The analysis of attenuation factors for therapeutic radioisotopes in Indonesia: Preparation of image quantification for radionuclide therapy dosimetry.

To The development of nuclear medicine in Indonesia can be seen by several factors, including the increasing number of patients who are diagnosed and treated utilizing nuclear medicine methods, the growing availability of locally manufactured radioisotopes for diagnosis and therapy, and the rising interest in performing dosimetry studies for radionuclide therapy. Since it is impossible to directly assess the organ dose in dosimetry studies for radionuclide therapy, image acquisition and quantification are utilized to explore how radiopharmaceuticals accumulate in the human body. The attenuation and calibration factors for the imaging instruments must be determined during the image quantification steps before the clinical procedures for the dosimetry research take place. The radioisotopes ¹⁵³Sm, ¹³¹I, and ¹⁷⁷Lu were used in this investigation because they have been proposed to contribute to cancer management in Indonesia. This study aims to evaluate at the effect of activity level on attenuation factors for image quantification. The experiment was carried out by acquiring images of ¹⁵³Sm, ¹³¹I, and ¹⁷⁷Lu at low (±2 mCi), medium (± 25 mCi), and high (± 50 mCi) activity. All radioisotopes were prepared in a 1 mL syringe and injected into the Mediso AnyScanS gamma camera equipped with Polymethyl methacrylate (PMMA) slab phantoms. The results reveal that the activity level does not affect the attenuation factors for ¹⁵³Sm and ¹⁷⁷Lu, which are around 0.12 ±0.008 cm^-1 and 0.11 ± 0.003 cm^-1, respectively. However, variability in ¹³¹I was high, around 0.07±0.037 cm^-1. To summarize, the activity level has only a little impact on the attenuation factor for ¹⁵³Sm and ¹⁷⁷Lu, but for ¹³¹I, multi-energy adjustment is required to obtain an attenuation factor of around 0.095 ±0.005 cm^-1. [ABSTRACT FROM AUTHOR]

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