Perforated Lightweight Broadband Metamaterial Absorber Based on 3-D Printed Honeycomb

Ghosh, Saptarshi,Lim, Sungjoon IEEE 2018 IEEE antennas and wireless propagation letters Vol.17 No.12

<P>This letter presents a broadband metamaterial absorber based on three-dimensional (3-D) printing technology. The proposed design comprises periodic arrays of honeycomb core as the constituent dielectric, onto which resistive paint has been deposited to realize broadband absorption. The novel feature of this structure is its perforated substrate geometry, which contributes to the mechanical strength and light-weight characteristics of the design. The structure also exhibits broadband absorption (greater than 90%) in a frequency range of 5.52–16.96 GHz under normal incidence, thus giving rise to a fractional bandwidth of 101.78%. An equivalent circuit model has been developed, and several parametric variations have been studied to analyze the absorption mechanism of the proposed geometry. The design has been fabricated using low-cost 3-D printing technology, and the resistive ink has been uniformly coated onto the substrate using screen printing technique. The prototype, while measured, shows reasonable agreement with the simulated response under normal incidence.</P>

Concurrent Chemoradiation with Weekly Cisplatin for the Treatment of Head and Neck Cancers: an Institutional Study on Acute Toxicity and Response to Treatment

Ghosh, Saptarshi,Rao, Pamidimukkala Brahmananda,Kumar, P Ravindra,Manam, Surendra Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16

Background: Concurrent chemoradiation with three weekly high dose cisplatin is the non-surgical standard of care for the treatment of locally advanced head and neck cancers. Although this treatment regime is efficacious, it has high acute toxicity, which leads not only to increased treatment cost, but also to increased overall treatment time. Hence, the current study was undertaken to evaluate the acute toxicity and tumor response in head and neck cancer patients treated with concurrent chemoradiation using $40mg/m^2$ weekly cisplatin, which has been our institutional practice. Materials and Methods: This single institution retrospective study included data for 287 head and neck cancer patients treated with concurrent chemoradiation from 2012 to 2014. Results: The mean age of the patients was 48.8 years. The most common site of involvement was oral cavity. Most of the study patients presented with advanced stage disease. The mean overall treatment time was 56.9 days. Some 67.2% had overall complete response to treatment as documented till 90 days from the start of treatment. According to the Radiation Therapy Oncology Group (RTOG) acute radiation morbidity scoring criteria, mucositis was seen in 95.1% of the patients. Dermatitis and emesis were observed in 81.9% and 98.6%, respectively. Regarding haematological toxicity, 48.8% and 29.6% suffered from anaemia and leukopenia, respectively, during treatment. Acute kidney injury was assessed using the Common Terminology Criteria for Adverse Events (CTCAE), and was found in 18.8% of the patients. Conclusions: Concurrent chemoradiotherapy with weekly cisplatin is an effective treatment regime for head and neck cancers with reasonable toxicity which can be used in developing countries, where cost of treatment is so important.

Weekly Cisplatin-Based Concurrent Chemoradiotherapy for Treatment of Locally Advanced Head and Neck Cancer: a Single Institution Study

Ghosh, Saptarshi,Rao, Pamidimukkala Brahmananda,Kumar, P Ravindra,Manam, Surendra Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16

Background: The organ preservation approach of choice for the treatment of locally advanced head and neck cancers is concurrent chemoradiation with three weekly high doses of cisplatin. Although this is an efficacious treatment policy, it has high acute systemic and mucosal toxicities, which lead to frequent treatment breaks and increased overall treatment time. Hence, the current study was undertaken to evaluate the efficacy of concurrent chemoradiation using 40 mg/m2 weekly cisplatin. Materials and Methods: This is a single institutional retrospective study including the data of 266 locally advanced head and neck cancer patients who were treated with concurrent chemoradiation using 40 mg/m2 weekly cisplatin from January 2012 to January 2014. A p-value of < 0.05 was taken to be significant statistically for all purposes in the study. Results: The mean age of the study patients was 48.8 years. Some 36.1% of the patients had oral cavity primary tumors. The mean overall treatment time was 57.2 days. With a mean follow up of 15.2 months for all study patients and 17.5 months for survivors, 3 year local control, locoregional control and disease free survival were seen in 62.8%, 42.8% and 42.1% of the study patients. Primary tumor site, nodal stage of disease, AJCC stage of the disease and number of cycles of weekly cisplatin demonstrated statistically significant correlations with 3 year local control, locoregional control and disease free survival. Conclusions: Concurrent chemoradiotherapy with moderate dose weekly cisplatin is an efficacious treatment regime for locally advanced head and neck cancers with tolerable toxicity which can be used in developing countries with limited resources.

Brain Metastases from Solid Tumors: an Institutional Study from South India

Ghosh, Saptarshi,Rao, Pamidimukkala Brahmananda Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.13

Background: Brain metastases are the most common intra-cranial neoplasms. The incidence is on a rise due to advanced imaging techniques. Aims: The objective of the study was to analyse the clinical and demographic profile of patients with brain metastases from primary solid tumors. Materials and Methods: This is a retrospective single institutional study covering 130 consecutive patients with brain metastases from January 2007 to August 2014. Results: Some 64.6% of the patients were females. The majority were in the sixth decade of life. The site of the primary tumor was the lungs in 50.8% of the cases. The overall median time from the diagnosis of the primary malignancy to detection of brain metastases was 21.4 months. Survival was found to be significantly improved in patients with solitary brain lesions when compared to patients with multiple brain metastases, and in patients undergoing surgical excision with or without cranial irradiation when compared to whole brain irradiation alone. The majority of the cases belonged to the recursive partitioning analysis class II group. Whole brain radiation therapy was delivered to 79% of the patients. Conclusions: Most of the patients with brain metastases in the study belonged to recursive partitioning analysis classes II or III, and hence had poor prognosis. Most of the patients in the Indian context either do not satisfy the indications for surgical excision or are incapable of bearing the high cost associated with stereotactic radiosurgery. Treatment should be tailored on an individual basis to all these patients.

Clinico-Morphological Profile and Receptor Status in Breast Cancer Patients in a South Indian Institution

Ghosh, Saptarshi,Sarkar, Shreyasee,Simhareddy, Samara,Kotne, Sivasankar,Rao, Pammidimukkala Bramh Ananda,Turlapati, Satya Prakash Venkatachalam Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.18

Background: Breast cancer is the most common malignancy in women worldwide and the second most common cancer in females in India. Receptor status may be important for survival. Objective: To analyse and correlate the clinical and morphological parameters with receptor status in breast carcinoma patients in a tertiary care institution in Southern India. Materials and Methods: This retrospective study involved 320 patients of breast cancer diagnosed in an oncology hospital over a period of $3^{1/2}$ years. Data was analysed using SPSS Version 21. Results: Some 60.6% patients with breast carcinomas belonged to the age group of 40 to 60 years. The most common histological type was infiltrating ductal carcinoma, not otherwise specified, accounting for 84.4% of patients. On immunohistochemistry, estrogen receptor (ER) and progesterone receptor (PR) were expressed in 56.3% and 53.1% of cases, respectively. Conclusions: Breast cancers in India, a developing country, occur in younger women and tend to be more aggressive with lower rates of ER and PR expression and higher histological tumor grades. Both ER and PR status of the tumors had significant associations with the patient age, pathological TNM stage and histological tumor grade.

A Multifunctional Reconfigurable Frequency-Selective Surface Using Liquid-Metal Alloy

Ghosh, Saptarshi,Lim, Sungjoon Institute of Electrical and Electronics Engineers 2018 IEEE transactions on antennas and propagation Vol.66 No.9

<P>This communication describes a miniaturized reconfigurable frequency-selective surface (FSS) that incorporates a liquid-metal alloy injected into an elastomer. The structure comprises a meandered pattern engraved on a flexible dielectric substrate, where the liquid metal [eutectic gallium indium (EGaIn)] adopts the geometry of the microfluidic channels. The novelty of the proposed design lies in its multifunctional response, switching from all-pass to bandpass/bandstop characteristic, depending on whether EGaIn is injected in the microchannels. The liquid-metal-filled structure, being asymmetric in nature, selectively realizes bandpass operation for a specific polarization, whereas bandstop response is observed under orthogonal polarization. Furthermore, the design exhibits miniaturization performance during bandpass response (at 1.37 GHz), corresponding to unit cell dimensions of <TEX>$0.059\lambda _{0} \times 0.059\lambda _{0}$</TEX>. The structure was analyzed through the derivation of equivalent circuit models and several parametric variations. Finally, the proposed multifunctional FSS was fabricated by laser etching, and the filter parameters were experimentally verified under normal as well as oblique incidence.</P>

Fluidically Reconfigurable Multifunctional Frequency-Selective Surface With Miniaturization Characteristic

Ghosh, Saptarshi,Lim, Sungjoon Professional Technical Group on Microwace Theory a 2018 IEEE transactions on microwave theory and techniqu Vol.66 No.8

<P>This paper presents a multifunctional reconfigurable frequency-selective surface (FSS) based on liquid-metal-filled microchannels engraved in an elastomeric substrate. The proposed FSS comprises two layers of periodic meandered patterns encased within the opposite sides of a dielectric, where the layers are arranged in orthogonal polarization with independent control of reconfigurability. The novelty of the design lies in its switching characteristic between four different working states (dual-polarized all pass, single-polarized low pass, single-polarized bandpass, and dual-polarized bandpass) with the injection of a liquid metal in the top and bottom microchannels. Moreover, the design exhibits miniaturization performance during one of the states (exhibiting dual-polarized bandpass response at 1.58 GHz) corresponding to the unit cell dimensions of <TEX>$0.052\lambda _{0} \times 0.052\lambda _{0}$</TEX>. The equivalent circuit models and parametric variations are extensively analyzed for understanding the design principles. Because any liquid-metal-based reconfigurable FSS structure has not been reported earlier, a detailed description of the fabrication and measurement procedure are presented in this paper. The experimental validation of the fabricated prototype also confirms the potential use of microfluidic technology-based reconfigurable structures in future.</P>

High Dose Rate Brachytherapy in Two 9 Gy Fractions in the Treatment of Locally Advanced Cervical Cancer - a South Indian Institutional Experience

Ghosh, Saptarshi,Rao, Pamidimukkala Bramhananda,Kotne, Sivasankar Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16

Background: Although 3D image based brachytherapy is currently the standard of treatment in cervical cancer, most of the centres in developing countries still practice orthogonal intracavitary brachytherapy due to financial constraints. The quest for optimum dose and fractionation schedule in high dose rate (HDR) intracavitary brachytherapy (ICBT) is still ongoing. While the American Brachytherapy Society recommends four to eight fractions of each less than 7.5 Gy, there are some studies demonstrating similar efficacy and comparable toxicity with higher doses per fraction. Objective: To assess the treatment efficacy and late complications of HDR ICBT with 9 Gy per fraction in two fractions. Materials and Methods: This is a prospective institutional study in Southern India carried on from $1^{st}$ June 2012 to $31^{st}$ July 2014. In this period, 76 patients of cervical cancer satisfying our inclusion criteria were treated with concurrent chemo-radiation following ICBT with 9 Gy per fraction in two fractions, five to seven days apart. Results: The median follow-up period in the study was 24 months (range 10.6 - 31.2 months). The 2 year actuarial local control rate, disease-free survival and overall survival were 88.1%, 84.2% and 81.8% respectively. Although 38.2% patients suffered from late toxicity, only 3 patients had grade III late toxicity. Conclusions: In our experience, HDR brachytherapy with 9 Gy per fraction in two fractions is an effective dose fractionation for the treatment of cervical cancer with acceptable toxicity.

Low‐cost and miniaturized metamaterial absorber using 3D printed swastika symbol

Kim, Minseok,Jeong, Heijun,Lim, Daecheon,Ghosh, Saptarshi,Lim, Sungjoon John WileySons, Inc. 2020 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS - Vol.62 No.4

<P><B>Abstract</B></P><P>In this paper, a low‐cost metamaterial (MM) absorber is proposed using 3‐dimensional (3D) printing technology. The unit cell of the proposed MM absorber is motivated from a swastika symbol to minimize the footprint size. For further miniaturization, the unit cell is 3D printed by stacking two blocks. The conductive top patterns are realized by painting with a silver ink. The proposed MM absorber consists of 2 × 4 unit cell array which is loaded in the rectangular waveguide. Its absorptivity is simulated and measured to demonstrate the performance. The simulated and measured absorptivity at 1.91 GHz are 99% and 92%, respectively.</P>

Role of lung ultrasound patterns in monitoring coronavirus disease 2019 pneumonia and acute respiratory distress syndrome in children

Roychowdhoury Satyabrata,Bhakta Subhajit,Mahapatra Manas Kumar,Ghosh Saptarshi,Saha Sayantika,Konar Mithun Chandra,Sarkar Mihir,Nandi Mousumi 대한소아청소년과학회 2022 Clinical and Experimental Pediatrics (CEP) Vol.65 No.7

Background: During the coronavirus disease 2019 (COVID-19) pandemic, lung ultrasonography (US) has been gaining importance in pediatric intensive care and emergency settings for the screening, diagnosis, and monitoring of pulmonary pathology.Purpose: To describe the pattern of lung US changes in patients with COVID-19 pneumonia and its potential role in monitoring ventilated patients.Methods: This prospective observational study included children aged 1 month to 12 years with a confirmed diagnosis of COVID-19. Lung US was performed using a high-frequency linear probe (5–12 MHz) in all children with moderate/severe respiratory symptoms within 24 hours of admission and then daily until the patient required oxygen therapy. Lung involvement severity was assessed using lung US scores, while lung aeration improvement or deterioration was measured using lung ultrasound reaeration scores (LUSReS).Results: Of 85 children with moderate to severe disease, 54 with pulmonary disease were included. Of them, 50 (92.5%) had an interstitial pattern, followed by pleural line abnormalities in 44 (81.5%), reduced or absent lung sliding in 31 (57.4%), and consolidation in 28 (51.8%). A significantly higher lung US score (median, 18; interquartile range [IQR], 11–22) was observed in ventilated versus nonventilated patients (median, 9; IQR, 6–11). LUSReS improvement after positive end-expiratory pressure titration was positively correlated with improved dynamic lung compliance and oxygenation indices and negatively correlated with the requirement for driving pressure. Successful weaning could be predicted with 100% specificity if loss of LUSReS ≤ 5.Conclusion: Interstitial syndrome, fragmented pleural line, and subpleural microconsolidation were the most prevalent lung US findings in children with COVID-19 pneumonia. Thus, lung US may have the ability to monitor changes in lung aeration caused by mechanical ventilation and predict its successful weaning in children with COVID-19.