Several x-ray spectra, including those of the ISO reference radiations, were measured by 2-hp Ge detectors. Measurements were carried out in different experimental conditions with regard to detector size, beam collimation, and SDD. A stripping procedure to improve the spectrum analysis was developed on the basis of a detailed evaluation (by means of a Monte Carlo method) of the detector's spurious effects. These effects include K-photon escape, Compton photon escape, electron escape, and collimation effect. The stripping procedure also allows us to determine directly the spectra of possible scattered radiation reaching the detector in addition to the primary beam. When the primary beam is heavily filtered, the leakage radiation from the x-ray tube housing scattered onto the detector may not be negligible even when the x-ray tube is provided with appreciable shielding. Possible practical consequence of these effects are discussed. The results obtained on the ISO x-ray spectra are in agreement with previous determinations. The advantage of the present procedure is its more immediate applicability to Ge detectors of any size and with different beam collimation conditions.

Mathematics↗

PubMedDate not supplied

Detection of sentinel node in breast cancer: pilot study with the imaging probe.

The commonly used gamma probes are easy to use but also give rough information when employed in radioisotope-guided surgery. When images are required for exact localization, a gamma camera as well as a probe have to be used. Position-sensitive photomultipliers have contemporaneously allowed high-resolution scintigraphy and miniaturization of gamma cameras. We have assembled a miniature gamma camera with a 1-square-inch field of view and an intrinsic resolution of about 1 mm. When the minicamera is collimated with a large-holed, highly sensitive collimator, it acquires a spatial resolution of 3 mm. This prototype has been tested in the detection of difficult-to-image breast cancer sentinel nodes. Five nodes that had not been found with the usual technique of an Anger camera plus conventional probe were checked with the miniature camera that we named imaging probe: it actually is small enough to be used as a probe and large enough to give an image. One of the five nodes was found and imaged. It was small, disease-free, close to the tumor and probably hidden by the Compton halo around the peritumoral injection site. Our pilot study shows that the imaging probe, although still a prototype, has certain advantages over conventional methods when lymph node localization is required during surgery.

Breast Neoplasms↗

PubMedDate not supplied

PLATO Treatment Planning System.

Explore the source record for details and available documents.

Humans↗

PubMedDate not supplied

Production of monoclonal antibodies against a new carcinoma-associated marker in view of developing a serological test.

By immunizing a mouse with human metastatic breast tumor cells from patient effusions and infiltrated lymph nodes, a monoclonal antibody (MLuC2), which identifies a new carcinoma-associated marker, was raised. The reactivity of this reagent was studied by immunohistochemistry on live and fixed cells from tumor cell lines and on frozen sections from surgical specimens. Besides reacting with 73% of breast carcinomas, MLuC2 also reacted with 93% of non-small cell lung carcinoma (NSCLC) and with a few normal tissues. The MLuC2-recognized molecule (CaMLuC2), whose MW was 90 KDa according to immunoblotting experiments, was found to be detectable in the serum and could therefore be of particular interest for serological diagnostic applications. Since the CaMLuC2 epitope was not polyexpressed on the bearing molecule, we produced a new generation of MAbs in order to define epitopes coexpressed with CaMLuC2 on the same 90 kDa molecule, and which are therefore suitable to develop a double-determinant immunoradiometric assay (DDIRMA) for the detection of this marker in the sera of lung carcinoma patients. Different analyses by immunohistochemistry, binding inhibition tests and DDIRMA, proved that the two new reagents developed, MLuC8 and MLuC9, recognize the same or closely related epitopes, which are however different from CaMLuC2, but which are all present on the same molecule. Preliminary immunoradiometric tests performed on sera from lung cancer and control patients showed a good specificity but a low sensitivity. In fact, only 42% of the 28 tested sera samples from NSCLC patients scored positive despite the fact that more than 90% of the NSCLC expressed the relevant antigen.

Antibodies, Monoclonal↗

PubMedDate not supplied

Study of a soluble tumor-associated marker composed of CEA related molecules recognized by three monoclonal antibodies.

Three MAbs, MLuC2, MLuC8 and MLuC9, directed against a molecule that is produced and secreted by carcinoma cells were studied with the aim of developing a double-determinant immunoradiometric assay (DDIRMA). We demonstrated by means of immunoblotting, immunodepletion and DDIRMA techniques, that MLuC9 reacted against the CEA molecule, whereas MLuC2 and MLuC8 reacted against a 90 Kd molecule related to CEA. The DDIRMA performed with the anti-CEA as a catcher MAb and the anti-90 Kd as a tracer MAb was found to be positive with the HT29 soluble extract, which suggests the existence of CEA/90 Kd dimeric molecules. The same reactivity was found when sera from patients with lung carcinomas were tested, which excludes that this molecule could be an artefact due to the cell solubilization procedures. The association between CEA and the 90 Kd molecule was further confirmed by immunodepletion experiments in which the immunoprecipitation with one MAb not only removed the recognized molecule, but also partially immunodepleted the material from the other.

Antibodies, Monoclonal↗