Development of a dosimeter prototype with machine learning based 3-D dose reconstruction capabilities

A 3-D dosimeter fills the need for treatment plan and delivery verification required by every modern radiation-therapy method used today. This report summarizes a proof-of-concept study to develop a water-equivalent solid 3-D dosimeter that is based on novel radiation-hard scintillating material. The active material of the prototype dosimeter is a blend of radiation-hard peroxide-cured polysiloxane plastic doped with scintillating agent P-Terphenyl and wavelength-shifter BisMSB. The prototype detector was tested with 6 MV and 10 MV X-ray beams at Ohio State University’s Comprehensive Cancer Center. A 3-D dose distribution was successfully reconstructed by a neural network specifically trained for this prototype. This report summarizes the material production procedure, the material’s water equivalency investigation, the design of the prototype dosimeter and its beam tests, as well as the details of the utilized machine learning approach and the reconstructed 3-D dose distributions.

Development of gated fiber detectors for laser-induced strong electromagnetic pulse environments

With the development of laser technologies, nuclear reactions can happen in high-temperature plasma environments induced by lasers and have attracted a lot of attention from different physical disciplines. However, studies on nuclear reactions in plasma are still limited by detecting technologies. This is mainly due to the fact that extremely high electromagnetic pulses (EMPs) can also be induced when high-intensity lasers hit targets to induce plasma, and then cause dysfunction of many types of traditional detectors. Therefore, new particle detecting technologies are highly needed. In this paper, we report a recently developed gated fiber detector which can be used in harsh EMP environments. In this prototype detector, scintillating photons are coupled by fiber and then transferred to a gated photomultiplier tube which is located far away from the EMP source and shielded well. With those measures, the EMPs can be avoided which may result that the device has the capability to identify a single event of nuclear reaction products generated in laser-induced plasma from noise EMP backgrounds. This new type of detector can be widely used as a time-of-flight (TOF) detector in high-intensity laser nuclear physics experiments for detecting neutrons, photons, and other charged particles.

A Novel High Quantum Efficiency MV X-Ray Detector For Image-Guided Radiotherapy

To develop a new MV x-ray detector with a high quantum efficiency and an adequate spatial resolution for image-guided radiotherapy, scintillating fibers with a diameter of 1 mm were embedded in lead to form a honeycomb pattern with a thickness of 2 cm. The properties of the detector were measured using a 6 MV beam on a Linac machine. The prototype detector has a quantum efficient of 35%, about an order of magnitude higher than that of current detectors used in the clinic. The spatial resolution of the prototype is comparable to that of video-based electronic portal imaging systems. The prototype detector can also suppress scattered signals which will help to improve the signal to noise ratio of the image. This work indicates that using scintillating fibers to generate and guide imaging signals, it is possible to increase the quantum efficiency and maintain an adequate spatial resolution for MV x-ray imaging.

A Novel High Quantum Efficiency MV X-Ray Detector For Image-Guided Radiotherapy

To develop a new MV x-ray detector with a high quantum efficiency and an adequate spatial resolution for image-guided radiotherapy, scintillating fibers with a diameter of 1 mm were embedded in lead to form a honeycomb pattern with a thickness of 2 cm. The properties of the detector were measured using a 6 MV beam on a Linac machine. The prototype detector has a quantum efficient of 35%, about an order of magnitude higher than that of current detectors used in the clinic. The spatial resolution of the prototype is comparable to that of video-based electronic portal imaging systems. The prototype detector can also suppress scattered signals which will help to improve the signal to noise ratio of the image. This work indicates that using scintillating fibers to generate and guide imaging signals, it is possible to increase the quantum efficiency and maintain an adequate spatial resolution for MV x-ray imaging.

Fabrication, characterization and analysis of a prototype high purity germanium detector for $$^{76}$$Ge-based neutrinoless double beta decay experiments

Experiments searching for the neutrinoless double beta decay in $$^{76}$$ 76 Ge are currently achieving the lowest background level and, in connection with the excellent energy resolution of germanium detectors, they exhibit the best discovery potential for the decay. Expansion to a ton scale of the active target mass is presently considered – in this case on-site production of the detectors may be an option. In this paper we describe the fabrication and characterization procedures of a prototype detector with a small p+ contact, which enhances the abilities of the pulse shape discrimination – one of the most important tools for background reduction. Simulations of the shapes of pulses from the detector were carried out and tuned, taking the advantage of the fact that all the parameters of the Ge crystal, cryostat and of the spectroscopic chain were known. As a result, the pulse shape analyses performed on the simulated and measured data agree very well. The worked out method allows to optimize geometry and crystal parameters in terms of pulse shape analysis efficiency, before the actual production of the detectors.