Preliminary study on image quantification of anthropomorphic phantoms for dosimetry protocol using MIRD 16 method

Internal dosimetry in radionuclide therapy practice is a raising issue since the Bonn Call for Action in 2012, which has stated that the organ dose assessment for radionuclide therapy practices should be improved. To develop the internal dosimetry assessment, an anthropomorphic phantom has been produced and developed. The authors aim to perform an evaluation of anthropomorphic phantoms using Medical internal Radiation Dosimetry (MIRD) no. 16 publication. The objective of study is to evaluate the image quantification method using anthropomorphic phantoms regarding the need of standardization in internal dosimetry protocol in Indonesia. The injected activities in dose calibrator and acquired activities in the images are evaluated. To perform image quantification, a series of anthropomorphic phantoms, which are kidneys, liver, bladder and heart, are constructed from Poly(methacrylic acid) (PMAA) and being placed into a torso phantom filled with water. A pair of anterior and posterior images then were acquired from planar gamma camera images. The results show that the activity of ^99mTc in phantoms have been found less than the result from dose calibrator. The difference activities were varied, respectively, right and left kidney, liver, bladder and heart, at about 4.17 %, 5.50 %, 6.43 %, 15.54 %, and 18.74 %. As a preliminary study, the authors have demonstrated the ability of the phantoms to be utilized for an image quantification using gamma camera planar images. However, it still needs more study using a commercial phantom to compare the results. These phantoms can be used for a tool in the development of dosimetry protocol. (author)