Radiation shielding assessment for interventional radiology personnel: Geant4 dosimetry of lead-free compositions

The inherent biological hazards associated with ionizing radiation necessitate the implementation of effective shielding measures, particularly in medical applications. Interventional radiology, in particular, poses a unique challenge as it often exposes medical personnel to prolonged periods of high x-ray doses. Historically, lead and lead-based compounds have been the primary materials employed for shielding against photons. However, the drawbacks of lead, including its substantial weight causing personnel's inflexibility and its toxicity, have raised concerns regarding its long-term impact on both human health and the environment. Barium tantalate has emerged as a promising alternative, due to its unique attenuation properties against low-energy x-rays, specifically targeting the weak absorption area of lead. In the present study, we employ the Geant4 Monte Carlo simulation tool to investigate various formulations of barium tantalate doped with rare earth elements. The aim is to identify the optimal composition for shielding x-rays in the context of interventional radiology. To achieve this, we employ a reference x-ray spectrum typical of interventional radiology procedures, with energies extending up to 90 keV, within a carefully designed simulation setup. Our primary performance indicator is the reduction in air kerma transmission. Furthermore, we assess the absorbed doses to critical organs at risk within a standard human body phantom protected by the shield. Our results demonstrate that specific concentrations of the examined rare earth impurities can enhance the shielding performance of barium tantalate. To mitigate x-ray exposure in interventional radiology, our analysis reveals that the most effective shielding performance is achieved when using barium tantalate compositions containing 15% Erbium or 10% Samarium by weight. These findings suggest the possibility of developing lead-free shielding solutions or apron for interventional radiology personnel, offering a remarkable reduction in weight (exceeding 30%) while maintaining shielding performance at levels comparable to traditional lead-based materials.

Effect of thermal processing and traditional flavouring mixture on mycotoxin reduction in pistachio

The effect of heating (roasting and microwave radiation heating) along with a traditional pistachio flavouring mixture (containing verjuice, thyme extract, and sodium chloride) was investigated on reducing aflatoxins (AFs) and ochratoxin A (OTA) in pistachios. The naturally and artificially contaminated samples were soaked in the flavouring mixture (for 5, 10 and 24 h) and then subjected to roasting (at 120 and 150 °C for 50 min) and heating by microwave radiation (6 and 10 min). The residual mycotoxins were determined by high-performance liquid chromatography. The results showed that all treatments were able to reduce mycotoxin content (aflatoxin B1, B2, G1, G2 and OTA) significantly (P<0.05), up to 85.7±2.5% (during roasting) and up to 72.5±2.6% (during heating by microwave radiation). The highest reduction of AFs and OTA (ranging from 51.7±2.3 to 85.7±2.5%) was found when the contaminated (naturally and artificially) samples were soaked in the traditional mixture for 24 h and roasted at 150 °C. It could be concluded that the traditional flavouring method in combination with the roasting process or heating by microwave radiation could be applied as a useful and safe method for mycotoxin degradation in pistachio. Although, complete elimination of mycotoxins was not achieved, the method reduced mycotoxins more than 60% without adverse effect on the taste and appearance of pistachios.

Chromosomal aberrations in ascetic fluid of metastatic gastric cancer patients: A clustering analysis

To date, no specific pattern of chromosomal abnormalities has been established in gastric cancer (GC). Cytogenetic analysis was performed using G-banding and fluorescence in situ hybridization (FISH) in 9 ascetic fluids from GC patients, and the clustering patterns of chromosomal abnormalities were studied. Twenty-six different types of chromosomal abnormalities were identified. In contrast to structural abnormalities, the gain or loss of chromosomes was infrequent. Moreover, five main clusters of chromosomal abnormalities were identified by clustering analysis. Extensive cytogenetic complexity, specific chromosomal abnormalities and karyotype heterogeneity are the main characterizations of GC. Some of the recurrent and novel chromosomal abnormalities with distinct clustering patterns identified in this study may play important roles for GC initiation and progression and could serve as promising diagnostic and prognostic markers in GC patients.

An Investigation to Determine an Optimum Protective Garment Material in Nuclear Medicine

AIM

The aim of this study is to find an optimum material to protect garment for protection against ⁹⁹T^cm radionuclide.

MATERIALS AND METHODS

Monte Carlo simulation code was applied to investigate radiation attenuation of 13 shielding materials including: Ba, gray Sn, white Sn, Sb, Bi, Bi₂O₃, BaSO₄, Sn/W, Sb/W, Pb and W with thicknesses of 0.5 and 1 mm to determine an optimum protective garment material in nuclear medicine against ⁹⁹Tc^m. Furthermore, the dose enhancement on the staff body was investigated for shielding materials such as tungsten and lead.

RESULTS

The findings of the simulations show that the maximum and minimum attenuation obtained with thicknesses of 1 mm W and 1 mm BaSO₄ were 96.46% and 14.2%, respectively. The results also demonstrate that tungsten does not cause any dose enhancement on staff body but this is not true for lead. Tungsten provides the highest radiation attenuation without dose enhancement on the body of staff.

CONCLUSION

Among materials evaluated, tungsten is the optimum material and it can be applied for the design of protective garment for nuclear medicine staff against ⁹⁹Tc^m.

Evaluation of the Modified Acute Physiology and Chronic Health Evaluation Scoring System for Prediction of Mortality in Patients Admitted to an Emergency Department

Objective

To evaluate the ability of the Modified Acute Physiology and Chronic Health Evaluation (M-APACHE II) scoring system for the prediction of mortality in patients admitted to a tertiary emergency department in Iran.

Methods

During the study period, all patients aged >12 years who had been admitted to the emergency department of a tertiary hospital in Tehran, Iran were enrolled in the study. Traumatic and poisoned patients and those who died immediately after arriving at the emergency room were excluded. Using the M-APACHE II, risk of mortality was calculated for each patient. Finally, expected and observed mortalities were compared and the accuracy of M-APACHE II for prediction of mortality was determined using receiver operating characteristics (ROC) analysis.

Results

During the study period, 389 cases including 236 males (60.7%) were enrolled into the study. The mean age of the patients was 60.6±19.4 years (range 14 to 98 years). 117 patients died (30%) while the M-APACHE II predicted 129 deaths. The greatest discrepancy between observed and expected deaths occurred at M-APACHE II scores ≥21. The constructed area under the ROC curve basng on predicted and observed death was 0.938 (95% confidence interval 0.915-0.961).

Conclusion

M-APACHE II is an accurate scoring system for predicting mortality in patients admitted to the emergency department. However, further studies are needed to confirm our findings.

Survey of aflatoxins in retail samples of whole and ground black and white peppercorns

A total of 126 local and imported samples of commercial white and black pepper in Malaysia were analysed for aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1, AFG2) content using high-performance liquid chromatography (HPLC) with a fluorescence detector (FD). An acetonitrile-methanol-water (17 : 29 : 54; v/v) mixture was used as a mobile phase and clean-up was using an immunoaffinity column (IAC). Seventy out of 126 (55.5%) samples were contaminated with total aflatoxins, although only low levels of aflatoxins were found ranging from 0.1 to 4.9 ng g(-1). Aflatoxin B1 showed the highest incidence of contamination and was found in all contaminated samples. There was a significant difference between type of samples and different brands (p < 0.05). The results showed black peppers were more contaminated than white peppers.

Assessing medical students' communication skills by the use of standardized patients: emphasizing standardized patients' quality assurance

OBJECTIVE

The objective structured examination is one of the most valid, reliable, and effective tools for assessing clinical and communication skills, often by use of standard patients (SPs). SPs can also be assessors of those skills. One of the crucial areas when utilizing SP-based assessment is the quality and consistency assurance of their portrayal of the case and their ability to fill in checklists in an adequate way. The aim of this study was to assess the validity and reliability of SPs' ability to assess students' communication skill via a Calgary-Cambridge checklist.

METHOD

This cross-sectional and correlational study was conducted at the Tehran University of Medical Science. We first analyzed validity; the criterion validity of the SPs' filling in the checklists was assessed through determining the correlation between the SPs' completed checklists and the checklists filled in by three physician raters individually and then reproducibility: it was assessed by a test-retest approach inter-rater reliability.

RESULT

The mean correlation for assessing the validity of SPs' completed checklists by individual SPs was 0.81. The inter-rater reliability was calculated by kappa coefficient, and the total correlation among the three raters was 0.85. The reliability of the test-retest approach showed no significant differences between the test and re-test results.

CONCLUSION

The increased number of medical students and different faculties' responsibilities such as doing educational, research, and health services duties assessing medical student communication skills is a complex issue. The results of our study showed that trained SPs can be used as a valid tool to assess medical students' communication skills, which is also more cost effective and reduces work load of medical faculties.

Reduction of mycotoxins in white pepper

A simple method for the reduction of aflatoxins B₁ (AFB₁), B₂ (AFB₂), G₁ (AFG₁), G₂ (AFG₂) and ochratoxin A (OTA) in white pepper was studied. Response surface methodology (RSM) was applied to determine the effect of four variables, which included time (20-60 min), temperature (30-70°C), calcium hydroxide (Ca(OH)₂) (0-1%) and hydrogen peroxide (H₂O₂) (1-3%) during the washing step of white pepper. The efficacy of the method was evaluated by the determination of mycotoxins by HPLC with fluorescence detection (FD). Statistical analysis showed that the experimental data could be adequately fitted into a second-order polynomial model, with a multiple regression coefficient (R²) in the range of 0.805-0.907 for AFG₂ and AFG₁, respectively. The optimal condition was 57.8 min, 62.0°C, of 0.6% (w/v) and 2.8% (v/v) for time, temperature, Ca(OH)₂ and H₂O₂ respectively. By applying the optimum condition, the mycotoxins reduction was found to be in the range of 68.5-100% for AFB₂ and AFG₁ respectively.

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing

The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).

Phase II trial of old age acute myeloid leukemia treatment by arsenic trioxide and low-dose subcutaneous cytosin arabinoside

7075

Background: AML is a disease of old age, but unfortunately due to several factors standard treatment can not be delivered to these patients. Here we tried to achieve to bet possible response to these patients. Methods: Eleven old age patients selected for this trial. Patients couldn't tolerate standard treatment of AML due to old age or comorbid disorders. Treatment consist of best supportive care plus administration of low dose ARA-C (20mg/day as SQ) for 10 days each months and arsenic trioxide 10 mg/day as 2 hour iv infusion each month. Patients followed by CBC and BMA/B when peripheral blood normalized or every other month. Results: This cohort consist of 8 men and 3 women. Median age was 75 y/o (55–80). Median WBC count Hb level and platelet count at presentation were 42,860μl, 8.3g/dl and 30,500/μl, respectively. Complete remission observed in 6 and partial remission in one patient (RR = 63.6%), but remission was short live, after 6 months one patient was in CR and one in PR. After 12 months, only one patient was in PR. Median survival was 6 months and 6 patients survive more than 6 months. Two patients are alive after 12 months. Conclusions: Although prognosis of old age AML remain poor, but with this type of treatment RR is acceptable. In this very high-risk group of very old AML, combination of ATO and ARA-C possibly could improve survival.

No significant financial relationships to disclose.

Alpha rhythm and hypofrontality in schizophrenia

OBJECTIVE

To reveal the EEG correlates of resting hypofrontality in schizophrenia (SZ).

METHOD

We analyzed the whole-head EEG topography in 14 patients compared to 14 matched controls by applying a new parameterization of the multichannel EEG. We used a combination of power measures tuned for regional surface mapping with power measures that allow evaluation of global effects.

RESULTS

The SZ-related EEG abnormalities include i) a global decrease in absolute EEG power robustly manifested in the alpha and beta frequency bands, and ii) a relative increase in the alpha power over the prefrontal brain regions against its reduction over the posterior regions. In the alpha band both effects are linked to the SZ symptoms measured with Positive and Negative Symptom Scales and to chronicity.

CONCLUSION

As alpha activity is related to regional deactivation, our findings support the concept of hypofrontality in SZ and expose the alpha rhythm as a sensitive indicator of it.

Carotid blood-flow velocity changes detected by Doppler ultrasound in determination of brain death in children. A preliminary report

To investigate the value of Doppler ultrasonography of the carotid arteries as a diagnostic test for the determination of brain death in children, we enrolled 17 patients in a blinded fashion in the pediatric intensive care unit of Memorial Miller Children's Hospital of Long Beach between the period of December 1990 and October 1992. After institutional review board approval and parental consent, children who sustained severe brain injury underwent Doppler ultrasonography study of their carotid arteries. Seven of 17 patients were diagnosed as having brain death by clinical criteria (complete loss of cerebral and brainstem functions) and electroencephalogram (EEG). Five of seven (71%) patients with the diagnosis of brain death had bilateral reverse flow (characteristic of increased cerebrovascular resistance and absent cerebral circulation) on their Doppler ultrasonography, yielding a specificity of 100% and sensitivity of 71.4% (P = 0.01). All surviving patients (five) and the five who did not fulfill the brain-death criteria at the time of Doppler ultrasonography and were later taken off life supportive measures had normal Doppler findings. These data indicate that Doppler ultrasonography of the carotid arteries is a very specific test and can be used as an adjunctive modality for determination of brain death in children.