A Monte Carlo study of organ and effective doses of cone beam computed tomography (CBCT) scans in radiotherapy

Cone-beam CT (CBCT) scans utilized for image guided radiation therapy (IGRT) procedures have become an essential part of radiotherapy. The aim of this study was to assess organ and effective doses resulting from new CBCT scan protocols (head, thorax, and pelvis) released with a software upgrade of the kV on-board-imager (OBI) system. Influence of the scan parameters that were changed in the new protocols on the patient dose was also investigated. Organ and effective doses for protocols of the new software (V2.5) and a previous version (V1.6) were assessed using Monte Carlo (MC) simulations for the International Commission on Radiological Protection (ICRP) adult male and female reference computational phantoms. The number of projections and the mAs values were increased and the size of the scan field was extended in the new protocols. Influence of these changes on organ and effective doses of the scans was investigated. The OBI system was modelled in EGSnrc/BEAMnrc, and organ doses were estimated using EGSnrc/DOSXYZnrc. The MC model was benchmarked against experimental measurements. Organ doses resulting from the V2.5 protocols were higher than those of V1.6 for organs that were partially or fully inside the scans fields, and increased by (3 to 13)%, (10 to 77)%, and (13 to 21)% for the head, thorax, and pelvis protocols for both phantoms, respectively. As a result, effective doses rose by 14%, 17%, and 16% for the male phantom, and 13%, 18%, and 17% for the female phantom for the three scan protocols, respectively. The scan field extension for the V2.5 protocols contributed significantly in the dose increases, especially for organs that were partially irradiated such as the thyroid in head and thorax scans and colon in the pelvic scan. The contribution of the mAs values and projection numbers was minimal in the dose increases, up to 2.5%. The field size extension plays a major role in improving the treatment output by including more markers in the field of view to match between CBCT and CT images and hence setting up the patient precisely. Therefore, a trade-off between the risk and benefits of CBCT scans should be considered, and the dose increases should be monitored. Several recommendations have been made for optimization of the patient dose involved for IGRT procedures

Ontogeny of sounds in the echolocating bat Hipposideros speoris

1. Young Hipposideros speoris emit multiharmonic sounds in groups of three to four notes. Newborns emit a relatively uniform pattern of FM- and FM/CF/FM-sounds. From ten days of age onwards the initial sound (first note) of a group is a FM-sound whereas the successive ones are CF/FM-sounds of consistently higher frequencies. At prevolant and volant stages of the bat's development most of the sound energy is concentrated in the second harmonic which is raised to the frequency range of the adults' CF/FM-sounds (127-138 kHz). Subsequently other harmonics disappear. 2. Harmonic components are suppressed or filtered out when they fall in a frequency range of approximately 65-75 kHz. This was found for bats of different ages regardless which fundamental frequency the suppressed harmonic components corresponded to, indicating a mechanical filtering process. These measurements coincide with the absence of the first harmonics in the same frequency range in the sounds of adults. 3. Temporal sound emission patterns were measured for bats of different ages. There was an increase in sound duration and an increase in the number of sounds (notes) per group as the bat matured to adulthood. 4. The sound emission of juveniles aids mothers in finding their young ones. Mothers located their infants even when the juveniles were displaced far from where they were left behind by their mothers. Behavioral experiments under both natural and captive conditions showed that the sound emission of young ones attracts mothers but do not give sufficient cues to allow the mother to discriminate their own from a group of young. 5. The ontogeny of the two types of sounds (CF/FM and complex harmonic FM) of adult Hipposideros speoris is discussed and compared with the vocalisations of other bat species

Compact broadband PCML bandpass filter with broad upper stop band

A simple broadband parallel coupled microstrip line (PCML) bandpass filter with compact design is proposed. A PCML structure with two feeding network of various widths is characterized by an equivalent J-inverter network. The extracted parameters indicate that the normalized J susceptance and equivalent electrical length are frequency dependent. A pair of PCML structure with middle resonator, without ground plane aperture at PCML structure and capacitive open-ended stub at the middle resonator, is proposed. The proposed design is further optimized by adjusting the length and width of the middle resonator. Three broadband bandpass filter with PCML structure of various coupling strengths have been designed. The simulated and measured insertion and return loss responses show good agreement with bandwidth of over 80%, return loss of better than -16 dB and 250% broad upper stopband

Single-stage parallel coupled microstrip line bandpass filter using weak coupling technique

The frequency-dispersive characteristic of a two-port parallel coupled microstrip line (PCML) can be obtained using equivalent J-inverter network parameters. The latter is obtained from its corresponding admittance parameters. Hence, the behaviour of transmission zero frequency, fundamental response frequency and harmonic response frequency of the PCML can be shown. The former is realigned by varying a centrally located single groove size to suppress the first spurious harmonic passband of the filter. Using the J-inverter parameters, the transmission zero of J-susceptance null of a PCML can be realigned by employing a single groove with specific dimension. This simultaneously cancels the first harmonic resonance. In this paper, the behaviour of the J-inverter parameters with varying coupling gaps is presented. The effect of having weak coupling characteristic is then presented. The proposed technique is then justified by two single-stage bandpass filters of PCML with weak coupling characteristic

Scientific Information on Gulf of Mannar - A Bibliography

Gulf of Mannar in the southeast coast of India extends from Rameswaram Island in the north to Kanyakumari in the south. It has a chain of 21 islands stretching from Mandapam to Tuticorin to a distance of 140 km along the coast. Each one of the islands is located anywhere between 2 and 10 km from the mainland. The Gulf of Mannar Biosphere Reserve was set up on 18th February 1989 jointly by the Government of India and the state of Tamilnadu. The government of Tamilnadu in G.O. M.S. No 962 dated 10th September 1986 notified under section 35(1) of the Wildlife (Protection) Act 1972 the intention to declare the 21 islands as Marine National Park for the purpose of protecting marine wildlife and its environment including depths of 3.5 fathoms on the bay side to 5 fathoms on the seaward side. The compilation of all available scientific literature in the form of an annotated bibliography of the Gulf of Mannar biosphere reserve has brought to light the existence of nearly 3,000 publications up to date. This covers the literature published from as early as 1864 to the current year. A large number of publications in the first half of the 20th century have brought out information on the variety of fauna and flora found in the Gulf of Mannar, their biology and ecology. A lot of emphasis on the fish and fisheries research has been given only in the second half of the 20th century. Emphasis is being given on biochemical aspects of flora and fauna in the later part of the 20th century and at present

Marketing in Malaysian Technology Firms

Today’s world technology recognizes Internet and World Wide Web as two of the main communication mediums in technology firms. modern technology and social networking turn out to be a part of a large number of people’s lives. technology firms are challenged with this fast-moving social network in organization that encourage viral marketing too. There has been little study about the effect of viral marketing towards technology firms. This paper aims to explore the factors that influence the effectiveness of viral marketing, determine the most influential factor and identify the impacts of onlinecontents that influence the effectiveness of viral marketing. a quantitative method was used and 384 respondents from Southern Region Malaysia participated in the survey. The results showed that all the motivational factors like playfulness, community-driven, perceived ease of use, and perceived usefulness had significant impact on the viral marketing in the Malaysian technology firms. Two other factors like critical mass and peer pressure were found to be insignificant in this study. The findings may contribute to the judgement on Malaysian technology firms about viral marketing that blend firm skills, knowledge and technical leadership roles to manage emerging technologies, develop innovative solutions and complex firm’s problems

Microwave filter research in Universiti Teknologi Malaysia

This paper describes four microwave filter configurations that have been recently developed over the past five years. These are a direct coupled cavity waveguide filter, an internally- coupled hairpin-line filter, a meander-gap hairpin line filter and a three-element parallel-coupled filter

An analysis on the approximate controllability results for Caputo fractional hemivariational inequalities of order 1 < r < 2 using sectorial operators

In this paper, we investigate the effect of hemivariational inequalities on the approximate controllability of Caputo fractional differential systems. The main results of this study are tested by using multivalued maps, sectorial operators of type (P, η, r, γ ), fractional calculus, and the fixed point theorem. Initially, we introduce the idea of mild solution for fractional hemivariational inequalities. Next, the approximate controllability results of semilinear control problems were then established. Moreover, we will move on to the system involving nonlocal conditions. Finally, an example is provided in support of the main results we acquired

Audition in vampire bats, Desmodus rotundus

1. Within the tonotopic organization of the inferior colliculus two frequency ranges are well represented: a frequency range within that of the echolocation signals from 50 to 100 kHz, and a frequency band below that of the echolocation sounds, from 10 to 35 kHz. The frequency range between these two bands, from about 40 to 50 kHz is distinctly underrepresented (Fig. 3B). 2. Units with BFs in the lower frequency range (10–25 kHz) were most sensitive with thresholds of -5 to -11 dB SPL, and units with BFs within the frequency range of the echolocation signals had minimal thresholds around 0 dB SPL (Fig. 1). 3. In the medial part of the rostral inferior colliculus units were encountered which preferentially or exclusively responded to noise stimuli. — Seven neurons were found which were only excited by human breathing noises and not by pure tones, frequency modulated signals or various noise bands. These neurons were considered as a subspeciality of the larger sample of noise-sensitive neurons. — The maximal auditory sensitivity in the frequency range below that of echolocation, and the conspicuous existence of noise and breathing-noise sensitive units in the inferior colliculus are discussed in context with the foraging behavior of vampire bats