Intracavitary moderator balloon combined with (252)Cf brachytherapy and boron neutron capture therapy, improving dosimetry in brain tumour and infiltrations

A simulation study on using 252Cf for the treatment of esophagus tumor in human phantom

Due to the sensitivity of this tissue, and the potential for metastasis of its cancer as well, finding accurate methods to be employed for the treatment of esophagus tumors is of especial interest for the researchers. The present study deals with a Monte Carlo simulation of ²⁵²Cf neutron brachytherapy for treating these tumors using MCNPX (Version 2.6.0) code. The widely accepted AAPM TG-43 protocol has been used to benchmark the simulated source and to examine the accuracy of the modeling. The MIRD human phantom has been used for dose evaluation in the mentioned tumor and in the surrounding normal tissues as well. To decrease the dose delivered to the healthy tissue, using appropriate shields has been proposed. Through dosimetric calculations for several candidates, Pt-Ir 10% with a thickness of 1 cm has been selected as the optimized shield. The depth-dose results as well as the isodose curves corresponding to the presence of the shielded ²⁵²Cf neutron source in the center of the simulated tumor offer this source as an appropriate candidate to be used for the treatment of the esophagus tumors and sparing normal tissues. For a suggested clinical condition of positioning the source inside the esophagus, the damage to the first depth in spine can be avoided by managing the treatment time.

Glucose-holmium for radiotherapy: Characterization and in vitro assays

BACKGROUND

The existence of saccharide-holmium complexes, containing mono or polysaccharide molecules, is an attractive hypothesis toward a radiation therapy (RT) with beta-emitters targeting high glucose metabolic human sites. To exam such hypothesis, the aim of this study was to investigate the possible chemical interactions of Ho and glucose molecules and if glucose may be a facilitator to holmium cell internalization based on in vitro uptake assays and mass spectrometry analyses.

METHODS

The ionic-solution preparations were based on glucose-anhydrous and holmium-nitrate hydrated in aqueous solution, in non-radioactive condition. The uptakes in MDAMB231 cell lineage were evaluated, at 0 and 50 µg mL^-1 holmium solution, in incubation times of 10, 30 and 50 min. The measurements of the holmium mass into the dried cell were evaluated by Neutron Activation Analysis - NAA method. Also, the ionic solution was tested in Electrospray Ionization Mass Spectrometry (ESI-MS) in order to identify Ho and glucose interactions.

RESULTS

There were intracellular holmium-uptake in MDAMB-231 of 3.6 ± 0.1, 6.8 ± 0.2 and 9.7 ± 0.3 μg increasing linearly with incubation time. The m/z ions at 523, 586, 649, 991 and 1054 were attributed to the positively loaded species containing Ho⁺³, glucose (GLU) and NO₃^-, making up the possible molecular compound formulae, involving Ho, GLU, and anions.

CONCLUSIONS

The findings of the in vitro assay and the ESI-MS suggested a suitable holmium cell uptake, increased in function of incubation time, due to the presence of glucose and holmium chemical interactions in solution.