A. Chaikh et al.: Radioprotection 2025, 60( 1), 50 – 56 55
ence remains small( less than 1 %) and confirms that the use of resin-based printing helps to minimize air gaps between layers unlike filament-based methods.
In this study, the dosimetric equivalence of the resin used for printing the bellies was measured and assessed by evaluating linear attenuation. However, these results should be used with a caution: i) the undefined proportion of resin chemical composition, using CHONS analyzer, was attributed to oxygen( 0,37 %); ii) the experimental conditions for evaluating the attenuation coefficient have some limitations, as described after.
The beam used for the attenuation coefficient evaluation thought measurement is polyenergetic, and its initial spectrum at the accelerator output is not considered. The average energy of a spectrum changes with the traversed thickness due to a variable probability of interaction of photons depending on their energy. Moreover, the use of a beam( 3 3cm 2) for the measurements produces scattered radiation contributing to the evolution of the spectrum.
The experimental setup assumes that the beam energy is constant regardless of the traversed thickness of RW3 or resin plates. This assumption explains why the evaluated attenuation coefficients are not constant with the traversed thickness. Nevertheless, it should be noted that from approximately 6 cm thickness, the coefficient tends to vary very little with the traversed thickness.
To account for the above limitations in the experimental method, the measured linear attenuation coefficient was compared, under the same conditions, to RW3 taken as reference water equivalent material.
The calculated and measured linear attenuation coefficient for the Verowhite resin agree within 12-15 % with water or RW3 plates depending on the approach, with the VeroWhite resin attenuating more than water or equivalent water for radiotherapy energies.
Given the dimensions of the printed bellies, the maximum thickness of resin traversed by the radiation is 10 cm. If the 15 % obtained deviation on the attenuation coefficient is applied to the traversed distance, it is like the radiation were passing through 11.5 cm instead of 10 cm. This deviation is deemed acceptable within the scope of our study. Indeed, the bellies were designed to represent the different trimesters, but only 3 specific months of pregnancy were modeled, leading to approximate dimensions for these trimesters. Furthermore, the phantom will be used in the context of a comparative parametric study to evaluate the effects of irradiation parameters on fetal dose, with the goal of providing practical recommendations for managing pregnant women in radiotherapy.
5 Conclusion
In this study, physically realistic bellies representing different trimesters of pregnancy were modeled and then printed using a 3D Printer( Stratasys) and Verowhite resin. To date, this is the first study to characterize the VeroWhite resin for clinical use in radiotherapy. The measured density agrees with the manufacturer’ s specifications within 1 %. The calculated and measured linear attenuation coefficients for VeroWhite agree within 12-15 % with those of water or RW3 plates, within the range of radiotherapy beams. The printed models will be used to assess the impact of irradiation parameters on fetal dose in radiotherapy.
Acknowledgments
The authors have nothing to report. The authors would like to thank the gynecologist for the contributions to this manuscript.
Funding
The authors received no financial support for the research.
Conflicts of interest
The authors declare that they have no conflict of interest.
Data availability statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Author contribution statement
A. Chaikh: methodology, measurements and writing original draft. A. Chaabane: methodology, 3D modeling and printing and measurements. C. Jardin and S. Bassot: assessment of chemical composition and the physical density. T. Beaumont: methodology and workflow. M. Chea, M. Khalal, C. Jenny: methodology and CT acquisition. S. Thomas, C. Huet: methodology, measurements and analysis. A. Isambert, M. Edouard: supervision and writing original draft. All authors contributed to review and editing of the manuscript.
Informed consent
This article does not contain any studies involving human subjects.
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