Thomas G. Mitchell, 71, a retired Navy Commander and Johns Hopkins University professor of radiation health sciences, died April 10, 1998 at Bethesda Naval Hospital after a heart attack.

Dr. Mitchell, who lived in Burtonsville, served in the Navy from 1945 to 1969. Most of his Navy career was spent in the Medical Service Corps and included tours of duty in the Korean and Vietnam wars. In the former, he was part of a medical unit attached to a minesweeping operation in a combat zone. He also had assignments at Bethesda Naval Hospital.

After his retirement from the Navy in 1974, he became an associate professor of physiology and biophysics at Georgetown University.

Dr. Mitchell, a native of Philadelphia, graduated from St. Joseph's College. He received a master's degree in nuclear physics from the University of Rochester and a doctorate in physiology and biophysics from Georgetown University. He was on the staff of Johns Hopkins University School of Hygiene and Public Health for 15 years until his retirement in 1989. During those years, he was an associate professor of nuclear medicine with Johns Hopkins University School of Medicine.

In retirement, he was active with Meals on Wheels in the Laurel and Burtonsville area and with charitable organizations through St. Mary's Catholic Church in Laurel, where he was a member. He also was a member of the Knights of Columbus, American Legion and Fleet Reserve Association.

He was a member of the American College of Radiology, Society of Nuclear Medicine and Health Physics Society.

His wife, Marie Annette Sullivan Mitchell, died in 1992.

Survivors include four sons, Thomas J., of Laurel, Joseph A., of Columbia, Michael J., of Burtonsville and Denis Mitchell of Hagerstown; two daughters, Marie Annette Mitchell Vaughn of Silver Spring and Mary Agnes Mitchell Gigliotti of Burtonsville; two brothers; three sisters; 16 grandchildren; and a great-grandson. His twin sons, Anthony Mitchell and Bryson Mitchell, both died in 1965.

On Friday, April 10, 1998, of Burtonsville, MD, beloved husband of the late Marie Annette Mitchell; loving father of Marie Annette Vaughan of Silver Spring, MD, Mary Agnes Mitchell Gigliotti of Burtonsville, MD, Thomas J. of Laurel, MD, Joseph A. of Columbia, MD, Michael J. of Burtonsville, MD and Denis Mitchell of Hagerstown, MD and the late Anthony and Bryson Mitchell; brother of Dorothy A. Murray, Margaret H. Campbell, Mary E. Whelan, Joseph T. and Cornelius G. Manga. Also survived by 16 grandchildren and one great grandchild. Visitation will be held on Sunday, from 2 to 4 and 7 to 9 p.m. and Monday, 9:30 to 11 a.m. at the FLECK FUNERAL HOME, INC., 7601 Sandy Spring Rd., Laurel, MD. Services will be held Monday, 12 noon at St. Mary of the Mills Catholic Church, 114 St. Mary's Place, Laurel, MD. Interment will follow at Arlington National Cemetery at 3pm. Memorial donations may be made to Bethlehem House, 1401 Lawrence St., NE, Wash., DC 20017