title: Use of maxillofacial laboratory materials to construct a tissue-equivalent head phantom with removable titanium implantable devices for use in verification of the dose of intensity-modulated radiotherapy.
abstract: The dose of radiotherapy is often verified by measuring the dose of radiation at specific points within a phantom. The presence of high-density implant materials such as titanium, however, may cause complications both during calculation and delivery of the dose. Numerous studies have reported photon/electron backscatter and alteration of the dose by high-density implants, but we know of no evidence of a dosimetry phantom that incorporates high density implants or fixtures. The aim of the study was to design and manufacture a tissue-equivalent head phantom for use in verification of the dose in radiotherapy using a combination of traditional laboratory materials and techniques and 3-dimensional technology that can incorporate titanium maxillofacial devices. Digital designs were used together with Mimics® 18.0 (Materialise NV) and FreeForm® software. DICOM data were downloaded and manipulated into the final pieces of the phantom mould. Three-dimensional digital objects were converted into STL files and exported for additional stereolithography. Phantoms were constructed in four stages: material testing and selection, design of a 3-dimensional mould, manufacture of implants, and final fabrication of the phantom using traditional laboratory techniques. Three tissue-equivalent materials were found and used to successfully manufacture a suitable phantom with interchangeable sections that contained three versions of titanium maxillofacial implants. Maxillofacial and other materials can be used to successfully construct a head phantom with interchangeable titanium implant sections for use in verification of doses of radiotherapy.
authors.affiliation: Maxillofacial laboratory, Abertawe Bro Morganwg University Health Board. Electronic address: kelly.morris3@wales.nhs.uk.
authors.forename: K
authors.initials: K
authors.lastname: Morris
mesh_terms: D000328:Adult; D000368:Aged; D059925:Anatomic Landmarks; D015921:Dental Implants; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012984:Software; D000076227:Stereolithography; D014025:Titanium / Q000737:chemistry; D014057:Tomography, X-Ray Computed
chemical_list: D015921:Dental Implants; D014025:Titanium
keywords: Dosimetry verification; IMRT; cancer; implants; radiotherapy phantom; titanium