follows: left eye (49 µSv), right eye (15 µSv), left hands (34 µSv), right hands (16 µSv), left legs (27 µSv), right legs (7 µSv), and thyroid glands (14 µSv). Notably, the received doses remained well within the maximum radiation dose limit established by the International Commission on Radiological Protection (ICRP). When calculating the maximum number of procedures that can be performed annually, we based it on the limit of the radiation dose that the eyes’ lenses should not exceed. Our findings revealed that the permissible number of procedures determined by the lens radiation dose limit, should not surpass 405 cases annually (equivalent to 34 cases per month). The radiation dose from therapeutic angiography procedures was discovered to be up to 5 times higher than that from diagnostic angiography procedures. The maximum accumulated radiation dose in the control room was 1.18 µSv/hr, which remained below the limit of the Department of Medical Sciences (< 3 µSv/hr). Conclusion: Radiologists receive less radiation from cerebral diagnostic angiography than therapeutic angiography. Organs on the left side were exposed to greater radiation levels than those on the right side. Wearing radiation protection devices during each procedure can reduce radiation exposure and mitigate long-term effects on radiologists. It is recommended to monitor and calculate the accumulated radiation dose of workers to ensure their exposure remains within safety limits.

Towards an active semi-anechoic room: simulations and first measurements

Semi-anechoic rooms are used for the acoustic characterisation of noise sources. They involve heavy infrastructures and thick absorbent lining. The aim of this work is to demonstrate a less expensive alternative by complementing a thin passive coating with an active technology. Previous work has achieved the active reduction of the pressure scattered by the reflective wall of a semi-anechoic room, in the 80–200 Hz frequency band. This work validated an innovative approach allowing to control the scattered pressure throughout the measurement volume, using a setup located over its periphery. This paper extends a previous presentation at Forum Acusticum dealing with the active control of the low-frequency reflections on the walls and ceiling of a semi-anechoic room [Pinhède et al., Forum Acusticum 2023, Torino, Italy, 11–15 September, 2023, https://doi.org/10.61782/fa.2023.0399]. We describe the design principles and the 2D semi-analytical and 3D finite element simulations of the control system that help optimise parameters such as the transducers number and locations. A full-scale demonstrator has been built to validate the control strategy. Acoustics measurements, which have been used to characterise the room acoustics and to update the simulation parameters are also presented and compared to an updated numerical model.

Design of HVAC System using the Phenomena of Diurnal Temperature fluctuation

The total energy usage of the domestic sector accounts for 35.3% of total global energy consumption of this percentage, 50% is used for room and domestic HVAC systems. We worked for designing a standard module to achieve the maximum temperature difference. In this paper Diurnal Temperature Variation phenomena has been studied. The standard Simulation of the HVAC system using Diurnal Temperature Variation has been performed. The current work is a scale down model of Ground Source Heat Pump which is totally renewable in nature. This scale down model works on Diurnal temperature variation. Diurnal temperature fluctuation is the temperature difference obtained during the daytime and night time with higher and lower soil temperature. Same phenomenon is used to obtain a cooling effect and heating effect as we go deeper inside the Earth. The current work is complete replica of Ground source heat pump where the application of this phenomenon is used. Air as a flowing media is used for heat transfer between soil. The air is meant to be flown through the capillary tubes and at certain depth we get a cooling or heating effect according to atmospheric conditions. Along with that we do have to care about the human leisure requirements, for the very purpose we are also passing some amount of fresh air along with reusing the cool air inside the room by flowing it through the walls of room to provide insulation against the infiltrating heat and other elements that add temperature inside the room. It has been identified the 10.40% reduction in atmospheric air and hence it can be concluded that the geothermal HVAC system can be a sustainable and energy efficient alternative to traditional HVAC system. Also identified that the geothermal HVAC systems offer a promising solution for reducing greenhouse gas emissions and increasing energy efficiency in the building sector.

An initial study on common concrete, titanium dioxide and tungsten dioxide for shielding of a standard external photon beam radiotherapy room

High-energy ionizing radiations have several applications including the treatment of various types of cancer. Advanced techniques such as IMRT (Intensity Modulated Radiation Therapy) and VMAT (Volumetric Modulated Arc Therapy) using high-energy photon beams have been largely used for radiation therapy of cancer. An important issue in radiotherapy is the evaluation of the shielding of the walls of the facility room housing a linear accelerator that produces high-energy photon beams. In this study we performed an estimation of the thicknesses of a standard radiotherapy room considering three different materials: common concrete, titanium dioxide (TiO2) and tungsten dioxide (WO2). It is assumed that patients are treated with photon beams of energies varying from 4 to 30 MeV and considering two types of treatments, only conventional and conventional plus IMRT and VMAT treatment. Results have shown an overall growth of thicknesses with energy, workload, area and type of treatment. At 1,000 Gy/week and 30 MeV photon energy the primary barrier thickness using concrete as the shielding material showed to be substantially higher as compared to TiO2 (143%) and WO2 (1,360%). Results have also indicated an overall linear increasing of volumes with the area used to construct the facility room.

Out-of-field dosimetry using a validated PHITS model and computational phantom in clinical BNCT.

The out-of-field radiation dose for boron neutron capture therapy (BNCT), which results from both neutrons and γ-rays, has not been extensively evaluated. To safely perform BNCT, the neutron and γ-ray distributions inside the treatment room and the whole-body dose should be evaluated during commissioning. Although, certain previous studies have evaluated the whole-body dose in the clinical research phase, no institution providing BNCT covered by health insurance has yet validated the neutron distribution inside the room and the whole-body dose. To validate the Monte Carlo model of the BNCT irradiation room extended for the whole-body region and evaluate organ-at-risk (OAR) doses using the validated model with a human-body phantom. First, thermal neutron distribution inside the entire treatment room was measured by placing Au samples on the walls of the treatment room. Second, neutron and gamma-ray dose-rate distributions inside a human-body water phantom were measured. Both lying and sitting positions were considered. Bare Au, Au covered by Cd (Au+Cd), In, Al, and thermoluminescent dosimeters were arranged at 11 points corresponding to locations of the OARs inside the phantom. After the irradiation, γ-ray peaks emitted from the samples were measured by a high-purity germanium detector. The measured counts were converted to the reaction rate per unit charge of the sample. These measurements were compared with results of simulations performed with the Particle and Heavy Ion Transport code System (PHITS). A male adult mesh-type reference computational phantom was used to evaluate OAR doses in the whole-body region. The relative biological effectiveness (RBE)-weighted doses and dose-volume histograms (DVHs) for each OAR were evaluated. The median dose (D50% ) and near-maximum dose (D2% ) were evaluated for 14 OARs in a 1-h-irradiation process. The evaluated RBE-weighted doses were converted to equivalent doses in 2Gy fractions. Experimental results within 60cm from the irradiation center agreed with simulation results within the error bars except at±20, 30cm, and those over 70cm corresponded within one digit. The experimental results of reaction rates or γ-ray dose rate for lying and sitting positions agreed well with the simulation results within the error bars at 8, 4, 11, 7 and 7, 4, 7, 6, 5, 6 out of 11 points, respectively, for Au, Au+Cd, In, Al, and TLD. Among the detectors, the discrepancies in reaction rates between experiment and simulation were most common for Au+Cd, but were observed randomly for measurement points (brain, lung, etc.). The experimental results of γ-ray dose rates were systematically lower than simulation results at abdomen and waist regions for both positions. Extending the PHITS model to the whole-body region resulted in higher doses for all OARs, especially 0.13Gy-eq increase for D50% of the left salivary gland. The PHITS model for clinical BNCT for the whole-body region was validated, and the OAR doses were then evaluated. Clinicians and medical physicists should know that the out-of-field radiation increases the OAR dose in the whole-body region.