Volume 22 (2016): Edizione 4 (December 2016)

A novel scheme for lesions classification in chest radiographs is presented in this paper. Features are extracted from detected lesions from lung regions which are segmented automatically. Then, we needed to eliminate redundant variables from the subset extracted because they affect the performance of the classification. We used Stepwise Forward Selection and Principal Components Analysis. Then, we obtained two subsets of features. We finally experimented the Stepwise/FCM/SVM classification and the PCA/FCM/SVM one. The ROC curves show that the hybrid PCA/FCM/SVM has relatively better accuracy and remarkable higher efficiency. Experimental results suggest that this approach may be helpful to radiologists for reading chest images.

Aim: To demonstrate a simple technique of cranio-spinal irradiation (CSI) in supine position using inter fraction moving field junctions to feather out any potential hot and cold spots.

Materials and Methods: Fifteen patients diagnosed with medulloblastoma were treated during the period February 2011 to June 2015 were included in this study. Out of fifteen patients in the study nine were male and 6 were female with a median age of 13.4 years (range 5-27 years). All the patients were positioned supine on CT simulation, immobilized using thermoplastic mask and aligned using room based laser system. Two parallel opposed lateral fields for the whole brain using an asymmetrical jaw with isocenter at C2 vertebral body. A posterior field also placed to cover the cervical and dorsal field using the same isocenter at C2. The second isocenter was placed at lumbar vertebral region to cover the remaining dorsal, lumbar and sacral region using an inter-fraction moving junction. Field-in-field and enhanced dynamic wedge used to homogeneous dose distribution when required.

Results and Discussion: In this study, we found that only two patients failed in the primary site, no radiation myelitis or recurrences in the filed junctions were reported in these fifteen patients with a median follow-up of 36.4 months. The automated sequence of treatment plans with moving junctions in the comfortable supine position negating the need for manual junction matching or junction shifts avoiding potential treatment errors and also facilitating delivery of anesthesia where necessary.

The effective energy calculated using the half-value layer (HVL) is an important parameter for quality assurance (QA) and quality control (QC). However constant monitoring has not been performed because measurements using an ionization chamber (IC) are time-consuming and complicated. To solve these problems, a method using radiochromic film (GAFCHROMIC EBT2 dosimetry film (GAF-EBT2) with slight energy dependency errors), a mobile scanner and step-shaped aluminum (SSAl) filter is developed. The results of the method using a mobile scanner were compared with those of the recommended method using an IC in order to evaluate its applicability. The difference ratios of the effective energies by each method using a mobile scanner with GAF-EBT2 were less than 5% compared with results of an IC. It is considered that this method offers a simple means of determining HVL for QA and QC consistently and quickly without the need for an IC dosimeter.

Visualization of markers is critical for imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). However, the size of the marker varies according to the imaging technique. While a large-sized marker is more useful for visualization in MRI, it results in artifacts on CT and causes substantial pain on administration. In contrast, a small-sized marker reduces the artifacts on CT but hampers MRI detection. Herein, we report a new ironcontaining marker and compare its utility with that of non-iron-containing markers. Five patients underwent CT/MRI fusion-based intensity-modulated radiotherapy, and the markers were placed by urologists. A Gold Anchor™ (GA; diameter, 0.28 mm; length, 10 mm) was placed using a 22G needle on the right side of the prostate. A VISICOIL™ (VIS; diameter, 0.35 mm; length, 10 mm) was placed using a 19G needle on the left side. MRI was performed using T2*-weighted imaging. Three observers evaluated and scored the visual qualities of the acquired images. The mean score of visualization was almost identical between the GA and VIS in radiography and cone-beam CT (Novalis Tx). The artifacts in planning CT were slightly larger using the GA than using the VIS. The visualization of the marker on MRI using the GA was superior to that using the VIS. In conclusion, the visualization quality of radiography, conebeam CT, and planning CT was roughly equal between the GA and VIS. However, the GA was more strongly visualized than was the VIS on MRI due to iron containing.