Internal dosimetry studies of 177Lu-BBN-GABA-DOTA, as a cancer therapy agent, in human tissues based on animal data

The goal of using radiopharmaceuticals for therapeutic purposes is twofold: first, the most damage to cancer cells and, second, the most negligible dose transfers to healthy tissues. As ¹⁷⁷Lu has the potential to cure a wide range of malignancies due to its varied range of beta energies, ¹⁷⁷Lu-BBN-GABA-DOTA has been developed for therapeutic applications. In addition, ¹⁷⁷Lu-BBN-GABA-DOTA can be over-expressed on gastrin-releasing peptide (GRP) receptors of the prostate, breast, small cell lung cancer, gastric, and colon tumors. The purpose of this study was to calculate the amount of dose absorption in human body organs using medical internal radiation dose (MIRD) and GATE code methods, after animal injection. In this study, the amount of absorbed dose in different organs (spleen, kidney, Lung, Pancreas, Heart, Adrenal, Intestine, Stomach, and Liver) were calculated for 1-MBq accumulation of ¹⁷⁷Lu-BBN-GABA-DOTA in source organs (spleen, kidney, Lung, Pancreas, Heart, Adrenal, Intestine, Stomach, and Liver) using Monte Carlo Simulation (GATE code) with Zubal phantom. Moreover, compared with MIRD method, the results of the simulation showed considerable consistency. It was estimated that a 1-MBq administration of ¹⁷⁷Lu-BBN-GABA-DOTA to the human body would result in an absorbed dose of 1.07E-02 mGy and 4.97E-02 (MIRD method) and 1.26E-02 mGy and 5.19E-02 (Gate code) in the Pancreas and adrenal 120 h after injection, respectively. The highest and lowest percentage differences between MIRD and Gate results are related to the Pancreas and spleen, respectively. Finally, the results showed that there is a good agreement between MIRD method and Gate code simulation for absorbed dose estimation.

ASSESSMENT OF WHOLE BODY, SKIN AND EYE LENS DOSES OF THE INTERVENTIONAL RADIOLOGISTS AT SELECTED HOSPITALS IN IRAN

High radiation doses to the body may lead to the stochastic/deterministic effects of ionizing radiation on the critical organs as well as causing the cataract in eye lens of the clinical staff in interventional radiology. In this study, the received doses of the eyes, skin and whole body of 38 clinical staff including physicians, residents, nurses and radiotechnologists in cardiac angiography departments in three selected hospitals were assessed using personal dosemeters during two bimonthly dosimetry periods. Moreover, the correlation coefficients among the measured dose components including eye lens dose, skin dose and whole body dose equivalent in both area of under and over their lead-apron were calculated for all these occupational groups. The results show that the occupational annual dose values of the clinical staff are below the annual dose limits recommended by International Commission on Radiation Protection. Furthermore, among the measured dose components, the highest correlation coefficient value was obtained between the eye lens dose and personal dose equivalent measured over the lead apron for all the occupational groups.

Optimized fabrication and characterization of TiO2–Nb2O5–Al2O3 mixed oxide nanotube arrays on Ti–6Al–7Nb

The TiO₂–Nb₂O₅–Al₂O₃ mixed oxide nanotube arrays on Ti67 are the promising nanostructured materials for metallic orthopaedic implants.

Semi-empirical relationship for photon buildup factor in soft tissue and water

Buildup factor of gamma and X-ray photons in the energy range of 0.2-2 MeV in water and soft tissue is computed using Monte Carlo code MCNP4C. The results are compared with the buildup factor data of pure water. A new relationship estimating buildup factor as a function of penetration depth, Compton scattering and energy absorption cross sections is introduced. The new relationship estimates buildup factor with 5 % deviation compared with the existing data.

Development of a high efficiency personal/environmental radon dosimeter using polycarbonate detectors

Passive radon dosimeters, based on alpha particle etched track detectors, are widely used for the assessment of radon exposure. These methods are often applied in radon dosimetry for long periods of time. In this research work, we have developed a highly efficient method of personal/environmental radon dosimetry that is based upon the detection of alpha particles from radon daughters, (218)Po and (214)Po, using a polycarbonate detector (PC). The radon daughters are collected on the filter surface by passing a fixed flow of air through it and the PC detector, placed at a specified distance from the filter, is simultaneously exposed to alpha particles. After exposure, the latent tracks on the detector are made to appear by means of an electrochemical etching process; these are proportional to the radon dose. The air flow rate and the detector-filter distance are the major factors that can affect the performance of the dosimeter. The results obtained in our experimental investigations have shown that a distance of 1.5 cm between the detector and the filter, an absorber layer of Al with a thickness of 12 microm and an air flow rate of 4 l min(-1) offer the best design parameters for a high efficiency radon dosimeter. Then, the designed dosimeter was calibrated against different values of radon exposures and the obtained sensitivity was found to be 2.1 (tracks cm(-2)) (kBq h m(-3))(-1). The most important advantages of this method are that it is reliable, fast and convenient when used for radon dose assessment. In this paper, the optimized parameters of the dosimeter structure and its calibration procedure are presented and discussed.

Bunk beds--a still underestimated risk for accidents in childhood?

A retrospective analysis of 218 bunk-bed accidents and a random sample survey with 991 family interviews were performed in order to establish guidelines for bunk-bed accident prevention. Falls from the top bed during sleep (35.1%) or while playing (34.4%) and falling off the ladder (23.2%) are the leading causes of bunk-bed accidents. Of the 218 children, 91 (41.7%) had sustained major injuries, including 3 polytrauma, 7 skull fractures, 44 cerebral concussions, 33 long bone fractures, 2 Lisfranc injuries, and 2 lacerations of the spleen. Of these accidents, 58.3% resulted in minor injuries with 18 fractures in other locations than the long bones or cranial vault, 89 contusions and sprains, 18 skin lacerations and 2 tooth fractures. A total of 23.8% of the accidents occurred in children under 3 years of age. The random sample survey demonstrated that in relation to age groups of children 30.8% (0%-45.8%) of families interviewed had been using bunk beds, with peaks at 3 years (29.8%), 7 years (36.5%) and 11 years (45.8%) of age. Of these bunk beds, 75.3% were equipped with side-rails, 57.3% had placed carpets alongside the bunk bed and 43.0% had used night lights.

CONCLUSION

There is only one recommendation: no bunk beds!!!

Periodontal files--a comparative study

Periodontal files are used by many dentists for instrumentation of root surfaces as a part of periodontal treatment. The purposes of this study were: 1) to examine, evaluate, and compare several periodontal files in 3 different conditions: new, used, and used/sharpened and 2) to evaluate the efficacy of 5 sharpening devices. The main characteristics observed included: the number, shape, and interval of blades; the active, rake, and lip angles; changes induced by wear; the influence of sharpening; and the type of metal surfaces comprising the blades. There was a wide range of active angles on each individual file, from a high of 75 degrees to a low of 51 degrees. The range of active angles for all blades on all new files was even greater, from a high of 87 degrees to a low of 30 degrees. Wear, observed on some but not all blades, was not extensive and appeared either as abrasion or, occasionally, as fracture of the blade edge. Sharpness scores (5 = sharpest and 1 = dullest) for new file blades were also extremely variable and spanned the full range of values, with a majority of blades scoring 3.5 and below. Attempts to sharpen files with several devices produced inconsistent results. All 5 sharpening devices had significant shortcomings. It was concluded that the extreme ranges both in active angles and in sharpness scores probably have a significant influence on effectiveness of root instrumentation.

[Spontaneous splenic rupture during portal triad clamping]

A 45-year-old woman underwent a resection for a hepatic metastasis of the liver caused by a carcinoma of the colon. Shortly after the Pringle maneuver severe hemorrhage from the upper left quadrant of the abdomen was observed. Exploration revealed a spontaneous parenchymal laceration of the spleen.