Immobilizing and positioning patients for radiotherapy

Purpose: To develop a new facility to irradiate partial body of zebrafish embryos and test the system with an actual radiobiology experiment. Method and Materials: This micro‐irradiator uses a 50 kV photon beam, miniature x‐ray, Xoft Inc. The source is inserted in a cylindrical brass collimator of 3 cm diameter and 3 cm long. A pinhole of 1 mm diameter along the central axis produces a well‐focused pinpoint beam with a sharp penumbra. A photodiode monitors the beam and provides readings for dose calculation. Specimens are irradiated at 6 mm from the collimator and they are accurately positioned on the beam using a video camera and a computer‐controlled movable table. The system was used to irradiate total and partial body of zebrafish embryos at 3 days post‐fertilization to investigate radiation induced apoptosis and microphages recruitment at 40 Gy for both irradiation modalities. Results: This irradiation facility is portable and can fit in any radiobiology lab. The image‐guidance and high precision of the movable table enable accurate specimen position. The beam monitoring system provides exact, fast, and easy dose determination. Total body zebrafish irradiation at 40 Gy shows a severe post‐treatment cell ablation effect and substantial apoptotic increase after 3 days post‐irradiation. For partial body irradiation, there is an increase in apoptotic cells and remarkable macrophages recruitment after 3 days post‐irradiation. Conclusion: This robust, simple, and effective image‐guided micro‐irradiator is an appropriate tool to accurately irradiate partial body of zebrafish embryos, cell cultures or any other small specimen used in radiobiology studies. The tests comparing total and partial zebrafish embryo irradiation revealed significant difference in cell response. In general, this novel micro‐irradiator has expanded the radiation modalities for very small animals used in radiobiology studies and opened the possibility to adventure deeper in radiotherapy research.

From 1974 to 1984, 442 consecutive patients with carcinoma of the uterine cervix (FIGO IIB: 139, IIIA:10, IIIB:221, IVA:72) were referred for combined intracavitary (IRT) and external radiotherapy (ERT). To improve local control and reduce late rectosigmoid morbidity the treatment strategy was changed from continuous (CRT) to split-course radiotherapy (SCRT) in 1978. Stage by stage the 5-year actuarial estimates of survival, local control, and late morbidity did not differ in relation to strategy. In the patients with tumours larger than 8 cm, the SCRT involved an increased dose in point B, a reduced dose in point A from the IRT, a lower total dose in point A, and a 34 days' prolongation of the total treatment time (TTT). The resulting 5-year actuarial local control rates were significantly lower compared with those after CRT. No difference of late severe morbidity was found except in IVA patients. In the patients with tumours between 4 and 8 cm, the SCRT involved a reduced dose in point A from the IRT, an increased total dose in point A and B, and a 50 days' prolongation of the TTT. In patients with stage IIB, the 5-year actuarial central local control rate was lower (p = 0.06), and the 5-year estimate of late severe morbidity significantly higher after SCRT compared with CRT. It is concluded that the increase of the dose in point B in the SCRT was insufficient to prevent the deleterious effect on local tumour control of either the lower dose from IRT in point A, or the prolonged TTT. The increase of the total dose in the SCRT may explain why the late morbidity was not reduced, and may suggest that the TTT is of no significant importance for the risk of late normal tissue damage.

Three discipline collaborative radiation therapy (3DCRT) special debate: FLASH radiotherapy needs ongoing basic and animal research before implementing it to a large clinical scale.

The need for accurate positioning in naval tactics is discussed with reference to relative and geographical positioning, large area battles, the Navy Tactical Data System and the Link systems, attack scenarios, mine warfare, Q-routes, and mine hunting and neutralizations. It is concluded that the evolution of modern naval warfare has led away from the careful and assiduous application of navigation and positioning information. The ease of obtaining a 'fix' and the imperatives of tactical threats have relegated this aspect to a lesser role. It is further argued that the trends toward over-the-horizon targeting/battles and strict emission controls, coupled with the more traditional tactics in antisubmarine warfare and mine warfare, continue to require good geographic positioning as a matter of paramount importance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

PurposeElekta XVI 5.0 allows for four‐dimensional cone beam computed tomography (4D CBCT) image acquisition during treatment delivery to monitor intrafraction motion. These images can have poorer image quality due to undersampling of kV projections and treatment beam MV scatter effects. We determine if a universal intrafraction preset can be used for stereotactic body radiotherapy (SBRT) lung patients and validate the accuracy of target motion characterized by XVI intrafraction 4D CBCT.MethodsThe most critical parameter within the intrafraction preset is the nominal AcquisitionInterval, which controls kV imaging acquisition frequency. An optimal value was determined by maximizing the kV frame number acquired up to 1000 frames, typical of pretreatment 4D CBCT. CIRS motion phantom intrafraction phase images for 16 SBRT beams were obtained. Mean target position, time‐weighted standard deviation, and amplitude for these images as well as target motion for three SBRT lung patients were compared to respective pretreatment 4D CBCTs. Evaluation of intrafraction 4D CBCT reconstruction revealed inclusion of MV only images acquired to remove MV scatter effects. A workaround to remove these images was developed.ResultsAcquisitionInterval of 0.1°/frame was optimal. The number of kV frames acquired was 567–1116 and showed strong linear correlation with beam monitor unit (MUs). Phantom target motion accuracy was excellent with average differences in target position, standard deviation and amplitude range of ≤0.5 mm. Target tracking for SBRT patients also showed good agreement. Evaluation of phase sorting wave forms showed that inclusion of MV only images significantly impacts intrafraction image reconstruction for patients and use of workaround is necessary.ConclusionsA universal intrafraction imaging preset can be used safely for SBRT lung patients. The number of kV projections with MV delivery parameters varies; however images with fewer kV projections still provided accurate target position information. Impact of the reconstruction workaround was significant and is mandated for all 4D CBCT intrafraction imaging performed at our institution.

Dose fractionation and regeneration in radiotherapy for cancer of the oral cavity and oropharynx: Tumor dose-response and repopulation

Local control of carcinoma of the tonsil by radiation therapy: An analysis of patterns of fractionation in nine institutions

Proceedings to the 6th Annual Conference of the Particle Therapy Cooperative Group North America (PTCOG-NA): 14-16 October 2019, Hosted by Miami Cancer Institute, part of Baptist Health South Florida, Miami, FL, USA.

Study on the activity and stability of urease immobilized onto nanoporous alumina membranes

Immobilized lipases have received great attention in food, environment, medicine, and other fields due to their easy separation, high stability (temperature, pH), and high storage properties. After immobilization, lipase transforms from a homogeneous to a heterogeneous state, making it easier to recover from the reaction substrate and achieve recycling, which is in line with the concept of green chemistry and reduces protein contamination in the product. There are various materials for enzyme immobilization, including polysaccharides from natural sources, inorganic compounds, carbon nanotubes, metal-organic framework materials, and so forth. Magnetic immobilization carriers have been widely studied due to their ability to achieve separation by adding a magnetic field. Its immobilization method can be simply divided into two categories: physical action (adsorption, embedding) and chemical binding (covalent, cross-linking). Some studies mainly discuss the immobilization support materials, immobilization methods, and applications of immobilized lipases in food. On this basis, our review also focuses on the changes in crosslinking agents for immobilized lipases, different methods to promote immobilization, new trends in the study of immobilized lipases, and proposes prospects for immobilized lipase research in the food industry.

Activity and stability comparison of immobilized NADH oxidase on multi-walled carbon nanotubes, carbon nanospheres, and single-walled carbon nanotubes

Abstract. In many unmanned aerial vehicle (UAV) applications a direct georeferencing is required. The reason can be that the UAV flies autonomous and must be navigated precisely, or that the UAV performs a remote sensing operation, where the position of the camera has to be known at the moment of the recording. In our application, a project called Mapping on Demand, we are motivated by both of these reasons. The goal of this project is to develop a lightweight autonomously flying UAV that is able to identify and measure inaccessible three-dimensional objects by use of visual information. Due to payload and space limitations, precise position and attitude determination of micro- and mini-sized UAVs is very challenging. The limitations do not only affect the onboard computing capacity, but they are also noticeable when choosing the georeferencing sensors. In this article, we will present a new developed onboard direct georeferencing system which is real-time capable, applicable for lightweight UAVs and provides very precise results (position accuracy σ &lt; 5 cm and attitude accuracy σ &lt; 0.5 deg). In this system GPS, inertial sensors, magnetic field sensors, a barometer as well as stereo video cameras are used as georeferencing sensors. We will describe the hardware development and will go into details of the implemented software. In this context especially the RTK-GPS software and the concept of the attitude determination by use of inertial sensors, magnetic field sensors as well as an onboard GPS baseline will be highlighted. Finally, results of first field tests as well as an outlook on further developments will conclude this contribution.

Advanced prostate cancer: The results of a randomized comparative trial of high dose irradiation boosting with conformal protons compared with conventional dose irradiation using photons alone

Immobilization is an excellent tool for enzymatic stabilization, improving the biocatalytic processes, allowing the reuse of the enzyme and promoting an easier separation of the molecule of interest. Currently, new enzymatic bonding processes are arising on solid supports, based on classical immobilization methods. Amongst the supports used, chitosan is a polysaccharide that offers a unique set of characteristics, as biocompatibility, biodegradability, non-toxicity and antibacterial properties. Thus, many enzymes has being immobilized on this support, including levansucrase, that is able to synthesize levan and fructooligosaccharides, two important biomolecules which have beneficial health properties. These review present different methods of immobilization (physical adsorption, entrapment, crosslinking and covalent bonding) for fructosyltransferases, as well as different immobilization matrices that can be applied in biotechnological processes. However, studies are still needed in order to adopt efficient immobilization techniques, in which the biocatalyst remains more stable, in order to become the process attractive to the industrial sector.

The compressive sensing imaging technique, based on the realization of random measurement via active or passive devices (e.g., DMD), has attracted more and more attention. For imaging target of interest within large uniform scene (e.g., ships in the sea), high-resolution image was usually reconstructed and then used to detect targets, however the process is time-consuming, and moreover only part of the image consists of the targets of interest. In this paper, the stepwise multi-resolution fast target detection and imaging method through the combination of different numbers of DMD mirrors was explored. Low resolution image for larger area target searching and successively higher resolution image for smaller area containing the targets were reconstructed. Also, non-imaging fast target detection was realized based on the detector energy intensity, which includes the steps of rough target positioning by successively opening DMD blocks and accurate target positioning by adjusting the rough areas via intelligent search algorithm. Simulation experiments were carried out to compare the proposed method with traditional method. The result shows the area of the ships are accurately positioned without reconstructing the image by the proposed method and the multi-level scale imaging for suspect areas is realized. Compared with traditional target detection method from the reconstructed image, the proposed method not only highly enhances the measuring and reconstruction efficiency but also improves the positioning accuracy, which would be more significant for large area scene.