A novel anthropomorphic multimodality phantom for MRI-based radiotherapy quality assurance testing

No prior work had resolved the challenge of creating a single device that mimics human tissue properties across both magnetic resonance imaging and computed tomography modalities. This gap motivated the development of specialized tools to support modern radiation therapy workflows. Prior research has shown that relying on magnetic resonance imaging alone for treatment planning requires rigorous validation against established clinical standards. That uncertainty drove the need for physical models that accurately replicate human anatomy. It was already known that traditional phantoms often fail to provide consistent contrast across different imaging platforms. This limitation hinders the transition toward magnetic resonance-only treatment simulation protocols. Researchers recognized that synthetic computed tomography generation requires precise physical validation to ensure patient safety. No prior work had resolved the integration of tissue-equivalent materials into complex, three-dimensional printed pelvic structures for this specific purpose.

The aim of this work is to develop and demonstrate the clinical utility of a three-dimensional printed anthropomorphic pelvic model for quality assurance testing. This study addresses the growing requirement for phantoms that provide consistent tissue contrast across multiple imaging modalities. The researchers seek to bridge the gap between magnetic resonance imaging-based processes and established computed tomography clinical standards. This investigation focuses on creating materials that accurately match the relaxation times and electron densities of human soft tissues and bone. The authors intend to validate an end-to-end treatment simulation workflow using this newly designed physical model. By comparing synthetic computed tomography images with standard scans, the team evaluates the precision of dose calculations for prostate radiation therapy plans. This effort aims to provide a reliable tool for clinical physicists to verify the accuracy of magnetic resonance-only treatment planning. The study ultimately seeks to facilitate the safe adoption of advanced imaging protocols in radiation oncology.

Review approach involved designing an anthropomorphic pelvic model based on a male anatomical template. The team utilized three-dimensional printing to fabricate the complex internal structure of the device. Review approach included filling tissue compartments with carrageenan-based substances to replicate specific relaxation times and electron densities. The investigators acquired both magnetic resonance and computed tomography images to verify the physical properties of these materials. Review approach required performing end-to-end testing of a treatment simulation workflow using synthetic computed tomography generation algorithms. The researchers delivered prostate radiation plans, specifically volumetric-modulated arc therapy and intensity-modulated radiation therapy, to the phantom. Review approach incorporated film dosimetry and ion chamber measurements to evaluate the accuracy of the delivered radiation dose. The team compared these experimental results against standard computed tomography-based planning data to assess performance.

Key findings from the literature demonstrate that the measured relaxation times and electron densities for muscle, prostate, and bone match reported in vivo values. Key findings from the literature show that film analysis achieved a 99.7% gamma pass rate for both intensity-modulated radiation therapy and volumetric-modulated arc therapy plans. Key findings from the literature reveal that ion chamber-measured dose discrepancies at the isocenter were 0.36% for intensity-modulated radiation therapy. Key findings from the literature indicate that the volumetric-modulated arc therapy plan exhibited a 1.67% dose discrepancy at the isocenter. Key findings from the literature establish that differences in dose volume histogram metrics between standard and synthetic computed tomography plans remained under 3%. Key findings from the literature highlight the consistency of the phantom across both 1.5 Tesla and 3.0 Tesla magnetic resonance imaging systems. Key findings from the literature confirm that the device provides tissue-like contrast suitable for rigorous quality assurance testing. Key findings from the literature suggest that the phantom successfully validates the entire treatment planning workflow from image acquisition to dose delivery.

Synthesis and implications indicate that this novel pelvic model successfully replicates human tissue characteristics for both magnetic resonance and computed tomography imaging. The authors suggest that the device serves as a reliable tool for validating synthetic computed tomography generation workflows. Synthesis and implications show that dosimetric measurements obtained from the model align closely with standard clinical expectations. The researchers propose that this phantom facilitates the transition toward magnetic resonance-only treatment planning by providing a robust testing platform. Synthesis and implications highlight that the observed dose discrepancies remain within acceptable clinical tolerances for prostate radiation therapy. The authors conclude that the model effectively bridges the gap between magnetic resonance imaging and computed tomography-based quality assurance protocols. Synthesis and implications suggest that the integration of tissue-equivalent materials enables accurate end-to-end testing of complex treatment delivery systems. The researchers propose that this technology supports the broader adoption of magnetic resonance-only radiotherapy simulation in clinical practice.