[Realization and Clinical Study of Robotic Technology in Cardiovascular Interventional Surgery].

The high incidence of cardiovascular diseases is a serious threat to human health, and endovascular surgery has become the standard treatment for most interventional cardiovascular diseases. The robotassisted endovascular surgery system further enhances surgeons' ability to perform minimally invasive endovascular procedures in interventional cardiology. This study presents a new robotic technique for coronary intervention from the perspective of clinical application. Aiming at clinical application scenarios, this scheme proposed an intuitive guide wire catheter mechanism design, which accurately and perfectly simulates the doctor's hand movements, realizes the positive and negative direction translation of the guide wire catheter, accurate torque control of the guide wire rotation and locking. The results of animal test showed that the R-OneTM has a high degree of dexterity, accuracy and stability,and meets the clinical needs.

Quantifying tumor-selective radiation dose enhancements using gold nanoparticles: a monte carlo simulation study.

Gold nanoparticles can enhance the biological effective dose of radiation delivered to tumors, but few data exist to quantify this effect. The purpose of this project was to build a Monte Carlo simulation model to study the degree of dose enhancement achievable with gold nanoparticles. A Monte Carlo simulation model was first built using Geant4 code. An Ir-192 brachytherapy source in a water phantom was simulated and the calculation model was first validated against previously published data. We then introduced up to 10(13) gold nanospheres per cm(3) into the water phantom and examined their dose enhancement effect. We compared this enhancement against a gold-water mixture model that has been previously used to attempt to quantify nanoparticle dose enhancement. In our benchmark test, dose-rate constant, radial dose function, and two-dimensional anisotropy function calculated with our model were within 2% of those reported previously. Using our simulation model we found that the radiation dose was enhanced up to 60% with 10(13) gold nanospheres per cm(3) (9.6% by weight) in a water phantom selectively around the nanospheres. The comparison study indicated that our model more accurately calculated the dose enhancement effect and that previous methodologies overestimated the dose enhancement up to 16%. Monte Carlo calculations demonstrate that biologically-relevant radiation dose enhancement can be achieved with the use of gold nanospheres. Selective tumor labeling with gold nanospheres may be a strategy for clinically enhancing radiation effects.

Investigation into the use of a MOSFET dosimeter as an implantable fiducial marker.

It may be possible to use a single device to measure the in vivo dose delivered during radiotherapy, as well as to localize the target volume. This potential, as well as the detectors' ability to relate dosimetry and localization, were evaluated using two implantable MOSFET dosimeters placed inside an acrylic pelvic phantom. A wedged-field photon plan and an eight-field prostate treatment plan were developed. For each plan, conditions were simulated so that detectors were in their correct positions or slightly displaced to represent patient setup error and/or organ motion. Doses measured by the two detectors after irradiation were compared to those calculated by the treatment planning software. Additionally, using localization software and kilovoltage images of each setup, the displacement of the detectors from their correct locations was calculated and compared to the induced physical displacement. For all alignments and detector positions, measured and calculated doses showed an average disagreement of 2.7%. The detectors were easily visualized radiographically and the induced detector displacements were typically recognized by the localization software to within 0.1 cm. The implantable detector functioned well as both an internal dosimeter and as an internal fiducial marker, and thus may be useful as a clinical tool to localize the target volume and verify dose delivery in vivo.

Reduction of miR-29a-3p induced cardiac ischemia reperfusion injury in mice via targeting Bax.

The current study mainly aimed to evaluate the expression and the potential mechanism of miR-29a-3p in the hearts of mice after cardiac ischemia reperfusion (CIR) injury. Quantitative PCR was carried out to assess the relative levels of miR-29a-3p in the hearts of a CIR injury mouse model. To the best of our knowledge, the current study is the first to show that the level of miR-29a-3p was significantly decreased in the hearts of CIR injury mouse models compared with that of sham controls. Moreover, the authors found that decreased miR-29a-3p levels enhanced the production of reactive oxygen species in cardiomyocytes. Meanwhile, the inhibition of miR-29a-3p induced substantial cardiomyocyte apoptosis. Further study showed that the inhibition of miR-29a-3p decreased the activation of Akt and p38, suggesting a stress-induced self-regulatory mechanism after CIR injury in primary cardiomyocytes. A dual luciferase assay and western blot analysis showed that Bax was a target gene of miR-29a-3p. The authors also measured the level of miR-29a-3p in the plasma of 100 acute myocardial infarction (AMI) patients and found that circulating miR-29a-3p was significantly decreased in AMI patients. Receiver operating characteristic curve analysis showed that miR-29a-3p could be used to screen AMI patients from healthy controls. Hence, the authors of the current study propose that reduced miR-29a-3p levels in primary cardiomyocytes contribute to CIR injury-related apoptosis mainly by targeting Bax.

Calculation of effective dose from measurements of secondary neutron spectra and scattered photon dose from dynamic MLC IMRT for 6 MV, 15 MV, and 18 MV beam energies.

Effective doses were calculated from the delivery of 6 MV, 15 MV, and 18 MV conventional and intensity-modulated radiation therapy (IMRT) prostate treatment plans. ICRP-60 tissue weighting factors were used for the calculations. Photon doses were measured in phantom for all beam energies. Neutron spectra were measured for 15 MV and 18 MV and ICRP-74 quality conversion factors used to calculate ambient dose equivalents. The ambient dose equivalents were corrected for each tissue using neutron depth dose data from the literature. The depth corrected neutron doses were then used as a measure of the neutron component of the ICRP protection quantity, organ equivalent dose. IMRT resulted in an increased photon dose to many organs. However, the IMRT treatments resulted in an overall decrease in effective dose compared to conventional radiotherapy. This decrease correlates to the ability of an intensity-modulated field to minimize dose to critical normal structures in close proximity to the treatment volume. In a comparison of the three beam energies used for the IMRT treatments, 6 MV resulted in the lowest effective dose, while 18 MV resulted in the highest effective dose. This is attributed to the large neutron contribution for 18 MV compared to no neutron contribution for 6 MV.

Determination of dosimetric characteristics of OptiSeed(TM) a plastic brachytherapy (103)Pd source.

A new (103)Pd plastic brachytherapy source, OptiSeed(TM) Model 1032P, is being introduced by International Brachytherapy sa (IBt). Measurements of the dose distributions about the source were performed using LiF thermoluminescent dosimeters (TLD-100) in Virtual Water(TM). MCNP5 calculations were performed to determine the dose distributions in Virtual Water(TM) and liquid water. The source dose rate constant, radial dose function, anisotropy function and anisotropy factor have been determined following the updated AAPM TG-43 recommendations. The measured dose rate constant in the Virtual Water(TM) phantom was determined to be 0.727+/-6.9% cGyh(-1)U(-1), and the computed value is 0.716+/-2.1% cGyh(-1)U(-1). The Monte-Carlo simulation yielded a dose rate constant of 0.665+/-2.1% cGyh(-1)U(-1) in water. The measured dose rate constant in water is 0.675+/-7.5% cGyh(-1)U(-1). It is determined by multiplying the dose rate constant measured in the Virtual Water(TM) phantom with the ratio of the value calculated in water to that in Virtual Water(TM). The average of the measured and calculated dose rate constant is 0.670+/-5.5% cGyh(-1)U(-1). The radial dose functions of the new source were measured for distances ranging from 1 to 7 cm in a Virtual Water(TM) phantom. The anisotropy functions in Virtual Water(TM) phantom were measured for distances of 2, 3, 5, and 7 cm. The Monte-Carlo computed radial dose functions, anisotropy functions, and anisotropy factors in both Virtual Water(TM) phantom and water are reported.

Calibration of indium response functions in an Au-In-BSE system up to 800 MeV.

Calibration of the response functions of a gold (Au)-indium (In) dual foil Bonner sphere extended (BSE) system was described. The response of the In and Au foil of the system was calculated using MCNPX code with different activation cross-sectional libraries: (ACTL and ENDF VI for gold and ACTL and 532DOS2 for In). To verify and correct the calculated response functions the Bonner sphere set (BSS) was irradiated using (252)Cf and (241)AmBe sources of known neutron strengths for neutrons ranging from thermal to 20 MeV, and was irradiated at the 800-MeV neutron beam of the Los Alamos Neutron Science Center. The neutron spectrum of the 800 MeV beam was determined using time-of-flight (TOF) technique. We observed that the uncertainty of activation cross section in the resonance region can result in great uncertainty in the MCNPX-calculated response functions of activation foil-based BSS. The MCNPX-calculated response functions must be corrected using neutron sources of known spectrum and strength.