Patent ID: 7180069

Claim:
A radiation detector for detecting a radioactive substance present in a tubule, or in the vicinity of said tubule comprising a detection unit having a bar-type scintillator which emits light by an incidence of radiation thereby transmitting the light from said scintillator through an optical fiber, wherein said detection unit is formed in a size capable of being inserted into the tubule while a roughened surface is provided on the peripheral surface of said scintillator, the diameter of said scintillator is set to be substantially 1.5 mm or less, said optical fiber for transmitting the light from said scintillator is an optical fiber aggregation which is obtained by bundling up thin optical fibers to have substantially the same diameter as that of said scintillator, said aggregation is divided into two optical fiber branches thereby dividing the light equally for transmitting to photomultipliers, said photomultipliers receive said divided lights for converting and amplifying each of said light into electric signals, and a counter circuit of a controller receives and counts said electric signals as pulse for obtaining coincidence.