Imaging radiation dose in breast radiotherapy by X-ray CT calibration of Cherenkov light.

Imaging Cherenkov emission during radiation therapy cancer treatments can provide a real-time, non-contact sampling of the entire dose field. The emitted Cherenkov signal generated is proportional to deposited dose, however, it is affected by attenuation from the intrinsic tissue optical properties of the patient, which in breast, ranges from primarily adipose to fibroglandular tissue. Patients being treated with whole-breast X-ray radiotherapy (n = 13) were imaged for 108 total fractions, to establish correction factors from the linear relationships between Cherenkov light and CT number (HU). This study elucidates this relationship in vivo, and a correction factor approach is used to scale each image to improve the linear correlation between Cherenkov emission intensity and dose ([Formula: see text]). This study provides a major step towards direct quantitative radiation dose imaging in humans by utilizing non-contact camera sensing of Cherenkov emission during the radiation therapy treatment.

Imaging Cherenkov photon emissions in radiotherapy with a Geiger-mode gated quanta image sensor.

The emission of Cherenkov photons from human and animal tissue can be observed during clinical x-ray or particle beam irradiation. However, imaging this weak emission with the necessary single-photon sensitivity in the clinical room is challenging because of milliwatt-level ambient room lighting and the presence of stray high-energy radiation. In this Letter, we demonstrate, to the best of our knowledge, the first Cherenkov imaging with a time-gated quanta image sensor employing a large single-photon avalanche diode (SPAD) array. Detecting single Cherenkov photons was possible with high photon avalanche gain, fast temporal gating, and moderately high ∼7% photon detection probability. Single-bit digitization and active SPAD quenching enabled stray x-ray noise suppression and photon-noise-limited imaging in a clinical environment. This type of imaging allows the knowledge of location, shape, and surface dose of the therapeutic beam radiotherapy with the stability of solid state-based detection.

Wide-field spontaneous Raman spectroscopy imaging system for biological tissue interrogation.

Raman spectroscopy has shown great promise as a method to discriminate between cancerous and normal tissue/cells for a range of oncology applications using microscopy and tissue interrogation instruments such as handheld probes and needles. Here we are presenting preliminary steps toward the development of a practical handheld macroscopic Raman spectroscopy instrument, demonstrating its capabilities to discriminate between different biological tissue types during ex vivo porcine experiments. The novel probe design can image a field of view of 25 mm2 with a spatial resolution <100 µm and an average spectral resolution of 95 cm-1, covering the fingerprint region between 450 to 1750 cm-1. The ability of the system to produce tissue maps based on molecular characteristics is demonstrated using a neural network machine learning technique.

Phase I/II study of verteporfin photodynamic therapy in locally advanced pancreatic cancer.

BACKGROUND: Patients with pancreatic cancer have a poor prognosis apart from the few suitable for surgery. Photodynamic therapy (PDT) produces localised tissue necrosis but previous studies using the photosensitiser meso-tetrahydroxyphenylchlorin (mTHPC) caused prolonged skin photosensitivity. This study assessed a shorter acting photosensitiser, verteporfin. METHODS: Fifteen inoperable patients with locally advanced cancers were sensitised with 0.4 mg kg(-1) verteporfin. After 60-90 min, laser light (690 nm) was delivered via single (13 patients) or multiple (2 patients) fibres positioned percutaneously under computed tomography (CT) guidance, the light dose escalating (initially 5 J, doubling after each three patients) until 12 mm of necrosis was achieved consistently. RESULTS: In all, 12 mm lesions were seen consistently at 40 J, but with considerable variation in necrosis volume (mean volume 3.5 cm(3) at 40 J). Minor, self-limiting extrapancreatic effects were seen in multifibre patients. No adverse interactions were seen in patients given chemotherapy or radiotherapy before or after PDT. After PDT, one patient underwent an R0 Whipple's pancreaticoduodenectomy. CONCLUSIONS: Verteporfin PDT-induced tumour necrosis in locally advanced pancreatic cancer is feasible and safe. It can be delivered with a much shorter drug light interval and with less photosensitivity than with older compounds.

Acacia proteinase inhibitors. Purification and properties of the trypsin inhibitors from Acacia elata seed.

Two trypsin inhibitors from the seed of Acacia elata, a legume of the subfamily Mimosoideae, were isolated by affinity chromatography on trypsin-Sepharose 4B and separated by chromatography on SP-Sephadex C-25 and Sephadex G-100. The two inhibitors, with molecular weights of about 20 000, were composed of two polypeptide chains linked by a disulfide bond. The two inhibitors had essentially the same amino acid compositions and both contained four half-cystine residues, no methionine and were rich in aspartic acid, glutamic acid, glycine and leucine. The inhibitors had isoelectric points of 6.4 and 5.9. The inhibitors stoichiometrically inhibited trypsin in the molar ratio of 1:1, alpha-chymotrypsin was inhibited also in a 1:1 molar ratio but the binding of the enzyme by the inhibitor was weaker and the inhibitor-chymotrypsin complex dissociated during the assay. Both enzymes are probably inhibited at an identical site. Amino-terminal sequence analysis of the two polypeptide chains of the inhibitors revealed extensive homology with the trypsin inhibitor from the silk tree (another Mimosoideae legume); both these inhibitors are homologous with the soybean trypsin inhibitor (Kunitz).

Localization of lectins in legume cotyledons.

High-resolution techniques for the localization of lectins are described. Concanavalin A (Con A) and phytohaemagglutinin (PHA) are localized using a fluorescent method with (FITC)-labelled immunoglobulins which bind to the lectins in sections of jack and red kidney bean cotyledons. Specificity is defined by the use of specific sugar inhibitors. Both Con A and PHA are found in cytoplasmic sites. Lectins with beta-glycoside specificity are detected with red-coloured artificial carbohydrate antigens. The beta-galactosyl and beta-glucosyl antigens bind specifically to clusters of spherical bodies in the intercellular spaces, to cell wall sites, and to the periphery of the cytoplasm associated with the cell membrane.