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Standardizing I-131 Outpatient Risk Stratification and Workflows

N Busse1*, K McCullough2, S Franz3, N Bunda-Randall4, (1) Denver Health, Denver, CO, (2) Colorado Associates in Medical Physics (CAMP), Colorado Springs, CO, (3) Colorado Associates in Medical Physics (CAMP), Berthoud, CO, (4) Colorado Associates in Medical Physics (CAMP), Pueblo, CO


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: Our private practice medical physics group consisting of 8 diagnostic and 9 therapeutic medical physicists discovered we were using different methods, forms, and instructions for outpatient I-131 restrictions. Our goal was to standardize, simplify, and improve consistency on I-131 thyroid therapy workflows. Practice environments include site-based and consulting physicists.

Methods: Based on results from a patient questionnaire, patients were placed into one of three categories based on potential risk. Category 1 patients are thyroid cancer remnant-ablation patients with a separate bedroom and bathroom at home who don’t have continual contact with children. Category 2 patients are thyroid cancer patients that don’t meet the requirements of Category 1 or hyperthyroid patients with a separate bedroom and bathroom at home who don’t have continual contact with children. Category 3 patients are hyperthyroid patients with complicating factors, including but not limited to, young children at home, work in food service or around young children, or dialysis.

Results: Category 1 patients received discharge instructions completed in advance representing six different scenarios (50, 100, and 200 mCi doses modeled as 2% or 5% slow-clearance compartment uptake depending on the presence or absence of metastatic nodules). Category 2 patients had restrictions calculated using the NCRP 155 example spreadsheets. Fractional uptake in the slow-clearance compartment for hyperthyroid patients was assumed to be equal to the 24 hour uptake value. If no uptake study was available, 60% was used.

Conclusion: In spite of regulatory permissiveness, generic discharge instructions should be discouraged for all hyperthyroid patients. Keeping doses to children below 1 mSv results in restrictions for hyperthyroid patients that will be substantially longer than those for thyroid cancer. In our group, we chose to limit restriction calculations with Category 3 patients to a sub-group of four physicists with more experience in challenging scenarios.


Radiation Protection, Nuclear Medicine


IM/TH- Radiopharmaceutical Therapy: General (most aspects)

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