Development of 3D Printed Phantom for Dose Verification in Radiotherapy for the Patient with Metal Artefacts Inside

One of the problems performing IMRT dose planning or plan verification using anthropomorphic phantoms for head and neck cancer patients is the presence of possible artefacts (dental crowns, metal dental implants, dental restoration materials.) inside the oral cavity. In many cases these artefacts are not accounted but may cause deviations from patient treatment plans due to enhanced scattering dose from the metal artefacts. Exploiting 3D printing technologies 3D dosimetry phantom corresponding to patient-specific anatomic structures with precisely positioned artefacts can be produced. Application of such 3D phantom in radiation therapy may contribute to more accurate dose planning and thus more efficient patient treatment. In this work we propose newly developed patient-specific 3D printed phantom of lower jaw with teeth which can be used for patient specific QA in IMRT. Developing this phantom DICOM image of the real patient was used for 3D reconstruction of patient's lower jaw with teeth. 3D shape of this anatomic structure was printed out using Zortrax M300 3D printer. High Impact Polystyrene (HIPS) which is characterized as having satisfactory bone tissue equivalency was used as printing material. Keeping in mind a real patient, possibility of covering of corresponding teeth with a metallic crown in the 3D printed jaw construction was foreseen. Prepared construction was fixed in dose gel matrix, thus forming dosimetry phantom for the evaluation of possible radiation treatment errors caused by artefacts located in this anatomic region of the patient. Investigation of 3D printed lower jaw phantom has shown its feasibility for the assessment of dose distortions related to the presence of metal artefacts in the mouth of the patient. Also potential for the application of 3D printed phantoms in radiotherapy quality assurance has been shown.