Biomedical subjects

Mohammad Mohammadi

Publications and source records attributed to Mohammad Mohammadi.

6 recordsLinked to original sources

PubMed2026

Flap Versus Tunneling for Horizontal Ridge Augmentation With FDBA and i-PRF: A Randomized Controlled Clinical Trial.

AIM: This study evaluated the efficacy of conventional flap and tunneling techniques for horizontal alveolar ridge augmentation using freeze-dried bone allograft (FDBA) particles combined with injectable platelet-rich fibrin (i-PRF). MATERIALS AND METHODS: Forty-five patients were randomly allocated to one of three groups (n = 15 each): conventional flap (CF), tunneling with membrane (TM), or tunneling without membrane (TnM). Preoperative ridge width was measured via cone beam computed tomography (CBCT). All augmentation procedures incorporated FDBA and i-PRF; an absorbable collagen membrane was applied in the CF and TM groups. Follow-up assessments, including CBCT imaging and histomorphometric analysis, were conducted 6 months postoperatively. For normally distributed data, ANOVA with Tukey's post hoc test and paired samples t-test were applied. Non-normally distributed data were analyzed using Kruskal-Wallis, Mann-Whitney U, and Wilcoxon signed-rank tests. RESULTS: Statistical analysis was performed on 43 patients. All groups demonstrated an increase in ridge width after 6 months. At the 2 mm level, the mean width gain was 1.28 mm (95% CI: 0.17 to 2.40) in the TM group, 2.85 mm (95% CI: 1.80 to 3.89) in the TnM group, and 1.95 mm (95% CI: 1.07 to 2.83) in the CF group. However, statistical analysis revealed no significant intergroup variation (p > 0.05). Histomorphometric assessments similarly demonstrated comparable outcomes across all groups, with no statistically significant differences observed (p > 0.05). CONCLUSION: Within the limitations of this study, the tunneling technique, regardless of membrane use, appears to be a clinically viable alternative to the conventional flap method for horizontal alveolar ridge augmentation. However, further studies with longer follow-up periods are required to substantiate these findings. TRIAL REGISTRATION: irct.behdasht.gov.ir identifier: IRCT 20101204005305N21.

Humans↗

PubMed2006

Evaluation of MLC leaf positioning using a scanning liquid ionization chamber EPID.

A method was developed to determine the accuracy of multileaf collimator (MLC) positioning using transmitted dose maps measured by a scanning liquid ionization chamber electronic portal imaging device (SLIC-EPID). Several MLC fields were designed, using the Varian C-series standard MLC-80, as reference fields for open fields. The MLC leaves were then shifted from the reference positions along the direction of MLC leaf movement towards the central axis from 0.1 to 1.6 mm. The electronic portal images (EPIs), acquired for each case, were converted to two-dimensional dose maps using an appropriate calibration method and the relative dose difference maps were then calculated. The experiment was then performed at non-zero gantry angles in the presence of an anthropomorphic phantom for typical prostate and head and neck fields. Several standard edge detection algorithms were also used in order to find the shifted MLC leaf position. In addition, the short-term reproducibility of MLC leaf positioning was evaluated using the above-mentioned methods. It was found that the relationship between the relative dose difference and MLC leaf spatial displacement is linear. A variation of 0.2 mm in leaf position leads to approximately 4% change in the relative dose values for open fields. The variation of the relative dose difference for phantom studies depends on the phantom positioning and the EPI normalization. From the standard edge detection algorithms, used in the current study, the 'Canny' algorithm was found to be the optimum method to identify the minimum detectable MLC leaf displacements with a precision of approximately 0.1 mm for all cases. However, the result of edge detection algorithms generally is binary and there is no additional information compared to the relative dose maps. The reproducibility of MLC positions was found to be within 0.3 mm. In conclusion, a SLIC-EPID can be used for regular quality assurance (QA) of MLC leaf positioning. Despite significant difference in the pixel size of the acquired SLIC-EPIs, it can be concluded that the SLIC-EPID can be used for MLC quality assurance protocols with similar accuracy compared to amorphous silicon (a-Si) EPID results.

Algorithms↗

PubMed2006

Prevalence of epilepsy and comorbidity of psychiatric disorders in Iran.

PROBLEM: To determine the lifetime prevalence of self- and other relative informants-reported epilepsy in nationwide study among Iranian adults of aged 18 years and over and to study the association of epilepsy with lifetime history of the psychiatric disorders. METHOD: Twenty-five thousand one hundred and eighty individual were selected through a randomized clustered sampling method from all the Iranian households; interviewed and used epilepsy questionnaire face-to-face at home in year 2001. From 12,398,235 households residing in Iran, 7795 families selected from 1559 clusters, 997 clusters were in urban and 582 were in rural areas, each cluster with 5 households were studied. The response rate was 90%. RESULTS: The prevalence of epilepsy was 1.8%. Epilepsy was more common in females, unemployed and higher educational level. It was not significantly associated with the age group, marital status and residential areas. The most common psychiatric disorders in subjects with epilepsy were major depressive disorder and obsessive compulsive disorder. The rate of lifetime suicidal attempt was 8.1%. CONCLUSION: Lifetime prevalence of epilepsy in Iran is not low. As the other communities, it is more common in females and unemployed. However, in contrast with the other studies, it was not more common among some age groups and unmarried and low educated subjects.

Adolescent↗

PubMed2006

Two-dimensional transmitted dose measurements using a scanning liquid ionization chamber EPID.

The use of a scanning liquid ionization chamber electronic portal imaging device (SLIC-EPID) for two-dimensional transmitted dosimetry was investigated and a calibration method was developed using extended dose range (EDR2) film. In order to convert pixel value to dose, the acquired SLIC-EPID pixel values were calibrated using an ionization chamber on the central axis. The relationship between pixel values, dose rate and absorbed dose was identified for various linac output repetition rates. To correct EPIs for dosimetric purposes, the off-axis ratio of dose profiles measured by EPIDs and EDR2 film was used to derive correction factor matrices (CFMs) for a range of source-to-EPID distances (SEDs). The corrected relative dose maps acquired for different conditions, including open and wedged fields, measured using a SLIC-EPID were compared with EDR2 film images using a gamma function algorithm with distance to agreement (DTA) = 2.5 mm and dose difference (DeltaDmax) = 1% criteria. The results showed that (a) for two-dimensional dosimetric purposes, EPIDs must be calibrated using appropriate two-dimensional correction factors and (b) SLIC-EPIDs can be used to measure the transmitted dose with good accuracy.

Algorithms↗

PubMed2006

Prevalence of social phobia and its comorbidity with psychiatric disorders in Iran.

This study explored the prevalence of social phobia (SP) in the general population of Iran, the sociodemographic characteristics of subjects with SP, and its comorbidity with the other lifetime psychiatric disorders. Our study was part of the nationwide study on the prevalence of psychiatric disorders in Iran. Overall, 25,180 Iranian subjects, age 18 years and over, from urban and rural areas of Iran were selected by a clustered random sampling method and interviewed face-to-face by 250 trained clinical psychologists using DSM-IV diagnostic criteria. Out of 12,398,235 households, 7,795 households in the form of 1,559 clusters of five households were selected. The statistical framework was based on the household lists available from the Department of Health in the provinces. The response rate was 90%. The lifetime prevalence of SP was 0.82%. The rate was 0.4% in males and 1.3% in females. The rate was higher in younger age groups and widows/widowers. It was not related to educational level and residential area. Specific phobia (66.7%), obsessive-compulsive disorder (17.4%), major depressive disorder (15%), and panic disorder (12.1%) were the most common lifetime psychiatric disorders among subjects with SP. The rate of SP in Iran is more similar to that in other Asian countries, and it is lower than that in Western countries. The rate of other psychiatric disorders among subjects with SP is more than that in the general population, and the most common psychiatric disorders were the other anxiety disorders and major depressive disorder.

Adolescent↗

PubMed2005

An epidemiological survey of psychiatric disorders in Iran.

BACKGROUND: The nation-wide epidemiological survey of psychiatric disorders in term of lifetime prevalence is not adequately known in Iran. The prevalence of lifetime psychiatric disorders was estimated among the population of aged 18 and over on gender, age group, educational level, occupational status, marital status, and residential area. METHODS: The subjects were 25,180 individuals selected through a clustered random sampling method. The psychiatric disorders were diagnosed on the bases of Diagnostic and Statistical Manual of Mental Disorders-IV criteria. It is the first study in which the structured psychiatric interview administered to a representative sample of the Iranian population age 18 and over by the 250 trained clinical psychologist interviewers. The data was entered through EPI-Info software twice in an attempt to prevent any errors and SPSS-11 statistical software was also used for analyses. The odds ratios and their confidence intervals estimated by using logistic regression. RESULTS AND DISCUSSION: The prevalence of psychiatric disorders was 10.81%. It was more common among females than males (14.34% vs. 7.34%, P < 0.001). The prevalence of anxiety and mood disorders were 8.35% and 4.29% respectively. The prevalence of psychotic disorders was 0.89%; neuro-cognitive disorders, 2.78% and dissociative disorders, 0.77%. Among mood disorders, major depressive disorder (2.98%) and among anxiety disorders, phobic disorder (2.05%) had the higher prevalence. The prevalence of psychiatric disorders among divorced and separated 22.31%; residents of urban areas 11.77%; illiterates 13.80%; householders 15.48%; unemployed 12.33% that were more than other groups. CONCLUSION: The mental health pattern in Iran is similar to the western countries, but it seems that the prevalence of psychiatric disorders in Iran may be lower than these countries. It is estimated that at least about 7 millions of Iranian population suffer from one or more of the psychiatric disorders. It shows the importance of the role of the psychiatric disorders in providing preventive and management programs in Iran.

Journal Article↗