Optimization of a customized simultaneous algebraic reconstruction technique algorithm for phase-contrast breast computed tomography.

Objective.To introduce the optimization of a customized GPU-based simultaneous algebraic reconstruction technique (cSART) in the field of phase-contrast breast computed tomography (bCT). The presented algorithm features a 3D bilateral regularization filter that can be tuned to yield optimal performance for clinical image visualization and tissues segmentation.Approach.Acquisitions of a dedicated test object and a breast specimen were performed at Elettra, the Italian synchrotron radiation (SR) facility (Trieste, Italy) using a large area CdTe single-photon counting detector. Tomographic images were obtained at 5 mGy of mean glandular dose, with a 32 keV monochromatic x-ray beam in the free-space propagation mode. Three independent algorithms parameters were optimized by using contrast-to-noise ratio (CNR), spatial resolution, and noise texture metrics. The results obtained with the cSART algorithm were compared with conventional SART and filtered back projection (FBP) reconstructions. Image segmentation was performed both with gray scale-based and supervised machine-learning approaches.Main results.Compared to conventional FBP reconstructions, results indicate that the proposed algorithm can yield images with a higher CNR (by 35% or more), retaining a high spatial resolution while preserving their textural properties. Alternatively, at the cost of an increased image 'patchiness', the cSART can be tuned to achieve a high-quality tissue segmentation, suggesting the possibility of performing an accurate glandularity estimation potentially of use in the realization of realistic 3D breast models starting from low radiation dose images.Significance.The study indicates that dedicated iterative reconstruction techniques could provide significant advantages in phase-contrast bCT imaging. The proposed algorithm offers great flexibility in terms of image reconstruction optimization, either toward diagnostic evaluation or image segmentation.

Geant4 implementation of inter-atomic interference effect in small-angle coherent X-ray scattering for materials of medical interest.

An extension to Geant4 Monte Carlo code was developed to take into account inter-atomic (molecular) interference effects in X-ray coherent scattering. Based on our previous works, the developed code introduces a set of form factors including interference effects for a selected variety of amorphous materials useful for medical applications, namely various tissues and plastics used to build phantoms. The code is easily upgradable in order to include new materials and offers the possibility to model a generic tissue as a combination of a set of four basic components. A dedicated Geant4 application for the simulation of X-ray diffraction experiments was created to validate the proposed upgrade of Rayleigh scattering model. A preliminary validation of the code obtained through a comparison with EGS4 and an experiment is presented, showing a satisfactory agreement.

Endoscopic ultrasound localization of a solitary insulinoma of pancreatic tail misdiagnosed as epilepsy: case report.

A 17-year-old female patient with features of epilepsy was treated with valproic acid. Two years later, hypoglycemia and hyperinsulinemia appeared. Transabdominal ultrasonography, spiral computed tomography, and indium-111 Octreoscan were performed without positive results. Endoscopic ultrasonography identified an oval tumor in the pancreatic tail with a color Doppler hypervascular pattern. Surgical enucleation decreased levels of insulin and C-peptide within 20 min, and the patient became free of symptoms and medications.

Biochemical modulation of fluorouracil with high dose methotrexate or folinic acid in advanced colorectal cancer patients. Gruppo Oncologico dell' Italia Meridionale (GOIM).

To compare the efficacy of two biochemical modulations of 5-Fluorouracil in advanced colorectal cancer, 104 patients were randomized to receive high dose methotrexate followed by 5-Fluorouracil and leucovorin rescue on day 1 (Arm A) or folinic acid and 5-Fluorouracil on day 1 to 5 (Arm B). Both treatments were repeated every 3 weeks. In the 92 evaluable patients, objective responses were observed in 34% in Arm A and 31% in Arm B, with a median duration of 7.5 and 8.5 months, respectively. Median overall survival was similar in both groups (12 versus 13 months, respectively). A statistically significant difference was found only between responders and non responders of group B (p = 0.004). Toxicity was mild. In conclusion, no difference in therapeutic activity was seen between the two treatments and additional biochemical modulation must be evaluated.