Search

Introduction: It is necessary to understand the importance of different energies in Fractionated Stereotactic Radiotherapy (FSRT) plans for better outcome. The study objective is to compare FSRT plans with Flattening Filter (FF) and Flattening Filter Free (FFF) beams.Material and Methods: Twelve patients with primary Brain Metastasis (BM), were selected and given 25 Gy in five fractions for which 6FF beams were angled in double arc. The Planning Target Volume (PTV) and Organs at Risk (OARs) were assessed using dosimetric indices after each plan was replanned with 6 FFF, 10 FF, and 10 FFF energies. Treatment time (TT) and Monitor Units (MUs) were also compared. Additionally, we compared portal dosimetry for dose agreement across all plans using the gamma analysis criterion.Results: PTV parameters of created plans showed better values when compared to 6 FF plans, where the most significant is with FFF plans which include D98%, D80%, D2%, D50% and Dose Gradient Index values of 6FFF plans. Among OARs, the most significant is the V10 value of (Brain-PTV) as (46.77±43.9) and maximum dose values of optic chiasm, brainstem, and left lens in 6FFF plans. Among technical parameters, the 6FFF plan showed significant TT value of (3.06±1.0) with p-value 4.13E-05. Better gamma analysis passing rates were achieved with FFF beams.Conclusion: Linear accelerator-based FSRT delivery of BM using 6 FFF beam results in better dosimetric indices, OAR sparing, fastest treatment delivery, and energy conservation with reduced peripheral and out-of-field dose for higher treatment modalities like Rapid arc.

Introduction: In head and neck cancer (HNC) radiotherapy, parotid, submandibular, and minor salivary glands are often incidentally irradiated. Hence, Xerostomia is the most significant disabling side-effect, to improve the quality of life, it should be reduced. The study was to evaluate the parotid dose and PTV coverage in post operated Oral cancer patients using Volumetric Modulated Arc Therapy (VMAT) technique.Material and Methods: The authors generated VMAT plans for 14 post operated oral cancer patients, where primary disease crossed midline or nodal stage ≥ 2. The doses to the moderate high-risk volume of the clinical target volume (CTV) and planning target volume (PTV) were 60Gy in 30 fractions. The low-risk volume received a dose to the CTV and PTV of 54Gy in 30 fractions. Plans were made for each patient, and the dose to D95 and D98 of target volumes was analyzed. The mean dose of the parotid and parotid minus PTV volumes were analyzed and compared with target doses (D98 & D95). Results: Median dose to the ipsilateral parotid gland was 54.45Gy and to the ipsilateral parotid gland minus PTV was 45.60Gy while to the contralateral parotid gland median dose was 16.31Gy, (mean is ranging from 14.01 to 17.06Gy) and to the contralateral parotid gland minus PTV was 14.92 (mean is ranging from 12.42 to 15.18Gy) after achieving the 95% coverage of PTV.Conclusion: Better sparing of contralateral parotid glands with the help of VMAT technique in post-operative HNC patients is possible, which can prevent xerostomia in most patients.

Introduction: The study aims to compare target coverage and critical structure dose difference between various dose computing algorithms with small segment dose calculation in Intensity Modulated Radiation Therapy (IMRT) and large segment dose calculation in 3-Dimensional Conformal Radiation Therapy (3DCRT) treatment plan for Head and Neck (H&N) tumor.Material and Methods: For the present study, thirty-eight H&N cancer patients were selected retrospectively. Twenty-seven patients were planned with IMRT plan using Monte Carlo (MC) algorithm and eleven patients with 3DCRT plan using Collapsed Cone/Superposition (CCS) algorithm. IMRT plan was recalculated with Pencil Beam (PB) and the 3DCRT plan was recalculated with MC and PB algorithms. An Independent student t-test was performed as a part of statistical analysis for dosimetric comparison of the p-value.Results: In the IMRT plan, mean dose, Conformity Index (CI), D2%, D98%, and D50% showed a significant difference in p-values (p

Highlights A high filling load (62% weight) printable magnetic composite has been elaborated from the dispersion of magnetocaloric Ni45Mn36.7In13.3Co5 metamagnetic shape memory alloy microparticles into a PCL polymer matrix. The composite material has been prepared by solution method, resulting in a very homogeneous particles dispersion into the matrix. The structural transitions in the polymer are not affected by the addition of the metallic microparticles, which in turn results in a significant increase of the mechanical consistency. The good ductility of the elaborated composite allows its extrusion in flexible printable filaments, from which 3D pieces with complex geometries have been grown. The heat transfer of the composite material has been assessed from finite element simulation. In spite of the achievable magnetocaloric values are moderated with respect to the bulk, numerical simulations confirm that, in terms of heat transference, a PCL/Ni‐Mn‐In‐Co wire is more efficient than a bulk Ni‐Mn‐In‐Co cubic piece containing the same amount of magnetic active material. The quite good magnetocaloric response of the composite and the possibility to print high surface/volume ratio geometries make this material a promising candidate for the development of heat exchangers for clean and efficient magnetic refrigeration applications. 3D printable magnetic composites developed from dispersion of MSMA in PCL. High filling factor and uniform dispersion characterized by SEM. Inclusion of microparticles does not affect polymeric structural transitions. Metallic fillers improve DMA response of 3D printed pieces. FEM simulations endorse PCL/MSMA composites for magnetic refrigeration. [ABSTRACT FROM AUTHOR]

ObjectivesTo assess the reliability and the minimal clinically important differences (MCID) for FVC% predicted in the Scleroderma Lung Study I and II.MethodsUsing data from SLS I and II (N=300), we evaluated the test-retest reliability for FVC% predicted (FVC%; screening vs. baseline) using intra-class correlation (ICC). MCID estimates at 12 months were calculated in the pooled cohort (SLS-I and II) using 2 anchors: Transition Dyspnea Index (≥change of 1.5 units for improvement and worsening, respectively) and the SF-36 Health Transition question: "Compared to one year ago, how would you rate your health in general now?", where "somewhat better" or "somewhat worse" were defined as the MCID estimates. We next assessed the association of MCID estimates for improvement and worsening of FVC% with patient reported outcomes (PROs) and computer-assisted quantitation of extent of fibrosis (QLF) and of total ILD (QILD) on HRCT.ResultsReliability of FVC%, assessed at a mean of 34 days, was 0.93 for the pooled cohort. The MCID estimates for the pooled cohort at 12 months for FVC% improvement ranged from 3.0 % to 5.3% and for worsening from -3.0% to -3.3%. FVC% improvement by ≥MCID was associated with either statistically significant or numerical improvements in some PROs, QILD, and QLF, while FVC% worsening ≥MCID was associated with statistically significant or numerical worsening of PROs, QILD, and QLF.ConclusionFVC% has acceptable test-retest reliability, and we have provided the MCID estimates for FVC% in SSc-ILD based changes at 12 months from baseline in two clinical trials. Clinical trial registration available at www.clinicaltrials.gov, IDs NCT00004563 and NCT00883129.

BackgroundIrritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) patients report similar gastrointestinal (GI) symptoms, yet comparisons of symptom severity between groups and with the general population (GP) are lacking.MethodsWe compared Patient-Reported Outcomes Measurement Information System (PROMIS® ) GI symptom scales measuring gastro-esophageal reflux (GER), disrupted swallowing, diarrhea, bowel incontinence, nausea/vomiting, constipation, belly pain, and gas/bloating in: (i) USA GP sample, (ii) IBS patients, and (iii) IBD patients from tertiary care and community populations. Symptom severity scores were based on T-score metric with mean 50±10 (standard deviation) relative to the GP.Key resultsOf 1643 patients enrolled, there were 253 IBS patients (68% F, mean age 45±15 years), 213 IBD patients (46% F, mean age 41±14 years), and 1177 GP subjects (57% F, mean age 46±16 years). IBS patients reported greater severity of GER, disrupted swallowing, nausea/vomiting, belly pain, gas/bloating, and constipation symptoms than their IBD counterparts (all P

Objective: This study aimed to analyze the effect of different gantry angles on portal imaging in terms of isocenter shifts and their dosimetric impact on dose delivery. Methods: Thirty patients with head and neck cancers were prospectively selected for this study. The reference anterior to posterior (AP) digitally reconstructed reference radiograph image was obtained at a gantry angle of 0°. The AP portal images were acquired at angles of 0°, 0.5°, 1°, 1.5°, and 2.0°. The average deviation of the isocenter shift with respect to the zero‐gantry angle was calculated. To check the dosimetric effects, the reference fluence was compared with different fluences measured at different isocenter shifts. Results: The average isocenter shift differences in the lateral direction were 0.7 mm, 1.3 mm, 1.9 mm, and 2.5 mm. The average difference was <±0.1 mm for isocenter shift in the longitudinal direction. The results of the statistical analysis showed that the average isocenter shift and gamma pass rate with respect to the different isocenter position errors were significant in the lateral direction. Conclusion: The results of this study showed that as the gantry angle increased, the isocenter shifted and the percentage of deviation in the lateral direction increased. [ABSTRACT FROM AUTHOR]

Introduction: Volumetric modulated arc therapy (VMAT) is an advanced technique used for radiotherapy treatment using different optimization modes. The present study aimed to evaluate Multi-criteria Optimization (MCO) influence on VMAT for Craniospinal Irradiation. Material and Methods: Fifteen CSI patients treated with 23.4 Gy/13 fractions followed by a boost dose of 6-MV flattening filter-free beams were chosen for this study. Conventional VMAT (c-VMAT) plans were generated for Elekta Versa HD™ linear accelerator. Keeping all other parameters constant, c-VMAT plans combined with MCO (MCO-VMAT) were created for comparison. We compared homogeneity index (HI), conformity index (CI), planning target volume (PTV) dose coverage (D98%), organ at risk (OAR) dose, normal tissue integral dose (NTID), volume receiving ≥ 5 Gy and ≥ 10 Gy by normal tissue, delivery time (DT), monitor units (MUs), and calculation time (CT). Results: Our findings demonstrated that HI and CI improved slightly in MCO-VMAT, in comparison with c-VMAT (P>0.05). No significant dose difference was observed in D98% for PTV and volume receiving the dose of ≥ 5 Gy, ≥ 10 Gy, and NTID (P>0.05). A slight increase was found in maximum dose to PTV in VMAT-MCO, compared to c-VMAT (P>0.05). The mean dose, max dose, and dose received by OAR were significantly lower in VMAT-MCO as compared to c-VMAT (p 0.05). Conclusion: The MCO-VMAT can be used for CSI, without compromising target coverage, reduced OAR dose by accepting a slight increase of MUs, delivery and calculation time as compare to c-VMAT.

The Treatment Planning System (TPS) in radiotherapy often faces challenges in optimizing techniques for large tumor volumes due to mechanical limitations, such as the over-travel distance of the Multileaf Collimator (MLC). This study compares the dosimetric outcomes of split field and open field techniques in Volumetric Modulated Arc Therapy (VMAT) for carcinoma tongue patients with large target volumes. Twenty-one patients treated with VMAT were evaluated using Eclipse™ TPS. The dosimetric parameters including conformity index, homogeneity index, and dose to Organs at Risk (OAR) were compared between split and open field techniques. Methods: VMAT plans utilizing two arcs were generated in Eclipse™ TPS with 6MV photon beams on a Truebeam STx Linear accelerator for all patients using both split and open field techniques. In the split field technique, fields were split along the X-Jaw direction. Optimization objectives and collimator angles were kept consistent for both techniques. Dosimetric data were collected and analyzed for conformity index, homogeneity index, and OAR doses. Results: The study revealed a 3% and 4% difference in homogeneity index, with conformity index values averaging 95% and 97% for split and open fields, respectively. Split field technique demonstrated reduced doses to OARs including Brainstem Dmax (9%), Spinal cord Dmax (6%), PORV cord Dmax (5%), Right Parotid Mean Dose (3%), Left Parotid Mean Dose (3%), Right Parotid (D50%) (5%), and Left Parotid (D50%) (2%), compared to the open field technique. The 50% isodose volume was also 4% lower in the split field technique. While the maximum dose remained identical, differences were observed in homogeneity index, conformity index, maximum dose, and mean dose to OARs. Conclusion: The split field technique demonstrates superior dosimetry outcomes with reduced doses to OARs compared to the open field technique, albeit with increased treatment time. Thus, the split field technique presents as a favorable option for planning large target volumes in carcinoma tongue cases. [ABSTRACT FROM AUTHOR]

Introduction: Radiation dose measurement plays a major role in Radiation Dosimetry. Effective dose delivery to the patient is ensured with the recommendation of some protocol called Quality assurance (QA). It is necessary to confirm that the beam that is used for treatment is a good quality beam and it is given by beam quality factor TPR 20/10 which is one of the QA protocols. Material and Methods: In the present TPR20,10 phantom both depth (20 and 10 cm) doses can be measured at the same procedure without changing any setup. As the reference condition is maintained, the Gelatin-based phantom is kept for irradiation in the Siemens Linear Accelerator (LINAC) machine. Initially Source Axis Distance (SAD) of 100 cm from the surface and 10×10 cm² of field size. The measurement is taken by ion chamber at 10 and 20 cm depth in gantry angles 90° and 270° And the ratio of these values is taken and compared with the measurements of the water-based TPR phantom. Results: The values for the TPR20,10 ratio for the Gelatin and water phantom are measured using the above method and the values are tabulated and compared. Likewise, the output measurements are done and tabulated for comparison. These measurements are carried out for several days to check the repeatability, and reproducibility of the phantom. Also, the measured set of values was analyzed using mean, median, standard deviation, etc. Conclusion: The fabricated phantom had good outcomes in its response. And the result projects that the phantom can be a better alternative for the other phantom materials and gelatin has more advantages over water, we conclude that gel can be used for better dosimetric procedures. [ABSTRACT FROM AUTHOR]

Byline: Bharath. Pandu, D. Khanna, P. Mohandass, Hima. Ninan, Rajadurai. Elavarasan, Saro. Jacob, Goutham. Sunny Purpose: The aim of the current study is to commission compensator-based total body irradiation (TBI) [...]