S. Spampinato

Dosimetric changes with computed tomography automatic tube-current modulation techniques

The study is aimed at a verification of dose changes for a computed tomography automatic tube-current modulation (ATCM) technique. For this purpose, anthropomorphic phantom and Gafchromic® XR-QA2 films were used. Radiochromic films were cut according to the shape of two thorax regions. The ATCM algorithm is based on noise index (NI) and three exam protocols with different NI were chosen, of which one was a reference. Results were compared with dose values displayed by the console and with Poisson statistics. The information obtained with radiochromic films has been normalized with respect to the NI reference value to compare dose percentage variations. Results showed that, on average, the information reported by the CT console and calculated values coincide with measurements. The study allowed verification of the dose information reported by the CT console for an ATCM technique. Although this evaluation represents an estimate, the method can be a starting point for further studies.

Investigation by pXRF of Caltagirone Pottery Samples Produced in Laboratory

Abstract In the study of archaeological ceramics, it is important to have compositional data to identify their origin and source. The fabric also provides useful information on the production technology, especially with regard to the firing steps. The work presented here is connected to this field and focuses on the main parameters related to the terracotta artefacts preparation. Thus, one can consider the effects in terracotta characteristics of different raw materials and firing parameters, in particular for pottery of Caltagirone, which is one of most important centres of pottery production in Italy, active since the Neolithic. To this end, terracotta samples have been reproduced in a laboratory setting according to the ancient procedure of Caltagirone manufacture, starting from clay and degreaser extraction in local historical sites. The analysis was conducted using a portable X-Ray Fluorescence (pXRF) spectrometer for elemental characterization of sand degreaser and of clays during each step of the realization process and in different firing conditions. SEM-ED techniques were also employed to verify the method and results for some of the samples after firing process. Framing the technological context of manufacture production, known in the specific case, it is also possible to identify potential outcomes and limits in the study of potsherds using pXRF technology, in applying the methodology to historic artefacts.

Validation of the CT–MRI image registration with a dedicated phantom

PurposeThe present study was aimed at verifying the automatic registration of the Focal (Elekta) platform with a dedicated phantom.Materials and methodsA phantom that simulates the pelvis region in a stylised way and finalised to the registration of computed tomography–magnetic resonance images was designed and realised. After acquiring the two sets of images, the registration was performed both in automatic and manual mode to verify whether they were comparable. To test the repeatability of the automatic registration, some known rigid transformations were imposed to the original images. If the registration method works correctly, parameters which bring the images into alignment must always be the same.ResultsAutomatic registration performed by the software did not prove satisfactory, whereas if a specific tool [volume of interest (VOI) tool] allowing the calculation to be limited to the landmark region was used, the registration parameters were comparable with those of the manual registration. Regarding the repeatability of the automatic registration, the software brought the images in the correct alignment performing translations and rotations along the longitudinal axis up to 40°, while it was not satisfactory for rotations along the transverse axes.ConclusionThe experimental results showed that in clinical application automatic registration is reliable if the VOI tool that includes visible landmarks in both studies is used. However, because the algorithm did not prove sensitive to rotations along the transverse axes, the position of the patient during the examinations plays a crucial role.