Preparation of a prototype radioactive probe for treatment of lacrimal ducts stenosis and a study of its dose distribution.

Our aim was to prepare a radioactive lacrimal passages probe, study its dose distribution in a phantom and suggest security indexes and therapeutic effective doses for brachytherapy. We prepared the radioactive probes by laying 125I particles into plastic tubes. We conducted temperature tests, pressure tests, soak tests and shock tests, to obtain security indexes. The dose distributions in phantom and wax matrix were also detected, and the surface dose rates on different parts of the phantom and the dose absorbed by the operator were examined. The radioactive lacrimal passage probe demonstrated no form changes in temperature tests, pressure tests and soak tests when using a surface radioactive contamination dose lower than 185 Bq. The probe was waferinged in shock tests with a surface radioactive contamination dose lower than 185 Bq. The dose detection in the phantom and the wax matrix showed that for distances of 1 mm-12 mm off the tube, there were statistical differences of the absorbed dose (P<0.05). However, for the range of 12 mm-40 mm, there was no statistical difference (P>0.05). The dose rates administered by the radioactive probe used for radiotherapy to the lacrimal passages were within safe limits both for the phantom (Sichuan Keyi Corporation, China) and the operator. In conclusion, our study showed that this prototype lacrimal passages probe can be a useful and effective method for clinical brachytherapy of lacrimal ducts stenosis.