George Meneely: Whole Body Counter (WBC)

Interest in body composition led Meneely to develop the first low level whole body counter (WBC) in a Medical School. The room was designed for counting the small amount of 1.46 MeV high energy emissions from naturally occurring 40K in the body. High sensitivity and excellent shielding against natural background was needed to obtain statistically significant data. A secondary advantage was that its high sensitivity made it possible to get accurate data from patients administered small amounts of tracers, not present in the natural environment. The system was also used to study contamination from industrial and environmental sources, including fallout from weapons testing. Because of its high sensitivity, the WBC was used to advantage in many studies in children and other radiosensitive populations where it was important to keep the radiation dose to a minimum and yet provide statistically significant results. The development of the WBC was sponsored by the Atomic Energy Commission by a grant to Meneely and Bob Lagemann, Chair of the Physics Department. This long standing contract (1959-1979) provided support for much of the research done in Nuclear Medicine. Many of these studies are described in the main text.

Since 40K is only 0.03% of naturally occurring potassium the number of events recorded is low, and it was necessary to decrease counts from natural background to achieve accurate data. From these measurements it was known that one could calculate lean body mass, as the fat content of 40K is extremely low. The room was enclosed by 8” thickness of steel. The inner surface of the steel was covered by thin layers of graded shielding (Cu, and Cd), with an outer thin covering layer of stainless steel. The steel was from pre World War II battleships to avoid 60 Co contamination used after 1945 in steel fabrication. To accommodate the device an extension was made to the Hospital building by construction toward  Garland Avenue.

The development of the room and the associated detectors and electronics required the collaboration of many faculty and students in the Physics Department, then Chaired by Robert Lagemann. At least 5 graduate students in Physics obtained their MS/PhDs on tasks related to the design and construction of the facility and its subsequent calibration and utilization with help from Charley Roos. Ray Weiland was an electrical engineer who had worked with Jack Dewitt, an earlier Vanderbilt graduate, and one of the founders of the Nashville Radio and Television station, WSM. Dewitt was an electronics genius who was the first person to bounce electromagnetic signals off the moon, and he made a number of suggestions that helped with the project. Jack was also distinguished by the fact that he had been dismissed from Vanderbilt for ghost writing thesis papers for other students. Jack had a shop in his backyard where he, Ray Weiland and Bob Hardy, an instrumentation savvy member of the Vanderbilt Physics Department, did a lot of the creative instrumentation support work.

System calibration is a major task for all devices and for whole body counter calibration the problem was especially difficult. Several different methods were applied. A plastic phantom that resembled a human was built, and called King Farouk, so named for reasons that remain obscure. It was used for 40K calibrations. An Alderson commercial phantom had different internal organs that could be filled with known amounts of radioactivity. The most definitive assessment of the accuracy of the calibration for 137Cs was done in later years when Chet Richmond and Phil Dean self administered known amounts of 137Cs. The increment in their measured body content was then known to reflect their body burden and they became walking  standards. The rate of loss from their body was established by serial counting. Thereafter, they were counted in almost all the major WBCs and the local accuracy thereby determined, and changes in local calibrations thereby accomplished. This was probably the best controlled of the many inter calibration programs ever conducted. Vanderbilt came out very close to the known value.

The steel room with a high efficiency air filter was adjacent to a comparable sized  instrumentation room. The heavy front door of the steel room had a large swing which took up a large part of the front office which housed a receptionist (usually a medical student’s wife), and Meneely’s long time friend, Con Overton Thompson Ball, his Executive Secretary. An adjacent area was Meneely’s office, and an outer area housed scientists, and visitors. One entered the Whole Body Counter Facility (WBC) by an outside dMaria Chairoor, or from the C-1107 corridor having to walk through what was then the OB-Gyn and Urology Clinic waiting room. The WBC facility contained a bathroom with a shower used by subjects to wash off fallout radioactivity from their hair and body surface prior to measurement in the counter. There was far more radioactivity on the outside of the body during the  high yield nuclear test periods than from the small amount of 40K in the body. The room had a metal chair, Marinelli type, on which the subject sat (in this case, Maria Heyssel) and a large unshielded  8” diameter x 4” thick NaI (Tl) crystal was situated over the subject’s abdomen while in a seated position.

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