THE INVESTIGATION OF P-32 WIRE FOR CATHETER-BASED ENDOVASCULAR IRRADIATION

The dose distribution from a P-32 source has been measured and calcula ted in order to evaluate its application in endovascular irradiation. The source dimension was 27 mm in length and 0.3 mm in diameter and wa s embedded in the end of a Ni-Ti wire. Dose measurements were performe d using radiochromic film in several specially designed tissue equival ent phantoms. Loevinger's point dose kernel was used for the calculati on. The approximate dose rate at a radial distance of 1.5 mm from the center of the source was found to be 6.75 cGy/s per GBq (0.25 cGy/s pe r mCi), which allows the delivery of a therapeutic dose in a short tim e interval with a satisfactory homogeneity without stepping the source . However, the dose rate falls off almost exponentially along the radi al distance. Therefore it may not be suitable for treating large diame ter vessel from a centrally located source, The effect of a curved P-3 2 wire source on the radial dose distribution was also investigated. T he results showed that for a maximum bend of 180 degrees the dose rate was increased by as much as 20% along the inner radial distance but d ecreased by as much as 20% along the outer radial distance compared to the dose along a straight wire. However, for curvatures normally enco untered in a clinical situation, the dose rate was changed less than 5 %. (C) 1997 American Association of Physicists in Medicine.