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Dosimetric impact of FFF over FF beam using VMAT for brain neoplasms treated with radiotherapy

100%

Manna S. , Kombathula S. H. , Gayen S. , Varshney S. , Pareek P.

Polish Journal of Medical Physics and Engineering

2021

tom Vol. 27, Iss. 3

191--199

Background: This study was conducted to assess the dosimetric impact of FFF beam plans on high-grade brain neoplasms using the VMAT technique when compared with FF beam plans. Material and Methods: Thirty patients with high-grade brain neoplasms, who had received radiotherapy using VMAT technique retrospectively were selected for this study. All the patients were planned for VMAT using 6MV_FF beam and the same plan was re-optimized using 6MV_FFF beam keeping the same dose constraint. Radiotherapy dose distribution on planning target volume (PTV) and organs at risk (OAR), target conformity index (CI), Homogeneity Index (HI), Low dose volume in the patient (V5, V10, V20, and V30), and Integral dose to the whole body in both plans were compared. Results: The PTV coverage and OAR’s showed no significant differences in dose distribution between the FFF and FF beam VMAT planning. There was a reduction of the average maximum dose in the right eye, left eye, right optic nerve, and left optic nerve using FFF beams. The reduction in average low dose volume was observed in V5, V10, V20, V30, and Mean Dose. Also, a significant reduction was observed in the integral dose to the whole body using the FFF beam. Conclusions: Using FFF beams with VMAT is doable for the treatment of high-grade brain neoplasms, and the delivery mode of the FFF beam in VMAT may yield similar results to FF beam which should be confirmed in a large scale prospective clinical trial.

Controllable fluids : materials with the ability to changing their physical properties

86%

Bik T.

Journal of KONES

2016

tom Vol. 23, No. 2

45--51

Controllable fluids (smart liquids) are the substances that change their properties under the influence of external physical fields. Changes of these liquids properties take place in a controlled manner and they are fully reversible. The ability to changing nature of work is a very important aspect that determines their vast application possibilities. It also makes they are occupying significant place in the modern engineering. Content of this report has been in turn devoted to systematization information on the properties and work of magnetically activated controllable fluids. There have been highlighted some commonalities and differences between two basic types of magnetic fluids (ferro- and magnetorheological fluids). Essential areas of controllable fluids application and their production methods have also been presented within this notice. It seems to be more than reasonable to explore this title issue using new methods of research and observations. They in fact directly create another chances for discovery unknown features or simply adapting the existing ones to current technical expectations. What are also important, smart liquids can be threaten as highly advanced materials which synthesis cover manipulation on the already known substances and do not cause any environmental pollution. Discovered over sixty years ago, they still signalize a great potential to development.

Effects of flattening filter (FF) and flattening filter-free (FFF) beams on small-field and large-field dose distribution using the VMAT treatment plan

86%

Plaza D. J. , Orzechowska K. M. , Ślosarek K. T.

Polish Journal of Medical Physics and Engineering

2021

tom Vol. 27, Iss. 2

137--141

Introduction: The aim of the study was to evaluate the influence of flattening filter (FF) and flattening filter-free (FFF) beams on small-field and large-field dose distribution using the VMAT treatment plan. Material and methods: Dose distribution calculations were performed for the VMAT technique in two locations: the larynx (small irradiation field; average 30.1 cm2) and gynecology (large irradiation field; average 173.1 cm2) using X- 6MV flattening filter (FF) and flattening filter-free (FFF) beams. The following values were compared: the number of monitor units, minimum doses, average doses in PTV and maximum average doses in OaR (spinal cord – in larynx radiotherapy, bladder and rectum - in gynecological radiotherapy) and RPI (Radiation Planning Index) coefficient. Results and Discussion: The performed statistical tests indicate that there is a significant difference (p <0.05) between the number of monitor units in the irradiation of large (gynecological) fields between the FF and FFF beams. The dose distributions show no statistically significant differences between the flattening filter and flattening-free filter beams (regardless of the field size). Conclusions: Due to the smaller number of monitor units, it is recommended to use flattening filter beams (FF) for largefield radiotherapy.