Nanoparticles, with their distinct properties that vary from their bulk material equivalent, continue to gain popularity for studies into multi-modal applications in medicine. This research introduces the use of thulium oxide nanoparticles for biological applications and characterizes the potential of this novel nanoparticle for image-guided radiotherapy of brain cancer. In this study, we investigate the structural characteristics of this nanoparticle, and reveal a significant dose enhancement towards radioresistant brain tumour cells in vitro that also underlies an improvement in the CT image contrast of brain tumours in vivo. The thulium oxide nanoparticles utilized in the investigations described in this article were measured to be 40-45 nm from x-ray diffraction and scanning electron microscopy data. In vitro investigations assessed the cell survival and DNA damage in 9 l gliosarcoma cells following irradiation with 150 kVp orthovoltage x-rays. Immediately after the 150 kVp irradiation (15 min) an increase in the number of γ-H2AX induced foci indicates the production of more double-strand DNA breaks. Following from the short time-frame irradiation outcomes, clonogenic cell survival assays confirmed long-term radio-sensitization, with the cell sensitivity increasing by a factor of 1.32 (measured at the 10% survival fraction) for the irradiated 9 l cells exposed to thulium nanoparticles. A simple CT experiment shows that our thulium nanoparticles suspended in water at concentrations >0.5 mg ml −1 (0.05-20 mg ml −1 investigated) are clearly observable against water. Extending the CT experiment to an in vivo investigation, cellular uptake of the nanoparticles was demonstrated through CT image enhancement of the cancer site in 9-to 10-week-old Fisher rats bearing 9 l gliosarcomas, 12 days after cell implantation. The 9 l cancer is clearly visible on the CT image after injecting 40 μg of nanoparticles (2 μl at 20 mg ml −1) directly to the cancer site (5.5 mm from the dura and 3.5 mm right laterally of the bregma, 5 mm depth). To our knowledge, this work demonstrates the first application of thulium nanoparticles in biology and medicine, for radiotherapy and image guidance purposes.

No abstract

Objectives: To develop a real-time dose-monitoring system to measure the patient's eye lens dose during neuro-interventional procedures. Methods: Radiation dose received at left outer canthus (LOC) and left eyelid (LE) were measured using Metal-Oxide-Semiconductor Field-Effect Transistor dosimeters on 35 patients who underwent diagnostic or cerebral embolization procedures. Results: The radiation dose received at the LOC region was significantly higher than the dose received by the LE. The maximum eye lens dose of 1492 mGy was measured at LOC region for an AVM case, followed by 907 mGy for an aneurysm case and 665 mGy for a diagnostic angiography procedure. Strong correlations (shown as R2) were observed between kerma-area-product and measured eye doses (LOC:0.78, LE: 0.68). Lateral and frontal air-kerma showed strong correlations with measured dose at LOC (AKL:0.93, AKF:0.78) and a weak correlation with measured dose at LE. A moderate correlation was observed between fluoroscopic time and dose measured at LE and LOC regions. Conclusions: The MO Skin dose-monitoring system represents a new tool enabling real-time monitoring of eye lens dose during neuro-interventional procedures. This system can provide interventionalists with information needed to adjust the clinical procedure to control the patient's dose. Key Points • Real-time patient dose monitoring helps interventionalists to monitor doses.• Strong correlation was observed between kerma-area-product and measured eye doses.• Radiation dose at left outer canthus was higher than at left eyelid

No abstract

Coronary angiography is a procedure used in the diagnosis and intervention of coronary heart disease. The procedure is often considered one of the highest dose diagnostic procedures in clinical use. Despite this, there is minimal use of dosimeters within angiographic catheterisation laboratories due to challenges resulting from their implementation. The aim of this study was to compare entrance dose delivery across locally commissioned c-arms to assess the need for real-time dosimetry solutions during angiographic procedures. The secondary aim of this study was to establish a calibration method for the MOSkin dosimeter that accurately produces entrance dose values from the clinically sampled beam qualities and energies. The MOSkin is a real-time dosimeter used to measure the skin dose delivered by external radiation beams. The suitability of the MOSkin for measurements in the angiographic catheterisation laboratory was assessed. Measurements were performed using a 30 × 30 × 30 cm(3) PMMA phantom positioned at the rotational isocenter of the c-arm gantry. The MOSkin calibration factor was established through comparison of the MOSkin response to EBT2 film response. Irradiation of the dosimeters was performed using several clinical beam qualities ranging in energy from 70 to 105 kVp. A total of four different interventional c-arm machines were surveyed and compared using the MOSkin dosimeter. The phantom was irradiated from a normal angle of incidence using clinically relevant protocols, field sizes and source to image detector distance values. The MOSkin was observed to be radiotranslucent to the c-arm beam in all clinical environments. The MOSkin response was reproducible to within 2 % of the average value across repeated measurements for each beam setting. There were large variations in entrance dose delivery to the phantom between the different c-arm machines with the highest observed cine-acquisition entrance dose rate measuring 326 % higher than the lowest measured cine-acquisition entrance dose rate and with the highest measured fluoroscopic entrance dose rate measuring 346 % higher than the lowest measured fluoroscopic entrance dose rate. This comparison of entrance dose delivery across local clinical c-arms demonstrated the disparity in entrance dose delivery across catheterisation laboratories and outlined a need for real-time dose monitoring systems for patients during angiographic procedures. Through use of our calibration method, an average MOSkin calibration of 7.37 mV/cGy was established. The calibration method allowed entrance dose to be measured across a range of beam energies and beam qualities without the input of the c-arm beam characteristics. This calibration factor was proven to reproduce entrance dose values to within 5 % value of the reference dosimeter's response, suggesting potential for further studies and utilisation of the dosimeter in this field.