OBJECTIVES Cone beam computed tomography (CBCT) in dentistry and maxillofacial surgery is a widely used imaging method for the assessment of various maxillofacial and dental pathological conditions. The objective of this study was to summarize the results of a multinational retrospective-prospective study that focused on patient exposure in this modality. METHODS The study included 27 CBCT units and 325 adult and paediatric patients, in total. Data on patients, clinical indications, technical parameters of exposure, patient dose indicator, or, alternatively, dose to phantom were collected. The dose indicator used was air kerma-area product, PKA. RESULTS In most scanners operators are offered with a variety of options regarding technical parameters, especially the field-of-view (FOV) size. The median and the third quartile value of PKA for adult patients in 14 different facilities were 820 mGy cm² and 1000 mGy cm² (interquartile range, IQR = 1058 mGy cm²), and 653 mGy cm² and 740 mGy cm² (IQR = 1,179 mGy cm²) for children, as reported by four different institutions. Phantom dose data were reported from 15 institutions, and median PKA ranged from 125 mGy cm² to 1951 mGy cm². Median PKA values varied by more than a tenfold between institutions, mainly due to differences in imaging protocol used, in particular FOV and tube current-exposure time product. CONCLUSIONS The results emphasize the need for a cautious approach to using dental CBCT. Imaging only when the clinical indications are clear, accompanied with the appropriate radiographic techniques and the optimum imaging protocol, will help reduce radiation dose to patients.

The main objective of this study was to investigate the correlation between the indoor and outdoor ambient dose equivalent rates measured by the ion chamber inside and around the historical sacral objects at a few locations in Bosnia and Herzegovina. The investigated objects made of the traditional building materials were built in the Late Medieval, Post Medieval, and Ottoman Period of Bosnia and Herzegovina history. The LUDLUM Model 9DP instrument based on a pressurized ion chamber was selected for natural low level radiation measurements since the ionisation chambers have higher sensitivities than the other types of detectors. The detection capability of the LUDLUM Model 9DP pressurized ion chamber was examined in the laboratory conditions with a source of low activity and under natural environmental radiation conditions by measuring the indoor and outdoor dose rates. A weak positive correlation was found between the ambient dose equivalent rates inside the historical sacral objects and the dose rates outside the objects. The average evaluated value of the indoor to outdoor dose rate ratio of 1.07 for the studied historic objects is less than that obtained for the contemporary building materials such as concrete. No study on the indoor to outdoor dose rate ratio in Bosnia and Herzegovina measured by the LUDLUM 9DP dose rate meter based on an ion chamber has been conducted yet. In addition to direct measurements, the first gamma spectrometric analysis of a few samples of building materials from the Late Medieval period in Bosna and Herzegovina was performed. The results of the gamma analysis revealed almost uniform distribution of primordial radionuclides in the investigated samples. It was demonstrated that such materials had the reduced content of radioactive isotopes compared to the contemporary building materials and therefore they could have potential advantages in specific applications related to the environmentally sustainable architecture.

Introduction: Precise mediastinal lymph node staging in patients with non-small cell lung carcinoma (NSCLC) provides important prognostic information and it is obligatory in treatment strategy planning. 18Fluoro-deoxy-glucose (18F-FDG) positron emission tomography - computerized tomography (PET-CT) based on detection of metabolic activity showed superiority in preoperative staging of lung carcinoma. Materials and Methods: Total number of 26 patients diagnosed with NSCLC were included in this retrospective, cross-sectional study. Status of mediastinal lymph nodes was assessed in all patients comparing contrast enhanced CT and 18F-FDG PET-CT findings. Discussion: We found in our study that 50% of patients had different N stage on contrast enhanced CT comparing to 18F-FDG PET-CT findings. Among the total number of patients which had different nodal status on PET-CT comparing to CT alone, we found in our study that 54% of patients had change in further therapy protocol after PET-CT change of nodal stage. Conclusion: Combined PET-CT which offers advantages of both modalities is excellent method for nodal (N) staging, so it is recommended in initial staging in patients with NSCLC. PET-CT used preopratively for mediastinal nodal staging has significant impact on further therapy planning and also has an consequential impact on health system savings.

AIM To evaluate possibilities of computed tomography (CT) perfusion in differentiation of solitary focal liver lesions based on their characteristic vascularization through perfusion parameters analysis. METHODS Prospective study was conducted on 50 patients in the period 2009-2012. Patients were divided in two groups: benign and malignant lesions. The following CT perfusion parameters were analyzed: blood flow (BF), blood volume (BV), mean transit time (MTT), capillary permeability surface area product (PS), hepatic arterial fraction (HAF), and impulse residual function (IRF). During the study another perfusion parameter was analyzed: hepatic perfusion index (HPI). All patients were examined on Multidetector 64-slice CT machine (GE) with application of perfusion protocol for liver with i.v. administration of contrast agent. RESULTS In both groups an increase of vascularization and arterial blood flow was noticed, but there was no significant statistical difference between any of 6 analyzed parameters. Hepatic perfusion index values were increased in all lesions in comparison with normal liver parenchyma. CONCLUSION Computed tomography perfusion in our study did not allow differentiation of benign and malignant liver lesions based on analysis of functional perfusion parameters. Hepatic perfusion index should be investigated in further studies as a parameter for detection of possible presence of micro-metastases in visually homogeneous liver in cases with no lesions found during standard CT protocol.