Development of an anthropomorphic phantom based on 3D printing for assessment of dose delivered to the eye and adjacent tissues

Abstract

The objective of this work was to build slices containing the eye region using 3D printing, to be inserted in an anthropomorphic phantom, allowing to perform the dosimetry of organs associated with the eye. The slices were built using PLA 3D printing for soft tissue and a mixture of calcium sulfate dihydrate and sodium chloride for the cranial bones. Different mixtures were tested to simulate bone tissue. The phantom containing LiF TLD 100 micro cubes in proper positions was validated for the determination of doses to the eye and to organs at risk. For the mass attenuation coefficient and energies between 1 and 10 MeV, the percentage differences between the data for the three mixtures and that for cortical bone was less than 2%. When analyzing the electronic density, all mixtures differed by more than 10% in relation to bone tissue. The use of Hounsfield Units as the only parameter to characterize the tissue equivalence is not recommended. The results showed that the mixture with 46% calcium sulfate is the closest to the cortical bone of the ATOM® phantom. The printed phantom containing TLDs was used to measure the doses in deeper regions of ocular system as the optical nerves and fundus of the eye. The results differed about 2% from the planned ones. For more superficial regions (like the lens), the use of dose compensators should be used to provide electronic equilibrium conditions. Results showed the feasibility of using the three-dimensional printed phantom developed.