9 research outputs found
Lattice_Karak: Lattice structure generator for tissue engineering, lightweighting and heat exchanger applications
Get PDFLattice structures result from biomimicry to create strong and lightweight materials. Triple Periodic Minimal Surface (TPMS) are complex geometry lattices which are highly challenging to design them using computer-aided drafting tools. Lattice_Karak resolves this problem by providing open-source software for generating TPMS. It has all the features for generating and modifying TPMS like density grading, cell size grading, hybridization and hierarchical unit cell. It also exports the generated TPMS into an STL file for further modeling and additive manufacturing. Lattice_Karak can generate scaffolds, heat sinks and porous structures, making it an excellent application for tissue engineering, lightweighting and heat exchanging. © 2022 The Author(s
Feasibility of Dose Reduction to the Left Anterior Descending Coronary Artery without Compromising Target Volume Coverage Using Tomotherapy Techniques
Get PDFBackground: Radiotherapy is associated with a high risk of heart disease in patients with left-sided breast cancer. Previously, the entire heart was considered an organ at risk (OAR) during planning. Studies have shown that the effect of radiation therapy depends on the dose to specific heart substructures. However, the tolerance dose of the left anterior descending coronary artery (LAD), an important cardiac substructure, is yet to be determined. This study aims to verify the feasibility of reducing the LAD dose with appropriate dose-volume constraints for patients undergoing left whole-breast radiotherapy, without compromising the target dose coverage, using tomotherapy techniques.Method: This retrospective study generated tomohelical and tomodirect plans initially without considering the LAD as OAR in the treatment planning. To reduce the LAD dose, plans were regenerated by including the LAD as an OAR with appropriate dose constraints. The dose-volume histogram parameters of these plans were compared with those of the initial plans of the respective types.Results: Tomohelical plans showed a 4.4% reduction in maximum dose and a 3.8% reduction in V15 for LAD, while tomodirect plans registered a 3% reduction in V15, with the conformity index remaining constant. Based on the LAD dosimetric results, considering the LAD as an OAR is associated with lower LAD doses without compromising the target volume coverage.Conclusion: It is feasible to reduce the LAD dose without compromising target volume coverage or affecting other OAR doses in patients with left breast cancer, using tomotherapy techniques
Trans-rectal ultrasound-guided hybrid intra-cavitary and interstitial brachytherapy in carcinoma cervix: A feasibility study from a tertiary cancer center in India
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Role of cardiac computed tomography and cardiovascular magnetic resonance imaging in guiding management and treatment of patients with atrial fibrillation: State of the art review
No full textAtrial fibrillation (AF) is the most common arrhythmia in clinical practice and is associated with high morbidity and mortality. In view of an aging population, the prevalence and incidence of AF are on the rise and are expected to double in the coming decades, posing a huge economic burden on already strained resources. New innovative therapies such as pulmonary vein isolation and percutaneous closure of the left atrial appendage have emerged. The current applications of such therapies would not have been possible without the pivotal role of multimodality cardiovascular imaging. The role of echocardiography in guiding therapy has been extensively reviewed. 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Optimal usage of cone beam computed tomography system with different field of views in image guided radiotherapy (IGRT)
Get PDFPurpose: To find methods for optimal usage of XVI (X-ray volume imaging) system in Elekta synergy linear accelerator with different field of views for same lesion in order to minimize patient dose due to imaging.Methods: 20 scans of 2 individual patients with ca sigmoid colon and ca lung were used in this study. Kilo voltage collimators with medium field of view were used as per the preset information. Images were reconstructed for another collimator with small field of view. The set up errors were evaluated with XVI software. Shift results of both methods were compared. Results: Variation in treatment set up errors with M20 and S20 collimators were ≤ 0.2 mm in translational and 0.30 in rotational shifts. Results showed almost equal translational and rotational shifts in both medium and small field of views with different collimators in all the scans. Visualization of target and surrounding structures were good enough and sufficient for XVI auto matching.Conclusion: Imaging with small field of view results less patient dose compared with medium or large field of views. It is Suggestible to use collimators with small field of view wherever possible. In this study, collimators with small field of view were sufficient for both patients though the preset information indicated medium field of view. But, it always depends on the area required for matching purpose. So, individual selection is important than preset information in the XVI system
A study of X-ray volume imaging system in image guided radiotherapy with variable gantry rotations
Get PDFPurpose: The main purpose of this work is to investigate the optimal usage of X-ray volume imaging (XVI) system in image-guided radiotherapy with different gantry rotations in order to reduce scanning volume.Methods: A total of 60 scans of 16 individual patients with breast and head and neck cancer were used in this study. Full and partial gantry rotations were performed at the same time with same setup on the couch using XVI system by changing the preset information. The reference and localization images were matched with this system. The set up errors were evaluated with XVI software.Results: Variation in translational errors with full and half gantry rotations in breast cases were <2 mm in 86.6% of measurements. Similarly, variations between full and partial gantry rotations in head and neck cases were <1 mm in 95.5% of measurements. Results showed almost similar translational and rotational shifts in both full and partial gantry rotations in the majority of the cases.Conclusion: Based on selected cases in this study, partial rotation of the gantry for acquiring 3D cone beam computerized tomography (CBCT) is very useful option in reducing scanning volume and total treatment time in IGRT. However, the use of partial rotation of the gantry depends on patient thickness and area to be reconstructed to track anatomical changes near to the target
Dose variation due to change in planned position for patients with carcinoma of the cervix undergoing high-dose-rate brachytherapy- 2D dose analysis
Get PDFPurpose: To assess the dosimetry to organs at risk (OARs) in lithotomy position with a planned time-dose pattern obtained from supine position. Methods: The sample consists of thirty patients with carcinoma of the uterine cervix, Stage II and III. Patients often feel discomfort in supine position (S position) when compared to lithotomy position (M position) due to relaxation of pelvic floor muscles after the insertion of applicator (tandem and ovoids) or before delivery of the treatment. Each patient was imaged with orthogonal X- ray radiographs simultaneously in two positions, i.e. S position and M position. Dwell time and dwell position pattern obtained from the optimized plan in S position was used to generate plan in M position. Following dose reference points (point A, pelvic wall points, bladder points, rectal, anorectum (AR point) and rectosigmoid (RS point) points) were identified for analysis in S and M positions. The dosimetric data for reference points generated by the Brachyvision TPS was analyzed.Results: Pelvic wall points registered lower doses in M position when compared to S position. Mean doses for right pelvic wall point (RPW) and left pelvic wall point (LPW) were reduced by -10.02 % and -11.5% in M position, respectively. International Commission on Radiation Units and Measurements (ICRU) bladder point also registered lower doses in M position with a mean dose of -6.8%. Rectal point showed dose reduction by mean of -6.4%. AR and RS points showed an increased dose in M position by a mean of 16.5% and 10%, respectively. Conclusion: Current dosimetry procedure serves as a model with time-dose pattern planned for S position, but delivered in M position, without dose optimization. Prioritization of comfort and position can be considered in conjunction with optimization of dose.
CT- and MRI-based gross target volume comparison in vestibular schwannomas
No full textAimThis study represents an enumeration and comparison of gross target volumes (GTV) as delineated independently on contrast-enhanced computed tomography (CT) and T1 and T2 weighted magnetic resonance imaging (MRI) in vestibular schwannomas (VS).BackgroundMultiple imaging in radiotherapy improves target localization.Methods and materials42 patients of VS were considered for this prospective study with one patient showing bilateral tumor. The GTV was delineated separately on CT and MRI. Difference in volumes were estimated individually for all the 43 lesions and similarity was studied between CT and T1 and T2 weighted MRI.ResultsThe male to female ratio for VS was found to be 1:1.3. The tumor was right sided in 34.9% and left sided in 65.1%. Tumor volumes (TV) on CT image sets were ranging from 0.251[[ce:hsp sp="0.25"/]]cc to 27.27[[ce:hsp sp="0.25"/]]cc. The TV for CT, MRI T1 and T2 weighted were 5.15[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]5.2[[ce:hsp sp="0.25"/]]cc, 5.8[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]6.23[[ce:hsp sp="0.25"/]]cc, and 5.9[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]6.13[[ce:hsp sp="0.25"/]]cc, respectively. Compared to MRI, CT underestimated the volumes. The mean dice coefficient between CT versus T1 and CT versus T2 was estimated to be 68.85[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]18.3 and 66.68[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]20.3, respectively. The percentage of volume difference between CT and MRI (%VD: mean[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]SD for T1; 28.84[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]15.0, T2; 35.74[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]16.3) and volume error (%VE: T1; 18.77[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]10.1, T2; 23.17[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]13.93) were found to be significant, taking the CT volumes as the baseline.ConclusionsMRI with multiple sequences should be incorporated for tumor volume delineation and they provide a clear boundary between the tumor and normal tissue with critical structures nearby
