Detection Of Cerenkov Radiation Research Articles

Visualization and Quantification of Radiochemical Purity by Cerenkov Luminescence Imaging.

Determination of radiochemical purity is essential for characterization of all radioactive compounds, including clinical radiopharmaceuticals. Radio-thin layer chromatography (radio-TLC) has been used as the gold standard for measurement of radiochemical purity; however, this method has several limitations in terms of sensitivity, spatial resolution, two-dimensional scanning, and quantification accuracy. Here, we report a new analytical technique for determination of radiochemical purity based on Cerenkov luminescence imaging (CLI), whereby entire TLC plates are visualized by detection of Cerenkov radiation. Sixteen routinely used TLC plates were tested in combination with three different radioisotopes (131I, 124I, and 32P). All TLC plates doped with a fluorescent indicator showed excellent detection sensitivity with scanning times of less than 1 min. The new CLI method was superior to the traditional radio-TLC scanning method in terms of sensitivity, scanning time, spatial resolution, and two-dimensional scanning. The CLI method also showed better quantification features across a wider range of radioactivity values compared with radio-TLC and classical zonal analysis, especially for β--emitters such as 131I and 32P.

Abstract ID: 97 A Monte Carlo study of resolving the radiation dose through the detection of Cerenkov radiation in Boron Neutron Capture

Radiation dose in boron neutron capture therapy (BNCT) is determined by both the epithermal neutron beam and Boron-10 distribution [1] , [2] . It is thus more complex and important to monitor the radiation dose comparing to other radiation treatment modalities. In this study, we investigated the feasibility of resolving the radiation dose with respect to the change of beam property and Boron-10 concentration through the detection of Cerenkov radiation during BNCT. Monte Carlo toolkit Geant4 was used to simulate the irradiation of epithermal neutron beam on phantom containing tumor region [3] . Cerenkov can be generated during BNCT and it is expected to be correlated with gamma dose. The depth and radial distributions of gamma dose were obtained under different characteristics of boron concentration and epithermal neutron beam. The relationship between the number of Cerenkov photons and gamma dose was explored based on simple phantom and Chinese reference radiation phantom. Results showed that the gamma dose is almost unchanged under different boron concentration distributions, even if the relative change of boron concentration reached 60 percent. The changes in the characteristics of epithermal neutron beam directly leads to the changes in the gamma dose. This indicated that gamma dose can be used to reflect the stability and delivery accuracy of epithermal neutron beam. Meanwhile, the response relationship between the number of Cerenkov photons and gamma dose was observed. As a preliminary result, it suggests the potential feasibility to monitoring the gamma dose and the stability of the epithermal neutron beam through the detection of Cerenkov radiation emitted during BNCT.

Cerenkov Luminescence Imaging at a Glance

Cerenkov luminescence imaging (CLI) is a new technique that has rapidly gained great interest in the molecular imaging field bridging optical imaging and nuclear medicine. Based on the detection of Cerenkov radiation (CR) in biological tissue, in only five years many different applications of CLI were developed spanning from cancer imaging to Alzheimer's disease and many different approaches were tested in order to increase its potentialities. In particular some efforts were made to transform CLI from a planar imaging technique into a tomographic technique or to shift the CR in a red-infrared radiation more suitable for biological applications. Moreover CLI, developed as a preclinical investigation, has obtained very quickly, interesting results on humans. Here we present a schematic and brief overview of the CLI landscape in order to show the principal results and applications to the biology. More precisely we focused on the potentialities of optical detection of ra- diotracers excluding the application of Cerenkov radiation obtained with the use of external radiation beam. Cerenkov luminescence imaging (CLI) has been recently introduced in the Optical Imaging (OI) landscape as a new pre-clinical imaging tool to investigate much pathology in vivo. It is based on the detection of light produced by high energy charged particle (like electron or positron) moving faster than the speed of light in a dielectric medium. When travelling in the medium the particle can polarize the sur- rounding molecules and, when they relax back, they can emit light in the form of radiation luminescence. This is the so- called Cerenkov radiation (CR). It occurs if the energy of the particle is greater than a threshold that is around 220 keV in biological tissues. The CR spectrum consists of continuous wavelengths throughout the ultraviolet, visible and near in- frared range. The intensity distribution is inversely propor- tional to the square of the wavelength. The emitted photons can be detected by a variety of light sensitive detectors, like photomultipliers, highly sensitive charge-coupled device (CCD), and others. CR was discovered by Pavel Alek- seyevich Cerenkov in 1932 and the theoretical analysis of the experimental data was provided by Frank and Tamm in 1937 (1). Due to faint emission the detection in biological tissues was very challenging. A very preliminary attempt was made by Burch in 1971 (2); he detected CR in human eye tumors treated with 32P with a photomultiplier tube, but this method was not employed subsequently and no imaging was performed. For a real imaging of CR emitted by tissues we had to wait for about 40 years. Now different applica- tions of CLI were developed and many efforts were done in order to increase the potentialities of the technique. In this review our goal was to present almost all the studies referred to CLI in biomedical field and we tried to organize them in one table (Table 1) for a fast consultation. In the table the

Multispectral Cerenkov luminescence tomography for small animal optical imaging

Quite recently Cerenkov luminescence imaging (CLI) has been introduced as a novel pre-clinical imaging for the in vivo imaging of small animals such as mice. The CLI method is based on the detection of Cerenkov radiation (CR) generated by beta particles as they travel into the animal tissues with an energy such that Cerenkov emission condition is satisfied. This paper describes an image reconstruction method called multi spectral diffuse Cerenkov luminescence tomography (msCLT) in order to obtain 3D images from the detection of CR. The multispectral approach is based on a set of 2D planar images acquired using a number of narrow bandpass filters, and the distinctive information content at each wavelength is used in the 3D image reconstruction process. The proposed msCLT method was tested both in vitro and in vivo using 32P-ATP and all the images were acquired by using the IVIS 200 small animal optical imager (Caliper Life Sciences, Alameda USA). Source depth estimation and spatial resolution measurements were performed using a small capillary source placed between several slices of chicken breast. The theoretical Cerenkov emission spectrum and optical properties of chicken breast were used in the modelling of photon propagation. In vivo imaging was performed by injecting control nude mice with 10 MBq of 32P-ATP and the 3D tracer bio-distribution was reconstructed. Whole body MRI was acquired to provide an anatomical localization of the Cerenkov emission. The spatial resolution obtained from the msCLT reconstructed images of the capillary source showed that the FWHM is about 1.5 mm for a 6 mm depth. Co-registered MRI images showed that the Cerenkov emission regions matches fairly well with anatomical regions, such as the brain, heart and abdomen. Ex vivo imaging of the different organs such as intestine, brain, heart and ribs further confirms these findings. We conclude that in vivo 3D bio-distribution of a pure beta-minus emitting radiopharmaceutical such as 32P-ATP can be obtained using the msCLT reconstruction approach.

Photocathodes for the Detection of Cerenkov Radiation in Deep-Water Neutrino Telescopes

The results from a comparative assessment of the applicability of various vacuum photodetectors with different types of photocathodes to next-generation neutrino telescopes are presented. It is shown how the spectrum of Cerenkov radiation is altered during its propagation through the waters of Lake Baikal and the Mediterranean Sea. The effect exerted by the dispersion of the medium on the duration of a Cerenkov light pulse is studied.

The Pleckstrin Homology Domain of Protein Kinase D Interacts Preferentially with the η Isoform of Protein Kinase C

The results presented here demonstrate that protein kinase D (PKD) and PKCeta transiently coexpressed in COS-7 cells form complexes that can be immunoprecipitated from cell lysates using specific antisera to PKD or PKCeta. The presence of PKCeta in PKD immune complexes was initially detected by in vitro kinase assays which reveal the presence of an 80-kDa phosphorylated band in addition to the 110-kDa band corresponding to autophosphorylated PKD. The association between PKD and PKCeta was further verified by Western blot analysis and peptide phosphorylation assays that exploited the distinct substrate specificity between PKCs and PKD. By the same criteria, PKD formed complexes only very weakly with PKCepsilon, and did not bind PKCzeta. When PKCeta was coexpressed with PKD mutants containing either complete or partial deletions of the PH domain, both PKCeta immunoreactivity and PKC activity in PKD immunoprecipitates were sharply reduced. In contrast, deletion of an amino-terminal portion of the molecule, either cysteine-rich region, or the entire cysteine-rich domain did not interfere with the association of PKD with PKCeta. Furthermore, a glutathione S-transferase-PKDPH fusion protein bound preferentially to PKCeta. These results indicate that the PKD PH domain can discriminate between closely related structures of a single enzyme family, e.g. novel PKCs epsilon and eta, thereby revealing a previously undetected degree of specificity among protein-protein interactions mediated by PH domains.

A Method for in Vivo Counting of Radiophosphorus in Insects by Detection of Cerenkov Radiation in Water

Radiophosphorus (32P) and many other radioisotopes can be detected very easily in a liquid scintillation system by the visible Cerenkov emission produced when their charged particles are slowed in a liquid medium such as water. In water, the Cerenkov threshold is 0.263 MeV, so that isotopes with charged-particle decay energies above this level can be readily detected. Experiments have been completed in our laboratories which define the necessary counting conditions for 32P in water, including the absolute efficiencies under varying conditions and in various developmental stages of the southern green stinkbug, Nezara viridula L.

Tachyons do not emit Čerenkov radiation in vacuum

1. Recently, many papers dealt with the so-called Cerenkov radiation in vacuum by tachyons. We arc referring in particular to the last one, appeared in Phys ica l Rev i ew D (1). We want to underline that tachyons are not expected to emit ~crenkov radiation in vacuum. Most o~ the previous pap~s (z'~) are characterized by ~n ~bitra~y, uncritical (*) extension of the usual energy-loss formula (4) for Superlumin~l velocities. Such an unjustified extension led of course to difficulties (~) or inconsistencies (3), one of them JONES was precisely engaged with (1). Even at first sight, that extension does not really appear to be sound, since---as is widely known (~)--~ercnkov radiation comes out not from the (~ radiating ~) particle itself, but from the (material) medium. So that, in the usual context, the very expression (~ Cerenkov radiation in vacuum ~ appears meaningless, unless one simultaneously provides a suitable theory about a possible (~ vacuum structure )). But most experimenters have been till now looking for tachyons through detection of Cerenkov radiation, assumed to exist in vacuum too, so that it is worth-while to criticize that assumption a bit more.