P-32 bremsstrahlung SPECT helps assess intracavitary therapy

A patient underwent intracavitary P-32 chromic phosphate therapy for a chest tumor. Tc-99m sulfur colloid instilled before the P-32 demonstrated uniform distribution of activity throughout the right pleural space, and the P-32 was immediately administered. Ten days later, SPECT imaging using bremsstrahlung radiation of the P-32 showed an unexpected loculation of the P-32. A subsequent chest CT scan demonstrated pleural infolding and fluid localization in the same area as the P-32, indicating that the bremsstrahlung SPECT study had, in fact, documented the final localization of the P-32, which was unexpected and different from the initial localization. The procedure used in this case may be of value in documenting the ultimate distribution of intracavitary P-32.