Dosimetry Effects Due to the Presence of Fe Nanoparticles for Potential Combination of Hyperthermic Cancer Treatment with MRI-Based Image-Guided Radiotherapy.

Nanoparticles have proven to be biocompatible and suitable for many biomedical applications. Currently, hyperthermia cancer treatments based on Fe nanoparticle infusion excited by alternating magnetic fields are commonly used. In addition to this, MRI-based image-guided radiotherapy represents, nowadays, one of the most promising accurate radiotherapy modalities. Hence, assessing the feasibility of combining both techniques requires preliminary characterization of the corresponding dosimetry effects. The present work reports on a theoretical and numerical simulation feasibility study aimed at pointing out preliminary dosimetry issues. Spatial dose distributions incorporating magnetic nanoparticles in MRI-based image-guided radiotherapy have been obtained by Monte Carlo simulation approaches accounting for all relevant radiation interaction properties as well as charged particles coupling with strong external magnetic fields, which are representative of typical MRI-LINAC devices. Two main effects have been evidenced: local dose enhancement (up to 60% at local level) within the infused volume, and non-negligible changes in the dose distribution at the interfaces between different tissues, developing to over 70% for low-density anatomical cavities. Moreover, cellular uptakes up to 10% have been modeled by means of considering different Fe nanoparticle concentrations. A theoretical temperature-dependent model for the thermal enhancement ratio (TER) has been used to account for radiosensitization due to hyperthermia. The outcomes demonstrated the reliability of the Monte Carlo approach in accounting for strong magnetic fields and mass distributions from patient-specific anatomy CT scans to assess dose distributions in MRI-based image-guided radiotherapy combined with magnetic nanoparticles, while the hyperthermic radiosensitization provides further and synergic contributions.

Effectiveness of the frequency rhythmic electrical modulation system for the treatment of chronic and painful venous leg ulcers in older adults.

Frequency rhythmic electrical modulation system (FREMS) is an innovative type of transcutaneous electrotherapy used in a rehabilitation setting for the treatment of pain, especially in diabetic patients. In a randomized clinical trial, we tested the hypothesis that FREMS is effective in the treatment of chronic and painful venous leg ulcers in 20 older patients. Group A (10 patients) received FREMS and topical treatment, whereas group B (10 patients) received topical treatment alone. Over a period of 3 consecutive weeks, 15 treatment sessions were done for each group. Wound healing and tissue repair were evaluated with the Visitrack digital planimetry system and photos. Pain was evaluated using the Visual Analogic Scale (VAS). The measurements were done at baseline and after 5, 10, and 15 days of treatment, with follow-up measurements after 15 and 30 days from the last treatment session. Group A showed a statistically significant decrease in ulcer area during the treatment and follow-up. The VAS score showed a statistically significant decrease after 5 and 10 days of treatment. Group B showed a statistically decrease in ulcer area after 5, 10, and 15 days of treatment with a reduction of VAS score only at 15 days of follow-up. At the end of the treatment, the comparison of the change in ulcer area and the change in VAS score of each group showed a statistically significant difference between groups, suggesting the therapeutic and analgesic efficacy of FREMS in reducing pain and area of chronic venous leg ulcers in older adults. Further investigation is needed to determine its reproducibility in larger case series or randomized clinical trials with longer follow-up periods.