Introduction: Long-term clinical evaluation of dental implants and their surrounding structures is of utmost importance to acquire knowledge about reasons for implant success and failure.However, accurate and reproducible results are difficult to obtain. The aim of the present study was to examine bone height around endosseous implants on DIGITAL conventional radiographs (DCR) and direct DIGITAL subtraction images (DSI) prior to loading.Materials and methods: In this experimental study, bone height around 10 implants in 6 patients was assessed by 2 observers. Standardized DIGITAL radiographs were obtained just a week and 3 months postoperatively and subtracted by means of EMAGO software. Then the observers evaluated bone height on DCRs and DSIs. MINITAB software and paired t-test were used for statistical analysis (a=0.05).Results: Comparative evaluation of bone height indicated significantly higher values on DCR than on DSI (p value=0.002). The observers also had statistically significant variability in this assessment (p value=0.00003).Conclusion: DSI demonstrated lower values of linear measurement of bone height around endosseous implants compared with DCR. Interobserver variability should be considered when comparing values from follow-up studies.

Creating a high‑ quality image with the low patient dose is one of the most important goals in medical X‑ ray imaging. In this study, the image quality parameters of the DIGITAL radiographic units in Tabriz city were considered and compared with the international protocols. The image quality parameters were measured at 11 high workload DIGITAL radiography (DR) imaging centers in Tabriz city, and the results were compared to DINN 6868/58 standards. All centers equipped with the direct DR units passed the spatial resolution, low contrast detectability, contrast dynamic range, and noise tests, while the computed radiography (CR) units only could pass the two last tests. The highest spatial resolution was observed 3. 2 lp/mm in the DR unit while the lowest one was 1. 8 lp/ mm in the CR unit. The highest noise was measured to be 0. 03 OD that was observed in the DR unit. The most difference between the nominal and measured peak kilovoltage and mAs was 3. 1% and 6. 8%, respectively. The entrance surface air kerma in all units was obtained <0. 63 mGy. The measured half‑ value layer range was between 2. 4 and 3. 54 mmAl. The physical parameters of image quality such as spatial resolution, contrast, and noise are robustness quantitative parameters for the assessment of the image quality performance of the units. Therefore, measurement and control of these parameters using two‑ dimensional PHANTOMs are very critical.

Background: The positron emission tomography (PET) technology has undergone continuous innovation in recent years. New-technology DIGITAL PETs are silicon photomultiplier (SiPM) PET systems with DIGITAL readouts, which contribute to improved image resolution. This study aimed to compare the image quality of sub-centimeter lesions of NEMA PET PHANTOM images obtained under identical imaging conditions (identical lesion volumes, identical activity and identical scanning time) using dPET, analog PET-1 and analog PET-2 acquired in the clinic. Materials and Methods: For image analysis, a standard NEMA IEC body PHANTOM was used. In the present study, the lesion detection performance of all PETs was evaluated in two categories, sub- and over-centimeter size. The imaging durations of this study were 1, 2, 3, and 5 minutes, while the injection doses were 2.33 and 5.33 kBq/ml for the 1/4 and 1/8 background-to-lesion ratios, respectively. For a quantitative assessment of image quality, a circular ROI with activity concentrations (ACmean) and the mean recovery coefficient were calculated for each lesion via the ACmean. Results: Our study revealed approximately 15% greater RCmean values for dPET with SiPM technology compared to the analog PET-2 with PMT technology. However, analog PET-1 exhibited a significant lack of performance, especially when compared to analog PET-2 and dPET. Conclusion: Although dPET, the first generation of dPETs analyzed in the present study, yields relatively better RCmean values than analog PETs, it is not able to entirely eliminate the unfavorable impacts of PVE for sub-centimeter lesions.

High energy electron beams are one of those ionizing radiation beams that are being widely used in nuclear medicine for treatment of cancerous tumors. However, these beams may also harm the healthy cells in traversing the patient body. Accordingly, knowing the dose distribution in a tissue-equivalent PHANTOM is the main requirement in an electron therapy treatment design. In recent years, great interest is attracted toward the application of DIGITAL holography method for accurate three dimensional measurement and monitoring of the absorbed dose. In this work, design and modelling of a mobile dosimetric instrument, which works based on the DIGITAL holography principles, are studied and a new approach is developed for measuring the absorbed dose of electron radiation using the DIGITAL holography technique with a laser beam. The proposed method for measuring the absorbed dose is also developed to be immune against the environmental noises that are present in difficult situations. Monte Carlo and numerical modelling of the instrument, demonstrate its capability in accurate measurement of the absorbed dose.

Introduction: PHANTOM studies facilitate the implementation of radiation dose surveillance as a function of radiographic technical parameters for minimizing patient radiation dose. The evidence of such investigations can then be used to evaluate technical parameters used in the radiographic procedures to reduce radiation dose without compromising the image quality. Material and Methods: This experimental study was carried out using an anthropomorphic PHANTOM and the Leeds test object. Computed radiographic system was utilized and the images were printed for objective evaluation. Dose-area-product (DAP) readings were obtained using a DAP meter for the technical parameters employed for the radiographic procedures. Results: The use of 0. 2 mm additional copper filtration resulted in the lowest radiation doses for all four radiographic procedures (i. e. posteroanterior chest, anteroposterior abdomen and lumbar sacral spine projections). The highest tube potential appropriate to the body part being imaged, patient size, image receptor response and required information resulted in the minimum radiation dose to the patient without compromising the image quality. The focus to film distance utilized for the radiographic procedure must be in accordance with the focus to grid distance specified by the manufacturer when using the bucky to eliminate grid “ cut-off. ” Conclusion: The optimization of image quality and radiation dose can be accomplished by using a PHANTOM and selecting the imaging parameters that yield an acceptable image quality with the lowest entrance surface dose while considering the adjustment for patient size.

Objective(s): Alternative normalization methods were proposed to solve the biased information of SPM in the study of neurodegenerative disease. The objective of this study was to determine the most suitable count normalization method for SPM analysis of a neurodegenerative disease based on the results of different count normalization methods applied on a prepared DIGITAL PHANTOM similar to one obtained using fluorodeoxyglucose-positron emission tomography (FDG-PET) data of a brain with a known neurodegenerative condition.Methods: DIGITAL brain PHANTOMs, mimicking mild and intermediate neurodegenerative disease conditions, were prepared from the FDG-PET data of 11 healthy subjects. SPM analysis was performed on these simulations using different count normalization methods.Results: In the slight-decrease PHANTOM simulation, the Yakushev method correctly visualized wider areas of slightly decreased metabolism with the smallest artifacts of increased metabolism. Other count normalization methods were unable to identify this slightly decreases and produced more artifacts. The intermediate-decreased areas were well visualized by all methods. The areas surrounding the grey matter with the slight decreases were not visualized with the GM and VOI count normalization methods but with the Andersson. The Yakushev method well visualized these areas. Artifacts were present in all methods. When the number of reference area extraction was increased, the Andersson method better-captured the areas with decreased metabolism and reduced the artifacts of increased metabolism. In the Yakushev method, increasing the threshold for the reference area extraction reduced such artifacts.Conclusion: The Yakushev method is the most suitable count normalization method for the SPM analysis of neurodegenerative disease.

Objective To determine the frequency of PHANTOM limb sensation (PLS) and PHANTOM limb pain (PLP) in children and young adults suffering landmine-related amputation.Materials & Methods All youths with amputation due to landmine explosions participated in this study. The proportions of patients with PHANTOM limb sensation/pain, intensity and frequency of pain were reported. Chi square test was used to examine the relationship between variables. Comparison of PLP and PLS between upper and lower amputation was done by unpaired t-test.Results There were 38 male and 3 female with the mean age of 15.8±2.4yr. The mean interval between injury and follow-up was 90.7±39.6 months. Twelve (44.4%) upper limb amputees and 11 (26.8%) lower limb amputees had PLS. Nine (33.3%) upper limb amputees and 7 (17.1%) lower limb amputees experienced PLP. Of 27 upper limb amputees, 6 (14.6%) and among 15 lower limb amputees, 6 (14.6%) had both PLS and PLP. One case suffered amputation of upper and lower limbs and was experiencing PLS and PLP in both parts. PLS had a significant difference between the upper and lower amputated groups.Significant relationship was observed between age of casualty and duration of injury with PLP.Conclusion PHANTOM limb sensation and pain in young survivors of landmine explosions appear to be common, even years after amputation.

Background & Aim: The majority of carious lesions are not well-defined radiolucencies. Approximately 40% demineralization is required for radiographic detection of a lesion. The actual depth of penetration of carious lesion is deeper than may be detected radiographically. However, DIGITAL subtraction images permit to detect 1-5% decrease of mineral mass per unit volume. The goal of the present study was to evaluate the accuracy of DIGITAL subtraction radiography in the detection of dental demineralization in vitro.Methods & Materials: This study was based on observational-diagnostic method which was done on 30 extracted human teeth, categorized in two groups A and B, each having 15 members. In each of teeth, one approximal enamel demineralization lesion was induced using an acidified system (PH=4.8). Direct DIGITAL radiography were obtained under standardized condition of teeth before demineralization. After 7 days, the teeth of group B and after 42 days, group A removed from acid and new radiographs were taken. The images of the 7th and 42nd days were subtracted from the baseline radiograph (before creation of the lesion). Then teeth were histologically evaluated. Direct DIGITAL and subtraction images were interpreted by three observers to detect presence or absence of the lesion, then the diagnostic accuracy of both methods was determined.Results: After 7 days, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value for incipient lesions in direct DIGITAL radiography were 0%, 80%, 40%, 0% and 44% respectively and in DIGITAL subtraction radiography were 66.7%, 86.7%, 76.7%, 83.4% and 72.3% respectively. However after 42 days the sensitivity, specificity and accuracy of both methods were 100%.Conclusion: DIGITAL subtraction radiography has a fairly acceptable accuracy in detection ofthe incipient proximal lesions in comparison with DDR. For moderate proximal lesions DSR has the same accuracy as DDR.

Introduction: The determination of accurate dose distribution is an issue of fundamental importance in radiotherapy, especially with regard to the fact that the human body is a heterogeneous medium. Therefore, the present study aimed to analyze the density and isodose depth profiles of 6 MV beam in a SP34 slab‐wooden dust (pine) ‐SP34 slab (SWS) heterogeneous PHANTOM.Materials and Methods: The density of SP34 slab, wooden dust of pine, and thoracic region of 10 patients were calculated using computed tomography (CT) images. The depths of isodose lines were measured for 6 MV beam on the CT images of the chest, SP34 slab PHANTOM, and SWS PHANTOM. Dose calculation was performed at the depths of 2, 13, and 21 cm in both PHANTOMs. Furthermore, patient-specific quality assurance (QA) was implemented using both PHANTOMs.Results: The mean densities of the lung, SP34 slabs, and wooden dust were 0.29, 0.99, and 0.27 gm/cc respectively. The mean depths of different isodose lines in the SWS PHANTOM were found to be equivalent to those in actual patients. Furthermore, the percentage variation between the planned and measured doses was higher in the SWS PHANTOM as compared to that in the SP34 PHANTOM. Furthermore, the percentage variation between the planned and measured doses in patient‐specific QA was higher in the SWS PHANTOM as compared to that in the SP34 PHANTOM.Conclusion: As the findings indicated, the density and isodose depth profiles of the SWS PHANTOM were equivalent to those of the actual thoracic region of human.