STANDARD OPERATING PROCEDURES
FOR IODINATIONS
INTRODUCTION
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.
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.
REGULATIONS
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.
PURCHASING
PROCEDURE
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.
PRE-IODINATION
PROCEDURES
- 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.
IODINATION PROCEDURES
- 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.
POST-IODINATION
PROCEDURES
- 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