Custom-made 3D-printed X-ray shield for tumor-specific irradiation of xenograft mice.

Background: Xenograft mouse models play an important role in preclinical cancer research, particularly in the development of new therapeutics. To test the efficacy of a combination therapy consisting of radiation and new drug candidates, it is crucial that only the tumor area is irradiated, while other parts of the body are shielded. In this study, a 3D-printed radiopaque back shield was designed for tumor-specific irradiation and evaluated in a xenograft mouse model.

Methods: Different radiopaque materials were initially tested for their shielding properties using the Multirad 225 X-ray irradiator and the most suitable material was used for printing a back shield with a tumor site-specific opening of the cover. Tumor bearing mice were irradiated four times with a dose of 3.5 Gy. To evaluate proper body shielding, blood samples, spleens and bone marrow were examined at the end of the experiment.

Results: A tungsten filament was identified to be most efficient for shielding and used to 3D print a pie-slice-shaped back shield with a tumor-site specific opening, while polylactic acid was used to print a scaffold that ensured proper positioning of the shield. The simple design allowed cost-efficient and fast 3D printing, easy handling and individual modifications of the tumor site openings. In terms of animal safety, the product provided sufficient shielding in the low-dose irradiation protocols of xenograft mice.

Conclusion: The custom-designed 3D-printed tungsten back shields provide proper shielding of the animals body and allow for subcutaneous tumor irradiation under standardized conditions.