Numerical simulation of radiotherapy beam interaction with soft tissues and PLA plastic for 3D printing of dosimetric phantoms

Introduction. In the development of new methods of radiotherapy, studies of the biological effects of sparsely (photons, electrons) and densely (protons, ions) ionizing radiation are relevant. Reproducibility is a challenge in preclinical studies. Dosimetric phantoms of laboratory animals are an effective tool for dose assessment, facilitating standardization of tests conducted under different conditions. existing phantoms often fail to address radiobiological issues like placing of biological samples or dosimetry detectors. A method for manufacturing dosimetric phantoms must be developed to accurately manufacturing products and modify their design in accordance with the task. Aim. This study develops a numerical model to simulate the interaction of photon, electron and proton therapeutic beams with 3D-printed PLA plastic samples and to determine the optimal 3D printing parameters for imitating soft tissues. Material and Methods. Fused filament fabrication proposed as effective means of creating such devices, given that the majority of polymers exhibit properties closely aligned with those of biological tissues, are employed in the manufacture of standard phantoms. A major advantage of 3D printing is the ability to make items with different specifications. Numerical simulation was employed to investigate the interaction of PLA plastic with an ionizing radiation used in radiotherapy. Results. the calculated depth dose distributions of different types of radiation in soft tissues and PLA plastic of varying densities were obtained. It was demonstrated that for adipose imitation using photons and electrons, it is necessary to utilise PLA plastic 3D-printed samples with a density of 0.91 g/cm³ (fill factor of 75 %); for muscle – 1.06 g/ cm³ (fill factor of 88 %). For proton and carbon ion, the density of PLA plastic samples for adipose imitation was determined to be 0.97 g/cm³ (fill factor of 80 %); for muscle – 1.11 g/cm³ (fill factor of 93 %). Conclusion. The study demonstrates that the interaction of PLA plastic with rarely and densely ionizing radiation may be differed. This is a crucial consideration when planning experiments using solid-state dosimetric phantoms.

1. Zhuikova L.D., Choinzonov E.L., Ananina O.A., Odintsova I.N. Oncological morbidity in the Siberian and Far Eastern federal districts. Siberian Oncology Journal. 2019; 18(6): 5–11. (in Russian). doi: 10.21294/1814-4861-2019-18-6-5-11.

2. Cancer care for the population of Russia in 2023. Ed. by A.D. Kaprin, V.V. Starinsky, A.O. Shakhzadova. Moscow, 2024. 262 p. (in Russian).

3. Koryakina E.V., Potetnya V.I., Troshina M.V., Efimova M.N., Baikuzina R.M., Koryakin S.N., Lychagin A.A., Pikalov V.A., Ulyanenko S.E. Comparison of biological efficiency of accelerated carbon ions and heavy recoil nuclei on Chinese hamster cells. Radiation and Risk. 2019; 28(3): 96–106. (in Russian).

4. Suckert T., Müller J., Beyreuther E., Azadegan B., Brüggemann A., Bütof R., Dietrich A., Gotz M., Haase R., Schürer M., Tillner F., von Neubeck C., Krause M., Lühr A. High-precision image-guided proton irradiation of mouse brain sub-volumes. Radiother Oncol. 2020; 146: 205–12. doi: 10.1016/j.radonc.2020.02.023.

5. Desrosiers M., DeWerd L., Deye J., Lindsay P., Murphy M.K., Mitch M., Macchiarini F., Stojadinovic S., Stone H. The Importance of Dosimetry Standardization in Radiobiology. J Res Natl Inst Stand Technol. 2013; 118: 403–18. doi: 10.6028/jres.118.021.

6. Esplen N., Therriault-Proulx F., Beaulieu L., Bazalova-Carter M. Preclinical dose verification using a 3D printed mouse phantom for radiobiology experiments. Med Phys. 2019; 46(11): 5294–303. doi: 10.1002/mp.13790.

7. Manmadhachary A., Malyala S.K., Alwala A.M. Medical applications of additive manufacturing. Proceedings of the International Conference on ISMAC in Computational Vision and Bio-Engineering. Springer International Publishing. 2019; 1643–53. doi: 10.1007/978-3-020-00665-5_152.

8. Tino R., Yeo A., Leary M., Brandt M., Kron T. A Systematic Review on 3D-Printed Imaging and Dosimetry Phantoms in Radiation Therapy. Technol Cancer Res Treat. 2019; 18. doi: 10.1177/1533033819870208.

9. Jusufbegović M., Pandžić A., Šehić A., Jašić R., Julardžija F., Vegar-Zubović S., Beganović A. Computed tomography tissue equivalence of 3D printing materials. Radiography (Lond). 2022; 28(3): 788–92. doi: 10.1016/j.radi.2022.02.008.

10. Okkalidis N. 3D printing methods for radiological anthropomorphic phantoms. Phys Med Biol. 2022; 67(15). doi: 10.1088/1361-6560/ac80e7.

11. Salmi M. Additive Manufacturing Processes in Medical Applications. Materials (Basel). 2021; 14(1): 191. doi: 10.3390/ma14010191.

12. Savi M., Andrade M.A.B., Potiens M.P.A. Commercial filament testing for use in 3D printed phantoms. Radiation Physics and Chemistry. 2020; 174(9). doi: 10.1016/j.radphyschem.2020.108906.

13. Cojocaru V., Frunzaverde D., Miclosina C.O., Marginean G. The Influence of the Process Parameters on the Mechanical Properties of PLA Specimens Produced by Fused Filament Fabrication-A Review. Polymers (Basel). 2022; 14(5): 886. doi: 10.3390/polym14050886.

14. Mille M.M., Griffin T.K., Maass-Moreno R., Lee C. Fabrication of a pediatric torso phantom with multiple tissues represented using a dual nozzle thermoplastic 3D printer. Journal of Applied Clinical Medical Physics. 2020; 21:(11): 226–36. doi: 10.1002/acm2.13064.

15. Auffray L., Gouge P.A., Hattali L. Design of experiment analysis on tensile properties of PLA samples produced by fused filament fabrication. The International. Journal of Advanced Manufacturing Technology. 2022; 118(3): 4123–37. doi: 10.1007/s00170-021-08216-7.

16. Larsson E., Ljungberg M., Strand S.E., Jönsson B.A. Monte Carlo calculations of absorbed doses in tumours using a modified MOBY mouse phantom for pre-clinical dosimetry studies. Acta Oncol. 2011; 50(6): 973–80. doi: 10.3109/0284186X.2011.582517.

17. Özseven A., Ümit K. Verification of Percentage Depth-Doses with Monte Carlo Simulation and Calculation of Mass Attenuation Coefficients for Various Patient Tissues in Radiation Therapy. Süleyman Demirel Üniversitesi Sağlık Bilimleri Dergisi. 2020; 11(2): 224–30. doi: 10.22312/sdusbed.705468.

18. Radiation Therapy Dosimetry: A Practical Handbook. Ed by A. Darafsheh. CRC Press. 2021. 504 p.

19. Geant 4 [Internet]. CERN, Geneva, c1998-2024 [cited 2024 Sep 1]. URL: https://geant4.web.cern.ch/.

20. Mettivier G., Guatelli S., Brown J., Incerti S. Advances in Geant4 application in Physics, Medicine and Biology frontiers. Phys Med. 2024; 124. doi: 10.1016/j.ejmp.2024.103371.

21. Ribon A., Apostolakis J., Dotti A., Folger G., Ivanchenko V., Kosov M., Uzhinsky V., Wright D.H. Status of GEANT4 hadronic physics for the simulation of LHC experiments at the start of LHC physics program. CERN-LCGAPP. 2010; 2.

22. Miloichikova I., Bulavskaya, A., Bushmina E., Dusaev R., Gargioni E., Gavrikov B, Grigorieva, A., Stuchebrov S. Development and verification of a Geant4 model of the electron beam mode in a clinical linear accelerator. Journal of Instrumentation. 2024; 19(7). doi: 10.1088/1748-0221/19/07/C07007.

23. DeWerd L.A., Kunugi K. Accurate Dosimetry for Radiobiology. Int J Radiat Oncol Biol Phys. 2021; 111(5): 75–81. doi: 10.1016/j.ijrobp.2021.09.002.

24. De Almeida C.E., Salata C. Absolute, reference, and relative dosimetry in radiotherapy. Dosimetry. IntechOpen. 2022. doi: 10.5772/intechopen.101806.

25. ICRP [Internet]. [cited 2024 Sep 10]. URL: https://www.icrp.org/index.asp.

26. National Institute of Standards and Technology [Internet]. ESTAR [cited 2024 Sep 10]. URL: https://physics.nist.gov/PhysRefData/Star/Text/ESTAR.html.

27. Khan F.M., Gibbons J.P. Khan’s the physics of radiation therapy. 5th ed. Lippincott Williams & Wilkins. 2014. 624 p.

28. Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose To Water. Vienna: International Atomic Energy Agency, 2024. doi: 10.61092/iaea.ve7q-y94k.