Development of a novel paediatric anthropomorphic phantom from epoxy based mixtures for 5 year age child bone tissue equivalency

Medical imaging phantoms are objects used for simulating human tissues, organs or whole body to ensure that systems and methods for imaging the human body are operating correctly. Anthropomorphic phantoms are special type of phantoms produced to best represent the human being in terms of sex, age, weight, size and appearance. In this study, it is aimed to produce a prototype of an anthropomorphic paediatric phantom to represent the 5 year old child for obtaining more accurate and sensitive response to radiation. 3D printing and moulding methods were employed for a paediatric phantom which has novelty since commercial products of anthropomorphic phantoms are not easily accessible in mostly countries. For the production of phantom bone parts, some inorganic compounds were added to a two-component solventless-epoxy matrix. To achieve this, Hounsfield unit (HU) values obtained from the Computed Tomography (CT) images taken between 80 and 120 kVp were already estimated for the test samples for mimicking the bone tissue for a 5-year-old child. In this study, a two-component room temperature vulcanized(RTV) silicone was also used to create real-sized flexible moulds for paediatric bone tissue. The epoxy based mixture prepared proper proportions of inorganic powders was filled in the RTV moulds, and waited for solidification until the end of its curing period. The skull, thoracic vertebrae, cervical, lower and upper extremities and all bone sections of the body that will form the bone tissues of the phantom were produced by the epoxy resin moulding method. As an indicative quantity, HU values were obtained from CT images representing the radiodensity(radiosensitivity) of tissues. For the paediatric bone tissue, HU value was determined to be 611 +/- 24 for mimicking a 5year-age child bone tissue complying with HU value of ORNL reference phantom. In addition to HU values of the produced bone tissue, it was validated in terms of its physical density, effective atomic number, and electron density. Thus, the developed novel paediatric phantom would be useful in quality control of X-ray systems and dose optimization studies for the effective application of most paediatric imaging protocols. The dosimetric measurements were made on the developed paediatric anthropomorphic phantom, and taken the CT images on it. The obtained results were compared with literature values, and they evaluated with the help of tables and graphs.