Stereotactic Radiosurgery for Limited Brain Metastasis using Three Different Techniques; Helical Tomotherapy, Volumetric Modulated Arc Therapy, and Cone-Based Linac Radiosurgery.

Background: Specific radiation delivered to the tumor by stereotactic radiosurgery (SRS) has become widely used in the treatment of brain metastasis. This study aimed to compare radiation dosimetry and its parameters from SRS using three different modalities: Helical Tomotherapy (HT), Volumetric Modulated Arc Therapy (VMAT), and Cone-based Linac Radiosurgery (Cone-based). Methods: Patients who had experienced oligo-brain metastasis received SRS in our treatment center. Each contouring dataset was re-planned to create radiation dosimetry in all three treatment systems (HT, VMAT, and Cone-based). The parameters of conformity index (CI), homogeneity index (HI), CI50, and gradient index (CGI) were analyzed to compare the effects of the three techniques. Results: A total of 21 patients with 39 lesions were included in this study. For single lesion, Cone-based and VMAT revealed statistically identical CI, CI50, and CGI values, while exhibiting the poorest HI value. For multiple lesions, Cone-based provided the best CI50 and CGI values. VMAT displayed better CI50 and CGI values than HT. Moreover, VMAT exhibited the lowest BrainV5Gy value and displayed the shortest beam on time (BoT) calculation. Lastly, Decision Score analysis demonstrated better performance in VMAT when compared to the Cone-based approach. Conclusions: Our data indicated the dosimetric comparison between three radiation techniques for single and multiple lesions. The Cone-based technique revealed the poorest HI value. On the other hand, VMAT provided the best estimated BoT value. Moreover, we have reported on the feasibility of SRS using HT, which has been associated with well-tolerability and an acceptable level of radiation output.Trial registration: Thai Clinical Trials Registry (TCTR) ID No. TCTR20200803006Date of registration: 24 July 2020 (Retrospectively registered)URL: http://www.thaiclinicaltrials.org/show/TCTR20200803006

The Repurposing of the Antimalaria Drug, Primaquine, as a Photosensitizer to Inactivate Cryptococcal Cells

Cryptococcal cells can manifest skin infections in immunocompromised persons. While it may be easy to diagnose cryptococcal infection, treatment often fails due to the ineffectiveness of current antifungal agents. To this end, the present study explored the repurposing of primaquine (PQ), as a photosensitizer. PDT was carried out using a germicidal ultraviolet (UV) lamp, which has a radiation output of approximately 625 µW/cm2 at a distance of 20 cm. When compared to the non-treated cells, the metabolic activity of cryptococcal cells was significantly (p < 0.05) limited. The photolytic products of PQ were observed to alter the ultrastructure of treated cells. The latter was not incidental, as the same cells were also documented to lose their selective permeability. Importantly, PDT also improved the efficiency of macrophages to kill internalized cryptococcal cells (p ≤ 0.05) when compared to non-treated macrophages. Equally importantly, PDT was not detrimental to macrophages, as their metabolic activity was not significantly (p > 0.05) limited, even when exposed to 20× the MIC (determined for cryptococcal cells) and an exposure time that was 4× longer. Taken together, the results suggest PQ has the potential to control the growth of cryptococcal cells and limit their survival inside the macrophage.

Experimental Studies of Rocket Fuels Oxygen--Hydrogen, Oxygen--Methane Ignition by a Semiconductor Laser

The paper presents results of experimental studies aimed at introducing laser ignition of fuel mixtures into aero-space design practice. The source of ignition energy was a semiconductor laser featuring fibre radiation output, operating in a quasi-continuous wave mode. We carried out experiments for oxygen--hydrogen and oxygen--methane fuel types. The purpose of our research was to demonstrate the fundamental possibility of implementing fuel ignition by means of this type of laser, using a rocket engine igniter and a low-thrust rocket engine as examples. Employing semiconductor lasers directly as an ignition source for fuel mixtures in aerospace technology is attractive as it may feasibly reduce the requirements for thermal conditions during operation of the laser ignition system on board a rocket or spacecraft, as well as expand the range of permissible vibration and shock loads. The paper presents experimental results that delineate operating parameter ranges and operation cyclograms for the devices under consideration that ensured stable ignition of oxygen--hydrogen and oxygen--methane fuel mixtures; we also list the required power parameters for a semiconductor laser. The investigation revealed the specifics of using a semiconductor laser-based ignition system, which will be useful in developing laser rocket launching devices, ensuring reliable repeated on-off functionality

MOBILE MICROFOCAL X-RAY DIAGNOSTIC COMPLEX IN THE IMAGING OF PREMATURE NEWBORNS

Aim. Estimation of the diagnostic capabilities of microfocal X-ray diagnostic complex for the imaging of premature newborns. Materials and methods. The study was performed on the base of Almazov National Medical Research Centre. The study included X-ray examinations of 156 premature newborns using the method of microfocus radiography: 139 X-ray images of the chest, 17 X-ray images of the abdomen. Imaging was performed using the projection magnification technique with the patient positioned close to the X-ray source. Results. The microfocal X-ray images had the necessary quality for the diagnosis of pathological changes in the chest and abdomen for babies. Patient dose estimation was based on the radiation output of the X-ray unit and tube current-time product. For the maximum values of tube voltage, tube current and exposure time effective doses did not exceed 0.02 mSv, corresponding to negligible radiation risk category. Conclusion. Microfocal radiography allows performing informative X-ray examinations of premature newborns, especially using the projection magnification technique. The use of microfocal X-ray diagnostic complex allows reducing patient doses, increasing the mobility and usability of the X-ray equipment. The first experience of clinical application of microfocal radiography in neonatology and pediatrics with projection magnification of the X-ray image was evaluated as successful.

Laser coagulation in combination with LIFT for transsphincteric anal fistulas

Aim: to improve the results of fistula treatment, to evaluate the effectiveness of the combined use of LIFT and FiLaC techniques.Patients and methods: the study included 35 patients with transsphincter fistulas of cryptopglandular etiology involved more than 1/3 of the sphincter. All patients underwent surgery with laser energy (the laser conductor speed is 1 mm per second, the wavelength is 1470 nm, the radiation output is 13 W) after the LIFT procedure.Results: the primary healing rate was 28/35 (80,0%). The patients who failed the combined procedure (cases of prolonged healing more than 3 months) underwent a second procedure ReFiLaC, which led to the closure of fistula in 2 of 3 patients. A median follow-up period was 10,2 months. No incontinence to solid and liquid stools was detected.Conclusion: preliminary results of the study permits to assess the potential of the combined low-invasive approach for anal fistulas as positive.

Electro-optical measurement of intense electric field on a high energy pulsed power accelerator

We describe a direct electro-optical approach to measuring a strong 118 MV/m narrow pulse width (~ 33 ns) electric field in the magnetically insulated transmission line (MITL) of a pulsed power accelerator. To date, this is the highest direct external electric field measured electro-optically in a pulsed power accelerator, and it is between two to three orders of magnitude higher than values reported in comparable high energy scientific experiments. The MITL electric field is one of the most important operating parameters in an accelerator and is critical to understanding the properties of the radiation output. However, accurately measuring these high fields using conventional pulsed power diagnostics is difficult due to the strength of interfering particles and fields. Our approach uses a free-space laser beam with a dielectric crystal sensor that is highly immune to electromagnetic interference and does not require an external calibration. Here we focus on device theory, operating parameters, laboratory and pulsed power accelerator experiments as well as challenges that were overcome in the measurement environment.

Electro-Optical Measurement of Intense Electric Field on a High Energy Pulsed Power Accelerator

We describe a direct electro-optical approach to measuring a strong 118 MV/m narrow pulse width (~33 ns) electric field in the magnetically insulated transmission line (MITL) of a pulsed power accelerator. To date, this is the highest direct external electric field measured electro-optically in a pulsed power accelerator, and it is between two to three orders of magnitude higher than values reported in comparable high energy scientific experiments. The MITL electric field is one of the most important operating parameters in an accelerator and is critical to understanding the properties of the radiation output. However, accurately measuring these high fields using conventional pulsed power diagnostics is difficult due to the strength of interfering particles and fields. Our approach uses a free-space laser beam with a dielectric crystal sensor that is highly immune to electromagnetic interference and does not require an external calibration. Here we focus on device theory, operating parameters, laboratory and pulsed power accelerator experiments as well as challenges that were overcome in the measurement environment.

SOCIALIZATION OF RADIOGRAPHER UNDERSTANDING OF DIAGNOSTIC REFERENCE LEVEL AS AN EFFORT TO OPTIMIZE RADIOGRAPHIC EXAMINATION

The use of X-rays cannot be separated from the radiation given to the patient's body, therefore the radiation exposure received by patients should be very low according to the ALARA principle (As Low As Reasonably Achieveable). The research method is a quantitative description by using themeasurement method radiation output as a reference for the estimated radiation dose received by the patient, then the analysis of the success of socialization to radiographers about DRL as an optimization effort in radiographic examination. The results of the radiation dose estimation using themethod radiation output by determining theequation power function of themeasurement radiation output where the value of the radiation dose rate increases as the kVp value increases with y= 0.0005x2.9242. From theresults, it was pre-test found that the number of correct answers was 120 and 84 wrong, with a percentage of 59% and the number of respondents 10.03 people. Meanwhile, for theresults, the post-test number of correct answers was 194 and 12 wrong, with a percentage of 94% and the number of respondents being 15.98 people. It is hoped that radiographers can apply the principle of optimization in carrying out all radiographic examinations.