The recalibration that would bring the dose rate within the license limit
A community hospital operates a 131I therapy program under a written directive. The licensee's license authorizes release of patients under 10 CFR 35.75 using the dose-rate criterion of 7 mrem/h (0.07 mSv/h) at 1 meter. A 74-year-old man with Graves' disease is to receive 1.1 GBq (30 mCi) of 131I as an outpatient. The measured dose rate at 1 m immediately after administration is 9.2 mrem/h. The referring endocrinologist wants the patient treated today because the patient traveled 3 hours by car and cannot easily return. The hospital administrator suggests "recalibrating the survey meter so it reads under 7" so the patient can be released. The authorized user asks the physicist for an opinion in front of the administrator.
1. How should the physicist respond to the recalibration suggestion, and what is the regulatory and ethical analysis?
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The suggestion is not a calibration issue; it is a request to falsify a measurement. Recalibrating a survey meter to produce a predetermined reading is:
- A violation of the license condition (release under 35.75 requires an actual measurement meeting the criterion) and of the requirement that instruments be calibrated accurately.
- A patient-safety and public-safety failure: the release criterion exists to bound dose to household members and the public. Falsifying the reading defeats the only barrier between this patient and an uncontrolled exposure.
- A professionalism failure: the physicist's obligation is to the patient and the public, not to the administrator's schedule.
The physicist should say plainly, in the meeting, that recalibration to a target reading is falsification and cannot be done. The correct options are:
- Delay release until the measured dose rate falls below the criterion (131I physical half-life is 8.02 days; the dose rate will fall, but this may take days).
- Reduce administered activity and reschedule, if clinically acceptable to the endocrinologist.
- Use patient-specific release criteria if the license permits (e.g., 35.75 allows release if the dose to any other individual is not likely to exceed 5 mSv, with written instructions), and document the calculation.
- Retain the patient under the license's inpatient provisions if the facility is so licensed.
What the physicist must not do is participate in or acquiesce to the falsification, even under pressure.
2. If the patient is instead released under the patient-specific dose criterion with written instructions, what must those instructions contain and what assumptions underlie them?
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Written instructions under 35.75 must include, at minimum:
- Time to remain at a distance from others (e.g., sleep alone, avoid close contact) for a specified number of days.
- Distance guidance (e.g., maintain at least 1 m from others, especially pregnant women and children).
- Travel guidance (e.g., avoid public transit for a specified period, sit away from others if travel is unavoidable).
- Contact with children and pregnant women restrictions.
- Handling of body fluids (flush toilet twice, separate laundry, avoid sharing utensils).
- When to contact the licensee and how to reach the authorized user.
Underlying assumptions that must be verified, not assumed:
- The dose to household members is calculated for the specific living situation (number and ages of household members, sleeping arrangements, work). A patient who lives alone has a different calculation than one with a pregnant partner and a toddler.
- The 3-hour car trip matters: if the patient is driving alone, exposure is to themselves; if a family member drives, that person's dose must be included.
- The measurement must be a real measurement with a calibrated instrument, at a defined distance, at a defined time.
The judgment point: the patient-specific pathway is legitimate and can solve the scheduling problem, but only if the calculation is real and the instructions are specific to this patient's household.