Holland, James F.

In radiation safety programs, particularly in large healthcare systems, personal dosimetry is often issued conservatively, leading to unnecessary monitoring of individuals with minimal exposure risk. This study describes a structured approach implemented at Mayo Clinic to evaluate the necessity and exchange frequency of dosimeters using two years of retrospective radiation dose data. Personnel were grouped based on job type and workplace conditions, then dosimetry data was analyzed at the 50th percentile, 95th percentile, and maximum levels against conservative thresholds. Regulatory requirements and managerial input were incorporated throughout the decision-making process. From 2020 to 2024, this method resulted in the reduction of dosimeter frequency for 82 individuals and complete removal for 1,067: reducing dosimeter issuance by 4,912 each year. The approach enabled a more efficient use of resources, allowing radiation safety efforts to be directed toward higher-risk groups and activities without compromising compliance or worker protection. This model provides a conservative, scalable framework for optimizing dosimetry programs in healthcare and potentially other radiation-using industries.

Abstract 1. Combinations of effective agents produce at least an additive increase in complete remission rates over that which can be achieved when the agents are used individually. 2. Patients who do not achieve complete remission with initial treatment have a significantly shorter survival. 3. Alternating MTX and 6-MP at 28-day intervals during remission does not prolong the duration of remission over that of combined concurrent 6-MP and MTX. 4. The administration of folic acid antagonists intrathecally at 28-day intervals during antimetabolite maintained remission did not prolong the duration of remission. Meningeal leukemia, however, occurred significantly less frequently in these patients. 5. The duration of combined 6-MP and MTX maintained remission is not greater than that of 6-MP maintained remission. 6. The toxicity of 6-MP and MTX in combination in patients in remission is additive. The above conclusions were drawn from this comparative study of combinations of chemotherapeutic agents in children with acute lymphocytic leukemia.

Abstract 1. A group of 64 myeloma patients was given a loading dose of Melphalan, 0.15 mg./Kg./Dx7. This was followed by a rest period to allow bone marrow recovery to occur, after which maintenance therapy with a maximum of 0.05 mg./Kg./D was started. 2. To obtain good results, drug doses were required which produced significant bone marrow depression. 3. Subjective improvement was noticed in about 65 per cent of patients; objective improvement, in 78 per cent. 4. Fifty-five per cent of the patients had a response as defined in this study. 5. No difference in survival was found between males and females, nor between patients with Bence Jones proteinuria and those without. 6. Patients who have been on treatment for 3 months and were then found to be responders lived longer than similarly treated patients classified as nonresponders.

Abstract Arabinosyl cytosine (ara-C), a synthetic pyrimidine nucleoside related to the normal metabolites cytidine and deoxycytidine, has been found capable of producing marrow remission at tolerable doses in acute myelocytic and acute lymphocytic leukemia in adults. There were 16 per cent remissions complete in all aspects, 3 per cent complete except for hemoglobin level, and 6 per cent partial remissions among 180 adults with acute myelocytic leukemia treated with any one of 8 variants of infusion duration or daily dose of ara-C. Twenty-four per cent of 37 adults with acute lymphocytic or unclassified leukemia had complete or partial remissions. The comparison of 1, 4, 12 and 24 hours infusion of ara-C (to total dose tolerated) does not show significant superiority for any one group. The complete remission rate with 1 or 12 hour infusions, however, is 25 per cent (superior to that obtained with 6-mercaptopurine) and the recommended schedule of treatment for ara-C based on these data is, therefore, daily infusions of 100 or 50 mg./m.2 in one hour for approximately 3 to 6 weeks followed by maintenance therapy of once weekly subcutaneous injection of 30 mg./m.2 of ara-C. Platelet transfusions should be available when ara-C is used.

Abstract The efficacy of three therapeutic programs for acute leukemia were compared. These programs included (1) Methotrexate (Phase I) followed by 6-mercaptopurine (Phase II); (2) 6-mercaptopurine (Phase I) followed by Methotrexate (Phase II); and (3) Combination Therapy, i.e., 6-mercaptopurine given in combination with Methotrexate. In children with acute lymphocytic leukemia the remission rate was 59 per cent for combination therapy, 47 per cent for 6-mercaptopurine, and 29 per cent for Methotrexate. The better remission rate for combination therapy is consistent with that predicted if it is assumed that 6-mercaptopurine and Methotrexate act independently. The median duration of complete remissions for the three treatments was not different (4 to 5 months). However, long lasting remissions were more frequent in patients receiving combination therapy. The median survival from the onset of therapy to death was 9 months. There were no differences between the three treatment programs as regards survival. In adults the remission rate was 15 per cent for combination therapy, 21 per cent for 6-mercaptopurine and 7 per cent for Methotrexate. As regards survival in adults, early deaths were more common in patients who received MTX as initial therapy, whereas after 5 months survival was somewhat better in those patients receiving combination therapy. In both children and adults there was no evidence that prior treatment with one of the antimetabolites altered response to the other antimetabolite. This result differs from those in animal models, and its effect on our concept of the mechanism of resistance is discussed. Responsiveness to the second course of antimetabolite therapy (Phase II) was as good as that to the first course of treatment. This was true for the remission rate, remission duration, and even for survival when appropriate corrections were made. Thus, responsiveness to drug therapy is maintained as the disease progresses temporally. It may be concluded therefore that new agents can be effectively studied in patients with "late" disease. Responsiveness to Phase II therapy was independent of responsiveness to Phase I. The most common and severe toxic manifestations related to the bone marrow and gastrointestinal tract. There were no major differences quantitatively in the toxicity for the three treatment programs in children in spite of the fact that the drugs were given in full dosage in the combination program. Oral ulcers and a generalized erythematous rash occurred significantly more frequently in patients receiving Methotrexate. Jaundice was significantly more frequent in adults and in patients receiving 6-MP.