Monte Carlo simulations and radiation dosimetry measurements of Pr-142 capillary tube-based radioactive implant (CTRI): a new structure for brachytherapy sources

Abstract

Previously, a promising -emitting praseodymium-142 glass seed was proposed for brachytherapy of prostate cancer. In accordance with the previous study, a Pr-142 capillary tube-based radioactive implant (CTRI) was suggested as a source with a new structure to enhance application of -emitting radioisotopes such as Pr-142 in brachytherapy.

Praseodymium oxide powder was encapsulated in a glass capillary tube. Then, a thin and flexible fluorinated ethylene propylene Teflon(A (R)) layer sealed the capillary tube. The source was activated in the Tehran Research Reactor by the Pr-141(n,gamma) Pr-142 reaction. Measurements of the dosimetric parameters were performed using GafChromic(A (R)) radiochromic film. In addition, the dose rate distribution of Pr-142 CTRI was calculated by modeling Pr-142 source in a water phantom using Monte Carlo N-Particle Transport (MCNP5) Code.

The active source was unreactive and did not leak in water. In comparison with the earlier proposed Pr-142 seed, the suggested source showed similar desirable dosimetric characteristics. Moreover, the Pr-142 CTRI production procedure may be technically and economically more feasible. The mass of praseodymium in CTRI structure could be greater than that of the Pr-142 glass seed; therefore, the required irradiation time and the neutron flux could be reduced.

A Pr-142 CTRI was proposed for brachytherapy of prostate cancer. The dosimetric calculations by the experimental measurements and Monte Carlo simulation were performed to fulfill the requirements according to the American Association of Physicists in Medicine recommendations before the clinical use of new brachytherapy sources. The characteristics of the suggested source were compared with those of the previously proposed Pr-142 glass seed.