Hall of Fame catcher Gary Carter is halfway done with his radiation treatment, his daughter wrote Monday night on a private family website. Carter, who is battling Stage 4 brain cancer, underwent his first day of radiation treatment on June 7. He still has a little more than three weeks remaining in the treatment process. He is also undergoing a year of chemotherapy and taking Avastin, a drug that is designed to prevent the growth of blood vessels that feed tumors. Carter had been battling through a severe chest cold in recent weeks. He underwent further X-rays on his chest last Friday, which revealed that he has "walking pneumonia."