Production of heterogenous bone radiopacity phantom using 3D printing

The aim is to obtain a heterogenous bone radiopacity phantom with adjustable radiopacity in different regions. The heterogenous 3D printed phantom can be used as bone equivalent in medical education, surgical planning, diagnostic radiology, and radiotherapy. This study utilized a hybrid approach, combining both direct and indirect methods, to create phantoms with realistic bone-equivalent radiodensity. Hollow, cube-shaped test blocks were produced using an SLA 3D printer with a photoreactive resin. The attenuation coefficients of the test blocks were evaluated using Dataviewer software by comparing materials such as calcium sulfate dihydrate, barium sulfate, and hydroxyapatite. The photoreactive resin was modified with hydroxyapatite to increase its radiodensity. A hollow jaw phantom model was then designed and printed using the hydroxyapatite-doped resin. The powder hydroxyapatite was added to the cavities of the printed phantom model. The average attenuation coefficient of barium sulfate was 208 ± 1.90 mm^- 1, calcium sulfate dihydrate was 187 ± 1.98 mm^- 1, hydroxyapatite was 128 ± 2.35 mm^- 1, and bone values, which were considered as reference values in the research, was 125 ± 14 mm^- 1. The observed difference between the hydroxyapatite added bone model and real bone was not statistically significant (Z:-0.175, p:0.860). The produced mandibular bone phantom has realistic attenuation coefficient values and heterogeneity in terms of radiological features. This study shows that the use of two different methods, which include hydroxyapatite material added into the photoreactive resin during the 3D printing process and the addition of hydroxyapatite as a powder to the gaps in the bone model obtained after printing, yields successful results in the production of bone-equivalent phantoms.