Syam Kumar | University of Kerala (original) (raw)

Papers by Syam Kumar

American Journal of Potato Research, 2010

New potatoes (also known as “baby potatoes”) are harvested at a young developmental age and have ... more New potatoes (also known as “baby potatoes”) are harvested at a young developmental age and have higher concentrations of some phytonutrients than mature tubers. Assessing the potential of new potatoes in the diet and their suitability as targets for further nutritional enhancement requires knowledge of how well targeted phytonutrients survive cooking. New potatoes from the cultivars ‘Piccolo,’ ‘Bintje’ and ‘Purple Majesty’ were microwaved, baked, boiled, steamed or stir-fried. LCMS analysis showed that total phenolics, chlorogenic acids, flavonols and vitamin C did not significantly decrease after cooking by any of these methods. Cooking typically resulted in an increase in the recoverable amounts of these compounds, with chlorogenic acid increasing from 2.14 to 2.92 mg/g DW and rutin from 7.4 to 13.2 μg/g DW after baking in ‘Purple Majesty.’ Supporting this finding is that antioxidant capacity showed similar results with Trolox equivalents increasing from 28.7 (raw) to 36.3 µmol/g DW after baking in ‘Bintje.’ These data suggest that new potatoes present an opportunity to more fully utilize the nutritional potential of potatoes. This work shows that significant loses of phenolic acids, vitamin C, and flavonols need not occur during cooking and confirms that these are viable targets to further increase by molecular or breeding approaches. Papas nuevas (también conocidas como “papas bebe”), se cosechan en una edad temprana de desarrollo y tienen concentraciones más altas de algunos fitonutrientes que los tubérculos maduros. El análisis del potencial de papas nuevas en la dieta y su ubicación como blancos de incremento nutricional adicional, requiere del conocimiento de qué tan bien los fitonutrientes de estudio sobrevivan al cocinado. Papas nuevas de los cultivares “Piccolo”, “Bintje” y “Purple Majesty” pasaron por microondas, puré, hervido, al vapor o al freído. El análisis de LCMS mostró que los fenoles totales, los ácidos clorogénicos, flavonoides y vitamina C, no disminuyeron significativamente después del cocinado por cualquiera de estos métodos. El cocinado típico dio por resultado un aumento en las cantidades recobrables de estos compuestos, con un aumento del ácido clorogénico de 2.14 a 2.92 mg/g en peso seco y de rutina de 7.4 a 13.2 μg/g de peso seco después del cocinado en puré de “Purple Majesty”. En respaldo a este resultado es que la capacidad antioxidante mostró resultados similares con equivalentes Trolox aumentando de 28.7 (crudo) a 36.3 µmol/g de peso seco después del cocinado como puré en “Bintje”. Estos datos sugieren que las papas nuevas presentan una oportunidad para una utilización más completa del potencial nutritivo de las papas. Este trabajo muestra que las pérdidas significativas de ácidos fenólicos, vitamina C, y flavonoides no necesariamente se tienen que presentar durante el cocinado, y confirma que estos son blancos viables para un aumento posterior por estrategias moleculares o de mejoramiento.

Medical Physics, 2010

[bold Purpose:] To study the dosimetric characteristics of 2D Seven29 ion chamber array and hence... more [bold Purpose:] To study the dosimetric characteristics of 2D Seven29 ion chamber array and henceforth to perform the patient specific QA for RapidArc treatment delivery in combination with Octavius phantom.[bold Method and Materials:] The dosimetric ...

Fuel and Energy Abstracts, 2009

Purpose/Objective(s): Patient positioning in partial breast irradiation (PBI) has been convention... more Purpose/Objective(s): Patient positioning in partial breast irradiation (PBI) has been conventionally guided with 2D images and recently with 3D images including cone-bean and fan-beam computed tomography (CT). The purpose of this work was to evaluate various methods of 2D and 3D image guidance and to identify optimal technique of CT guided delivery for PBI. Materials/Methods: In an in-house clinical trial enrolling patients to be treated with PBI on a CT-on-Rails and linac combo (CTVision, Siemens), the daily CT was acquired to reposition the patient. The diagnostic-quality daily CT allowed visualization of seroma and clips, thus, accurate localization of lumpectomy cavity. The digitally reconstructed radiographs (DRR) from the CT of the day were generated in this study to mimic the 2D portal images. The daily CT and DRRs of selected 9 patients treated in prone position were used in this study to compare dosimetric effects of commonly-used four image registration methods for patient repositioning: registration of the CT of the day with the planning CT based on the center of mass (COM) of lumpectomy cavity, and registration of the daily DRR (portal image for the day) with the planning DRR based on chest wall, surgical clips, or breast contours. An IMRT plan with 5-9 beams was generated for each patients based on the planning CT. This plan was applied to each daily CT to reconstruct the four plans for the four repositioning methods. Various dose-volume parameters including D95-PTV (dose covering 95% of PTV), D95-CTV and mean dose of the whole breast were compared. Results: The repositioning shifts consist systematic and random components (S, s) and were (4.5, 4.0), (3.2, 3.9), and (3.2, 4.5 mm), respectively, for clip, breast contour, and chest wall based alignments relative to those for the COM alignment. The average daily D95-PTV reduction from its planning value was 1.0, 4.4, 4.0 and 6.2% for COM, surgical clips, breast contour and chest-wall alignments respectively. The daily variation in the D95-PTV reduction was large for the DRR based methods, especially for the chest wall alignment, as compared to the COM method. Similar findings were obtained for D95-CTV. Conclusions: Comparing the various clinically-used image guidance methods in partial breast irradiation, the high-quality CT guided repositioning based on lumpectomy cavity is preferred for correcting interfractional setup errors and anatomic changes. The repositioning based on chest wall using 2D images should be avoided.

Medical Dosimetry

A treatment planning study was performed to evaluate the performance of volumetric arc modulation... more A treatment planning study was performed to evaluate the performance of volumetric arc modulation with RapidArc (RA) against 3D conformal radiation therapy (3D-CRT) and conventional intensity-modulated radiation therapy (IMRT) techniques for esophageal cancer. Computed tomgraphy scans of 10 patients were included in the study. 3D-CRT, 4-field IMRT, and single-arc and double-arc RA plans were generated with the aim to spare organs at risk (OAR) and healthy tissue while enforcing highly conformal target coverage. The planning objective was to deliver 54 Gy to the planning target volume (PTV) in 30 fractions. Plans were evaluated based on target conformity and dose-volume histograms of organs at risk (lung, spinal cord, and heart). The monitor unit (MU) and treatment delivery time were also evaluated to measure the treatment efficiency. The IMRT plan improves target conformity and spares OAR when compared with 3D-CRT. Target conformity improved with RA plans compared with IMRT. The mean lung dose was similar in all techniques. However, RA plans showed a reduction in the volume of the lung irradiated at V(₂₀Gy) and V(₃₀Gy) dose levels (range, 4.62-17.98%) compared with IMRT plans. The mean dose and D(₃₅%) of heart for the RA plans were better than the IMRT by 0.5-5.8%. Mean V(₁₀Gy) and integral dose to healthy tissue were almost similar in all techniques. But RA plans resulted in a reduced low-level dose bath (15-20 Gy) in the range of 14-16% compared with IMRT plans. The average MU needed to deliver the prescribed dose by RA technique was reduced by 20-25% compared with IMRT technique. The preliminary study on RA for esophageal cancers showed improvements in sparing OAR and healthy tissue with reduced beam-on time, whereas only double-arc RA offered improved target coverage compared with IMRT and 3D-CRT plans.

Fuel and Energy Abstracts, 2010

Head and neck cancers a b s t r a c t Aim: To evaluate the performance of volumetric arc modulati... more Head and neck cancers a b s t r a c t Aim: To evaluate the performance of volumetric arc modulation with RapidArc against conventional IMRT for head and neck cancers.

American Journal of Potato Research, 2010

New potatoes (also known as “baby potatoes”) are harvested at a young developmental age and have ... more New potatoes (also known as “baby potatoes”) are harvested at a young developmental age and have higher concentrations of some phytonutrients than mature tubers. Assessing the potential of new potatoes in the diet and their suitability as targets for further nutritional enhancement requires knowledge of how well targeted phytonutrients survive cooking. New potatoes from the cultivars ‘Piccolo,’ ‘Bintje’ and ‘Purple Majesty’ were microwaved, baked, boiled, steamed or stir-fried. LCMS analysis showed that total phenolics, chlorogenic acids, flavonols and vitamin C did not significantly decrease after cooking by any of these methods. Cooking typically resulted in an increase in the recoverable amounts of these compounds, with chlorogenic acid increasing from 2.14 to 2.92 mg/g DW and rutin from 7.4 to 13.2 μg/g DW after baking in ‘Purple Majesty.’ Supporting this finding is that antioxidant capacity showed similar results with Trolox equivalents increasing from 28.7 (raw) to 36.3 µmol/g DW after baking in ‘Bintje.’ These data suggest that new potatoes present an opportunity to more fully utilize the nutritional potential of potatoes. This work shows that significant loses of phenolic acids, vitamin C, and flavonols need not occur during cooking and confirms that these are viable targets to further increase by molecular or breeding approaches. Papas nuevas (también conocidas como “papas bebe”), se cosechan en una edad temprana de desarrollo y tienen concentraciones más altas de algunos fitonutrientes que los tubérculos maduros. El análisis del potencial de papas nuevas en la dieta y su ubicación como blancos de incremento nutricional adicional, requiere del conocimiento de qué tan bien los fitonutrientes de estudio sobrevivan al cocinado. Papas nuevas de los cultivares “Piccolo”, “Bintje” y “Purple Majesty” pasaron por microondas, puré, hervido, al vapor o al freído. El análisis de LCMS mostró que los fenoles totales, los ácidos clorogénicos, flavonoides y vitamina C, no disminuyeron significativamente después del cocinado por cualquiera de estos métodos. El cocinado típico dio por resultado un aumento en las cantidades recobrables de estos compuestos, con un aumento del ácido clorogénico de 2.14 a 2.92 mg/g en peso seco y de rutina de 7.4 a 13.2 μg/g de peso seco después del cocinado en puré de “Purple Majesty”. En respaldo a este resultado es que la capacidad antioxidante mostró resultados similares con equivalentes Trolox aumentando de 28.7 (crudo) a 36.3 µmol/g de peso seco después del cocinado como puré en “Bintje”. Estos datos sugieren que las papas nuevas presentan una oportunidad para una utilización más completa del potencial nutritivo de las papas. Este trabajo muestra que las pérdidas significativas de ácidos fenólicos, vitamina C, y flavonoides no necesariamente se tienen que presentar durante el cocinado, y confirma que estos son blancos viables para un aumento posterior por estrategias moleculares o de mejoramiento.

Medical Physics, 2010

[bold Purpose:] To study the dosimetric characteristics of 2D Seven29 ion chamber array and hence... more [bold Purpose:] To study the dosimetric characteristics of 2D Seven29 ion chamber array and henceforth to perform the patient specific QA for RapidArc treatment delivery in combination with Octavius phantom.[bold Method and Materials:] The dosimetric ...

Fuel and Energy Abstracts, 2009

Purpose/Objective(s): Patient positioning in partial breast irradiation (PBI) has been convention... more Purpose/Objective(s): Patient positioning in partial breast irradiation (PBI) has been conventionally guided with 2D images and recently with 3D images including cone-bean and fan-beam computed tomography (CT). The purpose of this work was to evaluate various methods of 2D and 3D image guidance and to identify optimal technique of CT guided delivery for PBI. Materials/Methods: In an in-house clinical trial enrolling patients to be treated with PBI on a CT-on-Rails and linac combo (CTVision, Siemens), the daily CT was acquired to reposition the patient. The diagnostic-quality daily CT allowed visualization of seroma and clips, thus, accurate localization of lumpectomy cavity. The digitally reconstructed radiographs (DRR) from the CT of the day were generated in this study to mimic the 2D portal images. The daily CT and DRRs of selected 9 patients treated in prone position were used in this study to compare dosimetric effects of commonly-used four image registration methods for patient repositioning: registration of the CT of the day with the planning CT based on the center of mass (COM) of lumpectomy cavity, and registration of the daily DRR (portal image for the day) with the planning DRR based on chest wall, surgical clips, or breast contours. An IMRT plan with 5-9 beams was generated for each patients based on the planning CT. This plan was applied to each daily CT to reconstruct the four plans for the four repositioning methods. Various dose-volume parameters including D95-PTV (dose covering 95% of PTV), D95-CTV and mean dose of the whole breast were compared. Results: The repositioning shifts consist systematic and random components (S, s) and were (4.5, 4.0), (3.2, 3.9), and (3.2, 4.5 mm), respectively, for clip, breast contour, and chest wall based alignments relative to those for the COM alignment. The average daily D95-PTV reduction from its planning value was 1.0, 4.4, 4.0 and 6.2% for COM, surgical clips, breast contour and chest-wall alignments respectively. The daily variation in the D95-PTV reduction was large for the DRR based methods, especially for the chest wall alignment, as compared to the COM method. Similar findings were obtained for D95-CTV. Conclusions: Comparing the various clinically-used image guidance methods in partial breast irradiation, the high-quality CT guided repositioning based on lumpectomy cavity is preferred for correcting interfractional setup errors and anatomic changes. The repositioning based on chest wall using 2D images should be avoided.

Medical Dosimetry

A treatment planning study was performed to evaluate the performance of volumetric arc modulation... more A treatment planning study was performed to evaluate the performance of volumetric arc modulation with RapidArc (RA) against 3D conformal radiation therapy (3D-CRT) and conventional intensity-modulated radiation therapy (IMRT) techniques for esophageal cancer. Computed tomgraphy scans of 10 patients were included in the study. 3D-CRT, 4-field IMRT, and single-arc and double-arc RA plans were generated with the aim to spare organs at risk (OAR) and healthy tissue while enforcing highly conformal target coverage. The planning objective was to deliver 54 Gy to the planning target volume (PTV) in 30 fractions. Plans were evaluated based on target conformity and dose-volume histograms of organs at risk (lung, spinal cord, and heart). The monitor unit (MU) and treatment delivery time were also evaluated to measure the treatment efficiency. The IMRT plan improves target conformity and spares OAR when compared with 3D-CRT. Target conformity improved with RA plans compared with IMRT. The mean lung dose was similar in all techniques. However, RA plans showed a reduction in the volume of the lung irradiated at V(₂₀Gy) and V(₃₀Gy) dose levels (range, 4.62-17.98%) compared with IMRT plans. The mean dose and D(₃₅%) of heart for the RA plans were better than the IMRT by 0.5-5.8%. Mean V(₁₀Gy) and integral dose to healthy tissue were almost similar in all techniques. But RA plans resulted in a reduced low-level dose bath (15-20 Gy) in the range of 14-16% compared with IMRT plans. The average MU needed to deliver the prescribed dose by RA technique was reduced by 20-25% compared with IMRT technique. The preliminary study on RA for esophageal cancers showed improvements in sparing OAR and healthy tissue with reduced beam-on time, whereas only double-arc RA offered improved target coverage compared with IMRT and 3D-CRT plans.

Fuel and Energy Abstracts, 2010

Head and neck cancers a b s t r a c t Aim: To evaluate the performance of volumetric arc modulati... more Head and neck cancers a b s t r a c t Aim: To evaluate the performance of volumetric arc modulation with RapidArc against conventional IMRT for head and neck cancers.