An international congress of radiology is being held in India for the first time, from September 19 to 23 , with the participation of 1,500 delegates from overseas and 2,500 from within the country. The 20th International Congress of Radiology, billed as the largest meeting on medical science ever held in the sub-continent,will facilitate exchange of technical information, and expertise among the 60 member nations of the International Congress of Radiology, congress chairman Samir Banerjee says.