I-123 thyroid imaging

Patient preparation

 * Discontinue any medications that interfere with thyroid uptake of radioiodine.
 * NPO for 4 hours prior to study.

Radiopharmaceutical
I-123

Dose and route of administration
100-400 microCi orally in capsule form

Time of imaging
At 4-6 or 24 hours

Equipment

 * Camera: Gamma camera
 * Collimator: 3- to 6-mm aperture pinhole collimator
 * Window: 20% energy window centered at 159 keV.

Procedure

 * Position the patient supine with the chin up and the neck extended.
 * Position the collimator so that the thyroid fills about two-thirds of the diameter of the field of view.
 * Obtain anterior, 45-degree LAO and RAO views (move the collimator, if possible, rather than the patient).
 * Obtain 100k-250k counts per view.
 * Mark the chin and suprasternal notch.
 * Note the position and mark palpable nodules and surgical scars.
 * Place marker sources lateral to the thyroid to calibrate size.