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中国生物医学工程学会
北京玛格泰克科技发展有限公司
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2017 Vol. 26, No. 1
Published: 2017-03-01
1
Investigation of lnter and Intra-fractional Uncertainties in Lung IMRT Delivery
Maria Das KJ, Arpita Agarwal, Yoganathan SA, Gowtharu Raj D, Shaleen Kumar
Changes in the tumour position due to inter and intra-fractional motion introduce uncertainty in IMRT delivery. In this work, we experimentally evaluated the effect of inter and intra-fractional motion uncertainties in the IMRT delivery. A lung patient was planned with rive field dynamic IMRT for a total dose of 60 Gy in 30 fractions using 6 MV photon beam at a dose rate of 400 MU/min. The plan was delivered on varian CL2100CD linear accelerator with millennium 120 MLC for a single fraction and measured using IMRT MatriXX placed on Quasar motion platform, aligned with respect to isocentre for planar as well as point dose measurements. This measurement was summated for 30 fractions and taken as a reference. 30 measurements were performed for each inter-fractional, intra-fractional and combined effect. The setup errors (Mean+SD) used to simulate the inter-fractional displacements were RL: -0.10+0.27 mm, SI: 0.17+0.45 mm, AP: -0.04+0.38 mm and Rot: 0.02+0.86 degree. The intra-fractional motion was simulated using the motion platform parallel to the MLC leaf motion, for an amplitude of 1 cm and a period of 4 s. The planner fluence of inter, intra-fractional motion and combination of both was analyzed against the reference using gamma criteria of 3%/3 mm. Similarly, the point dose measurements were also compared. The maximum deviation in point dose during a single fraction was -3.8%, 3.1% and -5.9% for inter-fractional, intra-fractional and combined respectively. The same resulted in deviation of -0.4%, -0.3% and 0.1% respectively when summated for 30 fractions. The percentage of pixels failing the gamma criteria during a single fraction was 28.0%, 16.4% and 28.5% for inter-fractional, intra-fractional and combined respectively. The same revealed 11.4%, 12.4% and 19.2% respectively when summated. Though the point dose deviations were nullified over 30 fractions, the planner fluence variation was observed to be considerable.
2017 Vol. 26 (1): 1-4 [
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36
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5
Dynamical Complexity Analysis in a Model of Electroencephalogram
LI Chun-sheng, ZHANG Xue
This paper studies a dynamical model of electroencephalogram(EEG). By linearizing the EEG model conditions for the stability of equilibrium point are obtained. Choosing excitatory inputs as bifurcation parameters, numerical simulations show that the EEG model exhibits a series of complex dynamics, including limit cycle, periodic doubling bifurcation, periodic halving bifurcation, chaotic bands with periodic windows.
2017 Vol. 26 (1): 5-10 [
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49
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11
Frequency Following Response of Speech-ABR by Instantaneous Energy Spectrum
PENG Xian, HUANG Jiang-hua, LIANG Yong, WANG Tao
A frequency following response(FFR) of speech auditory brainstem response (speech-ABR) elicited by the speech syllable /da/ contains three distinct waves named as D, E and F, corresponding to the structure of the stimulus sound. The detection and characterization of FFRs are critical in the study and application of speech-ABRs. Conventional methods detect the latencies of the waves in time domain by measuring the maximal amplitudes of the waveform in the preset windows, which suffers the problem of low quality of FFR waves. In this paper, we defined an instantaneous energy (IE) spectrum based on empirical mode decomposition (EMD) method (EMD-IE method) to detect FFR and measured the latencies of the waves. The results reveal that the FFRs are mostly evident on the second layer of the IE spectra, which would benefit the detection and measurement of the FFRs in clinic.
2017 Vol. 26 (1): 11-16 [
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42
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17
Complex Frequency Features for TCD Signal Analysis
LIU Wei-xiang, WANG Tian-fu, CHEN Si-ping, LUO Laurence, WANG Xiao-yi
In this paper, we report on using pattern recognition techniques for embolic signal (ES) detection based on transcranial doppler ultrasound (TCD) audio data collected via machine EMS-9 (from Shenzhen Delicate Electronics, Co. Ltd). Firstly, we adopted complex discrete fourier transform to get spectra of audio recordings; secondly, we used principal component analysis (PCA) for the visualization of selected signals, which makes it easy and intuitive to verify whether a signal contains an embolic component; finally we designed the classifier with support vector machines (SVM) for detection. With contrast to traditional methods of ES detection systems, the proposed approach considers two channel signals from the audio data collected by single transducer, and there is no predefined features for classification. The primary experimental results on real data are promising.
2017 Vol. 26 (1): 17-23 [
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38
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24
Design of the Control System for Thermal Treatment via Fuzzy Logic PID
SONG Ming-yang, CAI Zhang-hao, BAI Jing-feng, SUN Jian-qi
In this paper, a cryosurgery-hyperthermia system is proposed for taking advantage of the alternated cooling and heating treatment in tumor. A novel control system is proposed to ensure that the thermal system works effectively. Firstly, the tissue temperature around the probe is regulated and kept in a desired range when radio frequency ablation is operated. Secondly, precise control of temperature is achieved in hyperthermia treatment using fuzzy logic PID type controller. The results of ex vivo liver experiment demonstrate that this system could provide a rather good performance with the proposed control method.
2017 Vol. 26 (1): 24-30 [
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44
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31
Evaluation of Muscle Fatigue Based on Surface Electromyography and Subjective Assessment
ZU Xiao-qi, LI Yun, ZHOU Qian-xiang
To investigate the relationship between surface electromyography and subjective assessment of muscle fatigue, 20 young male volunteers participated in the experiment of pistol holding and aiming. sEMG of the anterior deltoid was recorded during the entire process, while fatigue assessments (Borg scale) were collected every 30 s. We divided the signal into several parts and then octave band method was used to calculate mean energy of each part, an equation was derived based on the relationship between the mean energy of sEMG and Borg scale. The results showed that the degree of local muscle fatigue could be described by a cubic curve, and could be used to evaluate and monitor muscle fatigue.
2017 Vol. 26 (1): 31-37 [
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21
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38
The Improvement of ECG Parameter Estimation Obtained by Up-sampling 500 Hz Data
YU Si-si, LIU Hong-xing, SUN Xing-guo
Nowadays, numerous commercial electrocardiographs (ECG) have 500 Hz output sampling rate, i.e., 2 ms corresponding sampling interval. Medical workers who have no background of signal processing may worry about whether such low 500 Hz output sampling rate data could support high-precision estimation of electrocardiogram parameters by being up-sampled. With intention to clarify the problem to the medical workers, this paper takes some simulating experiment to illustrate it. The experiment chose the RR interval and R peak amplitude as representative parameters to be estimated. The obtained results were as follows: for RR interval parameter, its estimation error can be lowered to below 0.3 ms by up-sampling; for R peak amplitude, its estimation error can be reduced to below 2.0 μV by up-sampling. It is believed that other ECG parameter estimation can also be improved similarly by up-sampling 500 Hz data.
2017 Vol. 26 (1): 38-46 [
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29
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