To ensure that all personnel conducting iodination receive a minimal amount of radiation exposure, the following procedures have been established and approved by the Radiation Safety Committee on 8/24/88.
Iodinations involve the use of relatively high concentrations of I-125 Sodium Iodide which is known to be volatile in air and readily absorbed by the thyroid gland if inhaled or absorbed internally. Uncapped vials of I-125 and laboratory contamination with I-125 may potentially lead to uptake in the thyroid gland and extra precautions are necessary above and beyond the normal Standard Operating Procedures for Unsealed Sources. It is estimated that the absorption of 1 microcurie of I-125 in the thyroid gland produces a dose of 5 Rad.
University regulations require that all iodinations be conducted during normal working hours in the special fume hood in Room 012 Rowell Building. This plexiglass hood has a charcoal filter attached to trap any airborne I-125 to minimize release to the environment and to personnel.
Orders for I-125 are placed through the Radiation Safety Office (RSO) using a standard University requisition. Upon delivery to the RSO, the package will be leak tested for contamination. The investigator will be informed of the availability of the package which will be stored in Room 012 Rowell Building.
Use of room 012 Rowell
- Iodinations may be scheduled Monday through Thursday during normal University working hours.
- Reservations must be made to use this room as there are several laboratory groups regularly conducting iodinations. Call the RSO (X62570) at least 48 hours in advance to reserve a time.
- All persons conducting iodination must be supervised by RSO personnel to ensure proficiency with safety procedures.
- Because of space limitations, no more than 2 persons will be permitted in the room during an iodination.
The RSO personnel will check the room before each iodination to:
- ensure an adequate supply of disposable gloves and lab coats (provided at no charge).
- set up the air sampling system.
- set up the containers for solid and liquid waste.
- place absorbent paper in fume hood and on the benches.
- Persons conducting iodination must hang up their regular lab coats outside Room 012 and must wear the disposable lab coats and booties provided by the RSO.
- Iodinators hands, feet and clothing will be checked for contamination. Plus, a pre-iodination thyroid burden test will be performed.
- Vials of I-125 must be opened only while in the plexiglass fume hood. Use a Hamilton syringe to aliquot I-125 if possible. Any vials containing I-125 brought outside the plexiglass hood must be capped.
- Film and finger badges must be worn by all persons.
- At least two pairs of disposable gloves plus one pair of arm length disposable gloves must be worn.
- All contaminated syringes, glassware, etc. must remain in Room 012. Storage drawers are available if needed. All items must be decontaminated before storage.
- If the iodinator leaves the room before the end of the procedure, the disposable lab coat, gloves and booties must be removed and the hands, feet and clothing must be checked for contamination.
- No smoking, eating or drinking will be permitted in the lab.
- Before leaving the iodination lab, the hands, feet, and clothing will be checked for contamination.
- If not contaminated the disposable lab coat will be reused. If the lab coat is slightly contaminated the coat will be stored for decay.
- Iodinator(s) must return to the RSO for a thyroid burden assay within 72 hours post-iodination.
At the completion of the iodination, RSO personnel will:
- count the charcoal filters in the air sampling system to determine if excessive airborne radiation was present.
- conduct a surface contamination check of the fume hood and general lab area.
- dispose of waste generated by the iodination and will bill the investigator.
Thyroid assay procedures
- Prior to the iodination, a thyroid burden test will be performed for each iodinator.
- Within 72 hours post-iodination, each iodinator will be required to return to the RSO for a follow-up thyroid burden test. The results will be kept on a permanent record.
- In the unlikely event of I-125 accumulation, the iodinator will be informed by the RSO and will be advised of the necessary course of action (see the attached sheet for the procedure).
- If the iodinator DOES NOT return within 72 hours, he/she will be in violation of the thyroid burden policy (see attached letter) and may be suspended from doing further iodinations.
REFERENCES 1. New England Nuclear; Iodine-125 Guide to Safe Handling; 12/77 2. Shapiro; Radiation Protection: A Guide for Scientists; Harvard 1981