Document Type: Original Article
Research Institute for Nuclear Medicine, Tehran University of Medical Sciences, Tehran, Iran
SPECT detects γ-rays from administered radiopharmaceutical within the patient body. γ-rays pass through different tissues before reaching detectors and are attenuated. Attenuation can cause artifacts; therefore different methods are used to minimize attenuation effects. In our study efficacy of Chang method was evaluated for attenuation purpose, using a custom made heart phantom. Due to different tissues surrounding heart, attenuation is not uniform more over activity distribution around heart is also non-uniform. In Chang method, distribution of radioactivity and attenuation due to the surrounding tissue is considered uniform. Our phantom is a piece of plastic producing similar SPECT image as left ventricle. A dual head, ADAC system was used in our study. Images were taken by 180° (Limited angle) and 360° (Total rotation). Images are compared with and without attenuation correction. Our results indicate that Chang attenuation correction method is not capable of eliminating attenuation artifact completely in particular attenuation effects caused by breast.