Intensity Modulation Techniques Research Articles

IMPLEMENTATION OF VLC USING ERROR CORRECTING TURBO CODES

This work showcases the analysis of an efficient VLC applications using error correcting turbo codes. It demonstrates how device switching, audio signal transfer and light switching is done using VLC. Compared to the conventional radio signal transfer, it is quiet advantageous as visible light frequency doesn’t need to be licensed for certain frequency or bandwidth. Data transmission needs to be secured, while reducing the error rates. Here, for device switching and data transfer we use turbo codes to reduce the error rates in data transfer. The proposed sytem has transmitter and receiver. In transmitter the data is modulated onto visible light using intensity modulation techniques, at the receiver end, a photodiode captures modulated light and converts it back into electrical signal.

3D-conformal very-high energy electron therapy as candidate modality for FLASH-RT: A treatment planning study for glioblastoma and lung cancer.

Pre-clinical ultra-high dose rate (UHDR) electron irradiations on time scales of 100ms have demonstrated a remarkable sparing of brain and lung tissues while retaining tumor efficacy when compared to conventional dose rate irradiations. While clinically-used gantries and intensity modulation techniques are too slow to match such time scales, novel very-high energy electron (VHEE, 50-250MeV) radiotherapy (RT) devices using 3D-conformed broad VHEE beams are designed to deliver UHDR treatments that fulfill these timing requirements. To assess the dosimetric plan quality obtained using VHEE-based 3D-conformal RT (3D-CRT) for treatments of glioblastoma and lung cancer patients and compare the resulting treatment plans to those delivered by standard-of-care intensity modulated photon RT (IMRT) techniques. Seven glioblastoma patients and seven lung cancer patients were planned with VHEE-based 3D-CRT using 3 to 16 coplanar beams with equidistant angular spacing and energies of 100 and 200MeV using a forward planning approach. Dose distributions, dose-volume histograms, coverage (V95% ) and homogeneity (HI98% ) for the planning target volume (PTV), as well as near-maximum doses (D2% ) and mean doses (Dmean ) for organs-at-risk (OAR) were evaluated and compared to clinical IMRT plans. Mean differences of V95% and HI98% of all VHEE plans were within 2% or better of the IMRT reference plans. Glioblastoma plan dose metrics obtained with VHEE configurations of 200MeV and 3-16 beams were either not significantly different or were significantly improved compared to the clinical IMRT reference plans. All OAR plan dose metrics evaluated for VHEE plans created using 5 beams of 100MeV were either not significantly different or within 3% on average, except for Dmean for the body, Dmean for the brain, D2% for the brain stem, and D2% for the chiasm, which were significantly increased by 1, 2, 6, and 8Gy, respectively (however below clinical constraints). Similarly, the dose metrics for lung cancer patients were also either not significantly different or were significantly improved compared to the reference plans for VHEE configurations with 200MeV and 5 to 16 beams with the exception of D2% and Dmean to the spinal canal (however below clinical constraints). For the lung cancer cases, the VHEE configurations using 100MeV or only 3 beams resulted in significantly worse dose metrics for some OAR. Differences in dose metrics were, however, strongly patient-specific and similar for some patient cases. VHEE-based 3D-CRT may deliver conformal treatments to simple, mostly convex target shapes in the brain and the thorax with a limited number of critical adjacent OAR using a limited number of beams (as low as 3 to 7). Using such treatment techniques, a dosimetric plan quality comparable to that of standard-of-care IMRT can be achieved. Hence, from a treatment planning perspective, 3D-conformal UHDR VHEE treatments delivered on time scales of 100ms represent a promising candidate technique for the clinical transfer of the FLASH effect.

Dual-Hop Optical Communication Systems Over Málaga Turbulence Under Pointing Error Impairments With Decode-and-Forward Protocol

As a promising technology, free-space optical (FSO) communication plays an important role in the next generation of wireless communication. A dual-hop FSO communication system with decode-and-forward (DF) protocol is proposed in this paper, considering the influences of the atmospheric turbulence (AT), atmospheric absorption and pointing error impairments, in which the Málaga distribution model is used to characterize the fading caused by AT in each link. The end-to-end statistical expressions of our proposed dual-hop Málaga-Málaga communication system are derived, such as the cumulative distribution function (CDF), probability density function and moment generating function. Thereafter, using the above statistical results, the accurate end-to-end expressions of outage probability, average bit error rate (ABER) and ergodic capacity are deduced under the direct detection intensity modulation and heterodyne detection techniques. Furthermore, the end-to-end asymptotic expressions for CDF and the ABER at high signal-to-noise ratio as well as simplified expressions from simple basic functions are obtained. The effects of different AT and pointing error impairments conditions on the proposed system are analyzed based on theoretical and numerical results. Finally, Monte Carlo simulation results indicate that all our novel deduced expressions are basically consistent with the numerical results.

Performance improvement of FSO communication systems using hybrid-ARQ protocols.

In release 16 of the third-generation project partnership, it has been suggested that hybrid-automatic repeat request (H-ARQ) protocols can be used to ensure robust communications. In this paper, we incorporate H-ARQ in the free-space optical (FSO) communication systems to improve their performance and communication link reliability. We derive novel, to the best of our knowledge, closed-form expressions for the outage probability of the FSO systems under the combined impact of gamma-gamma distributed atmospheric turbulence and pointing errors (PEs) for heterodyne detection and intensity modulation and direct detection techniques. This is accomplished using various H-ARQ protocols, such as, at least once, chase combing, and incremental redundancy (INR). Further, using outage probability expressions, we calculate throughput for the FSO systems using H-ARQ protocols. Useful insights into the FSO system performance are obtained through the asymptotic analysis for the considered H-ARQ protocols and detection techniques. It is observed through the numerical results that H-ARQ with INR performs better than the other considered H-ARQ protocols. We also draw a comparison between the outage performance of an FSO system with boresight PE and without boresight PE.

Performance analysis of different intensity modulation techniques over atmospheric turbulent free-space optical channels.

In this paper, we introduce a comprehensive study of the performance of intensity modulation (IM) techniques over gamma-gamma (GG) distributed free-space optical (FSO) channels. We derive closed-form expressions for the average bit error rate (BER) of thermal-noise-limited FSO systems adopting various IM techniques. The effect of atmospheric turbulence is studied. Comparisons are presented in terms of the transmitted peak power to achieve a certain BER. Results show that on-off keying, pulse amplitude modulation, and expurgated pulse-position modulation (EPPM) provide superior performance compared to other IM techniques. In addition, a proposal to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) is introduced by adding another modulation layer of EPPM. A closed-form expression for the average BER of the proposed hybrid OFDM-EPPM technique over GG turbulent FSO channel is derived. Moreover, an expression for the outage probability of the FSO system adopting the proposed OFDM-EPPM technique is presented. Results are investigated and compared to those of traditional OFDM and hybrid OFDM with PPM (OFDM-PPM). It is shown that the hybrid OFDM-EPPM technique outperforms the hybrid OFDM-PPM technique for the same data rate. Moreover, the hybrid OFDM-EPPM technique allows higher data rates with lower PAPR values compared to those of the hybrid OFDM-PPM technique for the same number of time slots.

Performance evaluation and enhancement of the modified OOK based IM/DD techniques for hybrid fiber/FSO communication over WDM-PON systems

In this paper, we have studied the performance evaluation and enhancement of a wavelength-division-multiplexing (WDM) for the passive optical network (PON) in the hybrid fiber/free-space optical (HFFSO) communication system using the modified on–off keying (OOK) based intensity modulation and direct detection (IM/DD) techniques. This work describes the design and analysis of the 8-channels WDM based on the PON-HFFSO transmission system at 2.5 Gbps under different atmospheric turbulence (AT) conditions. Inter-channel crosstalk (ICC), fluctuation, amplified spontaneous emission noise, AT, and impairments are investigated in the paper. A hybrid fiber/WDM-FSO over the PON structure using IM/DD and OOK significantly improves reliability link and accessibility as well as data rate, also improves the system capacity; hence the proposed model will reduce power consumption while maintaining system efficiency. Both impairments and ICC are investigated here and the results are presented in the form of bit-error-rate (BER), transmission distances, the required optical power, and electrical signal-to-noise ratios (SNRs). The system uses the modified OOK based on IM/DD to implement adaptive and electrical SNRs detection thresholds. Numerical results show that the SNR gap between the electrical-SNR-optimized detection system and adaptive detection system is 2.2 dB and 4.2 dB at a BER of 10−5 without a state offset ξ = 0 and ξ = 0.21, respectively. The proposed model enhances performance in terms of BER and electrical SNRs. An improvement in the power penalty of 2.0–4.0 dB at a BER of 10−12 can be potentially achieved using the modified OOK technique when impaired by the weak turbulence.

Performance Analysis of Intensity Modulation Techniques in Atmospheric Turbulent Channels

In this paper, we introduce a study for the performance of intensity modulation (IM) techniques over gamma-gamma (GG) distributed free-space optical (FSO) channels. We derived closed form expressions for the average bit-error rate (BER) of thermal noise-limited FSO systems adopting various IM techniques. The effects of the atmospheric turbulence and the propagation wavelength are studied. A comparison among different IM techniques in term of transmitted peak power to achieve certain BER is presented. Results show that OOK has the best BER compared with other IM techniques. In addition, according to peak power, PPM and MPPM are more power efficient than DPPM and DMPPM, respectively.

Comparison of dosimetric radiotherapy of whole left- breast cancer using conventional tangential wedge-based techniques (CTT) and three intensity modulation techniques (IMRT)

Introduction: Whole breast radiotherapy after breast-conserving surgery decrease the risk of local recurrence. this study investigates the dosimetric aspects of intensity modulated radiotherapy (IMRT) compared to conventional tangential wedge-based beams techniques (CTT) of the whole breast in early stages breast cancer patients. Materials and Methods: Computed tomography images of 35 patients with left sided breast cancer used for whole breast radiotherapy planning were examined. They were planned using four different radiotherapy technique, 1) conventional tangential wedge-based beams techniques (CTT); 2) six beams intensity modulated radiotherapy (IMRT-6F); 3) seven beams intensity modulated radiotherapy (IMRT-7F); and 4) nine beams intensity modulated radiotherapy (IMRT-9F). The PTV dose prescribed was 50 Gy in 25 fractions and V47.5 ≥ 95%. Dose distribution of PTV and OARs, the homogeneity index (HI), and conformity index (CI) were measured and compared to each other. Results: All of the IMRT plans improved CI (CTT: 0.93 ± 0.019; IMRT-6F: 0.95 ± 0.016; IMRT-7F: 0.96 ± 0.014; IMRT-9F: 0.97 ± 0.010), HI (CTT: 0.21 ± 0.021; IMRT-6F: 0.17 ± 0.013; IMRT-7F: 0.16 ± 0.014; IMRT-9F: 0.15 ± 0.018), mean dose PTV (CTT: 50.88 ± 0.48Gy; IMRT-6F: 51.93 ± 0.37Gy; IMRT-7F: 51.99 ± 0.38Gy; IMRT-9F: 52.14 ± 0.33Gy) and significantly increase volume of ipsilateral lung receiving more than 5Gy and 20Gy (V5Gy - V20Gy) (CTT: 20.05 – 12.69; IMRT-6F:41.69 -16.59; IMRT-7F: 42.13 – 16.74; IMRT- 9F: 48.284 - 17.26) too increase mean dose of Heart (CTT: 6.61 ± 1.47Gy; IMRT-6F: 6.33 ± 1.55Gy; IMRT- 7F: 7.35 ± 2.83Gy; IMRT-9F: 8.35 ± 3.64Gy) compared to CTT. Mean dose of contralateral Breast and contralateral Lung too increase than CTT. Conclusion: From the dosimetric point of view, the IMRT plans were not significantly advantageous over the 3DCRT plans. IMRT produces better the homogeneity and conformity index of the PTV, but increase low doses to OARs.

Performance Evaluation of High Speed Multicarrier System for Optical Wireless Communication

Optical wireless communication (OWC) in the infrared and visible range is quite impressive solution, especially where radio communication face challenges. Visible light communication (VLC) uses visible light over a range of 400 and 800 THz and is a subdivision of OWC technologies. With an increasing demand for use of wireless communications, wireless access via Wi-Fi is facing many challenges especially in terms of capacity, availability, security and efficiency. VLC uses intensity modulation and direct detection (IM/DD) techniques and hence they require the signals to certainly be real valued positive sequences. These constraints pose limitation on digital modulation techniques. These limitations result in spectrum-efficiency or power-efficiency losses. In this paper, we investigate an amplitude shift keying (ASK) based orthogonal frequency division multiplexing (OFDM) signal transmission scheme using LabVIEW for VLC technology.

A digitized universal filtered orthogonal frequency division multiplexing for next generation communication applications

Universal filtered orthogonal frequency division multiplexing (UF-OFDM) is an alluring next generation 5G waveform for communication with small bursts transmission. Moreover, there are arising applications in which short data packet transmissions are awaited to carry fault-finding messages that must be obtained with low latency and high reliability. Visible light communication (VLC) acts as an ideal technology to accomplish these requirements. VLC uses intensity modulation and direct detection techniques and hence they require the signals to certainly be real valued positive sequences. In this paper, a digitized UF-OFDM based on delta sigma modulation (DSM) is proposed. The implementation of the proposed digital UF-OFDM is analyzed in comparison with continuous-time domain representation of UF-OFDM (CT-UF-OFDM). The simulation result exhibits that the system which is projected has better SNR performance than the digitized OFDM. It is found that around 15.8 dB of SNR is improved using the proposed scheme as compared to digital OFDM.

Chemoradiotherapy versus surgery followed by postoperative radiotherapy in tonsil cancer: Korean Radiation Oncology Group (KROG) study

BackgroundTreatment of tonsil cancer, a subset of oropahryngeal cancer, varies between surgery and radiotherapy. Well-designed studies in tonsil cancer have been rare and it is still controversial which treatment is optimal. This study aimed to assess the outcome and failure patterns in tonsil cancer patients treated with either approaches.MethodsWe retrospectively reviewed medical records of 586 patients with tonsil cancer, treated between 1998 and 2010 at 16 hospitals in Korea. Two hundred and one patients received radiotherapy and chemotherapy (CRT), while 385 patients received surgery followed by radiotherapy and/or chemotherapy (SRT). Compared with the SRT group, patients receiving CRT were older, with more advanced T stage and received higher radiotherapy dose given by intensity modulation techniques. Overall survival (OS), disease-free survival (DFS), locoregional recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS), and clinicopathologic factors were analyzed.ResultsAt follow-up, the 5-year OS, DFS, LRRFS and DMFS rates in the CRT group were 82, 78, 89, and 94%, respectively, and in the SRT group were 81, 73, 87, and 89%, respectively. Old age, current smoking, poor performance status, advanced T stage, nodal involvement, and induction chemotherapy were associated with poor OS. Induction chemotherapy had a negative prognostic impact on OS in both treatment groups (p = 0.001 and p = 0.033 in the CRT and SRT groups, respectively).ConclusionsIn our multicenter, retrospective study of tonsil cancer patients, the combined use of radiotherapy and chemotherapy resulted in comparable oncologic outcome to surgery followed by postoperative radiotherapy, despite higher-risk patients having been treated with the definitive radiotherapy. Induction chemotherapy approaches combined with either surgery or definitive radiotherapy were associated with unfavorable outcomes.

A novel approach to generate a chirp microwave waveform using temporal pulse shaping technique applicable in remote sensing application

ABSTRACTMicrowave photonics is a prominent field in which photonic technologies are used to empower and extend the functionalities of microwave system which is a very tough exercise to fulfil directly in microwave domain. A photonic technique to generate a high chirp rate arbitrary microwave waveform using dual-drive LiNbO3 has been put forward and demonstrated experimentally in this paper. Nowadays in order to increase the Range-Doppler resolution of radar, the chirp microwave waveform is widely used. The Mach-Zehnder modulator (MZM) performs the intensity modulation techniques which can operate on the principle of electro-optic effect. In this paper, the authors used a very simple and straightforward method of producing chirped arbitrary millimetre waveform by change in phase at the two arms of dual-drive LiNbO3 MZM. The generated waveform has the 3 dB bandwidth of 12.6 GHz which exists in extremely high-frequency band applicable in high-frequency microwave radio relay, microwave remote sensing, radar range resolution and millimetre wave scanner. The proposed design is simpler, cost-effective and compact than the previously proposed model of chirped waveform generation using MZM and fibre Bragg grating.

Comparison of spinal Stereotactic Body Radiotherapy (SBRT) planning techniques: intensity-modulated radiation therapy, modulated arc therapy, and helical tomotherapy

Stereotactic body radiotherapy (SBRT) delivers a highly conformal, hypofractionated radiation dose to a small target with minimal radiation applied to the surrounding areas. Therefore, using the proper treatment planning techniques for SBRT is important. Intensity modulation techniques, such as static intensity-modulated radiation therapy (IMRT), modulated arc therapy (mARC), and helical tomotherapy (HT), are useful for spinal SBRT because of a rapid dose fall-off and spinal cord avoidance. This study compared the planning characteristics for hypofractionated spinal SBRT administered using 3 treatment techniques. The factors evaluated for spinal SBRT planning were dose coverage, cord avoidance, target conformity, homogeneity, and dose spillage. Target coverage was 82.74% ± 3.35%, 80.92% ± 0.81%, and 85.01% ± 7.27% for IMRT, mARC, and HT, respectively. HT was therefore a powerful technique with respect to target coverage. The spinal cord dose for HT (mean, 1763.96 cGy; standard deviation [SD], 164.48) was significantly different from those for mARC (mean, 1991.75 cGy; SD, 248.00) and IMRT (mean, 2053.24 cGy; SD, 164.48). In addition, the partial spinal cord volume at 2000 cGy for HT (mean, 0.12 cc, SD, 0.01) was significantly different from those for IMRT and mARC (0.50 ± 0.10 cc and 0.56 ± 0.25 cc, respectively). The conformity index was 1.30 ± 0.12, 1.08 ± 0.05, and 1.36 ± 0.23 for IMRT, mARC, and HT planning, respectively. mARC showed the highest conformity (p = 0.000). HT used a narrow field fan beam and exhibited remarkable improvement of target coverage and cord dose, offering an important benefit to spinal SBRT. mARC had the highest target conformity and better high- and intermediate-dose spillage than HT and IMRT did, respectively. These planning techniques have different advantages. In the case of spine SBRT, HT should be used for cord avoidance. In some cases, such as for a short treatment duration when the patient is considered to be in a poor general condition, mARC can be used.

Comparison between intensity modulation techniques in the prostate cancer treatment

Introduction Comparison between VMAT and IMRT, in terms of plan quality is great topic discussion in literature. Purpose Aim of this work is to assess VMAT dosimetric results compared to IMRT ones on prostate site. Materials and methods A comparison was made between IMRT and VMAT plans on the first 30 consecutive patients treated with VMAT moderately hypofractionated radiotherapy: 70.2 Gy/26 fractions of 2.7 Gy. IMRT and VMAT plans were elaborated by TPS Elekta Monaco® using a rabiobiological optimization approach. Plans were compared by evaluating D 105% , D 95% , D 93% , D 90% , D mean and D 0.5% for the PTV coverage, while for Organs at Risk (OARs), in addition to D mean and D 0.5% , the % of organ receiving 57, 61, 65.8 and 68.4 Gy (rectum), 57, 61, 65.8 and 68.4 (bladder), 35, 39.5 and 43.9 Gy (femoral heads) were considered of interest. Results Dosimetric analysis shows that PTV coverage is better with VMAT technique and that PTV D mean is higher than about 1 Gy in VMAT treatments: median value for the PTV D mean was 70,6 Gy in VMAT technique vs 69,7 Gy in IMRT. Regarding OARs sparing, VMAT technique offers a higher sparing of bladder (of about 5% of volume at 57,61 and 65 Gy) and femoral heads (of about 15% of volume at 30 Gy). Conclusions Respect to IMRT, VMAT offers higher plan quality with a better PTV coverage. Regarding OARs, VMAT offers higher sparing of bladder and femoral heads. Besides, VMAT is able to provide a considerable reduction in treatment time offering a better delivery efficiency.

EP-1664: Comparison between intensity modulation techniques in prostate cancer treatment

EP-1664: Comparison between intensity modulation techniques in prostate cancer treatment

Dosimetric study of volumetric arc modulation with RapidArc and intensity-modulated radiotherapy in patients with cervical cancer and comparison with 3-dimensional conformal technique for definitive radiotherapy in patients with cervical cancer

IntroductionFor patients with cervical cancer, intensity-modulated radiation therapy (IMRT) improves target coverage and allows dose escalation while reducing the radiation dose to organs at risk (OARs). In this study, we compared dosimetric parameters among 3-dimensional conformal radiotherapy (3D-CRT), “step-and-shoot” IMRT, and volumetric intensity-modulated arc radiotherapy (VMAT) in a series of patients with cervical cancer receiving definitive radiotherapy. Computed tomography (CT) scans of 10 patients with histologically proven cervical cancer treated with definitive radiation therapy (RT) from December 2008 to March 2010 at our department were selected for this study. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated following the guidelines of the Gyn IMRT consortium that included cervix, uterus, parametrial tissues, and the pelvic nodes including presacral. The median age was 57 years (range: 30 to 85 years). All 10 patients had squamous cell carcinoma with Federation of Gynecology and Obstetrics (FIGO) stage IB-IIIB. All patients were treated by VMAT. OAR doses were significantly reduced for plans with intensity-modulated technique compared with 3D-CRT except for the dose to the vagina. Between the 2 intensity-modulated techniques, significant difference was observed for the mean dose to the small intestine, to the benefit of VMAT (p < 0.001). There was no improvement in terms of OARs sparing for VMAT although there was a tendency for a slightly decreased average dose to the rectum: − 0.65Gy but not significant (p = 0.07). The intensity modulation techniques have many advantages in terms of quality indexes, and particularly OAR sparing, compared with 3D-CRT. Following the ongoing technologic developments in modern radiotherapy, it is essential to evaluate the intensity-modulated techniques on prospective studies of a larger scale.

Personalized Radiation Therapy of Breast Cancers May Not Incur Substantial Increase in Treatment Delivery Time

A retrospective investigation was performed examining the treatment delivery time for breast cancer patients treated in our clinics. We hypothesized that the use of highly personalized radiation treatments of breast cancers might increase treatment delivery time substantially. We identified patients with breast cancers who completed non-IMRT tangential beam radiation therapy (RT) in the last three years. All patients received a whole breast radiation dose of 45-50 Gy at 1.8-2.0 Gy/fraction or 42.5 Gy at 2.66 Gy/fraction. Boost treatments to the tumor bed were excluded in this study. Personalizing treatment plans based on each individual’s normal tissue and tumor anatomy for optimal target coverage and critical organ sparing required using various numbers of radiation fields, beam energies, intensity modulation techniques and active breathing control (ABC). Resulting costs in delivering the plans were evaluated in terms of the time spent to complete each treatment fraction through the course. We measured the time spent on individual fractions by determining the total time from the moment the first treatment field was beamed on to the completion of last treatment field (averaged over all fractions). Treatment delivery records of 253 patients were analyzed, of whom 69% (N = 175) received radiation to whole breast (WB) only, 18% (N = 45) to WB plus axillary nodes (WB+Ax), 4% (N = 10) to WB plus internal mammary nodes (WB+IM), and 9% (N = 23) to WB plus axillary and IM nodes (WB+Ax+IM). Timing records for a total of 6,808 delivered fractions were analyzed to obtain the average treatment times. 27% (N = 69) of the studied patients were treated with ABC, of whom, those receiving RT to WB only had treatment times of 4.2±0.2, 4.7±0.3, 5.3±0.4, and 5.6±0.4 min respectively corresponding to 5 through 8 radiation fields treated, while those receiving RT to WB+Ax had a treatment time of 9.9±2.5 min. In the non-ABC group, patients receiving RT to WB only had treatment times of 2.9±0.3, 3.3±0.7, 3.7±0.4, 4.1±0.6, 4.5±0.9, 4.4±0.3, and 5.2±0.9 min respectively for 2 to 8 treatment fields used. Those receiving RT to WB+Ax, WB+IM or WB+Ax+IM had treatment times of 7.5±2.2, 7.4±2.8, and 13.2±3.1 min respectively. Among patients who were treated to WB only, the treatment times were 4.0±0.9 and 4.9±0.6 min for the non-ABC and ABC groups, respectively. For patients treated to WB+Ax, WB+IM or WB+Ax+IM, the average treatment times were respectively 8.3±2.3, 7.4±2.8, and 13.2±3.1 min. The average time required to deliver individual treatment fraction increases with the number of radiation fields used. The maximum increment is less than two and half minutes per fraction, which will not significantly impact overall clinical throughput. A time increment of similar magnitude is also observed in patients treated with ABC compared to those without ABC.

Design and Construction Optical Fiber Sensor System for Detection the Stress and Fine Motion

Two main concepts in design and construction of stress and fine motion detection system using fiber optic sensor was included in this project. The first is design and construction concept using Intensity Modulation techniques using plastic multimode optical fiber(125μm dim)and has N A (0.27) with losses rate (2.1 db)and directionality about(25 db),and we used (He-Ne)laser source(632.8 nm)with (LLM-2 light power meter) to detect the variation in output laser power due to micro-displacement for movement body under test. The second concept include Modeling for laser beam tracking through fiber and that which reflected for mirror to detector. Variation in output power due to target movement was theoretical analyzed from study of variation of Gaussian front wave profile of using (MATLAB) program within displacement range from(0-5 mm).Non-linear relation between separated distance and beam intensity was investigated. Finally our design are evaluated in comporizim with published research which found compatible in Theoretical and experimental results.

Design and Construction Optical Fiber Sensor System for Detection the Stress and Fine Motion

Two main concepts in design and construction of stress and fine motion detection system using fiber optic sensor was included in this project. The first is design and construction concept using Intensity Modulation techniques using plastic multimode optical fiber(125μm dim)and has N A (0.27) with losses rate (2.1 db)and directionality about(25 db),and we used (He-Ne)laser source(632.8 nm)with (LLM-2 light power meter) to detect the variation in output laser power due to micro-displacement for movement body under test. The second concept include Modeling for laser beam tracking through fiber and that which reflected for mirror to detector. Variation in output power due to target movement was theoretical analyzed from study of variation of Gaussian front wave profile of using (MATLAB) program within displacement range from(0-5 mm).Non-linear relation between separated distance and beam intensity was investigated. Finally our design are evaluated in comporizim with published research which found compatible in Theoretical and experimental results.

Implementation of interrogation systems for fiber Bragg grating sensors

The development of two simple methods for wavelength-optical intensity modulation techniques for fiber Bragg grating (FBG) sensors is presented. The performance is evaluated by measuring the strain and temperature. The first method consists of a narrow band source, an optical circulator, an FBG, and a power meter. The source and Bragg reflected signal from the FBG need to be matched to get linear results with good power levels. The source spectral power levels are very critical in this study. The power reflected from a matched reference FBG is fed into the measuring FBG in the second method. Since the FBGs are matched, the entire power is reflected back initially. During the measurement, the change in the measurand causes the reflected power from the sensing FBG to vary. A costly high resolution spectrum analyzer is required only during the characterization of the FBG and source. The performances of two interrogators are compared by measuring the strain and temperature. In the second method, the strain measurements can be made insensitive to the temperature variation by selecting a source with a flat spectrum at the measurement range. Highlights of these methods are the portability, cost effectiveness and better resolution.