A single ascending dose study of single-stranded oligodeoxyribonucleotide RO7062931 in Chinese healthy volunteers.

RO7062931 is an N-acetylgalactosamine (GalNAc)-conjugated single-stranded oligodeoxyribonucleotide complementary to hepatitis B virus RNA. GalNAc conjugation targets the liver through the asialoglycoprotein receptor (ASGPR). This phase I single ascending dose (SAD) study evaluated the safety, tolerability, and pharmacokinetics of RO7062931 in Chinese healthy volunteers.

Adrenomedullin and diabetes.

Adrenomedullin (ADM) is a peptide hormone widely expressed in different tissues, especially in the vasculature. Apart from its vasodilatatory and hypotensive effect, it plays multiple roles in the regulation of hormonal secretion, glucose metabolism and inflammatory response. ADM regulates insulin balance and may participate in the development of diabetes.

Identifying patients with resistant hypertension and options for clinical management.

In addition to the increasing prevalence of hypertension, the number of patients with treatment-resistant hypertension is also rising. It is important to identify these patients in order to improve the treatment outcomes and to screen for potential secondary causes. Clinical characteristics of patients with resistant hypertension include advanced age, male gender, obesity, high salt intake and alcohol consumption.

Measuring solar UV radiation with EBT radiochromic film.

Ultraviolet radiation dosimetry has been performed with the use of a radiochromic film dosimeter called Gafchromic EBT for solar radiation exposure. The film changes from a clear colour to blue colour when exposed to ultraviolet radiation and results have shown that the colour change is reproducible within ±10% at 5 kJ m(-2) UV exposure under various conditions of solar radiation. Parameters tested included changes in season (summer versus winter exposure), time of day, as well as sky conditions such as cloudy skies versus clear skies.

Scanning orientation and polarization effects for XRQA radiochromic film.

Gafchromic XRQA radiochromic film, is an effective tool for quality assurance and dose assessment in kilovoltage radiotherapy and diagnostic applications. Like other Gafchromic film products, XRQA film exhibits a variation in dose to reflected optical density response with angle of rotation when analysed with a light source that is partially or fully polarised such as a desktop scanner. Although warnings are not given on manufacturers specifications, this can affect dosimetry accuracy and we recommend that it is essential to scan all XRQA films in the same orientation.

Measurement of dose reductions for superficial x-rays backscattered from bone interfaces.

Accurate measurement and knowledge of dose delivered during superficial x-ray radiotherapy is required for patient dose assessment. Some tumours treated near the surface (within the first few centimetres) can have large posterior bone structures. This can cause perturbations to dose delivered due to changed backscatter contributions from the bony structure as compared to full water or tissue scattering conditions.

Solid water phantom heat conduction: Heating and cooling rates.

Solid water is often the phantom material of choice for dosimetry procedures in radiotherapy high-energy X-ray and electron beam radiation calibration and quality assurance. This note investigates variation in heat conduction that can occur for a common commercially available solid water stack phantom when a temperature differential occurs between the phantom and ambient temperature. These variations in temperature can then affect radiation measurements and thus the accuracy of radiation dosimetry.

Measurement of radiotherapy superficial X-ray dose under eye shields with radiochromic film.

Accurate measurement and knowledge of dose delivered under eye shield during superficial X-ray radiotherapy is required for patient peripheral dose assessment. Critical structures can include the cornea, lens and retina. Measurement of dose under eye shields has been historically performed with Thermoluminescent Dosimeters (TLD's) due to their small size and design.

Megavoltage x-ray skin dose variation with an angle using grid carbon fibre couch tops.

It is well known that a skin dose from high-energy x-ray radiation varies with the angle of beam incidence or the presence of a radiotherapy linear accelerator couch top material. This note investigates changes produced to the skin dose from a Varian carbon fibre grid couch top at differing angles of incidence for 6 MV x-rays as is often the case clinically. Results have shown that the skin dose can easily be measured using an EBT Gafchromic film whereby the delivered skin dose can be quantified to a high level of spatial resolution, not easily achieved with other skin dose detectors.

X-Ray energy dependence of the dose response of SIRAD radiation dosimeters.

SIRADs (self-indicating instant radiation alert dosimeters) are designed to measure accident radiation doses. As the energy of radiation is usually unknown in such situations, a detector with a weak energy dependence of its response to dose would be ideal. We have studied the energy dependence of the dose response of SIRADs in the range from 50kVp to 10MV, which corresponds to photon equivalent energies from 25.

Visible absorption spectra of radiation exposed SIRAD dosimeters.

SIRAD badge dosimeters are a new type of personal dosimeter designed to measure radiation exposure up to 200 R and give a visual qualitative measurement of exposure. This is performed using the active dosimeter window, which contains a radiochromic material amalgamated in the badge assembly. When irradiated, the badges active window turns blue, which can be matched against the given colour chart for a qualitative assessment of the exposure received.

A practical method for determining organ dose during CT examination.

A practical method, based on depth dose, for determining organ dose during computed tomography (CT) examination is presented. For 4-slice spiral CT scans, performed at radii of 0, 37.5, 75.

Measurement of energy dependence for XRCT radiochromic film.

Gafchromic XRCT, radiochromic film is assessed over a broad energy range, from kilovoltage to megavoltage x rays for variations in reflected optical density to dose response. A large energy dependence was found with reflected optical density output for the same delivered dose varying from 7.8 +/- 0.

Measurement of high energy x-ray beam penumbra with Gafchromic EBT radiochromic film.

High energy x-ray beam penumbra are measured using Gafchromic EBT film. Gafchromic EBT, due to its limited energy dependence and high spatial resolution provide a high level of accuracy for dose assessment in penumbral regions. The spatial resolution of film detector systems is normally limited by the scanning resolution of the densitometer.

Independence of calibration curves for EBT Gafchromic films of the size of high-energy X-ray fields.

The EBT Gafchromic radiochromic film is a relatively new product designed specifically for dosimetry in radiation therapy. Due to the weak dependence of its response on the photon energy (variations are below 10% in the 50 kVp-10 MVp range), the film is ideal for dosimetry when the photon energy spectrum may be changing or unknown. In order to convert a map of optical densities into a map of absorbed radiation doses, a calibration curve constructed on the basis of standard calibration films is necessary.

Absorption spectra of irradiated XRCT radiochromic film.

Gafchromic XRCT radiochromic film is a self-developing high sensitivity radiochromic film product which can be used for assessment of delivered radiation doses which could match applications such as computed tomography (CT) dosimetry. The film automatically changes colour upon irradiation changing from a yellow to green/brown colour. The absorption spectra of Gafchromic XRCT radiochromic film as measured with reflectance spectrophotometry have been investigated to analyse the dosimetry characteristics of the film.

Post-irradiation colouration of Gafchromic EBT radiochromic film.

Gafchromic EBT (International Specialty Products, NJ, USA), radiochromic film is one of the newest radiation-induced auto-developing x-ray analysis films available for therapeutic radiation dosimetry in radiotherapy applications. Part of any radiochromic film product which undergoes a polymerization reaction for automatic darkening is an associated post-irradiation colouration whereby the film continues to darken after irradiation has ceased. The Gafchromic EBT film has been shown to produce an approximate 6% to 9% increase in post-irradiation optical density within the first 12 h of irradiation within the 1 Gy to 5 Gy dose range.

Weak energy dependence of EBT gafchromic film dose response in the 50 kVp-10 MVp X-ray range.

The energy dependence of the dose response of EBT Gafchromic film is assessed over a broad energy range, from superficial to megavoltage X-rays. The film is auto-developing and sensitive, it provides accurate dose assessment of low doses (about 1-2 Gy) used in radiotherapy. The energy dependence of the response of EBT film was found to be very weak: the variations do not exceed 10% over the range from 50 kVp to 10 MVp X-rays.

Fluorescent light effects on FWT-60 radiochromic film.

FWT-60 radiochromic film has been tested for colouration effects from fluorescent light sources and shown to produce a marked colouration when exposed to office fluorescent light sources showing an approximate 1 OD unit per 0.5 J m(-2) exposure to a broad ultraviolet (UV) UVA + UVB spectrum at the peak absorption wavelength. This produces a measurable and quantifiable response to UV exposure.

XR type-R radiochromic film x-ray energy response.

Gafchromic XR type-R radiochromic film is a relatively new product designed for use at clinical diagnostic x-ray energies both qualitatively and quantitatively. This short note investigates the energy response characteristics of this high-sensitivity radiochromic film for both diagnostic and therapeutic x-ray energies. Results are also compared to conventional silver halide x-ray film for energy response.

Reflection spectrometry analysis of irradiated GAFCHROMIC XR type R radiochromic films.

The absorption spectra of the GAFCHROMIC XR type R radiochromic film measured with reflectance spectroscopy have been investigated in order to analyze the dosimetry characteristics of the film. Like the XR type T film, this film features two peaks in its absorption spectrum, approximately at 676 and 618 nm, whose intensities increase with increasing absorbed dose. When the main absorption peak at 676 nm is used, the XR GAFCHROMIC type R film is approximately 1.

Peripheral dose measurement with a MOSFET detector.

The accuracy of a MOSFET dosimetry system with respect to peripheral therapeutic doses from high-energy X-rays has been evaluated. The results have been compared with ionisation chamber measurements in the same peripheral regions of the beam. For 6 MV and 18 MV X-ray beams, the MOSFET system in the high-sensitivity mode produces reproducibility of dose measurement with relative standard deviations within 1% of the maximal dose in the beam, if the measurement is made upto 15 cm away from the beam edge.

Absorption spectra analysis of exposed FWT-60 radiochromic film.

The visible absorption spectra of Radiachromic FWT-60 radiochromic film have been investigated to analyse the dosimetry characteristics of the film. The film is radiation sensitive to high absorbed doses. The visible absorption spectra of this film when exposed to photon radiation show a peak at 605 nm which is stable over the dose range of 0 Gy to 20 kGy.