E0405 Medical Engineering

Medical engineering plays a key role in advancing radiotherapy, particularly through the development of phantoms - engineered models that simulate human tissues and organs. These phantoms enable medical physicists to verify the accuracy and safety of radiation treatments. As radiation devices become more sophisticated, phantoms need to keep pace by incorporating a variety of capabilities, such as imaging contrast and organ motion simulation. This is where our team becomes essential. In our lab, we focus on designing anthropomorphic phantoms that accurately replicate human anatomy and movements. These models help improve the precision of radiotherapy, enhancing treatment effectiveness and patient safety in increasingly complex clinical settings. Additionally, we are responsible for the development of collimators, patient immobilization aids and patient positioning devices. In collaboration with our in-house workshop and external partners, we transform concepts into 3D CAD models, detailed drawings, and ultimately, prototypes of medical devices.

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Carbon ion radiotherapy is an innovative radiation treatment that shows great promise for targeting challenging malignancies like pancreatic cancer. However, achieving consistent and precise dose delivery can be difficult due to the motion of organs. To address this, we developed the Pancreas Phantom for Ion-beam Therapy (PPIeT), an anthropomorphic phantom designed to replicate breathing and gastrointestinal motion during radiotherapy. PPIeT includes a pancreas, two kidneys, a duodenum, a spine, and a spinal cord, all 3D-printed and filled with agarose-based mixture to achieve the anthropomorphic form and accurate imaging contrast in the CT and the MRI. PPIeT replicates breathing-induced organ motion and can mimic gastrointestinal motion. To test the motion effect during radiotherapy, we calculated a patient-like treatment plan for carbon ion therapy and conducted irradiations under both static and moving conditions. Dose measurements were performed using an ionization chamber and dosimetric films to quantify dose deviations in the different organs for pancreatic cancer treatment during carbon ion.

Related publications:

• Stengl, C., Panow, K., Arbes, E., Muñoz, I. D., Christensen, J. B., Neelsen, C., Dinkel, F., Weidner, A., Runz, A., Johnen, W., Liermann, J., Echner, G., Vedelago, J., & Jäkel, O. (2023). A phantom to simulate organ motion and its effect on dose distribution in carbon ion therapy for pancreatic cancer. Physics in medicine and biology, 68(24), 10.1088/1361-6560/ad0902.
• Stengl, C., Muñoz, I. D., Arbes, E., Rauth, E., Christensen, J. B., Vedelago, J., Runz, A., Jäkel, O., & Seco, J. (2024). Dosimetric study for breathing-induced motion effects in an abdominal pancreas phantom for carbon ion mini-beam radiotherapy. Medical physics, 51(8), 5618–5631. https://doi.org/10.1002/mp.17077.
• Weidner, A., Stengl, C., Dinkel, F., Dorsch, S., Murillo, C., Seeber, S., Gnirs, R., Runz, A., Echner, G., Karger, C. P., & Jäkel, O. (2022). An abdominal phantom with anthropomorphic organ motion and multimodal imaging contrast for MR-guided radiotherapy. Physics in medicine and biology, 67(4), 10.1088/1361-6560/ac4ef8.

Radiotherapy is one of the most prescribed tumor treatments, using high doses of ionizing irradiation to achieve tumor control and preserve healthy tissue from damage. As there may be significant differences between patient's morphology at the treatment day compared to the day of the planning we designed a new principle to acquire daily MR images for any final treatment position to enable irradiation without a gantry. Therefore, within the ARTEMIS Project (funded by the Federal Ministry of Education and Research (FMER), grant no. 13GW0436B) a patient fixation and rotation system was developed and tested for CT and MR scanners, as well as on the treatment table of a light ion beam treatment facility.

This patient immobilization and rotation system was designed and tested to enable MR and CT imaging directly before irradiation to adapt the treatment plan according to the daily tumor and organs at risk position and shape. Additionally, this setup enables radiation treatment from different angles even at a fixed horizontal beam-line, as the capsule can be rotated axially on the treatment table. Thereby, the need for an expensive gantry for irradiation might become obsolete. This may allow for much cheaper installation of treatment facilities with high quality image guidance.

After receiving the CE labelling, we will finally test the system with patients in the near future also in a CT environment. In the long term, the system may also be used for a low-cost MR-Linac solution.

Related Publications:

• Echner G, Dinkel F, Beyer C, Jäkel O. PO-1913 Development and test of a patient immobilization and rotation device for imaging and radiotherapy. Radiotherapy and Oncology. 2023;182:S1663-S4. DOI: 10.1016/S0167-8140(23)66828-8
• Dietrich KA, Klüter S, Dinkel F, Echner G, Brons S, Orzada S, Debus J, Ladd ME, Platt T. An essentially radiation-transparent body coil integrated with a patient rotation system for MR-guided particle therapy. Med Phys. 2024 Jun;51(6):4028-4043. doi: 10.1002/mp.17065.

Respiratory motion can cause target displacement, resulting in imaging artifacts and incomplete dose coverage. Advanced 4D radiotherapy using IGRT and SGRT addresses this issue, requiring a phantom for end-to-end testing to validate each step of the workflow, including imaging, dose delivery, and hardware/software components. The Breathing Radiotherapy Visual monitoring, Imaging and Dosimetric Anthropomorphic Phantom (BRaVIDA), a multifunctional phantom, simulates internal and external respiratory motion for comprehensive testing in RT. It mimics predefined respiratory motion patterns in the abdominal and thoracic regions, with organs that have CT Hounsfield units and MRI T1/T2 relaxation times comparable to human tissues.

Related Publication:

• Bakhtiari Moghaddam A, Runz A, Häring P, Seeber S, Möller M, Echner G. PO-2314 Development of an anthropomorphic 4D phantom for multimodal imaging, 4D radiation, and SGRT. Radiotherapy and Oncology. 2023;182

• Elter A, Dorsch S, Thomas S, Hentschke CM, Floca RO, Runz A, Karger CP, Mann P. PAGAT gel dosimetry for everyone: gel production, measurement and evaluation. Biomed Phys Eng Express. 2021 Jul 20;7(5). DOI: 10.1088/2057-1976/ac12a5
• Niebuhr NI, Johnen W, Echner G, Runz A, Bach M, Stoll M, Giske K, Greilich S, Pfaffenberger A. The ADAM-pelvis phantom-an anthropomorphic, deformable and multimodal phantom for MRgRT. Phys Med Biol. 2019 Feb 11;64(4):04NT05. DOI: 10.1088/1361-6560/aafd5f
• Gillmann C, Homolka N, Johnen W, Runz A, Echner G, Pfaffenberger A, Mann P, Schneider V, Hoffmann A, Troost E, Koerber S, Kotzerke J, Beuthien-Baumann. Technical Note: ADAM PETer – An anthropomorphic, deformable and multimodality pelvis phantom with positron emission tomography extension for radiotherapy. Med Phys. 2020. https://doi.org/10.1002/mp.14597
• Bayer V, Vedelago J, Dorsch S, Beyer C, Brons S, Johnen W, Biegger P, Weber U, Runz A, Karger C P. Carbon ion mono-energetic and spread-out Bragg peak measurements using nanocomposite Fricke gel dosimeters with LET-independent response. Rad Meas. 2024. 176, 107175. https://doi.org/10.1016/j.radmeas.2024.107175.

Armin Runz

Phone: +49 (0)6221/42-2589

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