Patent ID: 8399672

Claim:
A compound represented by the following formula (1), and a salt thereof: wherein R 1 , R 2 and R 3 each independently represents a group selected from the group consisting of a hydrogen, a hydroxyl group, an alkyl substituent with 1 to 4 carbon atoms, an alkoxy substituent having an alkyl chain with 1 to 4 carbon atoms and a halogen substituent, excluding the case where two or more of the substituents R 1 , R 2 and R 3 are hydrogen, R 4 is a group selected from the group consisting of a hydrogen, a hydroxyl group, an alkoxy group having an alkyl chain with 1 to 4 carbon atoms and a halogen substituent, and m is an integer of 1 to 4, provided that at least one of R 1 , R 2 , R 3 and R 4 represents a radioactive halogen substituent.