Radiation Injury Effect Of Iodine-125Seeds On Normal Larynx Tissue In Rabbits And The Environmental Radiation Dose

Objective: To study the effect of larynx and trachea and monitor the environmental radiationdose after implanted radioactive¹²⁵I in normal rabbit thyroid perichondrium。Methods:24New Zealand rabbits， weighing2.15-2.3kg， were randomly divided intoexperimental（n=12） and control groups（n=12）, each group was further divided into foursubgroups of7,30,60and120days. Iodine-¹²⁵ of0.8mCi was implanted into thyroidperichondrium in the treatment groups and nonradioactive seeds were implanted in the controlgroup. Taking the tissue of larynx for pathological examination with HE staining. At thedifferent time and distance measured the surrounding radiation dose of the treatment group,theresult were analyzed in Statistics.Results:（1）All the rabbits survived and the weight increased, didn’t appear dyspnea, stridor andanorexia.（2）Under the optical microscope, the thyroid cartilage, tracheal cartilage, laryngeal mucosaand tracheal mucosa was not observed damage in the control group. In the experimental group,the mucosa of vocal cord, supraglottic portion and tracheal had different damages, and thethyroid cartilage and tracheal cartilage didn’t observe damage.（3）With the increase of the distance and the prolong of the time, the radiation dose wasdecreasing，and with the increase of distance, the radiation dose decreased slowly. At the site of1meter from the seeds, the detected dose is close to the natural background radiation dose.Conclusions:（1） Radioactive¹²⁵I seed has little influence on the normal laryngeal tissue and the damagecan be repaired by the regeneration of the basal cell.（2） With the increase of the distance and the prolong of the time, the surrounding radiationdose has significantly reduced, the more the distance, the dose decrease more slowly,so it is easyprotection in the clinical application.