Author: Ali Al Asadi, Amanda Lynn DiCarlo, Anthony J. Doemer, Jessie Y. Huang, Ian Y Lee, Alexandra Moceri, Adam Robin, Lisa Scarpace, Mira Shah, Salim Siddiqui, Kundan S Thind 👨🔬
Affiliation: Henry Ford Innovations, Henry Ford Health 🌍
Purpose: For a patient who had two previous courses of external beam therapy for rectosigmoid adenocarcinoma and presented with painful, recurrent disease in the sacrum, this study describes the first use of Cs-131 LDR GammaTile therapy outside of the brain and demonstrates a novel use of 3D printing for pre-operative dose estimation.
Methods: A personalized 3D-printed model of the patient's spine was created using segmented MRI data, differentiating uninvolved bone, tumor, and dura, with a Stratasys J5 MediJet® Printer. This model was used to simulate surgical resection and placement of dummy radioactive sources. A CT scan of the model facilitated pre-operative dose calculations, encompassing physical dose using Eclipse planning software and biologically effective dose (BED) using MIM Maestro software. The predicted dose was then compared to the post-implant dosimetry for the actual patient.
Results: For the relevant organ at risk (sacral nerves), the max dose (D0.035cc) was calculated accurately within 8.0% for physical dose and within 10.0% for BED when comparing the dose estimated using our 3D-printed model and the actual delivered dose to the patient.
Conclusion: 3D printing can be used pre-operatively to estimate dose to critical organs at risk for patients receiving surgical resection followed by Cs-131 LDR implantation in the spine and can be especially valuable in the context of reirradiation.