Use of 2-(4-styrylphenyl)benzoxazole and plastic scintillator

Abstract

New composition of polymeric scintillator was revealed, which can be used particularly in medical diagnostics especially in productions of CT scanners, PET scanners and SPECT scanners.

Claims

1. Use of 2-(4-styrylphenyl)benzoxazole in production of polymeric scintillators, especially as the second fluorescent addition.

2. Polymeric scintillator, characterized in that it contains 2,5-diphenylooxazole in the amount from 1% w/w to 10% w/w and 2-(4-styrylphenyl)benzoxazole in the amount from 0.01% w/w to 0.1% w/w dissolved in the organic polymer, wherein the organic polymer has been selected among of polystyrene or polyvinyltoluene.

3. Polymeric scintillator according to claim 2 containing 2,5-diphenylooxazole in the amount around 2% w/w.

4. Polymeric scintillator according to claim 2, containing 2-(4-styrylphenyl)benzoxazole in the amount about 0.03% w/w.

Description

[0021] For better explanation of the invention essence the present description is illustrated by the figures, while:

[0022] in FIG. 1 there is presented flow chart of experimental system used to determine luminous efficiency of the scintillators;

[0023] in FIG. 2 there is presented the scheme of experimental system used to determine time resolution of the scintillators. The abbreviation PM stands for photomultiplier. The source was placed in the lead collimator with space width 1.5 mm.

[0024] Moreover, the description contains examples of the produced invention characterized below, which should not be identified with its essence defined above.

EXAMPLE 1

Obtaining Polymeric Scintillator

[0025] Synthesis of above mentioned scintillator was the result of dissolving additions: 2,5-diphenylooxazole and 2-(4-styrylphenyl)benzoxazolein monomer in the amount properly: 2% and 0.03% in the relation to mass of the sample and conduction of polymerization reaction of the prepared solution. Examples of the scintillator compositions are presented in the Table 1.

TABLE-US-00001 TABLE 1 Composition of example scintillators. The second addition: 2-(Stilbene-4- Polymer The first addition yl)benzoxazolein Polystyrene p-terfenyl, 2% wag. 0.03% w/w Polystyrene 2,5-diphenylooxazole, 2% w/w 0.03% w/w Polyvinyltoluene 2,5-diphenylooxazole, 2% w/w 0.01% w/w Polyvinyltoluene 2,5-diphenylooxazole, 2% w/w 0.02% w/w Polyvinyltoluene 2,5-diphenylooxazole, 2% w/w 0.03% w/w Polyvinyltoluene 2,5-diphenylooxazole, 2% w/w 0.04% w/w Polyvinyltoluene 2,5-diphenylooxazole, 2% w/w 0.05% w/w

[0026] Before the reaction, monomer (styrene, vinyltoluene) was cleaned by granules of activated alumina with 4A molecular sieve. Next, the proper amount of fluorescent additions were dissolved in liquid monomer, the solution was pour into glass ampoule, which was earlier silanized to avoid glass adhesion to polymer and was barbotaged by argon for a few minutes. The ampoule was closed tight in flame of the burner.

[0027] Polymerization process was initiated thermally. The temperature cycle used during scintillator production was following: 0.01 h-100° C., 4 h-140° C., 72 h-140° C., 10 h-90° C., 2 h-90° C., 12 h-30° C.

[0028] As a result of long synthesis, which lasted about 100 hours homogeneous scintillator was produced with good optical characteristics.

EXAMPLE 2

Optical Characteristics of Polymeric Scintillator According to the Invention

[0029] Scintillator obtained according with Example 1. was tested in the experiment described below.

[0030] To determine luminous efficiency of the scintillator experimental system presented in FIG. 1 was used. All samples were equally cut and polished, and wrapped with thread tape, with one edge unwrapped which was attached to photomultiplier window with optical gel EJ550. The source of gamma quanta was isotope 137 Cs emitting gamma quanta with energy 622 keV reacting with the scintillator. The measurement was performed for the samples containing 2-(4-styrylphenyl)benzoxazole and for the check standard of scintillators BC-420 from the company Saint Gobain. Using oscilloscope spectrum of signal height ending with Compton edge were registered. On the basis of the edge center luminous efficiency of the scintillator was determined. In the limits of measurement uncertainty it was confirmed that luminous efficiency of the scintillator which is the subject of this patent application does not differ from the luminous efficiency of the scintillator BC-420.

[0031] The time resolution was determined of the scintillator containing 2-(4-styrylphenyl)benzoxazole for registration of gamma quanta with energy 511 keV used in PET scanners. In the system presented in FIG. 2 two scintillators wrapped in the Vikuity foil were placed: the one examined and the check standard with the same size (14 mm×14 mm×20 mm). The check standard was the scintillator B-420 from the company Saint-Gobain. The scintillators were exposed in the middle of their length and the source emitting annihilating gamma quanta was isotope 22 Na. The energy of emitting gamma quanta was 511 keV. Using such prepared set the measurement of difference in time between signals from photomultipliers PM1 and PM2 as well as PM3 and PM4 was conducted. In the above mentioned system the time resolution determining interaction time of gamma quantum were really good, on the level of 50 ps. Similar value was received for the commercial scintillator BC-420.