Calculation of shielding performance of CRT concrete for proton therapy and optimal shielding design of treatment delivery room.

Proton therapy is becoming increasingly popular worldwide, and its shielding must be considered. The cathode ray tube (CRT) material is a glass containing heavy metal elements, these materials have become a good choice for the production of radiation-proof concrete. In this study, the ability of concrete containing CRT fragments as shielding materials for proton therapy rooms is evaluated in terms of neutron shielding ability, neutron reflection ability, ambient dose equivalent rate, and induced radioactivity. In addition, this concrete is compared with commonly used ordinary concrete, boron-containing concrete, and barite concrete. The results show that with the increase of CRT content (10%-90%), the transmitted neutron fluence decreases continuously (5.06 × 10-10 - 1.77 × 10-10 cm-2/particle), and the reflection of neutrons gradually increases (2.64 × 10-9 - 3.20 × 10-9 cm-2/particle), resulting in an increased potential to patients. When 50% CRT concrete is used, the ambient dose equivalent rate is below 3.80 µSv/h/nA, and 90% CRT concrete is below 3.11 µSv/h/nA. The trend of radionuclide activity of induced radioactivity from 0 to 60 min after irradiation for concrete with different CRT contents is 2.74-5.38 × 10-3 Bq/cm3, and the maximum photon fluence is 8.13 × 102 cm-2. In conclusion, the optimization model of the three-layer shielding structure of ordinary concrete, high CRT content concrete, and boron-containing concrete is proposed with ambient dose equivalent rate less than 1.88 µSv/h/nA, minimizing the reflected neutrons to which the patient is exposed. This study shows the protection performance of CRT concrete is better than ordinary concrete and barite concrete.

[1896: How nascent radiotherapy gathered Roentgen, Pasteur and the Lumière brothers]. / 1896 : comment la radiothérapie naissante a pu réunir Roentgen, Pasteur et les frères Lumière.

On the 4th July, 1896, in his medical office of Les Échelles (Savoie, France), Victor Despeignes performed the very first radiotherapy against cancer, documented by indisputable proofs. However, the intellectual and practical approach that leads to this first radiotherapy may appear unexpected to date. Indeed, it is likely that the treatment that Despeignes applied to his neighbour, who did not suffer from stomach cancer, was born with the indirect support of the Lumière brothers, on the basis of a biological theory (the parasitory theory of cancer) that is irrelevant today, with an experimental protocol based on experiments performed on tuberculosis et in a bifractionated model linked by the constraints of a district medical doctor.

Environmental risk assessment of CRT and PCB workshops in a mobile e-waste recycling plant.

The mobile e-waste recycling equipment was chosen as the object of this study, including manual dismantling, mechanical separation of cathode ray tubes (CRTs), and printed circuit boards (PCBs) in the two independent workshops. To determine the potential environmental contamination, the noise, the heavy metals (Cu, Cd, Pb), and the environmental impacts of the e-waste recycling processes in the two workshops of the mobile plant have been evaluated in this paper. This study determined that when control measures are employed, the noise within the two workshops (<80 dB) will meet the national standards. In the CRT workshop, Pb was the most polluting metal, with 2.3 µg/m(3) and 10.53 mg/g in the air and floor dust, respectively. The result of a health risk assessment shows that noncancerous effects are possible for Pb (hazard index (HI) = 3.54 in the CRT workshop and HI = 1.27 in the PCB workshop). The carcinogenic risks to workers for Cd are relatively light in both the workshops. From the results of life cycle assessment (LCA), it can be seen that there was an environmental benefit from the e-waste recycling process as a whole.

Inactivation effect of electron beam irradiation on fungal load of naturally contaminated maize seeds.

BACKGROUND: This work focuses on the effect of accelerated electrons (0.1-6.2 kGy) on naturally attached fungi on maize seeds. The fungal viability and corresponding inactivation kinetics were determined. The inactivation and radiosensitivity of the most abundant species in the contaminant fungi detected on maize seeds (Aspergillus spp., Penicillium spp. and Fusarium spp.) are discussed. RESULTS: Fungal contamination of maize seeds decreased significantly with increasing irradiation dose. The survival curve of total fungi determined by the blotter test showed a sigmoidal pattern that can be attributed to the mixture of fungal subpopulations with different radiation sensitivities. This behaviour could be modelled well (R² = 0.995) with a modified Gompertz equation. The predicted values for shoulder length and inactivation rate were 0.63 ± 0.10 kGy and 0.44 ± 0.04 kGy⁻¹ respectively. The sensitivity of the most common fungi to electron beam treatment followed the order Penicillium spp. > Fusarium spp. > Aspergillus spp., with total inactivation at irradiation doses of 1.7, 2.5 and 4.8 kGy respectively. CONCLUSION: The effect of electron beam treatment against fungi on naturally contaminated maize seeds depended on irradiation dose, allowing the control of maize fungal load.

PM10 and PM2.5 and health risk assessment for heavy metals in a typical factory for cathode ray tube television recycling.

The representative waste television recycling process was chosen as the object of this study, including manual dismantling and mechanical separation of printed circuit boards (PCBs) and cathode ray tubes (CRTs) in two independent workshops. During these recycling processes, fine particulate matter and heavy metals will be released into the air to impact the environment and the health of the workers. The mass concentrations of PM2.5 (particles below 2.5 µm diameter) in mechanical and dismantling workshops ranged from 252.6 to 290.8 µg/m(3) and from 112.7 to 169.4 µg/m(3), respectively. The average concentration of PM2.5 around the workshop was 98.5 µg/m(3). Meanwhile, the contents of PM10 (particles below 10 µm diameter) were all below the risk threshold, except that (360.4 µg/m(3)) monitored in the mechanical workshop. In two workshops, Pb (20.46 and 6.935 mg/g) was the most enriched metal in the PM2.5 samples, while in PM10, the concentration of Cu (27.76 and 31.80 mg/g) was the largest. The concentration of Cd was the least in both PM10 and PM2.5. Health risk assessment showed that the total hazard indexes for non-carcinogenic metal in PM2.5 monitored in mechanical and dismantling workshops and in the southeast of the workshops were 7.61, 3.01, and 1.57, respectively, all above the safety level. Furthermore, Pb (7.28 and 3.01) might possibly have a non-carcinogenic effect on the workers in two workshops, and the sequence of the hazard quotient (HQ) through the three exposure ways was ingestion > dermal contact > inhalation. The lifetime cancer risk of four targeted metals was Cr > Ni > Pb > Cd, which could be proven in all monitoring samples. This study aims to provide a large amount of valid data for the State Environmental Protection Department to develop relevant environmental standards and for companies to improve the waste television recycling system to be more efficiently and environmentally friendly.

Extraction of metallic lead from cathode ray tube (CRT) funnel glass by thermal reduction with metallic iron.

A novel and effective process of thermal reduction treatment with the addition of metallic iron (Fe(0)) to recover lead from cathode ray tube (CRT) funnel glass is introduced. The key technological breakthrough of this process is the use of a relatively lower temperature and an inexpensive reducing agent to extract the metallic lead. The influences of temperature, the reducing agent content, and the holding time for lead reduction were examined to determine the optimal extraction efficiency. The lead extraction efficiency first increased and then decreased with increasing temperature. The maximum lead extraction efficiency occurred at 700 °C. The growth of crystalline lead first increased significantly with an increase in the Fe content, reaching maximum growth at an Fe addition of 50 wt %. The most effective treatment time was determined to be 30 min, as the vitrification of lead back to the glass matrix occurred under longer treatment times. The experimentally derived results indicate that a 58 wt % lead extraction can be achieved with the optimized operational parameters (50 wt % Fe addition, heating at 700 °C for 30 min) in a single extraction operation.

Johann Wilhelm Hittorf and the material culture of nineteenth-century gas discharge research.

In the second half of the nineteenth century, gas discharge research was transformed from a playful and fragmented field into a new branch of physical science and technology. From the 1850s onwards, several technical innovations-powerful high-voltage supplies, the enhancement of glass-blowing skills, or the introduction of mercury air-pumps- allowed for a major extension of experimental practices and expansion of the phenomenological field. Gas discharge tubes served as containers in which resources from various disciplinary contexts could be brought together; along with the experimental apparatus built around them the tubes developed into increasingly complex interfaces mediating between the human senses and the micro-world. The focus of the following paper will be on the physicist and chemist Johann Wilhelm Hittorf (1824-1914), his educational background and his attempts to understand gaseous conduction as a process of interaction between electrical energy and matter. Hittorf started a long-term project in gas discharge research in the early 1860s. In his research he tried to combine a morphological exploration of gas discharge phenomena-aiming at the experimental production of a coherent phenomenological manifold--with the definition and precise measurements of physical properties.

Electron beam radiation effects on UHMWPE: an EPR study.

Electron paramagnetic resonance (EPR) technique has been employed to detect and characterise a series of different radical species generated in ultra-high molecular weight polyethylene (UHMWPE) via electron beam irradiation. Three different radical species have been found and assigned on the basis of their EPR spectra and of the related computer simulations. A secondary alkyl species, the prevalent one, is present immediately after irradiation, an allyl species appears only 24 h after irradiation when the alkyl species disappears.The third species, clearly visible at high microwave power only, has been observed for the first time and assigned to a tertiary alkyl carbon radical, whose formation is strictly connected with a Y-shape crosslink and a migration of the unpaired electron on a carbon atom localised in an adjacent position.

[Reparative regeneration of rat skin under influence of hollow cathode lamp (HCL) with manganese and copper line spectrum emission].

Influence of local light exposure by hollow cathode lamp with typical manganese and copper (HCL-Mn, Cu) line emission spectrum on posttraumatic regeneration rate of rat skin has been investigated. We performed the comparative analysis of the morphology and the differentiation ability of rat skin on the 15th and 24th days after full-thickness skin wound had been inflicted on rat dorsums. On the 15th day after injury, the experimental group (daily 30 s exposure for two weeks) showed scab loss, re-epithelialization, and hair regrowth, in contrast to the control rats, where scabs were still observed on the 24th day. Histological analysis revealed that in contrast to the control group the treatment with HCL-Mn, Cu resulted in the increased number of hair follicles and sebaceous glands, the decreased number of blood vessels and horizontal orientation of collagen fibers. The immunohistochemistry for OX-62 revealed that the number of dermal dendritic cells in the experimental groups was maximal on the 15th day, and then decreased to the 24th day after injury. The number of dermal dendritic cells was significantly lower in the control group. The immunohistochemistry for pan-keratins in the control animals revealed a high number of cells expressing different types of keratins, distributed in the main part of the epidermis on the 15th day after surgery, whereas in the experimental group the number of such cells was significantly lower and the cells were concentrated more close to the external part of the epidermis. The number of cells stained for keratin 19 was higher in the experimental group on the 15th day after surgery, whereas this number decreased in this group on the 24th day after surgery as compared to the control group. Thus, typical manganese and copper line spectrum emission emitted by hollow cathode lamp stimulates innate immunity, accelerates restoration of derma, skin epithelium and other skin derivates, and stimulates wound healing in general.

Comparison of 5-megapixel cathode ray tube monitors and 5-megapixel liquid crystal monitors for soft-copy reading in full-field digital mammography.

PURPOSE: To retrospectively compare the image quality, lesion detection, and the diagnostic efficacy of 5-megapixel (MP) cathode ray tube monitors (CRTs) and 5-MP liquid crystal display monitors (LCDs) for soft-copy reading in full-field digital mammography (FFDM). MATERIALS AND METHODS: Informed consent was waived by the Institutional Review Board for the data analysis. A total of 220 cases were compared with two 5-MP (2048×2560 pixels) CRTs and two 5-MP (2048×2560 pixels) LCDs. Nine aspects of image quality (brightness, contrast, sharpness, noise, skin, fat, retromamillary space, glandular tissue, and detection of calcifications) were evaluated. In addition, the detection of breast lesions (mass, calcifications) and diagnostic efficacy, based on the BI-RADS classification, were correlated with histologic results (n=70) and follow-up (n=150). RESULTS: Each aspect of the image quality was rated significantly better for 5-MP LCDs (p<0.05) compared to the 5-MP CRTs. With 5-MP CRTs, 31 masses and 119 calcifications were detected, compared to 30 and 121 with 5-MP LCDs. The differences in diagnostic efficacy between 5-MP CRTs and 5-MP LCDs were not significant (p=0.157) although 5-MP CRTs yielded two false-negative results. Both lesions were rated BI-RADS 3 with 5-MP CRTs. Both were invasive carcinomas at histology. The sensitivity, specificity, positive and negative predictive values, and accuracy were 0.966, 0.975, 0.933, 0.988, and 0.973 for 5-MP CRTs, compared to 1.0, 0.963, 0.903, 1.0, 0.973 for 5-MP LCDs. CONCLUSION: The image quality of 5-MP LCDs is significantly better than that of 5-MP CRTs for soft-copy reading in FFDM, based on histologic and follow-up correlation. However, lesion detection and diagnostic efficacy are comparable to 5-MP CRTs. The interpretation of the false-negative results suggests that the characterization of breast lesions with FFDM is not defined solely by the monitors, but is strongly influenced by the radiologist.

LCD versus CRT monitors for digital mammography: a comparison of observer performance for the detection of clustered microcalcifications and masses.

BACKGROUND: There are two types of soft-copy display of digital mammograms, cathode-ray tube (CRT) and liquid-crystal display (LCD) monitors, and these present different resolutions and noise characteristics. PURPOSE: To compare observer performances for the detection of clustered microcalcifications and masses in digital mammograms, using LCD and CRT monitors. MATERIAL AND METHODS: Four radiologists evaluated 100 digital mammograms. Of these, 28 mammograms depicted clustered microcalcifications (12 benign, 16 malignant), 18 depicted masses (10 benign, eight malignant), and 54 depicted no apparent abnormality. The images were stored uncompressed as Digital Imaging and Communications in Medicine (DICOM) files and randomized for two sessions of soft-copy reading. The readers independently read all cases displayed on two 5-megapixel LCD and two CRT monitors with an interval of 3 months. Observers were asked to rate using a five-point scale the likelihoods of microcalcifications and masses independently. Receiver operating characteristic analysis was used to analyze results. RESULTS: For the LCD and CRT monitors, average area-under-the-curve (A(z)) values for microcalcification detection were 0.977 (0.976, 0.970, 0.980, and 0.983 for the four readers) and 0.958 (0.910, 0.990, 0.976, 0.956), respectively. Corresponding A(z) values for masses were 0.971 (0.955, 0.990, 0.949, 0.989) and 0.944 (0.928, 0.966, 0.955, 0.925). No statistically significant difference was detected between the two monitor types (P>0.05). CONCLUSION: The LCD and CRT monitors are comparable in terms of detecting clustered microcalcifications and masses in digital mammograms.