Development of a 3D-printed canine head phantom for veterinary radiotherapy

TL;DR

This paper presents the development of a 3D-printed canine head phantom, UPDOG, for quality assurance in veterinary radiotherapy, accurately mimicking dog anatomy and enabling dose measurement validation.

Contribution

The study introduces UPDOG, a novel anatomically-correct 3D-printed phantom for veterinary radiotherapy QA, validated through CT imaging and dose measurements compared to Monte Carlo simulations.

Findings

UPDOG accurately mimics canine head anatomy in CT scans.

Dose measurements with UPDOG closely match Monte Carlo simulations.

UPDOG is effective for QA in veterinary kV radiotherapy.

Abstract

Purpose: To develop the Ultimate Phantom Dog for Orthovoltage Glioma Treatment (UPDOG), an anatomically-correct phantom which mimics a dog's head, for quality assurance (QA) of kilovoltage (kV) radiotherapy treatments. Methods: A computed tomography (CT) scan of a canine glioma patient was segmented into bone and soft tissue using 3DSlicer. The segments were converted to stereolithographic (STL) files and smoothed in Fusion360. A slit to accommodate a radiochromic film (RCF) was added at the location of the glioma tumor. UPDOG was 3D printed on a polyjet printer using VeroUltraWhite ($\rho$ = 1.19-1.20 g/cm\textsuperscript{3}) for the bone and Agilus30 ($\rho$ = 1.14-1.15 g/cm\textsuperscript{3}) for the soft tissue. CT scans of UPDOG were acquired on a clinical CT scanner. An LD-V1 RCF was inserted into UPDOG and irradiated with a kV x-ray source from two angles. The delivered dose to the RCF was compared to Monte Carlo (MC) simulations performed in TOPAS. Results: The bone and soft tissue segments in UPDOG were mimicked the patient anatomy well with tube voltage-dependent CT numbers. The contrast in HU was of 49, 47 and 50 HU for the 80, 100, and 120 kVp scans, respectively, sufficient for anatomy visualization. The irradiations delivered a maximum dose to RCF of 284 mGy which was compared to the results of MC simulations using a depth dose curve and central-axis (CAX) beam profiles. The mean difference in CAX profiles and PDD between RCF and MC results was 15.9\% and 2.3\%, respectively. Conclusions: We have demonstrated that UPDOG is a useful QA tool for kV canine radiotherapy. UPDOG successfully anatomically mimicked the dog anatomy, with a reduced but sufficient bone contrast. We showed that dose delivered to a canine glioma with kV x-rays can be successfully measured with an RCF positioned at the tumor location.