Estimation of linear and mass attenuation coefficients of soy–lignin bonded Rhizophora spp. particleboard as a potential phantom material using caesium-137 and cobalt-60

In this study, linear and mass attenuation coefficients of fabricated particleboards intended for use as phantom material were estimated using ¹³⁷Cs and ⁶⁰Co radiation sources. Particleboards made of Rhizophora spp. wood trunk bonded with soy flour and lignin were fabricated at a target density of 1.0 g cm^?3, with and without gloss finish coating. Elemental composition of the particleboards was obtained by means of energy dispersive X-ray (EDX) spectroscopy. Experimental setups were simulated via the GATE Monte Carlo (MC) package, with particle histories of 1?×?10⁶–1?×?10⁷. Linear and mass attenuation coefficients obtained from measurements and GATE simulations were compared and discussed. The percentage differences between the measured and simulated linear and mass attenuation coefficients of the samples were reasonably small (2.05–4.88% for ¹³⁷Cs and 3.24–5.38% for ⁶⁰Co). It is shown that all the particleboards have the potential to be used as phantom materials as the attenuation coefficients measured were in good agreement with those of water (calculated with XCOM) and with those simulated with the GATE toolkit. The use of gloss finish coating also did not show any significant effect on the attenuation coefficient of the phantom material. Verification of experimental results via GATE simulations has been shown crucial in providing reliable data for energy transmission studies. Based on the results achieved in this study, it is concluded that the studied material—Rhizophora spp. wood trunk bonded with soy flour and lignin including gloss finish coating—can be used in radiation dosimetry studies.

     

Neutron Activated Samarium-153 Microparticles for Transarterial Radioembolization of Liver Tumour with Post-Procedure Imaging Capabilities

Introduction

Samarium-153 (¹⁵³Sm) styrene divinylbenzene microparticles were developed as a surrogate for Yttrium-90 (⁹⁰Y) microspheres in liver radioembolization therapy. Unlike the pure beta emitter ⁹⁰Y, ¹⁵³Sm possess both therapeutic beta and diagnostic gamma radiations, making it possible for post-procedure imaging following therapy.

Methods

The microparticles were prepared using commercially available cation exchange resin, Amberlite IR-120 H⁺ (620–830 μm), which were reduced to 20–40 μm via ball mill grinding and sieve separation. The microparticles were labelled with ¹⁵²Sm via ion exchange process with ¹⁵²SmCl₃, prior to neutron activation to produce radioactive ¹⁵³Sm through ¹⁵²Sm(n,γ)¹⁵³Sm reaction. Therapeutic activity of 3 GBq was referred based on the recommended activity used in ⁹⁰Y-microspheres therapy. The samples were irradiated in 1.494 x 10¹² n.cm^-2.s^-1 neutron flux for 6 h to achieve the nominal activity of 3.1 GBq.g^-1. Physicochemical characterisation of the microparticles, gamma spectrometry, and in vitro radiolabelling studies were carried out to study the performance and stability of the microparticles.

Results

Fourier Transform Infrared (FTIR) spectroscopy of the Amberlite IR-120 resins showed unaffected functional groups, following size reduction of the beads. However, as shown by the electron microscope, the microparticles were irregular in shape. The radioactivity achieved after 6 h neutron activation was 3.104 ± 0.029 GBq. The specific activity per microparticle was 53.855 ± 0.503 Bq. Gamma spectrometry and elemental analysis showed no radioactive impurities in the samples. Radiolabelling efficiencies of ¹⁵³Sm-Amberlite in distilled water and blood plasma over 48 h were excellent and higher than 95%.

Conclusion

The laboratory work revealed that the ¹⁵³Sm-Amberlite microparticles demonstrated superior characteristics for potential use in hepatic radioembolization.