• Title/Summary/Keyword: Control device

Search Result 5,498, Processing Time 0.041 seconds

A Study on People Counting in Public Metro Service using Hybrid CNN-LSTM Algorithm (Hybrid CNN-LSTM 알고리즘을 활용한 도시철도 내 피플 카운팅 연구)

  • Choi, Ji-Hye;Kim, Min-Seung;Lee, Chan-Ho;Choi, Jung-Hwan;Lee, Jeong-Hee;Sung, Tae-Eung
    • Journal of Intelligence and Information Systems
    • /
    • v.26 no.2
    • /
    • pp.131-145
    • /
    • 2020
  • In line with the trend of industrial innovation, IoT technology utilized in a variety of fields is emerging as a key element in creation of new business models and the provision of user-friendly services through the combination of big data. The accumulated data from devices with the Internet-of-Things (IoT) is being used in many ways to build a convenience-based smart system as it can provide customized intelligent systems through user environment and pattern analysis. Recently, it has been applied to innovation in the public domain and has been using it for smart city and smart transportation, such as solving traffic and crime problems using CCTV. In particular, it is necessary to comprehensively consider the easiness of securing real-time service data and the stability of security when planning underground services or establishing movement amount control information system to enhance citizens' or commuters' convenience in circumstances with the congestion of public transportation such as subways, urban railways, etc. However, previous studies that utilize image data have limitations in reducing the performance of object detection under private issue and abnormal conditions. The IoT device-based sensor data used in this study is free from private issue because it does not require identification for individuals, and can be effectively utilized to build intelligent public services for unspecified people. Especially, sensor data stored by the IoT device need not be identified to an individual, and can be effectively utilized for constructing intelligent public services for many and unspecified people as data free form private issue. We utilize the IoT-based infrared sensor devices for an intelligent pedestrian tracking system in metro service which many people use on a daily basis and temperature data measured by sensors are therein transmitted in real time. The experimental environment for collecting data detected in real time from sensors was established for the equally-spaced midpoints of 4×4 upper parts in the ceiling of subway entrances where the actual movement amount of passengers is high, and it measured the temperature change for objects entering and leaving the detection spots. The measured data have gone through a preprocessing in which the reference values for 16 different areas are set and the difference values between the temperatures in 16 distinct areas and their reference values per unit of time are calculated. This corresponds to the methodology that maximizes movement within the detection area. In addition, the size of the data was increased by 10 times in order to more sensitively reflect the difference in temperature by area. For example, if the temperature data collected from the sensor at a given time were 28.5℃, the data analysis was conducted by changing the value to 285. As above, the data collected from sensors have the characteristics of time series data and image data with 4×4 resolution. Reflecting the characteristics of the measured, preprocessed data, we finally propose a hybrid algorithm that combines CNN in superior performance for image classification and LSTM, especially suitable for analyzing time series data, as referred to CNN-LSTM (Convolutional Neural Network-Long Short Term Memory). In the study, the CNN-LSTM algorithm is used to predict the number of passing persons in one of 4×4 detection areas. We verified the validation of the proposed model by taking performance comparison with other artificial intelligence algorithms such as Multi-Layer Perceptron (MLP), Long Short Term Memory (LSTM) and RNN-LSTM (Recurrent Neural Network-Long Short Term Memory). As a result of the experiment, proposed CNN-LSTM hybrid model compared to MLP, LSTM and RNN-LSTM has the best predictive performance. By utilizing the proposed devices and models, it is expected various metro services will be provided with no illegal issue about the personal information such as real-time monitoring of public transport facilities and emergency situation response services on the basis of congestion. However, the data have been collected by selecting one side of the entrances as the subject of analysis, and the data collected for a short period of time have been applied to the prediction. There exists the limitation that the verification of application in other environments needs to be carried out. In the future, it is expected that more reliability will be provided for the proposed model if experimental data is sufficiently collected in various environments or if learning data is further configured by measuring data in other sensors.

The Characteristics and Significance of 'Wanpan Changgeuk' Written by Heogyu (허규 연출 '완판 창극'의 특징과 의의)

  • Kim, Kee-hyung
    • (The) Research of the performance art and culture
    • /
    • no.20
    • /
    • pp.5-30
    • /
    • 2010
  • It has been diversified and serious attempt to establish the identity of Changgeuk, but it is still independent dramaturgy or the current unformed progressive art. In this situation, exploring works of the identity of changgeuk that is base on the performed individual and specific works in the title of Changgeuk is needed. The 80s and 90s Heo, Gyu was leading an active life as a director who was responsible for directing of Changgeuk. He dramatized Siljeon Pansori -which is a group of Pansori missing text- as well as 5-remained Songs in Pansori and he presented a number of creative Changgeuk works on stage. Especially, the completion of dramatizing 5-remained Songs in Pansori under the name of 'Wanpan Changgeuk -which means full version performance without omit-' is the one of his big achievement by performing "Heungbojeon" on the stage 1982 and "Jeokbyeokga" 1985. The purposes of this research are confirmation of Heo's direction of the formulation and considering its characteristics & significance through 'Wanpan Changgeuk' which written by Heo. Heo was a practical play who was interested in the subjective formulation of national culture and creative transmission for Korean traditional performance. He tried to formulate Changgeuk to a representative performance of Korea. In the process he pointed out those problems, (1) interpretation of a work problem, (2) actor's creative problems, (3) structure problem of theater for Changgeuk. He indicated that the other challenges are to use of the stage & device, to overcome sentimentalism, to stylize acting, to improve own quality, to control the speed and length of the song, to choose the suitable musical accompaniment, to create new repertories problems, and etc. Changgeuk is classified in 3 group by origin, (1)dramatizing of 5-remained Songs, (2)dramatizing of 7-missing Songs, (3)creative dramatizing. It contains all of 3 types that Heo's work. The dramatizing of remained 5 Songs are the great importance among those works. Heo hoped that Chaggeuk has become the most representative art work of Korea by performing 'Wanpan Changgeuk' compiled heritage of Korea's outstanding artistic achievement. The characteristics of 'Wanpan Changgeuk' can be summarized following four. (1) Directing attitudes that emphasizes tradition, (2) Accepting the elements of traditional performance actively, (3) Valuing the classy and ethic, (4) Emphasizing humor and active utilizing of the secondary characters. Heo's 'Wanpan Changgeuk' shows a peak of the artistic level which Changgeuk can be reached. He want to make Changgeuk a Korean representative artistic performance by compiling Pansori heritage and accommodating Korean traditional performance. Heo continued his effort to present Pansori's authenticity and to dramatize from beginning to end without missing. It shows very well that 'Wanpan Changgeuk' takes 4~5 hours for playing. It looks Heo's achievement in the 'Wanpan Changgeuk' influenced Changgeuk significantly since then. Heo's 'Wanpan Changgeuk' is matrix of 'Wanpan JangMak Changgeuk' attempted in the 1990s. Especially, their intent is consistent to synthesize texts and to show all the virtue of Pansori. But 90's 'Wanpan JangMak Changgeuk' aim for large stage, fancy device & costume and variety contents compared with 'Wanpan Changgeuk'. Recently, producers have tried not to make a impressive Changgeuk but to make a interesting one. They usually organize performance within 2 hours and prefer orchestral music to its unique sound. In those point of view, it seems that Heo's idle in 'Wanpan Changgeuk' has become one of target to conquer in these days.

Depth Control and Sweeping Depth Stability of the Midwater Trawl (중층트롤의 깊이바꿈과 소해심도의 안정성)

  • 장지원
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.9 no.1
    • /
    • pp.1-18
    • /
    • 1973
  • For regulating the depth of midwater trawl nets towed at the optimum constant speed, the changes in the shape of warps caused by adding a weight on an arbitrary point of the warp of catenary shape is studied. The shape of a warp may be approximated by a catenary. The resultant inferences under this assumption were experimented. Accordingly feasibilities for the application of the result of this study to the midwater trawl nets were also discussed. A series of experiments for basic midwater trawl gear models in water tank and a couple of experiments of a commercial scale gears at sea which involve the properly designed depth control devices having a variable attitude horizontal wing were carried out. The results are summarized as follows: 1. According to the dimension analysis the depth y of a midwater trawl net is introduced by $$y=kLf(\frac{W_r}{R_r},\;\frac{W_o}{R_o},\;\frac{W_n}{R_n})$$) where k is a constant, L the warp length, f the function, and $W_r,\;W_o$ and $W_n$ the apparent weights of warp, otter board and the net, respectively, 2. When a boat is towing a body of apparent weight $W_n$ and its drag $D_n$ by means of a warp whose length L and apparent weight $W_r$ per unit length, the depth y of the body is given by the following equation, provided that the shape of a warp is a catenary and drag of the warp is neglected in comparison with the drag of the body: $$y=\frac{1}{W_r}\{\sqrt{{D_n^2}+{(W_n+W_rL)^2}}-\sqrt{{D_n^2+W_n}^2\}$$ 3. The changes ${\Delta}y$ of the depth of the midwater trawl net caused by changing the warp length or adding a weight ${\Delta}W_n$_n to the net, are given by the following equations: $${\Delta}y{\approx}\frac{W_n+W_{r}L}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}{\Delta}L$$ $${\Delta}y{\approx}\frac{1}{W_r}\{\frac{W_n+W_rL}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}-{\frac{W_n}{\sqrt{D_n^2+W_n^2}}\}{\Delta}W_n$$ 4. A change ${\Delta}y$ of the depth of the midwater trawl net by adding a weight $W_s$ to an arbitrary point of the warp takes an equation of the form $${\Delta}y=\frac{1}{W_r}\{(T_{ur}'-T_{ur})-T_u'-T_u)\}$$ Where $$T_{ur}^l=\sqrt{T_u^2+(W_s+W_{r}L)^2+2T_u(W_s+W_{r}L)sin{\theta}_u$$ $$T_{ur}=\sqrt{T_u^2+(W_{r}L)^2+2T_uW_{r}L\;sin{\theta}_u$$ $$T_{u}^l=\sqrt{T_u^2+W_s^2+2T_uW_{s}\;sin{\theta}_u$$ and $T_u$ represents the tension at the point on the warp, ${\theta}_u$ the angle between the direction of $T_u$ and horizontal axis, $T_u^2$ the tension at that point when a weights $W_s$ adds to the point where $T_u$ is acted on. 5. If otter boards were constructed lighter and adequate weights were added at their bottom to stabilize them, even they were the same shapes as those of bottom trawls, they were definitely applicable to the midwater trawl gears as the result of the experiments. 6. As the results of water tank tests the relationship between net height of H cm velocity of v m/sec, and that between hydrodynamic resistance of R kg and the velocity of a model net as shown in figure 6 are respectively given by $$H=8+\frac{10}{0.4+v}$$ $$R=3+9v^2$$ 7. It was found that the cross-wing type depth control devices were more stable in operation than that of the H-wing type as the results of the experiments at sea. 8. The hydrodynamic resistance of the net gear in midwater trawling is so large, and regarded as nearly the drag, that sweeping depth of the gear was very stable in spite of types of the depth control devices. 9. An area of the horizontal wing of the H-wing type depth control device was $1.2{\times}2.4m^2$. A midwater trawl net of 2 ton hydrodynamic resistance was connected to the devices and towed with the velocity of 2.3 kts. Under these conditions the depth change of about 20m of the trawl net was obtained by controlling an angle or attack of $30^{\circ}$.

  • PDF

Standard Chemotherapy with Excluding Isoniazid in a Murine Model of Tuberculosis (마우스 결핵 모델에서 Isoniazid를 제외한 표준치료의 예비 연구)

  • Shim, Tae Sun;Lee, Eun Gae;Choi, Chang Min;Hong, Sang-Bum;Oh, Yeon-Mok;Lim, Chae-Man;Lee, Sang Do;Koh, Younsuck;Kim, Woo Sung;Kim, Dong Soon;Cho, Sang-Nae;Kim, Won Dong
    • Tuberculosis and Respiratory Diseases
    • /
    • v.65 no.3
    • /
    • pp.177-182
    • /
    • 2008
  • Background: Isoniazid (INH, H) is a key drug of the standard first-line regimen for the treatment of tuberculosis (TB), yet some reports have suggested that treatment efficacy was maintained even though INH was omitted from the treatment regimen. Methods: One hundred forty C57BL/6 mice were infected with the H37Rv strain of M. tuberculosis with using a Glas-Col aerosol generation device, and this resulted in depositing about 100 bacilli in the lung. Four weeks after infection, anti-TB treatment was initiated with varying regimens for 4-8 weeks; Group 1: no treatment (control), Group 2 (4HREZ): 4 weeks of INH, rifampicin (R), pyrazinamide (Z) and ethambutol (E), Group 3: 1HREZ/3REZ, Group 4: 4REZ, Group 5: 4HREZ/4HRE, Group 6: 1HREZ/3REZ/4RE, and Group 7: 4REZ/4RE. The lungs and spleens were harvested at several time points until 28 weeks after infection, and the colony-forming unit (CFU) counts were determined. Results: The CFU counts increased steadily after infection in the control group. In the 4-week treatment groups (Group 2-4), even though the culture was negative at treatment completion, the bacilli grew again at the 12-week and 20-week time points after completion of treatment. In the 8-week treatment groups (Groups 5-7), the bacilli did not grow in the lung at 4 weeks after treatment initiation and thereafter. In the spleens of Group 7 in which INH was omitted from the treatment regimen, the culture was negative at 4-weeks after treatment initiation and thereafter. However, in Groups 5 and 6 in which INH was taken continuously or intermittently, the bacilli grew in the spleen at some time points after completion of treatment. Conclusion: TThe exclusion of INH from the standard first-line regimen did not affect the treatment outcome in a murine model of TB in the early stage of disease. Further studies using a murine model of chronic TB are necessary to clarify the role of INH in the standard first-line regimen for treating TB.

Normative blood pressure references for Korean children and adolescents (한국 소아 청소년 정상 혈압 참고치)

  • Lee, Chong Guk;Moon, Jin Soo;Choi, Joong-Myung;Nam, Chung Mo;Lee, Soon Young;Oh, Kyungwon;Kim, Young Taek
    • Clinical and Experimental Pediatrics
    • /
    • v.51 no.1
    • /
    • pp.33-41
    • /
    • 2008
  • Purpose : It is now understood that blood pressure (BP) measurement in the routine pediatric examination is very important because of the relevance of childhood BP to pediatric health care and the development of adult essential hypertension. There hasn't been a reference table of BP for Korean children and adolescents up to now. This study was to make normative BP references and to provide criteria of hypertension for Korean children and adolescents. Methods : BP measurements were done on 57,433 Koean children and adolescents (male: 29,443, female: 27,990), aged 7 to 20 years, in 2005. Heights and weights were measured simultaneously. Oscillometric devices, Dinamap Procare 200 (GE Inc., Milwaukee, Wi, USA), were used for the measurements. BPs were measured 2 times and mean levels were gathered for the analysis. Outliers of 2,373 subjects with overweight per height, over +3SD, were excluded for the analysis. For the BP centiles adjusted by sex, age and height, fixed modified LMS method which was adopted from the mixed effect model of 2004 Task Force in NHLBI (USA) was used. Results : Normative BP tables for Korean children and adolescents adjusted for height percentiles (5th, 10th, 25th, 50th, 75th, 90th, 95th), gender (male, female) and age(7 to 18 years) were completed. Height centiles of Korean children and adolescents are available from Korean Center for Disease Control and Prevention homepage, http://www.cdc.go.kr/webcdc/. Criteria of hypertension (95th, 99th percentile) and normal range of BP (50th, 90th) adjusted for height percentiles, age and gender were made. Conclusion : This is the first study to make normative BP tables and define hypertension for the Korean children and adolescents. Reliability and accuracy of Dinamap Procare 200 oscillometer for BP measurements remains debatable.

Oestrus Induction, Plasma Steroid Hormone Profiles and Fertility Response after CIDR and eCG Treatment in Acyclic Sahiwal Cows

  • Singh, Harpreet;Luthra, R.A.;Khar, S.K.;Nanda, Trilok
    • Asian-Australasian Journal of Animal Sciences
    • /
    • v.19 no.11
    • /
    • pp.1566-1573
    • /
    • 2006
  • The study was conducted on 30 true acyclic Sahiwal cows (15 cows, ${\geq}90$ days postpartum; 15 postpubertal heifers, ${\geq}30$ months of age) and a similar 20 untreated controls (10 cows, 10 heifers). An 'Eazi' breed Controlled Internal Drug Release (CIDR) device (containing 1.38 g progesterone) was inserted intravaginally for 7 days (days 0 to 7) followed by 500 IU eCG i.m. at CIDR removal in all the treated animals. Heifers also received 5 mg oestradiol valerate i.m at CIDR insertion. The reproductive performance of these animals was recorded in terms of oestrus induction response, conception and pregnancy rates. Plasma progesterone ($P_4$) and oestradiol-$17{\beta}$ ($E_2$) profiles of 4 representative animals from each treatment group before, during and after CIDR treatment were also monitored. An oestrus induction response of 100% was observed in treated cows and heifers. The majority of cows (53.3%) and heifers (60%) were induced to oestrus within 24-36 and 36-48 h, respectively after CIDR withdrawal; with mean intervals of $44{\pm}3.18$ and $48{\pm}2.35h$, respectively. The conception rate at induced oestrus was higher in cows (40%) than heifers (20%). The final pregnancy rates after 2 subsequent oestruses were 80 and 60% in cows and heifers, respectively (overall 70% for all treated animals). In comparison, only 10% of control animals (2 cows only, 2/20) showed oestrus and become pregnant (10%) during theentire study period. The pretreatment (day 0) mean plasma P4 levels were statistically (p>0.05) similar in cows and heifers ($0.40{\pm}0.04$ and $0.49{\pm}0.11ng/ml$, respectively). The peak $P_4$ levels were observed on day 1 in cows ($13.94{\pm}1.41ng/ml$) and day 2 in heifers ($19.15{\pm}3.30ng/ml$) with a progressive decline up to the day of CIDR withdrawal ($3.35{\pm}0.92$ and $8.79{\pm}1.71ng/ml$, respectively). Mean $P_4$ levels on day 9 and 10 in cows and heifers did not differ significantly from their respective day 0 values and the lowest values were recorded on day 10 both in cows and heifers ($0.13{\pm}0.03$ and $0.14{\pm}0.02ng/ml$, respectively). Wide variations in individual pretreatment $E_2$ levels were observed both in the cows (range = 4-26, mean = $13.00{\pm}4.65pg/ml$) and heifers (range = 10-14, mean = $11.50{\pm}0.96pg/ml$). Thereafter also, $E_2$ levels in cows showed variation and reached a peak level ($53.50{\pm}2.99pg/ml$) on day 8. In heifers, peak mean $E_2$ level ($111.25{\pm}39.81pg/ml$) was recorded on day 1, followed by a non-significant decline on day 2, a significant fall on day 6 and a non-significant increase on day 9 and 10. However, mean $E_2$ levels on days 7 (p<0.05), 8 and 9 (p<0.01) were significantly higher in cows compared to heifers. The post-CIDR withdrawal mean highest $P_4$ and lowest $E_2$ levels coincided with the period when the majority of animals were induced to oestrus. CIDR and eCG treatment resulted in effective induction of oestrus with satisfactory pregnancy rates in true acyclic Sahiwal cows and heifers.

Comparative evaluation for leaf position accuracy according to gantry angle variation in MLC quality assurance using electronic portal imaging device(EPID) and GafChromic EBT3 film (전자포탈영상장치(EPID)와 GafChromic EBT3 film을 이용한 다엽콜리메이터 정도관리 시 갠트리 각도 변화에 따른 엽의 위치 정확성 비교 평가)

  • Yang, Myung Sic;Park, Ju Kyeong;Lee, Seung Hun;Lee, Sun Young;Kim, Jung Soo;Kwon, Hyoung Cheol;Kim, Yang Su
    • The Journal of Korean Society for Radiation Therapy
    • /
    • v.29 no.2
    • /
    • pp.83-91
    • /
    • 2017
  • Objectives: The purpose of this study was to evaluate the error of the leaf position accuracy of the MLC due to the gravity effect according to the gantry angle by using picket fence test using EPID and GafChromic EBT3 film. Materials and Methods: A 5 cm solid phantom was placed on the table and the SAD was set to 100 cm. The EBT3 film was placed exactly over the solid phantom and covered a 1.5 cm solid phantom and the picket fence test was performed. The EPID was measured under the same conditions as the EBT3 film at SID 100 cm. The gantry angles were measured at $0^{\circ}$, $90^{\circ}$, $180^{\circ}$ and $270^{\circ}$ in order to evaluate the position of the MLC according to the gantry angle. For the geometric evaluation of the MLC, the leaf position accuracy of the MLC was analyzed using the analysis program. Results: In case of EPID, when the gantry angle was changed to $0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$, the difference of the position errors of the leaves was 0.18 mm, 0.31 mm, 0.20 mm, 0.26 mm on the average and the maximum values of the errors were respectively 0.44 mm, 0.54 mm, 0.34 mm, 0.44 mm. In case of EBT3 film, when the gantry angle was changed to $0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$, the difference of the position errors of the leaves was 0.19 mm, 0.21 mm, 0.19 mm, 0.31 mm on the average and the maximum values of the errors were respectively 0.35 mm, 0.45 mm, 0.36 mm, 0.48 mm. Conclusion: In this study, we analyzed the position error of the leaf of the MLC according to the gantry angle, and confirmed the position error of the leaf by gravity effect. As a result of comparing the leaf position accuracy using EPID and EBT3 film according to the variation of gantry angle, a larger error occurred in the error analysis method using EPID than that of EBT3 film. Therefore, in the case of IMRT based on MLC, as well as verification of accurate dosimetry should be conducted, it is considered that the quality control and verification for the precise operation of the MLC will be needed. and it is necessary to compare and verify the method of analysis.

  • PDF

A Polarization-based Frequency Scanning Interferometer and the Measurement Processing Acceleration based on Parallel Programing (편광 기반 주파수 스캐닝 간섭 시스템 및 병렬 프로그래밍 기반 측정 고속화)

  • Lee, Seung Hyun;Kim, Min Young
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.50 no.8
    • /
    • pp.253-263
    • /
    • 2013
  • Frequency Scanning Interferometry(FSI) system, one of the most promising optical surface measurement techniques, generally results in superior optical performance comparing with other 3-dimensional measuring methods as its hardware structure is fixed in operation and only the light frequency is scanned in a specific spectral band without vertical scanning of the target surface or the objective lens. FSI system collects a set of images of interference fringe by changing the frequency of light source. After that, it transforms intensity data of acquired image into frequency information, and calculates the height profile of target objects with the help of frequency analysis based on Fast Fourier Transform(FFT). However, it still suffers from optical noise on target surfaces and relatively long processing time due to the number of images acquired in frequency scanning phase. 1) a Polarization-based Frequency Scanning Interferometry(PFSI) is proposed for optical noise robustness. It consists of tunable laser for light source, ${\lambda}/4$ plate in front of reference mirror, ${\lambda}/4$ plate in front of target object, polarizing beam splitter, polarizer in front of image sensor, polarizer in front of the fiber coupled light source, ${\lambda}/2$ plate between PBS and polarizer of the light source. Using the proposed system, we can solve the problem of fringe image with low contrast by using polarization technique. Also, we can control light distribution of object beam and reference beam. 2) the signal processing acceleration method is proposed for PFSI, based on parallel processing architecture, which consists of parallel processing hardware and software such as Graphic Processing Unit(GPU) and Compute Unified Device Architecture(CUDA). As a result, the processing time reaches into tact time level of real-time processing. Finally, the proposed system is evaluated in terms of accuracy and processing speed through a series of experiment and the obtained results show the effectiveness of the proposed system and method.

A Study on Dosimetry for Small Fields of Photon Beam (광자선 소조사면의 선량 측정에 관한 연구)

  • 강위생;하성환;박찬일
    • Progress in Medical Physics
    • /
    • v.5 no.2
    • /
    • pp.57-68
    • /
    • 1994
  • Purpose : The purposes are to discuss the reason to measure dose distributions of circular small fields for stereotactic radiosurgery based on medical linear accelerator, finding of beam axis, and considering points on dosimetry using home-made small water phantom, and to report dosimetric results of 10MV X-ray of Clinac-18, like as TMR, OAR and field size factor required for treatment planning. Method and material : Dose-response linearity and dose-rate dependence of a p-type silicon (Si) diode, of which size and sensitivity are proper for small field dosimetry, are determined by means of measurement. Two water tanks being same in shape and size, with internal dimension, 30${\times}$30${\times}$30cm$^3$ were home-made with acrylic plates and connected by a hose. One of them a used as a water phantom and the other as a device to control depth of the Si detector in the phantom. Two orthogonal dose profiles at a specified depth were used to determine beam axis. TMR's of 4 circular cones, 10, 20, 30 and 40mm at 100cm SAD were measured, and OAR's of them were measured at 4 depths, d$\sub$max/, 6, 10, 15cm at 100cm SCD. Field size factor (FSF) defined by the ratio of D$\sub$max/ of a given cone at SAD to MU were also measured. Result : The dose-response linearity of the Si detector was almost perfect. Its sensitivity decreased with increasing dose rate but stable for high dose rate like as 100MU/min and higher even though dose out of field could be a little bit overestimated because of low dose rate. Method determining beam axis by two orthogonal profiles was simple and gave 0.05mm accuracy. Adjustment of depth of the detector in a water phantom by insertion and remove of some acryl pates under an auxiliary water tank was also simple and accurate. TMR, OAR and FSF measured by Si detector were sufficiently accurate for application to treatment planning of linac-based stereotactic radiosurgery. OAR in field was nearly independent of depth. Conclusion : The Si detector was appropriate for dosimetry of small circular fields for linac-based stereotactic radiosurgery. The beam axis could be determined by two orthogonal dose profiles. The adjustment of depth of the detector in water was possible by addition or removal of some acryl plates under the auxiliary water tank and simple. TMR, OAR and FSF were accurate enough to apply to stereotactic radiosurgery planning. OAR data at one depth are sufficient for radiosurgery planning.

  • PDF

Extra Dose Measurement of Differential Slice Thickness of MVCT Image with Helical Tomotherapy (토모테라피 치료 시 MVCT Image의 Slice Thickness 차이에 따른 선량 비교)

  • Lee, Byungkoo;Kang, Suman
    • Journal of the Korean Society of Radiology
    • /
    • v.7 no.2
    • /
    • pp.145-149
    • /
    • 2013
  • Helical Tomotherapy is an innovative means of delivering intensity modulated radiation therapy (IMRT) using a device that merges features of a linear accelerator and helical computed tomography (CT) scanner. Hereat, during helical tomotherapy process, megavoltage computed tomography (MVCT) image are usually used for guiding the precise set-up of patient before/after treatment delivery. But which would certainly increase the total dose for patients, this study was to investigate the imaging dose of MVCT using the cylindrical "Cheese" phantom on a tomotherapy machine. A set of cylindrical "Cheese" phantom was adopted for scanning with respectively pitch value (1, 2, 3 mm) with same number slice (10 slice), same length (approximately 9 cm) and phantom set-ups on the couch of tomotherapy system. The average MVCT imaging dose were measured using A1SL ion chamber inserted in the phantom with preset geometry. The MVCT scanning average dose for the cylindrical "Cheese" phantom was 2.24 cGy, 1.02 cGy, 0.81 cGy during respectively pitch value (pitch 1, 2, 3 mm) with same number slice (10 slice), and same length's average dose was 2.47 cGy, 1.28 cGy, 0.88 cGy respectively (pitch 1, 2, 3 mm). Two major parameters, the assigned pitch numbers and scanning length, where the most important impacts to the dose variation. The MVCT dose was inversely proportional to the CT pitch value. The results may provide a reliable guidance for proper planning design of the scanning region, which is valuable to help minimize the extra dose to patient. Questionnaires were distributed to Radiology departments at hospitals with 300 sickbeds throughout the Pohang region of North Gyeongsang Province concerning awareness and performance levels of infection control. The investigation included measurements of the pollution levels of imaging equipment and assistive apparatuses in order to prepare a plan for the activation of prevention and management of hospital infections. The survey was designed to question respondents in regards to personal data, infection management prevention education, and infection management guidelines.