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Papers by kesavan govindaraj

Research paper thumbnail of Design and fabrication of indigenous multi-rotational thorax phantom for patient-specific quality assurance of IMRT and VMAT

Radiation Effects and Defects in Solids, Jun 3, 2022

Research paper thumbnail of Statistical Analysis on Impact of Image Preprocessing of CT Texture Patterns and Its CT Radiomic Feature Stability: A Phantom Study

Asian Pacific Journal of Cancer Prevention

Recent advances in quantitative imaging (radiomics) traits are utilized to determine how well a t... more Recent advances in quantitative imaging (radiomics) traits are utilized to determine how well a tumor is benign or malignant (Bayanati et al., 2015). Radiomics is also renowned for characterizing tumor heterogeneity and phenotypes using high throughput quantified features derived from clinical standards of image-based biomarkers related to pathologic, genomic, proteomic, and clinical data (Lambin P et al., 2012). It is used as a predictive tool for clinical decision-making in detecting Non-small cell lung cancer (NSCLC) tumor genetic mutations (Weiss GJ et al., 2014). The response evaluates an early potential biomarker for therapy (Bertelsen et al., 2011; Bernchou

Research paper thumbnail of A Dosimetric Analysis of Modified Volumetric Modulated Arc Therapy for Bone Marrow Sparing Radiotherapy in Cervical Cancer-An alternative Approach to Conventional VMAT

Asian Pacific Journal of Cancer Prevention, Dec 1, 2022

Background: External beam radiotherapy remains the primary treatment modality in cervical cancer.... more Background: External beam radiotherapy remains the primary treatment modality in cervical cancer. Nowadays Intensity Modulated Radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) are increasingly being used to reduce normal tissue toxicity. The drawback of conventional VMAT is that a considerable volume of pelvic bone marrow receives a low dose. aim: We analyzed whether there was a way to reduce the volume of the low dose regions of bone marrow, and assessed the potential benefit of conventional-4Arc (C-4Arc VMAT), and Modified-4Arc (M-4Arc VMAT) over the conventional 2 ARC VMAT. Materials And Methods: Twelve clinically proven locally advanced cervical cancer patients treated with concurrent chemo-radiotherapy by Conventional VMAT (RapidArc) in dual rotation mode (C-2Arc VMAT) were selected for this study.C-4Arc VMAT and M-4Arc VMAT dose plans were generated for these twelve patients and these three different types of plans were evaluated for the quality and compared dosimetrically. Results: M-4Arc VMAT designs exhibited a greater bone marrow sparing when compared with conventional VMATs with respect to volume receiving 5Gy to 35Gy without compromising PTV dose coverage. M-4Arc VMAT plans, the bone marrow volume receiving 30 Gy (V30Gy),40Gy (V40Gy), and mean doses were lower than the C-4 Arc plan and a similar result was observed for V50(Gy) also when comparing with the standard 2 Arc plan. In modified VMAT plans, the rectum and bladder dose volumes were lower than standard VMAT. Similarly, the bowel bag V35(Gy), V40(Gy), V50(Gy), mean doses. The right and left femoral head doses were reduced significantly when compared to conventional VMAT plans. Conclusion: The M-4Arc VMAT plans are better than the C-2Arc and C-4Arc VMAT plans for reducing the dose to bone marrow by limiting the MLC field width travel.

Research paper thumbnail of Métodos mecânicos para o controle do biofilme dentário supragengival

Desde os tempos mais remotos da civilização humana, a estética sempre foi fator de socialização. ... more Desde os tempos mais remotos da civilização humana, a estética sempre foi fator de socialização. Atualmente é imprescindível na conquista do suces-so de qualquer ser humano, entendendo-se suces-so nos níveis pessoal, profissional, econômico ou social. ...

Research paper thumbnail of A feasibility and pilot study of the clinical efficacy of a custom designed handgrip device to improve patient immobilisation for the external beam radiotherapy of oesophageal cancers

Radiation Effects and Defects in Solids

Research paper thumbnail of Dosimetric Characteristics of Transparent Bolus for External Beam Radiotherapy

Introduction: In radiotherapy, the bolus is often used while treating the tumor under the uneven ... more Introduction: In radiotherapy, the bolus is often used while treating the tumor under the uneven surfaces of the patients for correcting the anatomical irregularities and increasing skin dose. Wet cotton and wet gauze are still used in developing countries, since the use of wet cotton and wet gauze has certain disadvantages, there is a need for transparent bolus which should be similar to a universally accepted bolus in terms of properties with a lower cost (50% less expensive). Material and Methods: The present study was conducted to investigate the characteristics of transparent bolus (Senflab) material, such as transmission factor, percentage depth dose (PDD), stability over time and high dose, homogeneity and transparency using 6 and 15 MV photons beam and 12, 15, and 18 MeV electrons beam. Moreover, the new bolus material was compared with those of the commercially available Superflab and RW3 slab. Results: The percentage difference in the transmission factor of Senflab was les...

Research paper thumbnail of Analyzing the Possibility of Utilizing CBCT Radiomics as an Independent Modality: A Phantom Study

Aim: To verify if computed tomography (CT) radiomics were reproducible by cone beam CT (CBCT) rad... more Aim: To verify if computed tomography (CT) radiomics were reproducible by cone beam CT (CBCT) radiomics by using Catphan® 504. Materials and Methods: Catphan® 504 was imaged using the default IGRT OBI CBCT imaging protocols and CT scanner. Seven known density image regions of the phantom were segmented and image feature was extracted by Imaging Biomarker Explorer (IBEX) software. The 49 selected features from four feature categories were analyzed by considering each region of interest (ROI) segment as individual image set. Correlation was studies using interclass correlation coefficient (ICC) and Pearson’s correlation coefficient. Results: The ICC of the three feature categories, namely intensity, GLCM, and GLRLM was significant (p-value<0.05) in comparison with CT, while the ICC of the fourth feature category, NID, was no significant. The average absolute Pearson’s correlation coefficient from the features of the images was as follows: CT: r=0.679±0.257, CBCThead: r=0.707±0.231,...

Research paper thumbnail of Design and Development of In-House Multichannel Applicator for HDR Vaginal Brachytherapy and Dosimetric Comparision with Single Channel Applicator

Asian Pacific Journal of Cancer Prevention

Introduction: Endometrial cancer (EC) is a leading cause of female cancer in developed countries.... more Introduction: Endometrial cancer (EC) is a leading cause of female cancer in developed countries. The total abdominal hysterectomy and bilateral salpingo-oophorectomy with pelvic lymph node dissection is the primary management of endometrial cancer. Afterwards vaginal brachytherapy can be preferred either alone or combined with external beam radiotherapy to avoid the vault recurrence. This study was to assess the in-house multichannel applicator for HDR vaginal brachytherapy and dosimetric compression with the single channel applicator through DVHs. The main objective of this study was to design and development of an in-house multichannel applicator for HDR vaginal brachytherapy and dosimetric compression with the single channel applicator through DVHs. Materials and Methods: The multichannel applicator is a solid cylinder with 3 cm diameter, 13 cm length. It has a central channel surrounded by eight channels with a periphery arrangement in a single circle. We randomly selected eleven patients with endometrial carcinoma and 7Gy/per fraction of HDR dose was prescribed to CTV. Retrospectively, two 3D inverse treatment plans were created for each patient, with single channel loading and multichannel loading and the dose distribution of both plans could be compared. CTV coverage, rectum and bladder doses were compared. Results: The DVH analysis showed statistically significant difference between single and multichannel plan, that is for D95 of CTV (p=0.008), D100 of CTV (p=0.004) and 2cc of CTV (p=0.003). The p value for 1cc, 2cc and V70 are 0.003, 0.003 and 0.003 for rectum. On the other hand, bladder DVHs showed large difference between single and multichannel plan yet it is not statistically significant, and the p values for 1cc, 2cc and V 80 are 0.012, 0.009 and 0.225. Conclusion: The authors conclude that in house multichannel applicator with 3D inverse treatment planning techniques improves the dosimetric advantage over single channel applicators.

Research paper thumbnail of Design and fabrication of indigenous multi-rotational thorax phantom for patient-specific quality assurance of IMRT and VMAT

Radiation Effects and Defects in Solids, Jun 3, 2022

Research paper thumbnail of Statistical Analysis on Impact of Image Preprocessing of CT Texture Patterns and Its CT Radiomic Feature Stability: A Phantom Study

Asian Pacific Journal of Cancer Prevention

Recent advances in quantitative imaging (radiomics) traits are utilized to determine how well a t... more Recent advances in quantitative imaging (radiomics) traits are utilized to determine how well a tumor is benign or malignant (Bayanati et al., 2015). Radiomics is also renowned for characterizing tumor heterogeneity and phenotypes using high throughput quantified features derived from clinical standards of image-based biomarkers related to pathologic, genomic, proteomic, and clinical data (Lambin P et al., 2012). It is used as a predictive tool for clinical decision-making in detecting Non-small cell lung cancer (NSCLC) tumor genetic mutations (Weiss GJ et al., 2014). The response evaluates an early potential biomarker for therapy (Bertelsen et al., 2011; Bernchou

Research paper thumbnail of A Dosimetric Analysis of Modified Volumetric Modulated Arc Therapy for Bone Marrow Sparing Radiotherapy in Cervical Cancer-An alternative Approach to Conventional VMAT

Asian Pacific Journal of Cancer Prevention, Dec 1, 2022

Background: External beam radiotherapy remains the primary treatment modality in cervical cancer.... more Background: External beam radiotherapy remains the primary treatment modality in cervical cancer. Nowadays Intensity Modulated Radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) are increasingly being used to reduce normal tissue toxicity. The drawback of conventional VMAT is that a considerable volume of pelvic bone marrow receives a low dose. aim: We analyzed whether there was a way to reduce the volume of the low dose regions of bone marrow, and assessed the potential benefit of conventional-4Arc (C-4Arc VMAT), and Modified-4Arc (M-4Arc VMAT) over the conventional 2 ARC VMAT. Materials And Methods: Twelve clinically proven locally advanced cervical cancer patients treated with concurrent chemo-radiotherapy by Conventional VMAT (RapidArc) in dual rotation mode (C-2Arc VMAT) were selected for this study.C-4Arc VMAT and M-4Arc VMAT dose plans were generated for these twelve patients and these three different types of plans were evaluated for the quality and compared dosimetrically. Results: M-4Arc VMAT designs exhibited a greater bone marrow sparing when compared with conventional VMATs with respect to volume receiving 5Gy to 35Gy without compromising PTV dose coverage. M-4Arc VMAT plans, the bone marrow volume receiving 30 Gy (V30Gy),40Gy (V40Gy), and mean doses were lower than the C-4 Arc plan and a similar result was observed for V50(Gy) also when comparing with the standard 2 Arc plan. In modified VMAT plans, the rectum and bladder dose volumes were lower than standard VMAT. Similarly, the bowel bag V35(Gy), V40(Gy), V50(Gy), mean doses. The right and left femoral head doses were reduced significantly when compared to conventional VMAT plans. Conclusion: The M-4Arc VMAT plans are better than the C-2Arc and C-4Arc VMAT plans for reducing the dose to bone marrow by limiting the MLC field width travel.

Research paper thumbnail of Métodos mecânicos para o controle do biofilme dentário supragengival

Desde os tempos mais remotos da civilização humana, a estética sempre foi fator de socialização. ... more Desde os tempos mais remotos da civilização humana, a estética sempre foi fator de socialização. Atualmente é imprescindível na conquista do suces-so de qualquer ser humano, entendendo-se suces-so nos níveis pessoal, profissional, econômico ou social. ...

Research paper thumbnail of A feasibility and pilot study of the clinical efficacy of a custom designed handgrip device to improve patient immobilisation for the external beam radiotherapy of oesophageal cancers

Radiation Effects and Defects in Solids

Research paper thumbnail of Dosimetric Characteristics of Transparent Bolus for External Beam Radiotherapy

Introduction: In radiotherapy, the bolus is often used while treating the tumor under the uneven ... more Introduction: In radiotherapy, the bolus is often used while treating the tumor under the uneven surfaces of the patients for correcting the anatomical irregularities and increasing skin dose. Wet cotton and wet gauze are still used in developing countries, since the use of wet cotton and wet gauze has certain disadvantages, there is a need for transparent bolus which should be similar to a universally accepted bolus in terms of properties with a lower cost (50% less expensive). Material and Methods: The present study was conducted to investigate the characteristics of transparent bolus (Senflab) material, such as transmission factor, percentage depth dose (PDD), stability over time and high dose, homogeneity and transparency using 6 and 15 MV photons beam and 12, 15, and 18 MeV electrons beam. Moreover, the new bolus material was compared with those of the commercially available Superflab and RW3 slab. Results: The percentage difference in the transmission factor of Senflab was les...

Research paper thumbnail of Analyzing the Possibility of Utilizing CBCT Radiomics as an Independent Modality: A Phantom Study

Aim: To verify if computed tomography (CT) radiomics were reproducible by cone beam CT (CBCT) rad... more Aim: To verify if computed tomography (CT) radiomics were reproducible by cone beam CT (CBCT) radiomics by using Catphan® 504. Materials and Methods: Catphan® 504 was imaged using the default IGRT OBI CBCT imaging protocols and CT scanner. Seven known density image regions of the phantom were segmented and image feature was extracted by Imaging Biomarker Explorer (IBEX) software. The 49 selected features from four feature categories were analyzed by considering each region of interest (ROI) segment as individual image set. Correlation was studies using interclass correlation coefficient (ICC) and Pearson’s correlation coefficient. Results: The ICC of the three feature categories, namely intensity, GLCM, and GLRLM was significant (p-value<0.05) in comparison with CT, while the ICC of the fourth feature category, NID, was no significant. The average absolute Pearson’s correlation coefficient from the features of the images was as follows: CT: r=0.679±0.257, CBCThead: r=0.707±0.231,...

Research paper thumbnail of Design and Development of In-House Multichannel Applicator for HDR Vaginal Brachytherapy and Dosimetric Comparision with Single Channel Applicator

Asian Pacific Journal of Cancer Prevention

Introduction: Endometrial cancer (EC) is a leading cause of female cancer in developed countries.... more Introduction: Endometrial cancer (EC) is a leading cause of female cancer in developed countries. The total abdominal hysterectomy and bilateral salpingo-oophorectomy with pelvic lymph node dissection is the primary management of endometrial cancer. Afterwards vaginal brachytherapy can be preferred either alone or combined with external beam radiotherapy to avoid the vault recurrence. This study was to assess the in-house multichannel applicator for HDR vaginal brachytherapy and dosimetric compression with the single channel applicator through DVHs. The main objective of this study was to design and development of an in-house multichannel applicator for HDR vaginal brachytherapy and dosimetric compression with the single channel applicator through DVHs. Materials and Methods: The multichannel applicator is a solid cylinder with 3 cm diameter, 13 cm length. It has a central channel surrounded by eight channels with a periphery arrangement in a single circle. We randomly selected eleven patients with endometrial carcinoma and 7Gy/per fraction of HDR dose was prescribed to CTV. Retrospectively, two 3D inverse treatment plans were created for each patient, with single channel loading and multichannel loading and the dose distribution of both plans could be compared. CTV coverage, rectum and bladder doses were compared. Results: The DVH analysis showed statistically significant difference between single and multichannel plan, that is for D95 of CTV (p=0.008), D100 of CTV (p=0.004) and 2cc of CTV (p=0.003). The p value for 1cc, 2cc and V70 are 0.003, 0.003 and 0.003 for rectum. On the other hand, bladder DVHs showed large difference between single and multichannel plan yet it is not statistically significant, and the p values for 1cc, 2cc and V 80 are 0.012, 0.009 and 0.225. Conclusion: The authors conclude that in house multichannel applicator with 3D inverse treatment planning techniques improves the dosimetric advantage over single channel applicators.