Leonidas D. Marinelli Inventions Information

Leonidas D. Marinelli (28 November 1906 – 13 September 1974), was born in Argentina and died in Hinsdale, DuPage County, Illinois was an American radiologist, health physicist and inventor.

Marinelli was born of Italian parents in Buenos Aires, Argentina, on November 28, 1906, eldest son of 6 children of bank owner Vincenzo Marinelli and Amelia Sammartino Marinelli. At age 11, he returned with widowed mother and children to Agnone, Italy, seat of the Marinelli family bell makers. Leonidas graduated the Volta Institute of Naples, October, 1925, with the gold medal prize for highest honors. In January, 1926, he emigrated to New York City and supported himself as a meter tester while working his way through Cooper Union Night School of Electrical Engineering. In 1929 Dr. Gioacchino Failla, former student of Mme. Marie Curie, hired Marinelli to the biolphysical laboratory at Memorial Cancer Hospital, New York City, known today as Memorial Sloan Kettering Cancer Center). Hardly a year later, Leonidas adapted the x-ray roentgen unit for the measurement of low-level gamma ray radiation, not previously quantifiable, which made X-ray and radium radiation comparable by the same unit. By 1933 he coauthored his first publication with Failla, Edith Quimby, and John E. Rose. In 1938 he completed all course requirements for the PhD at Columbia University and had published 5 papers in radiological journals.

Dr. John E. Rose would become Health Physics and radiological physics division director at Argonne. Rose was involved with radiation detection instrumentation, including hand and foot monitors and other detectors. Further note regarding Rose: it was in the Manhattan District of U.S. Army Corps of Engineers that the name "health physics" was born, and great advances were made in radiation safety. From the beginning, the leaders of the Manhattan District recognized that a new and intense source of radiation and radioactivity would be created, and thus, in the summer of 1942, asked Ernest O. Wollan, a cosmic ray physicist at the University of Chicago, to form a group to study and control radiation hazards. Thus, Wollan was the first to bear the title of health physicist. He was soon joined by Carl G. Gamertsfelder, recently graduated physics baccalaureate, and Herbert M. Parker, the noted British-American medical physicist. By mid 1943, six others had been added: Karl Z. Morgan, James C. Hart, Robert R. Coveyou, Ole G. Landsverk, Ph.D. of the Ryerson Physical Laboratory, University of Chicago, L.A. Pardue and Dr. John E. Rose.

Within the Manhattan District, the name health physicist seems to have been derived in part from the need for secrecy (and hence a code name for radiation protection activities) and the fact that there was a group of mostly physicists working on health related problems. Thus, their activities included development of appropriate monitoring instruments, developing physical controls, administrative procedures, monitoring areas and personnel, and radioactive waste disposal—in short, the entire spectrum of modern-day radiation protection problems. It was in the Manhattan District that many of the modern concepts of protection were born, including the rem unit, which took into account the biological effectiveness of the radiation, and the maximum permissible concentration (MPC) for inhaled radioactivity. Indeed, it was in the Manhattan District that modern day radiation protection effects, born in the early days of x-ray and radium, realized their maturity.

In 1935 Marinelli became an Assistant Physicist.

In the 1940s Marinelli became an independent scientist. In 1941 his papers dealt with post-irradiation blood studies and with early tracer work on cancer; in 1942 with the production of chromosomal breaks in plant cells and with the theory of time distribution of radiation treatments. In February, 1942, he published the theoretical basis for internal radiation dosimetry that provided the basis for nuclear medicine. In 1946, he published its systematic application to the radioactive treatment of functional cancer of the thyroid. This breakthrough was followed by autoradiography techniques and by a Review of Modern Physics report on beta rays. The explosive growth of radiation medicine enlarged his responsibilities as Head of Physics at Memorial-Sloan Kettering Institute. In 1948 he added to his publication of internal radiation dosimetry the supplementary biological considerations contributed by Edith Quimby. Economic ease permitted him now to enjoy fully his role of husband and father of a wonderful family.

In 1948 he moved to the Argonne National Laboratory, with a position on the University of Chicago faculty. Here, with John Rose, he provided early leadership and scientific direction of the Radiological Physics Division.

Maturity was marked by authorship of textbook articles on dosimetry in the Annual Review of Nuclear Science, in Radiation Biology, and in the Handbook of Medical Radiology. His studies of physics dealt now with electron diffusion from point sources in airand with the cosmic ray background. In radiology he pioneered the detection of minimal burdens of radioactivity in humans, studying their distribution andvariation in tissues and the epidemiology of chronic low levels of radiation.The Center for Human Radiobiology, which now has the responsibility for all AEC-supported research on the effects of internally deposited radioisotopes, grew out of his effort.

Nature granted Marinelli a generous amount of vitality and healthy spirits, but then allowed an early onset of health problems that sadly shortened his life and his warm contact that had been enjoyed by all who were blessed to know him.

The following footnote regarding the Marinelli beaker is found in a report by R.F. Hill, G.J. Hine and L.D. Marinelli (1950) of the Sloan-Kettering Institute in New York:"This equipment first designed by one of the present authors (L.D.M.) and in use in this laboratory since 1943, can now be obtained from Technical Associates, Inc. Glendale, California."

In the 1940s and 1950s, the main application of the Marinelli beaker was the analysis of I-131 in liquids (e.g., urine). The original version of the Marinelli beaker, pictured here, consisted of a pyrex/glass laboratory beaker with a central hollow tube projecting from the bottom. A detector, usually a glass GM tube designed for gamma counting, was positioned in the central tube while the beaker was filled with the sample. Since the sample effectively surrounded the detector, the counting efficiency was greater than would be the case if the sample were in any other type of container.

A laboratory often used Marinelli beakers of different sizes - small beakers for small volume samples and large beakers for large volume samples. While it was always possible to increase the volume of a small sample by dilution so that it would fill a large beaker, this sacrificed counting efficiency.

Until the mid-to-late1950's when liquid scintillation countings came along and gamma scintillators (NaI crystals) became larger and more widely available, the major options for counting liquid samples were Marinelli beakers, jacketed (annular) GM tubes, and dipping GM tubes . Since Marinelli beakers could hold larger volume samples than annular GMs, they had a higher counting efficiency for gamma rays. On the other hand, their efficiency for beta particles was lower than that of annular GM tubes because the betas had to penetrate the glass of the beaker as well as the GM tube wall. Dipping GM tubes, which were dipped into the radioactive solution, were primarily used for beta emitters. While the problem was not as severe as with the annular GM, they could be difficult to clean - a potential problem with long-lived radionuclides.A different type of alternative was to dry the sample and count it with an end window GM or electroscope (e.g., the Landsverk Model L-75). However, the preparation of dried samples was difficult to perform in a reproducible manner and it risked the volatilization of the iodine.

As NaI detectors became more widely available, workers started to use the type of sample container that most people think of today as the Marinelli beaker: a relatively large plastic jar/beaker with an annular bottom that slid over the NaI crystal (e.g., Haigh, 1954 and Dratz, 1957). Sometimes referred to as a "well-bottom" container, the end of the well was sealed so that the container "hung" from the top of the detector.

Held a patent for "Apparatus for counting fast neutrons in the presence of gamma rays", US #2795703 A.

1958 Janeway Medal awarded by the American Radium Society.

Marinelli, L. D. (1942). Dosage Determination with Radioactive Isotopes, Am. J. Roentgenology, Radium, 47 (2), 210-216.

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