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Dosimetric Impact of Inter-Fraction Variation in Interstitial HDR Brachytherapy

International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2013年第4期2卷 111-116页

作者： Saravanan Kandasamy K. S. Reddy vivekanandan nagarajan Parthasarathy Vedasoundaram Gunaseelan Karunanidhi Department of Radiotherapy Regional Cancer Centre Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry India Department of Radiotherapy Regional Cancer Centre Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry India Medical Physics Department Cancer Institute (WIA) Chennai India

Background: Patient setup errors in External Beam Radiotherapy (EBRT) are minimized to a great extent, due to recent technological developments but in contrary brachytherapy received least attention in inter-fraction catheter movement and its impact in dose delivery. This article deals with inter-fraction interstitial catheter movement and its impact in dose delivery to the target. An attempt is made to study the dosimetric impact of this variation. Objectives: The objective of the study is to evaluate the inter-fraction variation in the position of implanted interstitial applicators and to assess the dosimetric impact in interstitial High Dose Rate (HDR) brachytherapy. Materials and Methods: 55 patients treated for carcinoma tongue, breast, buccal mucosa, cervix, floor of mouth and soft tissue sarcoma over a period of 2 years (December 2011-May 2013) were considered. All the patients underwent CT scan on the next day of the implant and 3D planning was done either by Eclipse or Oncentra Master plan Treatment Planning System (TPS). Patients were treated by HDR brachytherapy remote after-loading units, either by Gamma Med iX plus or Microselectron. At the end of the last fraction, CT scan was repeated and re-planning done. The variation in position of the implanted applicators/catheters and its impact on dosimetric parameters were evaluated and analyzed. Results: The range of positional displacement of the interstitial catheters ranges from 4.5 mm to 6.8 mm. The maximum variation in prescribed dose to D90 of Clinical Target Volume was 10.88%. Conclusions: If the total duration of interstitial implant of HDR brachytherapy extends for more than a week from the day of imaging, it is recommended to do CT imaging and re-plan again. It is mandatory to suture the buttons of the implant to the skin. Edema and movement of organs (e.g., tongue) are the main cause for the positional variation of the catheters.

关键词： HDR Brachytherapy Interstitial Implant Inter-Fraction Variation Dosimetric Variation

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Postmastectomy Scar Boost Irradiation Using HDR Surface Mould Brachytherapy by 3D Image-Based Volume Optimization

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2013年第4期2卷 139-146页

作者： Neelakandan Vijayaprabhu Karunanithi Gunaseelan nagarajan vivekanandan Nagamuthu Karthik Cholayil Shamsudheen K. S. Reddy Department of Medical Physics Anna University Chennai India Department of Medical Physics Cancer Institute (WIA) Chennai India Department of Radiotherapy Regional Cancer Center Jawharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry India

Introduction: During postmastectomy radiotherapy (PMRT), it is recommended to boost the postmastectomy surgical scar with additional 10 Gy in 5 fractions in the patients with close or positive surgical margins. The electron beam therapy, though cumbersome, is usually preferred since it has the desired rapid fall of a dose beyond R85. An alternative but easier and reproducible treatment method for PMRT surgical scar boost using 3D CT image-based HDR surface mould brachytherapy is introduced and analyses of the target coverage and dose nearby organs-at-risk (OARs) using this method are evaluated in this study. Methods and Materials: This study includes twelve patients (five left-sided and seven right-sided chest wall), who were planned and treated with CT-image based surface mould HDR brachytherapy for chest wall scar boost (CWB) using Catheter Flap SetTM (Varian Medical Systems, USA) that were given concurrently during external beam radiotherapy (EBRT) treatments. Since no guidelines are available for delineating clinical target volume (CTV) structure to be used for postmastectomy scar boost, the CTV in this study was a uniform 5-mm thick volume drawn at 5 mm beneath the skin (CTVhdr_evl) and its extent was made conforming to the boost area marked on the skin and made visible in CT images by radiopaque wires. Results: Prescribed dose (PD) to CTVhdr_evl is 7.5 Gy in 3 fractions, and 2.5 Gy per fraction. The CTVhdr_evl volume receives the PD with mean V100%, V98% and V95% values which are 98.57%, 99.63% and 100% respectively. The mean dose for heart (MHD) is 2.71 Gy in left-sided CWB and 1.80 Gy in right-sided CWB plans. Mean lung dose (MLD) is 2.48 Gy for ipsilateral lung and 0.76 Gy for contralateral lung. Maximum dose to contralateral breast is 4.93 Gy and the mean dose is 0.79 Gy. The mean percent dose to the skin volume overlying the CTVhdr_evl is 138.6% and 3.7% of skin volume received 200% of the PD. Conclusion: The 3D image-based HDR surface mould achieved good

关键词： Postmastectomy Radiation Surgical Scar Boost HDR Surface Mould Catheter Flap

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Inter-Fraction and Intra-Fraction Variation in the Absorbed-Dose Delivery during Interstitial High Dose Rate Brachytherapy—A Study Using MicroMOSFET <i>In-Vivo</i>Dosimeter

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2017年第4期6卷 445-456页

作者： Seenisamy Ramapandian vivekanandan nagarajan Ashutosh Mukherji Parthasarathy Vedasoundaram K. S. Reddy Vivekanandam Singhavajala Vijayaprabhu Neelakandan Department of Radiotherapy RCC JIPMER Pondicherry India Department of Medical Physics Cancer Institute Chennai India Department of Oncology MGMC & RI Puducherry India

Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, inter-fraction and inter-application variations. In-vivo dosimetry is the direct method to monitor the radiation dose delivered to a patient during radiotherapy. In this study, assessment of the inter-fraction and intra-fraction variations in the interstitial Brachytherapy was done with microMOSFET. Aim: To analyze the inter-fraction variations in dose delivery during interstitial HDR Brachytherapy and to compare the measured point dose with the TPS-calculated point dose, intra-fraction variation, using the microMOSFET in-vivo dosimeter. Materials and Methods: From May 2014 to February 2016, 22 patients with Head and Neck cancers and 8 patients with Soft-Tissue Sarcomas (STS) were selected for this study. All these patients underwent CT imaging more than 24 hours after the application. Brachyvision 3DTPS and GammaMed Plus iX HDR unit were used for treatments. MicroMOSFET in-vivo dosimeter after calibration was used for the measurements of dose inside the treated volume. Intra & Inter-fraction variations were analyzed and reported. Results: The SD of inter-fraction variation among 22 Head & Neck patients ranges from 2.14% to 14.26%. Minimum & maximum dose variation with first fraction dose of patients ranged from -22.33% to +26.71% and the mean doses were -6.42% to +19.76%. Differences of TPS dose and microMOSFET measured first fraction dose, intra-fraction variation, ranged from -12.36% to +5.05%. The SD of inter-fraction variation for 8 STS patients was from 2.81% to 14.43%. Minimum and maximum doses vary from -38.72% to +25.74% and mean dose varies from -21.5% to +12.53%. Differences of point doses of TPS and measured, intra-fraction variation, were from -5.86% to 4.88%. Conclusions: MicroMOSFET has the potential to minimize the gross errors during mul

关键词： MicroMOSFET Interstitial Brachytherapy MicroMOSFET in Brachytherapy In-Vivo Dosimetry in Brachytherapy Dose Verification in Brachytherapy

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An <i>In-Vivo</i>Study during Combined Intracavitary and Interstitial Brachytherapy of Gynaecological Malignancies Using microMOSFET

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2017年第2期6卷 162-173页

作者： Ramapandian Seenisamy vivekanandan nagarajan Ashutosh Mukherji Parthasarathy Vedasoundaram K. S. Reddy Vivekanandam Singhavajala Vijayaprabhu Neelakandan Department of Radiotherapy RCC JIPMER Puducherry India Department of Medical Physics Cancer Institute Adyar Chennai India Department of Oncology MGMC & RI Puducherry India

Aim: To analyze the inter-fraction, intra-fraction uncertainties and to verify the delivered total dose with planned dose in the combined intracavitary-interstitial brachytherapy of gynaecological cancer patients using microMOSFET in-vivo dosimeter. Materials and Methods: Between May 2014 and March 2016, 22 patients who underwent brachytherapy treatments with an applicator combination of CT/MR compatible tandem, ring and Syed-Neblett template-guided rigid needles were included in this study. Specially designed microMOSFET, after calibration, was used to analyze the variations in dosimetry of combined intracavitary-interstitial application. Results: The standard deviation for Inter-fraction variation among 22 combined intracavitary interstitial applications ranged between 0.86% and 10.92%. When compared with the first fraction dose, the minimum and maximum dose variations were −9.5% and 26.36%, respectively. However, the mean doses varied between −5.95% and 14.49%. Intra-fraction variation, which is the difference of TPS calculated dose with first fraction microMOSFET-measured dose ranges from −6.77% to 8.68%. The variations in the delivered total mean dose in 66 sessions with planned doses were −3.09% to 10.83%. Conclusions: It is found that there was a gradual increase in microMOSFET measured doses as compared to the first fraction with that of subsequent fractions in 19 out of 22 applications. Tumor deformation and edema may be the influencing factors, but the applicator movements played a major role for the variations. We find that the microMOSFET is an easy and reliable system for independent verification of uncertainties during ICBT-ISBT treatments.

关键词： microMOSFET Intra-Fraction Variations in Brachytherapy Inter-Fraction Variations in Brachytherapy Combined Intracavitary and Interstitial Brachytherapy In-Vivo Dosimetry in Brachytherapy Applicator Displacement Brachytherapy Uncertainties

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Synthesis and Crystal Structure of an Anionic Linear Trinuclear Copper(Ⅱ) Complex Containing 2-Thenoyltrifluoroacetonato and Acetato Ligands

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Chinese Journal of Structural Chemistry 2014年第1期33卷 19-26页

作者： LOGANATHAN nagarajan ROODT Andreas Department of Chemistry University of the Free State

A novel anionic trinuclear linear copper（II） complex {[Et3NH][Cul.5（CH3COO）- （TTA）3] } 2 （1, TTA = 2-thenoyltrifluoroacetonate） has been synthesized in a direct reaction involving copper（]l） acetate monohydrate, TTA and excess triethylamine base in dichloromethane solvent. Green colored X-ray quality crystals of 1 were grown from n-hexane solvent at room temperature. The data were collected at 100 K. Compound I crystallizes in the monoclinic P21/n space group （a = 11.2141（8）, b = 19.0965（13）, c = 17.3680（14） A, β = 90.225（2）°, V= 3719.3（5） A3, Mr = 1840.14, Dc = 1.643 Mg/m3, F（000） = 1866, μ = 1.129 mm^-1 and Z = 2）. The asymmetric unit of 1 contains two copper atoms, one of which lies on a crystallographic inversion center with 50% occupancy.

关键词： copper crystals acetate monoclinic 1,3-diketonates

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Facile synthesis and characterization of acetate intercalated Co-La layered double hydroxide

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Journal of Rare Earths 2017年第5期35卷 474-479页

作者： Meenakshi Pokhriyal Sitharaman Uma Rajamani nagarajan Materials Chemistry Group Department of Chemistry University of Delhi

Layered double hydroxide（LDH） comprising of Co^2＋ and La^3＋-ions with acetate counter anion was successfully synthesized by hydrogen peroxide catalyzed hydrolysis reaction and characterized extensively. The observed reflections in the powder X-ray diffraction pattern could be indexed in P3 space group with a=0.316 nm and c=2.97 nm. Lattice fringes of distances corresponding to the peaks observed in X-ray diffraction pattern were observed in high resolution transmission electron microscopic images. UV-visible diffuse reflectance spectroscopy results confirmed the presence of Co（OH）6 along with the presence of charge-transfer band due to the interlayer carboxylate anion. Magnetization measurements at room temperature indicated high spin configuration of Co^2＋-ion in the sample exhibiting paramagnetic behavior. The mixed metal oxide from calcination was used to reconstruct the parent layered structure. Intercalation experiments with other organic anions in Co-La LDH proved be successful.

关键词： layered acetate interlayer hydroxide hydrolysis anion calcination carboxylate reconstruct intercalation

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Design of Deep Reinforcement Learning Controller Through Data-assisted Model for Robotic Fish Speed Tracking

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Journal of Bionic Engineering 2023年第3期20卷 953-966页

作者： Palmani Duraisamy Manigandan nagarajan Santhanakrishnan Amirtharajan Rengarajan Robotics Lab School of EEESASTRA Deemed UniversityThanjavurTamil Nadu613401India Department of ECE School of EEESASTRA Deemed UniversityThanjavurTamil Nadu613401India

It is common for robotic fish to generate thrust using reactive force generated by the tail’s physical motion, which interacts with the surrounding fluid. The coupling effect of the body strongly correlates with this thrust. However, hydrodynamics cannot be wholly modeled in analytical form. Therefore, data-assisted modeling is necessary for robotic fish. This work presents the first method of its kind using Genetic Algorithm (GA)-based optimization methods for data-assistive modeling for robotic fish applications. To begin, experimental data are collected in real time with the robotic fish that has been designed and fabricated using 3D printing. Then, the model’s influential parameters are estimated using an optimization problem. Further, a model-based deep reinforcement learning (DRL) controller is proposed to track the desired speed through extensive simulation work. In addition to a deep deterministic policy gradient (DDPG), a twin delayed DDPG (TD3) is employed in the training of the RL agent. Unfortunately, due to its local optimization problem, the RL-DDPG controller failed to perform well during training. In contrast, the RL-TD3 controller effectively learns the control policies and overcomes the local optima problem. As a final step, controller performance is evaluated under different disturbance conditions. In contrast to DDPG and GA-tuned proportional-integral controllers, the proposed model with RL-TD3 controller significantly improves the performance.

关键词： Bioinspired robot Data-assisted model Genetic algorithm Reinforcement learning control Robotic fish

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Runnel development on granitic boulders on the foothills of Mount Kinabalu(Pinosuk Gravel Formation,Sabah,N Borneo)

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Journal of Mountain Science 2016年第1期13卷 46-58页

作者： Dominique DODGE-WAN Ramasamy nagarajan Department of Applied Geology Curtin University SarawakCDT25098009 Min.SarawakMalaysia

Runnels are characteristic erosional features on karstified soluble rocks and can occasionally develop on less soluble rocks(*** and granites) but are poorly reported in *** research summarizes boulder distribution,size,petrology and runnel morphology in a Pleistocene post-glacial mudflow on Mount *** goal is to investigate the runnel formation on *** of boulders by cyanobacteria,mosses,lichens and higher plants is observed and related to rock surface meso-scale and micro-scale *** coarse porphyritic texture of the granite contributes to the fragmentation and mechanical weathering of large K-feldspar crystals in the *** damp runnel micro-environment is preferentially covered with mosses further enhancing weathering and *** runnels deepen,the remnant protruding fins of rock weaken and may break *** runnels are subaerial pseudokarst features,not the result of dissolution.

关键词： Mount rock dissolution granite break glacial weathering erosion fragmentation shallow

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DFT investigation of NH3 gas interactions on TeO2 nanostructures

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Progress in Natural Science:Materials International 2016年第2期26卷 129-138页

作者： V.nagarajan R.Chandiramouli School of Electrical & Electronics Engineering SASTRA University

The structural, electronic and adsorption properties of NH3on pristine, Sn and F substituted TeO2nanostructures were investigated using density functional theory with B3LYP/Lan L2 DZ basis set. The electronic properties of pristine, Sn and F incorporated TeO2nanostructures were explained with ionization potential, HOMO–LUMO gap and electron af fi nity. The dipole moment and point group of rutile TeO2nanostructures were also reported. The structural stability of pristine, Sn and F substituted TeO2nanostructures were investigated in terms of formation energy. The adsorption properties of NH3 on TeO2were studied and the proper adsorption sites of NH3on TeO2materials were identi fi ed and discussed with the suitable parameters such as adsorption energy, HOMO–LUMO gap, Mulliken population analysis and average energy gap variation. The results show that the substitution of fl uorine in TeO2nanostructure enhances NH3 adsorption properties in mixed gas environment.

关键词： TeO2 Gas sensing Adsorption Mulliken charge Dipole moment Energy gap

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Optical absorption of Tl^+ ions in KBr_(1-x)I_x:TlI mixed crystals

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Nuclear Science and Techniques 2009年第4期20卷 208-218页

作者： Eswaran P Ravisankar R nagarajan S Department of Physics SMK Fomra Institute of Technology Department of Physics Government Arts CollegeThiruvannamalai Department of Physics Pondicherry Engineering College

Optical absorption spectra of the mixed crystals of KBr1-xIx:Tl+ crystals studied at room temperature are *** absorption spectra indicated the appearance of additional bands on the low energy side of the Characteristic A,B and C absorption bands of KBr:Tl+ single crystals with increasing iodine *** with earlier reports,the additional bands were attributed to the complex Tl+centers in the mixed configuration surrounded by Br-and I-ions as nearest *** absorption spectra of gamma irradiated mixed crystals showed F band,which shifts towards low energy side with the composition of iodine ions in the mixed crystals.

关键词：能级核技术光谱吸收碘离子

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