Preparation and fabrication of a full-scale, sagittal-sliced, 3D-printed, patient-specific radiotherapy phantom.

Daniel F Craft,Rebecca M Howell

doi:10.1002/acm2.12162

Abstract

PurposePatient‐specific 3D‐printed phantoms have many potential applications, both research and clinical. However, they have been limited in size and complexity because of the small size of most commercially available 3D printers as well as material warping concerns. We aimed to overcome these limitations by developing and testing an effective 3D printing workflow to fabricate a large patient‐specific radiotherapy phantom with minimal warping errors. In doing so, we produced a full‐scale phantom of a real postmastectomy patient.MethodsWe converted a patient's clinical CT DICOM data into a 3D model and then sliced the model into eleven 2.5‐cm‐thick sagittal slices. The slices were printed with a readily available thermoplastic material representing all body tissues at 100% infill, but with air cavities left open. Each slice was printed on an inexpensive and commercially available 3D printer. Once the printing was completed, the slices were placed together for imaging and verification. The original patient CT scan and the assembled phantom CT scan were registered together to assess overall accuracy.ResultsThe materials for the completed phantom cost $524. The printed phantom agreed well with both its design and the actual patient. Individual slices differed from their designs by approximately 2%. Registered CT images of the assembled phantom and original patient showed excellent agreement.ConclusionsThree‐dimensional printing the patient‐specific phantom in sagittal slices allowed a large phantom to be fabricated with high accuracy. Our results demonstrate that our 3D printing workflow can be used to make large, accurate, patient‐specific phantoms at 100% infill with minimal material warping error.

Highlights

Commercially available anthropomorphic phantoms can be used for end-to-end quality assurance (QA) of new treatment techniques
This approach was chosen with the goal of minimizing the extent and effects of material warping on our phantom. 3D-printed objects warp primarily from their contact with the print bed, so orienting all the slices in the sagittal plane accomplishes two things
The process of cropping the computed tomography (CT) scan, converting it to a 3D model, and slicing it into 2.5-cm slices took less than 30 min once we were familiar with the workflow

Summary

Introduction

Commercially available anthropomorphic phantoms can be used for end-to-end quality assurance (QA) of new treatment techniques. Such phantoms are generally available in only four forms: male, female, child, and infant. These phantoms have average body mass indices, but most patients’ individual anatomy differs greatly from that of the representative phantoms. Patient-specific phantoms have many potential uses in radiotherapy but are generally not commercially available. This lack can be attributed to the development time and expense required to individualize the production process. Three-dimensional (3D) printing is one tool that potentially can be used to inexpensively custom-fabricate patient-specific phantoms

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