of the onset of leukemia.* In this patient, however, the total dose of irradiation given in a series of some 15 to 20 diagnostic proceduresis in all likelihood much less than 100 R. Figures on the irradiation dosage generated by the old Picker portable units employed by the Army during World War If may beavailable from the Atomic Energy Commission or the Armed Forces Institute of Pathology. Although these instruments were poorly columnated and permitted scatter to unshielded portions of the anatomy, the estimated dose or irradiation per fluoroscopic study (which provided a much higher tissue dose than the diagnostic X-ray) is approximately 0.25 R. A rough estimate then of this patient’s total radiation exposure stemming from the initial treatment and follow-up of his tibia! fracture was in the neighborhood of 5 R, certainly not exceeding 20 R. Secondly, thetibia in an adult man is not site of proliferative hematopoietic marrow. If adequate shielding of the axial skeleton was provided during the diagnostic X-ray procedures, the patient should have received no exposure of hematopoietic bone marrow. From these considerations, therefore, this reviewer concludes that the patient had insufficient radiation exposure to proliferative hematopoietic marrow to increase his probability of radiation leukemogenesis on the basis of the diagnostic X-ray procedures required by the treatment of his combat injury and its follow-up. The role of chronic osteomyelitis and the genesis of acute leukemia is more obscure than that of irradiation. The patient’s record, however, did not substantiate chronicity of the patient’s osteomyelitis for more than three years following his initial injury. Thereis, finally, no conclusive evidence that a localized chronic osteomyelitis increases the probability of acute 5. Court Brown, W. M., and Doll, R., Mortality from Cancer and Other Causes After Radiotherapy for Ankylosing Spondylitis, Brit. Med. J., 1: 1782-1790 (1961). 6. Evans, R.D., The Effect of Skeletally Deposited Alpha-Ray Emitters in Man (Silvanus Thompson Memorial Lecture), Brit. J. Radiol., 39: 881-895 (1966). 7, Hasterlik, R. J., Finkel, A. J., and Miller, C. E., The Cancer Hazards of Industrial and Accidental Exposure to Radioactive Isotopes, Ann. N.Y. Acad. Sci., 114: 832-837 (1964). 8. Stewart, A., Pennybacher, W., and Barber, R., Adult Leukemias and Diagnostic X-Rays, Brit. Med. J., 2: 882-890 (1962). Findings of the BVA and Basis for \n_ finding that the materially to the veteran’s death the Board said: The opinions expressed by physicians on behalf of the appellant and those obtained by this Administration are essentially the same. The possibility of an etiological relationship between the veteran's service-connected disabilities with treatment for such conditions andhis leukemia is conceded. The probability of such relationship, however, is shown to be remote or speculative, rather than reasonable. The fact that radiation cannot be “excluded” as a factor does not satisfactorily demonstrate the existence of a substantial doubt. Recourse to speculation or conjecture is prohibited. leukemia. | would conclude, therefore, that though one, on theoretical grounds, cannot exclude the possible etiologic role of radiation ex posure and chronic infection in the genesis of acute leukemia after a latent period of some 19 years, there is no definite evidence either from this patient’s military medical record or from available medical knowledge that this patient’s war wound with resultant osteomyelitis and necessary diagnostic X-ray exposure played any etiologic role in the genesis ofhis terminal leukemia. REFERENCES 1. International Commission on Radiological Protection, The Evaluation of Risks from Radiation, ICRP Publication 8, Pergamon Press, Oxford, 1966. 2. Seltser, R., and Sartwell, R. E., The Influence of Occupational Exposure to Radiation on the Mortality of American Radiologists and Other Medical Specialists, Amer. J. Epidemiology, 81: 2-22 (1965). 3. Court Brown, W. M., and Doll, R., Expectation of Life and Mortality from Cancer Among British Radiologists, Brit. Med. J., 2: 181-187 (1958). 4. Court Brown, W. M., and Doll, R., Leukemia and Aplastic Anemia in Patients Irradiated for Ankylosing Spondylitis, Brit. Med. J., 2: 1327-1332 (1965). 46 Decision: service-connected disability did not cause or contribute substantially or 47