Standardization and application of external (in air) Particle Induced Gamma Emission (PIGE) method for rapid and non-destructive quantification of light elements at major to trace concentrations in coal, bottom ash and coke samples

Coal is an important energy source and its quality evaluation in terms of ash content and other element like B and F is a necessity. An external (in air) Particle...

Carbon range verification with 718 keV Compton imaging

Carbon ion radiotherapy is a sophisticated radiation treatment modality because of its superiority in achieving precise dosage distribution and high biological effectiveness. However, there exist beam range uncertainties that affect treatment efficiency. This problem can be resolved if the clinical beam could be monitored precisely in real-time, such as by imaging the prompt gamma emission from the target. In this study, we performed real-time detection and imaging of 718 keV prompt gamma emissions using a Si/CdTe Compton camera. We conducted experiments on graphite phantoms using clinical carbon ion beams of 290 MeV/u energy. Compton images were reconstructed using simple back-projection methods from the energy events of 718 keV prompt gamma emissions. The peak intensity position in reconstructed 718 keV prompt gamma images was few millimeters below the Bragg peak position. Moreover, the dual- and triple-energy window images for all positions of phantoms were not affected by scattered gammas, and their peak intensity positions were approximately similar to those observed in the reconstructed 718 keV prompt gamma images. In conclusion, the findings of the current study demonstrate the feasibility of using our Compton camera for real-time beam monitoring of carbon ion beams under clinical beam intensity.

CTNI-29. SAFETY AND FEASIBILITY OF RHENIUM-186 NANOLIPOSOME (186RNL) IN RECURRENT GLIOMA: THE RESPECT™ PHASE 1 TRIAL

BACKGROUND Liposomal rhenium-186 (186RNL) is a potent source of beta particles with short path length, variable dose rate, high radiation density and gamma emission. Preclinically, 186RNL delivered via convection enhanced delivery (CED) achieves very high doses of targeted radiation with a wide therapeutic index. We report the results of ReSPECT, the first in man, dose escalation phase 1 trial of 186RNL in recurrent glioma. METHODS Following computer assisted treatment planning and placement of intracranial catheter(s), we performed a single administration of 186RNL by CED. We obtained whole body planar and SPECT/CT imaging on days 1-8 following treatment for dosimetry and distribution and followed patients for safety, progression and survival. RESULTS Twenty-one patients across 7 cohorts received 1.0-22.3mCi in a volume of 0.6-8.80mL. Mean tumor volume was 8.3mL (0.9-22.8mL). Patients had a mean of 1.7 recurrences, 5 received prior bevacizumab. Overall, 19/21 patients and all after cohort 4 had grade 4 glioma (glioblastoma). We used a CED rate of 5-20µl/min per catheter, with 1-4 catheters used per patient. Mean absorbed radiation dose to the tumor was 255Gy (8.9-740Gy) while exposure outside the brain was negligible. The mean percentage tumor in the treated volume (Tu/Tv) was 60.3% (19.8%-100%). Thus far, we have observed no dose limiting toxicities, one grade 3 treatment related adverse event (AEs), and the majority of AEs were mild in intensity. The incidence and severity of AEs did not correlate with increasing dose. Mean Tu/Tv in patients not receiving prior bevacizumab was 75% vs. 48% in those that had. Thus far, overall survival (OS) in 16 bevacizumab naïve patients is 49 weeks with 7 (44%) patients still alive and a positive correlation of OS to Tu/Tv. CONCLUSIONS 186RNL achieves high absorbed doses without significant toxicity with favorable overall survival.

Bayesian Activity Estimation and Uncertainty Quantification of Spent Nuclear Fuel Using Passive Gamma Emission Tomography

In this paper, we address the problem of activity estimation in passive gamma emission tomography (PGET) of spent nuclear fuel. Two different noise models are considered and compared, namely, the isotropic Gaussian and the Poisson noise models. The problem is formulated within a Bayesian framework as a linear inverse problem and prior distributions are assigned to the unknown model parameters. In particular, a Bernoulli-truncated Gaussian prior model is considered to promote sparse pin configurations. A Markov chain Monte Carlo (MCMC) method, based on a split and augmented Gibbs sampler, is then used to sample the posterior distribution of the unknown parameters. The proposed algorithm is first validated by simulations conducted using synthetic data, generated using the nominal models. We then consider more realistic data simulated using a bespoke simulator, whose forward model is non-linear and not available analytically. In that case, the linear models used are mis-specified and we analyse their robustness for activity estimation. The results demonstrate superior performance of the proposed approach in estimating the pin activities in different assembly patterns, in addition to being able to quantify their uncertainty measures, in comparison with existing methods.

Radioactivity and Nuclear Reactions

Radioactivity and Nuclear Reactions gives an overview of nuclear chemistry with emphasis on radioactive decay, binding energy and nuclear stability. Modes of radioactive decay are discussed, along with writing and balancing nuclear equations. Decay modes covered include alpha emission, beta emission, gamma emission, positron emission, and electron capture, along with a summary of how each type of decay process affects the parent radioisotope and determines the daughter isotope formed. Nuclear transmutation induced by changes in the nuclei is discussed. The chapter covers the kinetics of radioactive decay including the relationship between the half-lives of radioisotopes and radioisotopic dating. The chapter concludes with a quantitative coverage of the energy of nuclear reactions including the interconversion of mass and energy via the mass defect.

Idea of an experimental technique for quantitative passive gamma emission tomography on irradiated nuclear fuel assemblies

An idea is presented in which passive gamma emission tomography of irradiated nuclear fuel is developed to enable quantitative information of the spatial activity distribution of selected isotopes within the fuel rods of the assembly. The idea is based on using well-known calibration sources mounted in the measurement device during measurement. The image reconstruction would include the sources, thereby enable quantification of the activity distribution. Should the idea be proven viable, the outcome would be valuable to the global community dealing with characterisation of nuclear fuel in terms of safety, security, safeguards and fuel development.

Rapid imaging of special nuclear materials for nuclear nonproliferation and terrorism prevention

We introduce a neutron-gamma emission tomography (NGET) technique for rapid detection, three-dimensional imaging, and characterization of special nuclear materials like weapons-grade plutonium and uranium. The technique is adapted from fundamental nuclear physics research and represents a previously unexplored approach to the detection and imaging of small quantities of these materials. The method is demonstrated on a radiation portal monitor prototype system based on fast organic scintillators, measuring the characteristic fast time and energy correlations between particles emitted in nuclear fission processes. The use of these correlations in real time in conjunction with modern machine learning techniques provides unprecedented imaging efficiency and high spatial resolution. This imaging modality addresses global security threats from terrorism and the proliferation of nuclear weapons. It also provides enhanced capabilities for addressing different nuclear accident scenarios and for environmental radiological surveying.