Radiophosphorus test

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The radiophosphorus test , syn. 32 P- uptake test , is an earlier diagnostic procedure in nuclear medicine that was used to search for malignant melanoma of the choroid in the human eye.

The test was first published in 1952 by an interdisciplinary working group from Cleveland. He used the selective accumulation of the radioactive phosphorus - isotope 32 P but (an artificial beta emitter with 0.7 MeV beam energy and 14 days half-life) in this type of tumor in order looking similar to that of the benign nevi distinguish, hemangiomas and other changes in the choroid . About 500 microcuria of the substance were injected intravenously in the form of phosphate . It accumulated in a way that was not clearly understood in melanoma tissue with high metabolic activity; a connection with the high rate of division of cancer cells could not be confirmed. With the help of a special measuring probe (ionization chamber, comparable to a Geiger counter ), the radiation above the raised or visible tumor was measured several times over the next three days and compared with an inconspicuous part of the cornea or the other eye. Thomas et al. suggested assuming melanoma if the ratio of the measured values ​​was greater than 1.6 and stated an accuracy of 99% for their test.

Radiophosphorus test at the Charité , 1973

The sensitivity of the test was limited because of the low penetration of the beta particles (2 mm) emitted by the radiophosphorus on superficial tumors; the measuring probe had to be placed directly on the locally anesthetized eyeball. There have been attempts with gamma emitters, but as early as the 1960s the nuclear medicine procedures in ophthalmology were more and more abandoned in favor of greatly improved sonography and are no longer relevant today.

Individual evidence

  1. ^ Charles I. Thomas, Jack S. Krohmer, John P. Storaasli: Detection of intraocular tumors with radioactive phosphorus: A preliminary report with special reference to differentiation of the cause of retinal separation. In: Archives of Ophthalmology. Vol. 47, No. 3, 1952, ISSN  0093-0326 , pp. 276-286, doi : 10.1001 / archopht.1952.01700030284002 .
  2. ↑ a b Esther NM Overkleeft, Wieke Zuidervaart, H. Monique H. Hurks, Paul HC Eilers, Didi de Wolff-Rouendaal, Martine J. Jager: Prognostic value of the disodium phosphate 32P uptake test in uveal melanoma. A long-term study. In: Archives of Ophthalmology. Vol. 121, No. 10, 2003, pp. 1398-1403, doi : 10.1001 / archopht.121.10.1398 .
  3. ^ Charles I. Thomas, John P. Storaasli, Hymer L. Friedell: Radioactive Phosphorus in the detection of intraocular neoplasms. A report of 150 cases. In: American Journal of Roentgenology. Vol. 95, No. 4, 1965, ISSN  0361-803X , pp. 935-941 (PDF; 884 kB) .
  4. ↑ DP Graves, JM Cappin: The use of radioisotopes in the diagnosis of intraocular Tumors. In: Proceedings of the Royal Society of Medicine. General Reports. Vol. 61, No. 10, October 1968, ISSN  0141-0768 , pp. 1037-1038, PMC 1902769 (free full text, PDF).