Impact of radiopacified bone cement on radiotherapy dose calculation

Abstract

Background and purpose: Radiopacifiers are introduced to bone cements to provide the appearance of bone in kilovoltage (kV) radiographic images. For higher energy megavoltage (MV) radiotherapy treatment beams, however, these radiopacifiers do not cause a bone-like perturbation of dose. This study therefore aimed to determine the impact of the barium-contrasted plastic-based cement materials on radiotherapy dose calculations. Materials and methods: The radiological properties of a physical sample of bone cement were characterised by computed tomography (CT) imaging and transmission measurements. Monte Carlo simulations of percentage depth-dose profiles were performed to determine the possible dose error for MV treatment beams. Dose differences were then investigated for clinical volumetric modulated radiotherapy treatment plans, with and without density overrides applied. Results: Differences of up to 7% were observed at the downstream interface of a 0.6 cm thick bone cement layer, compared to bone. Differences in planning target volume dose-volume metrics varied between −0.5% and 2.0%. Conclusion: Before planning radiotherapy treatments for patients who have undergone cranioplasty, every effort should be made to identify whether a radiopacified bone cement has been implanted. Density overrides should be applied to minimise dose calculation errors, whenever bone cement is used.

A novel hybrid design and modelling of a customised graded Ti-6Al-4V porous hip implant to reduce stress-shielding: An experimental and numerical analysis

“…The resin was consequently left for 24 h to solidify completely. In a clinical setting, cemented hip stems are fixed in position with bone cement with approximate density and Young’s modulus of 1.78 g/mL and 3.0 GPa respectively ( Crowe et al, 2020 ). However, since the cure time of bone cement is very rapid and gives us less time to fix the stem in the desired position, epoxy resin with a similar density (1.69 g/mL) and Young’s modulus (2.5 GPa) as bone cement was used to fix the stem inside the femoral bone.…”

“…However, since the cure time of bone cement is very rapid and gives us less time to fix the stem in the desired position, epoxy resin with a similar density (1.69 g/mL) and Young’s modulus (2.5 GPa) as bone cement was used to fix the stem inside the femoral bone. Both bone cement and the selected epoxy resin have a cured density which falls within the established range of human bone densities, 1.18 g/mL to 1.92 g/mL making them suitable for better force distribution from the stem onto the surrounding cortical bone ( Crowe et al, 2020 ). In all configurations ( Figures 3B–D ), the artificial bone was mounted according to ISO 7206–4:2010 standard.…”

Comparative Evaluation of Two Glass Polyalkenoate Cements: An In Vivo Pilot Study Using a Sheep Model

“…As can be seen in Figure 9a,b, both GPCA samples were visually more radiopaque than PMMA (Figure 9c). PMMA is not a radiopaque material, therefore radiopacifiers such as barium sulphate (BaSO 4 ) or zirconium dioxide (ZrO 2 ) are usually added in order to make the cement radiopaque [52]. These radiopacifiers are not part of the polymeric chain, whereas in GPC, ions such as Sr 2+ exist in the glass phase, which makes the GPC more radiopaque compared to PMMA [53].…”