Single Irradiation Research Articles

Numerical study on THz radiation of two-dimensional plasmon resonance of GaN HEMT array

The GaN high electron mobility transistor (HEMT) has been considered as a potential terahertz (THz) radiation source, yet the low radiation power level restricts their applications. The HEMT array is thought to improve the coupling efficiency between two-dimensional (2D) plasmons and THz radiation. In this work, we investigate the plasma oscillation, electromagnetic radiation, and the integration characteristics of GaN HEMT targeting at a high THz radiation power source. The quantitative radiation power and directivity are obtained for integrated GaN HEMT array with different array periods and element numbers. With the same initial plasma oscillation phase among the HEMT units, the radiation power of the two-element HEMT array can achieve 4 times as the single HEMT radiation power when the array period is shorter than 1/8 electromagnetic wavelength. In addition, the radiation power of the HEMT array varies almost linearly with the element number, the smaller array period can lead to the greater radiation power. It shows that increasing the array period could narrow the main radiated lobe width while weaken the radiation power. Increasing the element number can improve both the radiation directivity and power. We also synchronize the plasma wave phases in the HEMT array by adopting an external Gaussian plane wave with central frequency the same as the plasmon resonant frequency, which solves the problem of the radiation power reduction caused by the asynchronous plasma oscillation phases among the elements. The study of the radiation power amplification of the one-dimensional (1D) GaN HEMT array provides useful guidance for the research of compact high-power solid-state terahertz sources.

Design and simulation of a low-energy single ion irradiation system for micro/nano-biosample investigation

A low-energy single ion irradiation system is developed in its initiation in Thailand to follow one of the trends in novel ion beam technology exploitation. Single ion irradiation of materials is a highly technological development of ion beam technology. The developed single ion irradiation systems worldwide are primarily in the MeV-energy range and for single cell studies, and recently the trend has been extended to the low-energy range (< 100 keV) but focused on microelectronic applications. Based on our previous research on low-energy ion beam irradiation of biological cells and DNA, we design and simulate a low-energy single ion implantation system, aiming at eventual construction of such a novel ion beam apparatus for applications to the biological studies. In the system, the ion energy is decreased to orders < 1 keV by the existing deceleration lens, then the low-energy ion beam passes through µm slits, and finally, low-energy single ions are obtained by beam scanning with appropriate frequencies from scanner plates and detected by a single ion detection device. Conceptual design, calculation and simulation of this single ion system are presented.

Immunohistochemical and histochemical analysis of the rat skin after local electron irradiation.

Skin cancer is the most frequently diagnosed type of cancer among all malignant neoplasms. The decrease in mitotic activity and the death of intact keratinocytes arise due to the constantly renewing epithelium being highly sensitive to ionizing radiation. The aim of the study is immunohistochemical evaluation of the proliferative-apoptotic balance of keratinocytes, the fibrous component of the skin, and the expression of pro-inflammatory and anti-inflammatory cytokines after single or fractional local electron irradiation. Wistar rats (n = 80) were taken from the ITM&B Vivarium (Sechenov University) and divided into groups: I-control, which were injected with saline; and experimental groups, local electron irradiation at doses: II-8 Gy (single), III-40 Gy (single), IV-summary dose 78 Gy (fractional; 13 Gy per day for 6 days). We performed histological analysis, histochemical analysis using Masson, safranine, and picrosirius red staining, immunohistochemical (Ki-67, caspase-3, p53, types I and III collagens, IL-1, IL-6, IL-4, and IL-10) and morphometric analysis of skin fragments of the outer surface of the thigh, irradiated in accordance with the design of the experiment. The early and delayed effects of local electron irradiation at different doses were studied. After local electron irradiation, dose-dependent morphological changes in the skin of the experimental groups were observed: violation of the histoarchitectonics of the skin confirmed by morphological and morphometric analysis, the proliferation of connective tissue according to the results of histochemical and immunohistochemical studies with signs of the radiation-induced skin fibrosis development, an increase in the levels of pro- and anti-inflammatory cytokines. We observed the most pronounced signs of radiation-induced skin damage in the group of fractional irradiation after 3 months. 8 Gy and 40 Gy single local electron irradiation leads to a shift in the proliferative-apoptotic balance of keratinocytes toward their apoptosis, which activity is directly correlated with the dose of ionizing radiation, and 78 Gy in fractions leads to partial desquamation of the epithelium and inflammatory infiltration. In addition, after 3 months a significant increase in the expression of type I and III collagen fibers and the development of radiation-induced skin fibrosis takes place against the background of 78 Gy fractional local electron irradiation.

Stimulation of Mesenchymal Stem Cells Proliferation from the Femur of Wistar Rats by Nanosecond Microwave Radiation: Dependence on the Number of Pulses

The effect of nanosecond repetitively pulsed microwave radiation (RPM, 50–4000 pulses, pulse repetition rate of 13 Hz, peak power flux density of 140 W/cm2, carrier frequency of 10 GHz) on the stimulation of me-senchymal stem cells (MSC) proliferation was studied. The effect of exposure was assessed by the change in the number of cells in the culture after a single irradiation with a different number of pulses. The most pronounced effect exerted by the impact with 100 and 50 pulses, and the effect is realized with a maximum speed after 24 hours.

Morphofunctional characteristics of proliferation and apoptosis of germinal epithelium: pathogenesis of temporary azoospermia after local electron irradiation.

At present, the violation of male reproductive function caused by electron irradiation, leading to a decrease in the proliferative activity of germ cells, as well as the development of methods for its correction are relevant. The effect of leukocyte-poor platelet-rich plasma (LP-PRP) growth factors, which have a high regenerative capacity for the restoration of spermatogenesis, remains poorly understood. Objective of the study: immunohistochemical (IHC) assessment of the proliferation of germinal epithelium after electron irradiation with a dose of 2 Gy. Wistar rats (n=60) were divided into groups (conventional names): (I) control (n=30), which were injected with saline; (II) single local irradiation of the testes with electrons at a dose of 2 Gy (n=30). Animals were gradually withdrawn from the experiment over 11 weeks: 5 animals one week after irradiation, and then 5 animals once every 2 weeks. The testes were studied by histological and IHC methods using antibodies to Ki-67, Bcl-2, and p53. Terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) method was used to study DNA fragmentation in germ cells, which were stained with TdT solution (Thermo Fisher, USA) and incubated for 60 minutes. The nuclei were counterstained with 4',6-diamidino-2-phenylindole (DAPI) (blue spectrum) (Thermo Fisher), and the luminescence intensity was controlled in a fluorescent microscope with a set of fluorescein isothiocyanate (FITC) filters (green spectrum). IHC analysis of testes after irradiation showed a shift in the proliferative-apoptotic balance towards apoptosis of germ cells: a decrease in the expression levels of Ki-67 (16.3%±1.1%, P<0.05) and Bcl-2 (9.1%±1.1%, P<0.05), an increase in p53-positive cells (74.8%±1.2%, P<0.05) by the end of the experiment. In the experimental model, local irradiation of the testes with electrons at a dose of 2 Gy causes the development of focal hypospermatogenesis, affecting up to 1/8 of the sections of the tubules (in the first week) with a subsequent increase to 1/4 (in the second month), with a tendency to recovery in the third month (temporary azoospermia). The basis of focal hypospermatogenesis is the irradiation-induced proliferative-apoptotic imbalance towards the dominance of apoptosis, which is most pronounced in the pool of spermatogonia.

Glycolysis inhibition for synergistic phototherapy of triple-negative breast cancer.

Phototherapy is a local and precise therapeutic technique for tumor treatment. However, the therapeutic effects of photothermal and photodynamic therapies are inevitably encountered by hypoxia of the tumor microenvironment and heat shock protein induced by hyperthermia, respectively. Herein, we found that mannose, a glucose analog, could reverse tumor hypoxia by inhibiting glycolysis of cancer cells and suppressing the expression of heat shock protein through inhibiting cellular adenosine triphosphate (ATP) generation. Next, we used lipid nanoparticles simultaneously loaded with indocyanine green (ICG) and mannose molecules, named imLipo, for tumor therapy. Both in vitro and in vivo experiments evidenced that the imLipo nanoplatform has significant therapeutic efficacy through synergistic phototherapy under single near-infrared laser irradiation. This work shows that glycolysis inhibition can overcome the challenges of phototherapy. In addition, all three parts (mannose, ICG, and lipid) of imLipo are clinically approved and our designed nanoplatforms have great potential for future tumor treatment.

A planning-based feasibility study of MR-Linac treatment for anal cancer radiation therapy.

The hybrid magnetic resonance image (MRI) scanner and radiation therapy linear accelerator (MR-Linac) has the potential to enhance clinical outcomes for anal cancer (AC) patients with improved soft tissue visualization and daily plan adaption but has planning and delivery limitations due to the incorporation of MRI. We aimed to identify if Elekta Unity MR-Linac-based radiation therapy is feasible for anal cancer. Ten prospectively enrolled AC patients treated with radical chemoradiotherapy were replanned for MR-Linac treatment using departmental planning criteria. For comparison, and to reduce interobserver variability, volumetric modulated arc radiation therapy (VMAT) plans were also created for each patient by the same single senior radiation therapist. Plans were compared using departmental dosimetric plan criteria, as well as conformity and homogeneity indices, monitor units (MUs) and measured plan delivery (beam-on) time. Results were deemed clinically acceptable. Target and organ at risk (OAR) doses were comparable between MR-Linac plans and VMAT plans, although PTV45Gy D98% coverage was compromised in 3 of 10 MR-Linac plans due to caudocranial length exceeding the limits of the MR-Linac. MR-Linac plans had lower MUs, median of 689.1 vs 849.65 (p = 0.002), but took over twice as long to deliver, 529.5s vs 224s (p = <0.0001) as VMAT plans. MR-Linac planning and treatment of AC is feasible for a subset of patients. The current physical limitations of the Elekta Unity system mean patients with large caudocranial elective PTV45Gy target volumes may not be covered dosimetrically to the required clinical standard. Longer image verification and treatment delivery times of the MR-Linac also mean patient selection and intrafractional IGRT are likely to be integral to ensuring high quality clinical outcomes in this rare cancer.

Low-dose X-ray radiodynamic therapy solely based on gold nanoclusters for efficient treatment of deep hypoxic solid tumors combined with enhanced antitumor immune response.

Background: Radiodynamic therapy (RDT) is an emerging novel anti-cancer treatment based on the generation of cytotoxic reactive oxygen species (ROS) at the lesion site following the interaction between low-dose X-ray and a photosensitizer (PS) drug. For a classical RDT, scintillator nanomaterials loaded with traditional PSs are generally involved to generate singlet oxygen (1O2). However, this scintillator-mediated strategy generally suffers from insufficient energy transfer efficiency and the hypoxic tumor microenvironment, and finally severely impedes the efficacy of RDT. Methods: Gold nanoclusters were irradiated by low dose of X-ray (called RDT) to investigate the production of ROS, killing efficiency of cell level and living body level, antitumor immune mechanism and biosafety. Results: A novel dihydrolipoic acid coated gold nanoclusters (AuNC@DHLA) RDT, without additional scintillator or photosensitizer assisted, has been developed. In contrast to scintillator-mediated strategy, AuNC@DHLA can directly absorb the X-ray and exhibit excellent radiodynamic performance. More importantly, the radiodynamic mechanism of AuNC@DHLA involves electron-transfer mode resulting in O2 -• and HO•, and excess ROS has been generated even under hypoxic conditions. Highly efficient in vivo treatment of solid tumors had been achieved via only single drug administration and low-dose X-ray radiation. Interestingly, enhanced antitumor immune response was involved, which could be effective against tumor recurrence or metastasis. Negligible systemic toxicity was also observed as a consequence of the ultra-small size of AuNC@DHLA and rapid clearance from body after effective treatment. Conclusions: Highly efficient in vivo treatment of solid tumors had been achieved, enhanced antitumor immune response and negligible systemic toxicity were observed. Our developed strategy will further promote the cancer therapeutic efficiency under low dose X-ray radiation and hypoxic conditions, and bring hope for clinical cancer treatment.

Development of a specialised calibration and infra-red emissivity correction to enable the temperature monitoring of intermediate level nuclear waste using thermal imaging

The temperature measurement of intermediate level nuclear waste containers is vital to monitor thermal stability and track temperature trends over time. The use of thermal imaging for this monitoring has numerous advantages compared to using a single spot radiation thermometer, and Sellafield wish to employ this approach for their ‘3 m3 box’ intermediate level waste containers. In order to achieve this objective with confidence a custom temperature calibration is required for low uncertainty temperature measurement. Another key consideration for practical non-contact temperature measurement is the emissivity of the surface being measured at the relevant infrared wavelengths, as such the emissivity of the Sellafield 3 m3 box materials was measured and then corrected for. The implementation of a calibrated instrument and emissivity correction were validated using temperature controlled, 1:10 scale model 3 m3 box containers within a climatic chamber. The surface temperature of the scale containers was determined to an uncertainty of ± 6.5 °C (k = 2.1) for the container walls, ± 3.5 °C (k = 2.1) for the container lid and ± 1.5 °C (k = 2.1) for the container vents. The measurement techniques used to determine the temperature of the 1:10 scale 3 m3 box containers were therefore successful and there is a clear development path to monitoring the containers in storage using thermal imaging.

Design of a Single Circular Radiator With Multiple Patterns for a UWB Three-Axis Monopulse System

Design of a Single Circular Radiator With Multiple Patterns for a UWB Three-Axis Monopulse System

Study on occupational exposure of medical staff caused by induced radioactivity in the treatment room of medical heavy-ion facility

Heavy-ion radiotherapy is currently recognized as the most advanced particle therapy method and is being vigorously promoted and applied worldwide. This method can rapidly generate radiation and induce radioactivity during treatment. However, the induced radioactivity, which is the primary source of exposure for medical staff, does not disappear following therapeutic application in the treatment room. In this study, we investigated the characteristics, dose rate distribution, and impact of this induced radioactivity on medical staff in the treatment room (uniform scanning mode) at Gansu Wuwei Tumor Hospital using experimental measurement and Monte Carlo simulation. We found that the exposure dose experienced by medical staff is predominantly related to the irradiated patients for single irradiation and the irradiated beam delivery system for long-term irradiation. The half-lives of the main radionuclides ranged from a few minutes to tens of minutes for single irradiation and from tens of days to hundreds of days for long-term irradiation. The primary radionuclide contributors are 15O, 11C, 176Ta, and 177W. We also estimated the personal dose experienced by the medical staff in the treatment room in relation to their working patterns. The results showed that the maximum annual exposure dose of medical staff in the horizontal treatment direction under the current model was 0.728 mSv. We hypothesized that an appropriate increase in the patient's treatment could reduce the annual exposure dose of medical staff to 0.650 mSv without changing the total treatment time per day. Finally, some suggestions were made to reduce the exposure of medical staff to unwanted radiation.

Exploring the Relationship between Yield and Its Attributing Traits in the Induced (M2) and Recurrent Irradiated (RM2) Population of Finger Millet (Eleusine coracana L. Gaertn) Using Path Coefficient Analysis

Mutation breeding has evolved as an efficient tool for creating novel variability. Induced mutagenesis is the method of treating the base material only once, whereas recurrent mutagenesis involves subjecting the first generation (M1) to another dose of mutagen for creating extensive spectrum of genetic variations in the population. Path coefficient analysis in the induced and recurrent irradiated population measures the strength of relationship between yield attributing traits and grain yield, both directly and indirectly. The present investigation was undertaken during Kharif, 2019-20 at the K block, GKVK, University of Agricultural Sciences, Bangalore. The two genotypes of finger millet viz., GPU 28 and KMR 204 have undergone single and recurrent irradiation with different doses of gamma rays (300Gy, 400Gy) and EMS (0.1%) at Bhaba Atomic Research Centre, Mumbai. Observations were recorded for 9 quantitative traits viz., days to 50% flowering, plant height, productive tillers plant-1, ear head plant-1, fingers ear-1, finger length, panicle weight plant-1(g), test weight (g) and grain yield plant-1 (g). The studies on path analysis revealed that panicle weight and test weight established positive and direct effect towards grain yield in the induced population of finger millet. Similarly, in the recurrent irradiated population with gamma rays panicle weight, test weight, finger ear-1, 50% flowering, ear plant-1 and finger length showed direct positive effect for grain yield whereas in the recurrent irradiated population with EMS panicle weight followed by test weight, fingers ear-1, plant height, productive tillers plant-1, finger length and 50 % flowering exhibited direct positive effect for grain yield. Henceforth, direct selection based on grain yield and its attributing traits would benefit in developing high yielding variety in the crop improvement programme of finger millet.

MIMO ANTENNA ARRAY WITH DIRECTIONAL DIAGRAM SPREAD FOR 5G SMARTPHONES

Multiple-input/multiple-output technology can exponentially increase the data transfer rate and spectrum efficiency without any need of increasing the transmission power and bandwidth. It is the most promising technology to be used in the upcoming 5G communications. To be more accurate, the fourth generation smartphones are set to use the long-term evolution MIMO technology and operate in multi-bands. Therefore, MIMO antennas are to use in future portable devices such as mobile handsets and tablets. A new multiple-input/multiple-output (MIMO) antenna design is introduced for future smartphones. The proposed design contains four pairs of double-fed circular-ring resonators located at different edges of the smartphone printed circuit board (PCB) with an FR-4 substrate and a dimension of 75 × 150 mm2. The antenna elements are fed by 50-Ohm microstriplines and provide polarisation and radiation pattern diversity function due to the orthogonal placement of their feed lines. By inserting a rectangular slot under each microstrip feed-line, the mutual coupling characteristic of the antenna ports is reduced. A good frequency bandwidth (S11 ≤ − 10 dB) of 3.3–3.9 GHz has been obtained for the smartphone antenna array. Nevertheless, for S11 ≤ −6 dB, this value is 3.1–4.3 GHz. More than 3 dB realised gain and 80% total efficiency are achieved for the single element radiator. The design provides not only sufficient radiation coverage supporting different sides of the mainboard but also the polarisation diversity. In addition, sufficient properties are obtained in the vicinity of human-hand/human-head. The proposed MIMO antenna design is also capable to generate dual- or multi-band function. Moreover, a new and compact phased array millimeter-wave (mm-wave) antenna design with end-fire radiation beams is introduced which can be easily integrated into smartphones.

Development and comparison of local solar split models on the example of Central Europe

Solar radiation influences many and diverse fields like energy generation, agriculture and building operation. Hence, simulation models in these fields often rely on precise information about solar radiation. Measurements are often restricted to global irradiance, whereby measurements of its single components, direct and diffuse irradiance, are sparse. However, information on both, the direct and diffuse irradiance, is necessary for simulation models to work reliably. In this study, solar separation models are developed using 10-min training data from two different locations in Austria. Direct horizontal irradiance is predicted via regressing the direct fraction using several objective functions. The models are first trained on a data set including data from both locations, and evaluated regarding root mean squared deviation (RMSD), mean bias deviation (MBD), and coefficient of determination (R2) on measured and estimated direct normal irradiance. The two best performing models are then selected for further analysis. This analysis comprises of an evaluation of the models per season, transferability of trained modes between two locations in Austria, a transferability and generalisability study conducted for four more locations in Central Europe, and a comparison with the trusted Engerer model. The solar separation model with polynomial terms up to order three and Ridge regularisation outperforms the second model based a logistic term in combination with mixed quadratic terms as well as the Engerer model.

Serious Illness Communication Training Among Radiation Oncology Residents

Education and specific training on serious illness communication skills for radiation oncology residents is lacking. The Accreditation Council for Graduate Medical Education requires radiation oncology residents to demonstrate interpersonal and communication skills; however, implementing specific training to address this poses an ongoing challenge. This study assesses the feasibility and effectiveness of a radiation oncology specific serious illness communication curriculum at a single radiation oncology residency program. The primary objectives were to assess observable communication skills among radiation oncology residents and their perceived level of preparedness and comfort with patient encounters surrounding serious illness. Each resident participated in a baseline simulated patient encounter. Two virtual half-day experience-based learning sessions led by faculty experts trained in teaching serious illness communication were held. The training consisted of brief didactic teaching, with the emphasis on small group guided practice with simulated patients in scenarios specific to radiation oncology. Each resident participated in a postcourse simulated patient encounter. Three blinded faculty trained in serious illness communication completed objective assessments of observable communication skills to compare pre- and postcourse performance. A t test based on validated assessments reviewed by blinded faculty demonstrated significant improvement in overall observable communication skills among radiation oncology residents in the postcourse encounter compared with the precourse encounter (P=.0067). Overall, 8 of 9 (89%) residents felt more comfortable and prepared with radiation oncology-specific serious illness communication after the course compared with prior. The simulated patients rated the overall average resident performance higher on the postcourse assessment (Likert 4.89/5) compared with the precourse assessment (Likert 4.09/5), which trended toward a significant improvement (P=.0515). Radiation oncology residents had a significant improvement in observable communication skills after participating in an experience-based training curriculum. This course can serve as an adaptable model that may be implemented by other radiation oncology residency programs.

Flash-Effect in Radiotherapy of Tumors and the Problems of its Radiobiological Substantiation

The published data regarding radiation therapy of tumors treatment with ultrahigh dose rate radiation has been analyzed. In 2014, the authors, among whom the most mentioned are Vincent Favaudon and MarieCatherine Vozenin, named it the flash effect. Note, however, that a member of our laboratory, S.V. Kozin in the collaboration with ITEP researchers, back in 1984, having studied the reaction of a graft tumors and the mice skin after the proton irradiation with the ultrahigh and ordinary dose rates, concluded that: ‘... an increase in the radiation dose rate to ultrahigh, without significantly changing radiation reactions of tumors, leads to the protection of the mice skin, which is associated with the manifestation of the effect of radiation-chemical absorption of oxygen. Thus, under certain conditions of radiotherapy, one can expect to receive a therapeutic gain due to use the radiation with a high dose rate’. Consideration of the expediency and possibility of using a single irradiation with a dose rate of tens of Gy/s in radiation therapy of tumors is now given a special attention. It can be considered as established that less damage to the skin, lungs, intestines, and some other tissues occurs in this case in comparison with the usual dose rates used for the radiation therapy. Moreover, a number of studies indicate an increase in radiation damage to the tumors, or at least a much smaller decrease in the degree of their damage. The radiobiological mechanisms remain unclear. The effect itself is of undoubted clinical and experimental interest and justifies the conduct of experimental and clinical studies, as well as the need to take it into account when developing new equipment for radiation therapy and dosimetry accompanying the treatment process.

Моделирование процессов в полупроводниковых структурах при радиационном воздействии

The radiation impact of outer space has an impact on electronic equipment and their characteristics change. The paper considers the simulation of the process of motion of holes generated in the oxide, which cause local deformation of the potential field of the lattice. Jumps of polarons make the motion of holes dispersed and highly dependent on temperature and oxide thickness. The article presents the temperature dependences of the voltage shift after a single radiation pulse. When holes move to the Si/SiO2 interface, some of the holes are captured by traps. The effect of the influence of the capture cross section on the increase in holes in traps is noticeable in the electrical dependence of the increase in the number of oxide traps immediately after irradiation. The graphs of the dependence of the threshold voltage shift due to oxide traps on the electric field in the oxide are plotted in this work. Immediately after its appearance, the charge of oxide traps begins to be neutralized. To study this process, time, temperature, and electrical dependences are plotted, and the ratio of trapped electrons to the number of trapped holes is shown for dry and wet gate oxide technologies at different oxide thicknesses. Thus, the influence of temperature and radiation influences on the motions of holes and oxide traps in semiconductor structures is shown.

RT-3 TREATMENT RESULTS OF AVAGAMMA THERAPY FOR RECURRENT GLIOBLASTOMA COMBINED WITH GAMMA KNIFE AND BEVACIZUMAB

Abstract Purpose We report the treatment results of AVAgamma therapy combining gamma knife (GK) and bevacizumab (Bev) for recurrent glioblastoma. Subjects From August 2013 to July 2022, 56 patients with recurrent glioblastoma treated with AVAgamma therapy as salvage therapy at the time of relapse after initial treatment. When the irradiation volume of GK was 15 ml or less, a single irradiation with a marginal dose of 20 to 26 Gy was performed. More than that received a single marginal dose of 12-15 Gy in two fractions or 8 Gy in three fractions. The mean therapeutic marginal dose was 23.9 Gy. Bev was administered 10 mg / kg or 15 mg / kg 1 to 10 times after GK. Methods Median progression-free survival (mPFS) and median survival (mOS) from AVAgamma treatment, and mOS and 5-year survival rate from initial treatment were compared with historical controls (GK group: 30 patients) who received only GK at the time of recurrence. Results The mPFS from AVAgamma therapy was 6 months, PFS-6m was 39%, OS-6m was 76%, and mOS was 10 months. The mOS from initial treatment was 25 months, which was prolonged compared to 21 months in the GK group (p=0.05). The 5-year survival rate for recurrent glioblastoma was 5% in the GK group and 22% in the AVAgamma group (p=0.04). The 5-year survival rate for glioblastoma with KPS is 70% or more at recurrence was 0% in the GK group and 33% in the AVAgamma group (p=0.017). Discussion Combined use of Bev with GK was considered to provide local control of recurrent lesions and prolong life prognosis in patients with good KPS at the time of recurrence. Conclusion AVAgamma therapy is thought to prolong the survival of recurrent glioblastoma and play an important role as salvage treatment.

Realising high aspect ratio 10 nm feature size in laser materials processing in air at 800 nm wavelength in the far-field by creating a high purity longitudinal light field at focus

In semiconductor and data storage device manufacturing, it is desirable to produce feature sizes less than 30 nm with a high depth-to-width aspect ratio on the target material rapidly at a low cost. However, optical diffraction limits the smallest focused laser beam diameter to around half of the laser wavelength (λ/2). The existing approach to achieving nanoscale fabrication is mainly based on costly extreme ultraviolet (EUV) technology operating within the diffraction limit. In this paper, a new method is shown to achieve materials processing resolution down to 10 nm (λ/80) at an infrared laser wavelength of around 800 nm in the far-field, in air, well beyond the optical diffraction limit. A high-quality longitudinal field with a purity of 94.7% is generated to realise this super-resolution. Both experiments and theoretical modelling have been carried out to verify and understand the findings. The ablation craters induced on polished silicon, copper, and sapphire are compared for different types of light fields. Holes of 10–30 nm in diameter are produced on sapphire with a depth-to-width aspect ratio of over 16 and a zero taper with a single pulse at 100–120 nJ pulse energy. Such high aspect ratio sub-50 nm holes produced with single pulse laser irradiation are rarely seen in laser processing, indicating a new material removal mechanism with the longitudinal field. The working distance (lens to target) is around 170 µm, thus the material processing is in the far field. Tapered nano-holes can also be produced by adjusting the lens to the target distance.

Stereotactic Radiotherapy in the Management of Ventricular Tachycardias: More Questions than Answers?

Stereotactic body radiotherapy is a recent promising therapeutic alternative in cases of failed catheter ablation for recurrent ventricular tachycardias (VTs) in patients with structural heart disease. Initial clinical experience with a single radiation dose of 25Gy shows reasonable efficacy in the reduction of VT recurrences with acceptable acute toxicity. Many unanswered questions remain, including unknown mechanism of action, variable time to effect, optimal method of substrate targeting, long-term safety, and definition of an optimal candidate for this treatment."