international commission on Radiation units and measurements ( ICRU). 1982 Picture archiving and communication system ( PACS) become available. 1983 The first grain film emulsion is developed. 1984 Laser stimulable phosphor for computed radiography appear. 1988 A superconducting quantum interference device for magneto encephalography ( MEG) is first used. 1989 The SI adopted by the NCRP and most scientific and medical societies. 1990 The Xeromammography system is produced. 1990 Helical CT is introduced. 1991 Twin slice CT is developed. 1992 The mammography quality standard Acts ( MQSA) is passed. 1996 Digital radiography that uses thin film transistor ( TFT) is developed. 1997 Charge coupled device ( CCD) digital radiography is introduced. 1997 Amorphous selenium flat panel image receptor is demonstrated by Rowlands. 1998 Multislice CT is introduced. 1998 Amorphous silicon CsI image receptor is demonstrated for digital radio