Assessment of the Effectiveness of a Portable NIRS Instrument in Controlling the Mixer Wagon Tuning and Ration Management

The adoption of the mixer wagon and total mixed ration aimed to decrease dysmetabolic diseases and improve feed efficiency in dairy cows. Differences between theoretical and eaten diets are imputable to errors in diet preparation or cow feed sorting. We proposed a method to measure the chemical composition and particle size distribution of the ration and determined its peNDF content through a portable Near Infra-Red spectrophotometer that allowed the calculation of two indexes: the homogeneity and the sorting indexes. In a cohort of 19 Italian Holstein breeding farms, we studied the correlation of these indexes with the mixer wagon settings. Determination coefficients in the validation (Rv2) for dry matter, crude protein, aNDF, and starch were 0.91, 0.54, 0.86, and 0.67, respectively. The ration fractions (%, w/w of wet weight) retained by the 3.8 and 1.8 mm sieves, and the bottom showed Rv2 of 0.46, 0.49, and 0.53, respectively. The homogeneity index regressed negatively with the mixer wagon load fullness (R2 = 0.374). The homogeneity-binary classification showed an odds ratio of 1.72 for dry matter and 0.39 for aNDF (p < 0.05). The sorting-binary classification showed an odds ratio of 2.54 for aNDF (p < 0.05). The studied farms showed low peNDF values (median = 17.9%).

A Numerical Investigation into the Effect of Homogeneity on the Time-Dependent Behavior of Brittle Rock

To investigate the brittle creep failure process of rock material, the time-dependent properties of brittle rocks under the impact of homogeneity are analyzed by the numerical simulation method, RFPA-Creep (2D). Deformation is more palpable for more homogeneous rock material under the uniaxial creep loading condition. At a low stress level, diffusion creep may occur and transition to dislocation creep with increasing applied stress. The law for increasing creep strain with the homogeneity index under a constant confined condition is similar to the uniaxial case, and dislocation creep tends to happen with increasing confining pressure for the same homogeneity index. The dilatancy index reaches its maximum at a high stress level when rock approaches failure, and the evolution of the dilatancy index with the homogeneity index under the same confining pressure is similar to the uniaxial case and is more marked than that under the unconfined condition. Both uniaxial and triaxial creep failure originate from the ductile damage accumulation inside rock. The dominant shear-type failure is exhibited by uniaxial creep and the conventional compression case presents the splitting-based failure mode. Under confining pressure, the creep failure pattern is prone to shear, which is more notable for the rock with higher homogeneity.

Comparison of dosimetry in head and neck cancer patients treated with intensity modulated radiation therapy and helical tomotherapy

Background: This study was conducted to compare dosimetric parameters and dose to specific organs at risk (spinal cord and parotids) between intensity modulated radiation therapy (IMRT) and helical tomotherapy (HT) in head and neck squamous cell carcinomas (HNSCC).Methods: Thirty patients with histologically proven HNSCC were treated with chemo radiotherapy, to a dose of 60-70 Gray in 30-35 fractions. This study consists of two arms; IMRT arm and tomotherapy arm. Fifteen consecutive patients treated under IMRT and 15 patients were treated under helical tomotherapy, along with concurrent chemotherapy. PTV1 encompasses low risk planning target volume (PTV) which receives 50 Gy; PTV2 encompasses intermediate risk PTV which receives 54-60 Gy and PTV3 encompasses high risk PTV which receives 66-70 Gy. After completion of planning, dose to the organs at risk (OARs) and targets, homogeneity index and conformity index were evaluated, and tabulated.Results: On evaluation of plans we found that V95% in PTV1, PTV2 and PTV3 were 91.82%, 96.85% and 90.67% respectively for IMRT and 99.25%, 99.68% and 99.73% respectively for tomotherapy. For PTV3, V110% was 0.11% for IMRT and 0.01% for tomotherapy. Homogeneity index in IMRT arm was 0.285 and it was 0.206 in tomotherapy arm. Conformity index was found to be 1.04 for IMRT plans and 1.06 for tomotherapy plans. When mean dose to contra lateral parotids was evaluated, it was 26.91 Gy in IMRT arm and 25.97 Gy in tomotherapy arm. Max dose to spinal cord was better in tomotherapy (43.07 Gy in IMRT and 34.41 Gy in tomotherapy).Conclusions: There was statistically significant reduction in spinal cord maximum dose and point doses in tomotherapy plans compared to IMRT plans. The decrease in spinal cord dose can increase the tolerance reserve which can be useful in dose escalation or re-irradiation if required. There was also decrease in contra lateral parotid doses (not statistically significant). There was significant improvement in V95% in tomotherapy arm compared to IMRT arm, indicating the significantly superior coverage of target volumes in helical tomotherapy plans compared to IMRT plans. V110% (hot spots) inside the target was very minimal in tomotherapy arm compared to IMRT arm. Conformity index, homogeneity index between two arms were comparable.

Dosimetric Effect of Respiratory Motion On Planned Dose In Whole-Breast Volumetric Modulated Arc Therapy Using Standard And Ultra-Hypofractionation

Background and purpose: The interplay effects of respiratory motion and MLC movement on the planned dose in right-sided whole-breast irradiation (WBI) were studied by simulating hypofractionated VMAT treatment courses.Materials and methods: Ten patients with phase-triggered 4D-CT images were included in the study. VMAT plans targeting the right breast were created retrospectively with prescription doses of 26 Gy (5 fractions) and 40.05 Gy (15 fractions). 3D-CRT plans were generated as a reference. All plans were divided into respiratory phase-specific plans in fraction-by-fraction basis. The phase-specific dose distributions were deformed and superimposed onto the planning image, forming the course-specific, respiratory motion perturbed dose distribution. Distributions were compared with the original plans and changes due to respiratory motion and choice of fractionation were evaluated.Results: The respiratory motion perturbed PTV coverage (V95%) decreased by 1.7% and the homogeneity index increased by 0.02 for VMAT techniques, compared to the planned values. Highest decrease in CTV coverage was 0.7%. The largest dose differences were located in the areas of steep dose gradients parallel to respiratory motion. The largest difference in DVH parameters between fractionation schemes was 0.4% of the prescribed dose. Clinically relevant changes to the doses of organs at risk were not observed.Conclusion: The VMAT techniques were found feasible for WBI with 5 and 15-fraction treatments in terms of respiratory motion induced error. The CTV dose coverage was retained despite the decrease in PTV coverage. No clinical significance was found due to the choice of fractionation.

Distribution and Conservation Status of the Hyrcanian Wood Frog (Rana pseudodalmatina) in Azerbaijan

In Azerbaijan, the Hyrcanian wood frog (Rana pseudodalmatina) usually inhabits forests in the Talysh Mountains and the Lenkoran Lowland from –28 to 2265 m above sea level. Drier regions to the north and west of the Talysh Mountains limit the species distribution. The species can locally penetrate to a no forested zone in the northern and western foothills of the Talysh Mountains and the Zuvand Desert. In order to study the distribution and estimate ecological preferences of the species, we applied MaxEnt using 98 localities from Azerbaijan, Iran, and Turkmenistan. The range of the species covers mainly pre-Caspian slopes of the Talysh and Alborz ridges. Of the parameters included in the model, the precipitation of driest month and the habitat homogeneity (index related to vegetation types) were variables with highest percentage contributions. Based on our data, in Azerbaijan R. pseudodalmatina is very common species in most places and in some localities is the most numerous amphibian species. The frog does not avoid human-transformed biotopes. The main factors influenced on a local declining of R. pseudodalmatina are the introduction of fishes (including invasive) and the common raccoon, destruction and contamination of suitable breeding water bodies. The most suitable method of conservation of the frog is construction of new ponds for their reproduction and wintering.

Assessment of planning reproducibility in three-dimensional field-in-field radiotherapy technique for breast cancer: impact of surgery-simulation interval

The three-dimensional field-in-field (3-D FIF) technique for radiotherapy is an advanced, state-of-the-art method that uses multileaf collimators to generate a homogeneous and conformal dose distribution via segmental subfields. The purpose of this study is to evaluate the dosimetric reproducibility of 3-D FIF plans using the original simulation computed tomography (iCT) scans and re-simulation CT (rCT) scans for whole breast irradiation (WBI) schedule. This study enrolled a total of 34 patients. The study population underwent iCT scans for standard WBI and took rCT scans after 45 Gy of WBI for cone down boost plans. The dosimetric parameters (V105%, V103%, V100%, V98%, V95%, V90%, V50%), plan quality indices (conformity index, homogeneity index) and clinical parameters (isocenter-breast axis, isocenter-lung axis, soft tissue volumes within radiation field, lung volumes within radiation field) were assessed. The median time interval from surgery to iCT was 33 days and from iCT to rCT was 35 days. All dosimetric parameters exhibited statistically significant differences between iCT and rCT among cohorts with a surgery-iCT interval of < 60 days. Homogeneity index showed a statistically significant increase from iCT to rCT among all cohorts. Soft tissue volumes (p = 0.001) and isocenter-breast axis (p = 0.032) exhibited statistically significant differences among cohorts with surgery-iCT interval < 60 days. Regarding the reproducibility of the 3-D FIF WBI plans, significant changes were observed in dosimetric and clinical factors, particularly in study cohorts with a surgery-simulation interval < 60 days. The main contributing factor of these transitions seemed to be the changes in volume of the soft tissue within the WBI field. Further confirmative studies are necessary to determine the most suitable timing and technique for WBI.

Volumetric Modulated Arc Therapy (VMAT): A modern radiotherapy technique - A single institutional experience

Objective: To evaluate VMAT plans for conformity and homogeneity of radiation dose to the target in order to share our experience as a pioneering institute to use VMAT technology in Pakistan. Methods: Since December 2014 to January 2018, 530 patients of various anatomical sites were treated by VMAT technique at Neurospinal Cancer Care Institute (NCCI) Karachi Pakistan. ERGO++ planning system (Version 1.7.2) was used to develop VMAT plans with single or multiple arcs by the rotation of couch and gantry. The plans were evaluated by calculating Conformity Index (CI) and Homogeneity Index (HI) and critical organ (OARs) doses of individual tumor sites. Results: The average CI of various sites was 1.4 (range: 1.0–2.0) and average HI of various sites was 1.20 (range: 1.07–1.374), respective critical organ doses were adequately achieved. Conclusions: VMAT treatment planning technique showed good conformal and homogeneous target coverage with sparing of organs at risk and reduced treatment delivery time. With these features, safety of VMAT technique may allow its routine clinical use, though it is still under investigation in many areas. Abbreviations Used:CI: Conformity Index, HI: Homogeneity Index, GI: Gradient Index, SIB: Simultaneous Integrated Boost, SRS: Stereotactic Radiosurgery, SBRT: Stereotactic Body Radiotherapy, VMAT: Volumetric Modulated Arc Therapy, MLCs: Multi-leaf Collimators, MU: Monitor Units, DAM: Dynamic Arc module, TV: Target Volume, MD: Maximum Dose, PD: Prescription Dose, RTOG: Radiation Therapy Oncology Group, Linac: Linear accelerator. doi: https://doi.org/10.12669/pjms.37.2.2647 How to cite this:Rashid A, Ahmad Z, Memon MA, Hashim ASM. Volumetric Modulated Arc Therapy (VMAT): A modern radiotherapy technique-A single institutional experience. Pak J Med Sci. 2021;37(2):---------. doi: https://doi.org/10.12669/pjms.37.2.2647 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Analysis of Geometric and Dosimetric Effects of Bra Application to Support Large or Pendulous Breasts During Radiotherapy Planning: A Retrospective Single-Center Study

Purpose: To evaluate geometric and dosimetric effects of bra application during radiotherapy planning for breast cancer patients with large and pendulous breasts. Materials and Methods: Twenty patients with chest sizes >38 inches between April 2019 and July 2019 underwent radiotherapy planning with and without a radiation bra (Chabner XRT®). Geometric and dosimetric parameters included the breast volume, superior-inferior (SI) distance, separation (S) as the distance of the longest diameter of the clinical target volume (CTV), conformity number (CN), and homogeneity index (HI) of CTV. The organs at risk (OARs) were defined as the lungs, heart, and liver. Results: The use of the radiation bra provided mean changes of −0.51 cm for S, −1.45 cm for SI, and −61.18 cc for breast volume (all P < 0.05). Breast volume was correlated with bra-related changes in cross diameter (r = 0.641, P = 0.002) and volume (r = 0.680, P = 0.001). Significant dose reductions were observed for the lungs (mean V10: 19.58 cc, V20: 17.13 cc, Dmean: 86.24 cGy) and heart (Dmean: 170.23 cGy). No significant differences were observed for CN (0.62-0.67) and HI (0.19-0.20) of the CTV. Conclusion: The application of a radiation bra was associated with better geometric and dosimetric planning parameters, with a smaller CTV and lower doses to the OARs (lungs and heart) in the radiotherapy field. In addition, we expect that bra use during radiotherapy would provide emotional benefits.

Validity and reliability of the questionnaire that measures the perception of speech-language-hearing therapists regarding the use of information and communication technologies (ICTs) in speech-language-hearing evaluation and intervention processes

ABSTRACT Purpose: to study the validity and reliability of the questionnaire that measures the perception of speech-language-hearing therapists, regarding the use of information and communication technologies (ICTs) in evaluation and intervention processes. Methods: a descriptive, cross-sectional, observational, nonexperimental study. A total of 123 professionals from the Region of Valparaíso, Chile, with degrees in speech-language-hearing therapy, participated in the study. They answered the questionnaire that measures their opinion and knowledge on the use of ICTs. Results: the questionnaire had an adequate level of stability, as the Cronbach's α and Guttman's λ6 coefficient values were respectively 0.85 and 0.95. When studying each item, adequate levels of stability were obtained. On the other hand, the corrected homogeneity index (CHI) yielded values lower than 0.2 for items A8, A9, A17, A18, A26, A27, A42, A43, and A46, which suggests not considering them due to a lack of correlation between these items and the overall questionnaire score. Regarding content validity, assessed with the Question Appraisal System, 100% of the questions presented no major semantic problems. Conclusion: the results of the study indicate that the ICT questionnaire is valid and reliable.

A Study of Dose Painting with IMRT Guided by Perfusion-weighted Magnetic Resonance Imaging for Brain Metastases

Purpose: To investigate dose escalation for brain metastases (BM) subvolumes with low cerebral blood flow (CBF) using dose-painting technology based on MR 3D arterial spin labeling (3D-ASL) images.Methods: A total of 50 patients with single BM were selected for this study. CT and MR simulation images, including contrast-enhanced T1-weighted (T1W) images and CBF images, were obtained. The gross tumor volume (GTV) was determined by fusion of contrast-enhanced CT and T1W images, and this volume was divided into high- and low-perfusion areas according to the difference in CBF. Sub-volume with less than 25% of the maximum CBF was defined as hypoxic region GTVH which was settled for dose escalation. The planning target volume (PTV) and PTVH were calculated from the GTV and the GTVH, respectively. The PTVN was calculated by subtracting the PTVH from the PTV. Plan 1 was defined as the conventional plan with a prescription dose of 60 Gy for the PTV. Plan 2 and Plan 3, respectively, escalated the prescription dose for the PTVH to 72 Gy with and without the maximum dose constrained based on Plan 1. Dosimetric indices were compared among the three plans.Results: On average, the GTV volume was 34.53 cm3, and the GTVH volume was 16.95 cm3, accounting for 49.09% of the GTV. Compared to Plan 1, the D2%, D98% and Dmean values of the PTVH escalated by 20.50%, 19.32%, and 19.60%, respectively, in Plan 2 and by 24.05%, 6.77%, and 17.00%, respectively, in Plan 3 (all P<0.05). The doses administered in Plans 2 and 3 were 73.67±0.34 Gy and 72.37±0.61 Gy, respectively (both P<0.05). In Plans 2 and 3, respectively, the conformity index of PTVH was increased by 45.45% and 63.64%; meanwhile, the homogeneity index was sacrificed, increasing from 0.04 to 0.05 and 0.11 (all P<0.05). Plan 2 achieved better values of D98% and Dmean, as well as a smaller increase in the homogeneity index, than Plan 3. The doses received by organs at risk (OARs) did not significantly differ between the conventional plans and the boost plans (all P >0.05).Conclusions: Targeted dose escalation guided by the 3D-ASL-based CBF differences in BM effectively escalated the dose delivered to low-CBF subvolumes without increasing the dose to OARs.