Suspended Screen Research Articles

Semi-automatic positioning of the protective screen based on integration with C-arm X-ray device

In fluoroscopy guided interventional procedures, a ceiling suspended screen is used to protect personnel for scattered X-ray radiation arising from patient treatment. The correct positioning of the screen is crucial for proper occupational radiation protection. The proposed solution in this paper provides reliable and efficient protection from scattered radiation, based on an X-ray device and the protective screen merging into one system via an appropriate interface. After the initial manual positioning, automatic repositioning of the screen is executed, by curving the screen laterally, clockwise or counterclockwise, and then with the upper or lower edge forward. All potential clinical situations were analyzed, considering the need for screen position correction: the semi-automatic solution is designed and realized to follow medical procedure in order to maintain an efficient level of staff radiation protection. Furthermore, the assessment of the occupational radiation dose, provided for screen position optimization, will be included into the radiation dose structural report. With application of the universal interface, the presented solution can be applied not only to newly manufactured ones, but to existing C-arm X-ray devices as well.

Helping to know if you are properly protected while working in interventional cardiology

Occupational protection is still a challenge for interventional cardiology. One of the main problems is the occasional improper use of the ceiling suspended screen. We present a methodology to audit the correct use of the shielding using active electronic dosimeters. To improve the protection, we suggest the use of an alert based on the ratio between the occupational dose per procedure, measured by a personal electronic dosimeter over the lead apron, and the dose measured by an unshielded dosimeter, located at the C-arm. The new electronic dosimeters and the automatic dose management systems allow processing the dosimetric data for individual procedures and for the radiation events, sending the values (wireless) to a central database. We selected six interventional cardiologists and analysed 385 interventional procedures involving about 30 000 radiation events. Our results suggest that for individual procedures, standard values of the ratio between operator dose and the C-arm reference dose, should be between 1%–2% for a proper use of the shielding. Percentage values ≥5%–10% for individual procedures, require an analysis of the different radiation events to identify the lack of occupational protection and suggest corrective actions. In our sample, half of the operators should improve the use of the shielding in around 20% of the procedures. Using this ratio as an alert to operators allows optimising occupational radiation protection and discriminating between high occupational doses derived from complex procedures and high doses due to the improper use of the protective screen.

Radiation Exposure of Surgical Team During Endourological Procedures: International Atomic Energy Agency-South-Eastern European Group for Urolithiasis Research Study.

Introduction: Fluoroscopy-guided endourology procedures require proper radiation protection to minimize radiation risk. This multicenter study aimed at investigating radiation protection practice and related radiation exposure of operating team members. Materials and Methods: Six endourology centers from the South-Eastern European Group for Urolithiasis Research answered questionnaires and collected data of 315 procedures performed within a 3-months period, with simultaneous measurement of dose to staff and dose area product (DAP) to patient. A pair of calibrated personal dosimeters, one for body and one for eye-lens dose, was worn by all key staff members. Dosimeters were centrally calibrated, measured, and analyzed. Results: The annual workload ranged from 173 to 865 procedures per center. Practice of personal dose monitoring and use of radiation protection shielding was found to be inconsistent. Lead aprons and thyroid collars were used by all, whereas protective eyewear was used in only half of centers. Due to the regular use of protective aprons, the whole-body dose of all 44 monitored staff members was safely below the regulatory dose limits. Eye-lens dose of 17 (14 urologists and 3 assisting staff) was above the dosimeter detection level, and dose per procedure varied from <10 to 63 μSv. The highest annual eye-lens dose of 13.5 mSv was found for the surgeon in the busiest department by using an over-the-couch X-ray tube without a ceiling suspended screen. Working closer to patient body with no protection resulted in a six-time higher eye-lens dose per DAP for a surgeon compared with others in the same center. Lower eye-dose per procedure was associated with lower DAP to patient and with the use of an under-the-couch tube, lower fluoroscopy pulse rate, collimation, fluoroscopy time, and acquired images. Conclusions: The study results call for the need to establish standard protocols about use of fluoroscopy during endourology procedures and to increase radiation protection knowledge and awareness of surgical staff.

41A Influence of radiation protection equipment on the operator and patient dosimetry in coronary angiography

Introduction To reduce exposure to the workers in interventional radiology, Collective Protection Equipment (CPE) are used (low lead curtains and their vertical extension, ceiling suspended screen …). For the same purpose, radio-attenuator soft screens (RADPAD®) have been developed. The objective of this study is to evaluate the influence of the CPE and the RADPAD® on the operator’s dosimetry in coronary angiography; we also measured patient’s skin-dose without and with the utilization of the RADPAD®. Methods Firstly, the interventional radiology equipment has been positioned at the tube incidence LAO 0°. The dose at different heights along the operator’s body (50, 75, 100, 125, 150 and 175 cm) was measured without the use of any CPE, and then by adding them successively (low curtains, vertical extension of the low curtains, ceiling suspended screens and then the radio-attenuator screen RADPAD®). Secondly, the skin dose of a phantom placed on the patient’s table was measured at three different distances from the ceiling screen, with and without RADPAD® at a tube voltage of 68 kVp in LAO 0° and then at 125 kVp in LAO 0° and LAO 30°. Results The use of the three CPE shows an attenuation of the radiation dose by 76% at the height of 175 cm along the operator’s body, it increases by 3.8% when using the RADPAD®. At low voltage, the use of the RADPAD® increases patient’s dose by 13% in the region near the ceiling screen. However, it attenuates the dose by 85.5% at 26 cm form this latter. At high voltage, the dose decreases at all of the three measure points; the effect of the RADPAD® varies depending on the distance from the screen and the tube angle. Conclusions Collective Protection Equipment are effective to decrease operator’s exposure in coronary angiography. The RADPAD® allows a significant reduction of the patient’s dose far the ceiling screen.

Radiation protection for surgeons and anesthetists: practices and knowledge before and after training

The use of radiological activity in the operating room (OR) and a regulatory decrease of the eye lens dose warrant an assessment of how medical staff are protected from radiation. This study aims to evaluate practices and knowledge in radiation protection (RP) for OR doctors before and after training. A descriptive study of surgeons and anesthetists in a French public hospital center was conducted in 2016. An ad hoc questionnaire concerning occupational practices and knowledge about RP was distributed before and one month after RP training. Among 103 doctors attending the training, 90 answered the questionnaire before the training. Results showed a lack of knowledge and good practice in RP. Most of the participants (86.7%) had never been trained in RP and recognized insufficient knowledge. Most of them (92.2%) wore a lead apron, 50.0% a thyroid-shield, 5.6% lead glasses, 53.3% a passive dosimeter and 17.8% an electronic dosimeter. None of them benefitted from collective protective equipment such as a ceiling suspended screen. The questionnaire following the training was completed by only 35 doctors. A comparison before and after training results showed an improvement in knowledge (scores of correct responses: 5.5/16 before and 9.5/16 after training) but not in RP good practices (scores of correct responses: 3.2/7 before and 3.3/7 after training). One training session appears to be insufficient to improve the application of the safety rules when x-rays are used. Communication needs to be improved regarding RP among anesthetists and surgeons, such as training renewal, workstation analysis in OR related to x-ray use and occupational medical follow-up. Otherwise, radiological risks in OR need to be given better consideration, such as radio-induced cataract risk. It is necessary to encourage the use of dosimeters and protective equipment and to strengthen access to lead glasses and collective protective equipment, such as ceiling suspended screens. All these recommendations ensure the received dose is reduced to as low as is reasonably achievable.

Prostatic artery embolization: radiation exposure to patients and staff

The aim of this study was to evaluate the radiation doses to patients and staff received from the first cases of prostatic artery embolization (PAE) conducted in a public hospital in Recife, Brazil. Five PAE procedures for 5 men diagnosed with benign prostatic hyperplasia were investigated. In order to characterize patient exposure, dosimetric quantities, such as the air kerma-area product (PKA), the cumulative air kerma at the interventional reference point (Ka,r), the number of images, etc, were registered. To evaluate the possibility for deterministic effects, the peak skin dose (PSD) was measured using radiochromic films. For evaluation of personal dose equivalent and effective dose to the medical staff, thermoluminescent dosemeters (TLD-100) were used. The effective dose was estimated using the double dosimetry alghoritm of von Boetticher. The results showed that the mean patient’s PSD per procedure was 2674.2 mGy. With regard to the medical staff, the mean, minimum and maximum effective doses estimated per procedure were: 18 μSv, 12 μSv and 21 μSv respectively. High personal equivalent doses were found for the feet, hands and lens of the eye, due to the use of multiple left anterior oblique projections and the improper use of the suspended lead screen and the lead curtain during procedures.

Alloyed screens: Harry Bertoia and the Manufacturers Hanover Trust Building – 510 Fifth Avenue

Harry Bertoia was a prolific and innovative artist of the post-war period. His contributions to sculpture have been largely overlooked as a result of his connections with commercial design and architecture. Bertoia’s sculpture, however, reflected a moment of scientific discovery and technological innovation, when artists, designers, and architects created a visual language in response to these developments, often through the use of new materials, and when corporate collaborations were not met with the same cynicism that they are today. This article focuses on two of Bertoia’s sculptures: a bronze standing screen for Gordon Bunshaft’s 1954 landmark Manufacturers Hanover Trust Building in New York and a suspended altarpiece screen for Saarinen’s chapel at the Massachusetts Institute of Technology in 1955. Both sculptures partition space while simultaneously functioning as integral, unifying elements within the architectural structure. They furthered the ideology and vision – idealistic or not – of mid-century modernist architecture and the promise of modern life.

Efficacy of Radiation Safety Glasses in Interventional Radiology

This study was designed to evaluate the reduction of the eye lens dose when wearing protective eyewear in interventional radiology and to identify conditions that optimize the efficacy of radiation safety glasses. The dose reduction provided by different models of radiation safety glasses was measured on an anthropomorphic phantom head. The influence of the orientation of the phantom head on the dose reduction was studied in detail. The dose reduction in interventional radiological practice was assessed by dose measurements on radiologists wearing either leaded or no glasses or using a ceiling suspended screen. The different models of radiation safety glasses provided a dose reduction in the range of a factor of 7.9-10.0 for frontal exposure of the phantom. The dose reduction was strongly reduced when the head is turned to the side relative to the irradiated volume. The eye closest to the tube was better protected due to side shielding and eyewear curvature. In clinical practice, the mean dose reduction was a factor of 2.1. Using a ceiling suspended lead glass shield resulted in a mean dose reduction of a factor of 5.7. The efficacy of radiation protection glasses depends on the orientation of the operator's head relative to the irradiated volume. Glasses can offer good protection to the eye under clinically relevant conditions. However, the performance in clinical practice in our study was lower than expected. This is likely related to nonoptimized room geometry and training of the staff as well as measurement methodology.

The Relationship between Serum Osteopontin Levels and Isolated Coronary Artery Ectasia

Aims: Occupational head exposure of radiation was suggested to be associated with brain tumors in interventional cardiologists. The brain is of particular interest, because it is one of the least protected organs during interventional procedures. Our aim was to investigate the efficacy of the lead cap in radiation protection of the head and compare it with that of a ceiling mounted lead glass screen in a real life setting. Our secondary goal was to test the comfort and convenience of the lead cap when worn on a regular daily basis. Methods-Results: Radiation dose to the operator was recorded by the three dosimeters placed outside the lead cap, inside the cap and outside the apron at the level of trunk for a total of 18 months. Only the lead cap (Burkhart Roentgen International, St Petersburg, Florida, USA) but not the ceiling suspended protective glass screen was used during the first three months of measurement of radiation dose to the head. Later concomitant use of both protection devices was analyzed. The dosimeter outside the cap recorded a dose of 2.77 mSv radiation when the ceiling mounted screen was not used during the first 3 months. The doses were 2.4 to 12.5 times higher in comparison to the measurements that were recorded when the ceiling suspended screen was used. However, a remarkable dose of radiation (ranged between 1.16-0.22 mSv) was received by the operators head despite the use of ceiling mounted screen. Yet, even without the protection of the ceiling mounted screen, the dose recorded by the dosimeter inside the lead cap during the first period was <0.1 mSv (Table). As expected, the doses to the head recorded by the dosimeter inside the cap during the next 15 months period were also less than 0.1 mSv with the use of the ceiling mounted screen. Therefore, a cap with only 0.5 mm lead equivalence reduced the dose to the head to ignorable levels regardless of the use of the screen. Conclusions: A cap with only 0.5 mm lead equivalence was much more protective than the mounted screen and reduced the dose to the head to ignorable levels regardless the use of the mounted screen. Although being a subjective conclusion, the operator regularly wearing the lead cap reported that the lead cap is reasonably comfortable and offers an acceptable wearing comfort when used on daily practice.

Seeing the Light: A Classroom-Sized Pinhole Camera Demonstration for Teaching Vision

We describe a classroom-sized pinhole camera demonstration (camera obscura) designed to enhance students' learning of the visual system. The demonstration consists of a suspended rear-projection screen onto which the outside environment projects images through a small hole in a classroom window. Students can observe these images in a darkened classroom. Instructors can demonstrate the function of the lens and pupil and the structural basis for nearsightedness and farsightedness. Students who saw the demonstration as part of a lecture on the visual system learned more (i.e., showed greater performance gains from pretest to posttest) than a comparable group of students who received the lecture only. Students reacted favorably to the demonstration. These data suggest that incorporating the demonstration into class presentations on vision can improve student learning.

Absorção de água e potencial fisiológico em sementes de soja de diferentes tamanhos

A absorção de água por sementes de soja, em função do tamanho, ocorre em diferentes intensidades podendo ter relação com seu potencial fisiológico. A marcha de absorção de água em sementes de soja e sua relação com o potencial fisiológico foram avaliados no presente trabalho. Sementes do cultivar BRS-155 foram classificadas, com base na espessura, em peneiras de crivos oblongos (6,75; 6,35; 5,95; 5,55; 5,15; 4,75 e 4,35 x 19 mm). As retidas nas peneiras 6,35; 5,55 e 4,75 x 19 mm foram submetidas à hidratação controlada (pré-condicionamento) com posterior secagem até atingirem o grau de umidade inicial. A evolução da hidratação foi avaliada por meio da pesagem das sementes de três em três horas, em oito períodos e 5 repetições, e, o potencial fisiológico, pelos testes de germinação, envelhecimento acelerado e condutividade elétrica, antes e após a hidratação. As sementes submetidas à hidratação apresentaram diferenças de qualidade, em relação às não hidratadas, exclusivamente no teste de condutividade elétrica. Entre os diferentes tamanhos, as sementes retidas na peneira 4,75 mostraram qualidade inferior às demais no tratamento sem hidratação, em todos os testes e, com exceção do envelhecimento acelerado sem hidratação, as retidas na peneira 5,55 mm apresentaram potencial fisiológico superior às dos demais tamanhos. A absorção de água é mais intensa em sementes menores e, de modo geral, as sementes de tamanho menor ou maior em 0,79 mm em relação às de tamanho médio, são de qualidade inferior.

Stromal cells derived from spleen or bone marrow support the proliferation of rat natural killer cells in long-term culture.

Rat nylon wool nonadherent bone marrow cells were propagated for up to 75 days in co-culture with stromal cells derived from either spleen or bone marrow. Interleukin (IL) 1 enhanced the ability of spleen stroma to support the long-term culture of natural killer (NK) cells, ostensibly by inducing these support cells to synthesize other cytokines. Flow cytometry studies indicated that the nylon wool separation procedure enriched the concentrations of mature NK cells from 7.9% to 38.1% for splenocytes and from 3.8% to 19.5% for bone marrow cells. Analyses of the adherent zones of suspended nylon screen NK cell cultures revealed substantial numbers of large granular lymphocytes that expressed NK 323+/MOM/3F12/F2- phenotypes. The presence of both mature and immature cells of the NK lineage in this matrix was inferred by the presence of both IL-2 receptor (IL-2R) positive and IL-2R negative, and OX-8+ and OX-8- NK 323+ cells over the greater than 4-month experimental period. Suspended nylon screen cultures displayed a greater potential for producing cytolytic cells than either co-cultures of bone marrow nonadherent cells on stroma monolayers or suspension cultures. The large granular lymphocytes produced in suspended nylon screen cultures could be transformed into active killers of YAC-1 targets by IL-2. In contrast to bone marrow nonadherent cells, more splenic nylon-wool-passed cells displayed a mature NK phenotype, but their proliferative potential and ability to be transformed into cytolytic cells by IL-2 decreased rapidly in culture. In the suspended nylon screen culture system, NK cells migrate from the underlying stroma in stages as they mature, retain their cytolytic potential, and manifest a capacity for self-renewal. Cultured cells were routinely dissociated into single cell suspensions via enzyme treatment and were reinoculated onto "fresh" nylon screen/stromal cell templates after passage through nylon wool columns. These co-cultures continued to generate cytolytic cells in numbers greater than those of the initial inoculum.

Differential effects of drugs upon hematopoiesis can be assessed in long-term bone marrow cultures established on nylon screens.

Hematotoxicity is associated with exposure to chemotherapeutic drugs and numerous other agents. Most measurements of the hematopoietic effects of prospective therapeutic drugs and environmental agents have been made in animal models. We tested the influence of various drugs on hematopoiesis in long-term cultures of Long-Evans rat bone marrow cells. These cultures were established on nylon screen-bone marrow stromal cell templates that were suspended in liquid medium. Previous phenotypic analyses of adherent zone cells of suspended nylon screen bone marrow cultures (NSBMC) using monoclonal antibodies and flow cytometry indicated that they maintain a multilineage character for extended periods in culture and display continuous proliferation of hematopoietic progenitors (colony-forming unit culture [CFU-C]). NSBMC of various ages were incubated for 21 hr with several concentrations of beta-D-cytosine arabinofuranoside, 5-fluorouracil, cyclophosphamide, or methotrexate. Adherent zone cells were dissociated enzymatically, phenotyped by flow cytometry, and assayed for colony-forming unit culture content. beta-D-cytosine arabinofuranoside, 5-fluorouracil, and methotrexate treatment of bone marrow cultures resulted in a dose-related diminution in colony-forming unit culture numbers in the adherent zones of NSBMC. Phenotypic analyses revealed similar trends but certain of these drugs manifested lineage specificities. Toxicity was also related to cyclophosphamide dose, but the presence of bone marrow stroma was necessary to demonstrate this effect in vitro. A subpopulation of these cells was found to metabolize ethoxyfluorescein ethyl ester to fluorescein after induction with 2,3,7,8-tetrachlorodibenzo-p-dioxin, an effect which was quantified by flow cytometry. NSBMC may be used to ascertain lineage-specific toxicities and evaluate the effects of drugs on the proliferation of hematopoietic progenitor cells.

Hematopoiesis on Suspended Nylon Screen-Stromal Cell Microenvironments

A three-dimensional culture system for the growth of primate and rodent bone marrow was developed in our laboratory. This method involves the seeding of stromal cells onto a nylon screen and the inoculation of fresh or cryopreserved bone marrow hematopoietic cells after stromal cell processes had extended across 3 to 4 out of every 5 mesh openings. Stromal cells attach, grow, and secrete matrix proteins which contribute to an intricate microenvironment for the support of multilineage hematopoiesis, which was observed for greater than 270 days in the rat model and for greater than 12 weeks in the human system, as evidenced by flow cytometry analysis and in vitro clonogenic assays. The adherent zones of these suspended nylon screen cultures consisted primarily of immature cells. These cultures could also be used as substrates for cytotoxicity measurements; treatment of rat bone marrow cultures of various ages with cytosine beta-D arabinofuranoside, cyclophosphamide, 5-fluorouracil, or methotrexate resulted in a dose-dependent decrease in CFU-C numbers and altered the phenotypic distribution of hematologic cells in the adherent zone. The use of a modification of this method to generate large numbers of active cytolytic cells after greater than 75 days culture of rat bone marrow-derived natural killer cells is described also. Suspended nylon screen bone marrow culture also has potential uses in genetic insertion and graft vs. host disease studies, blood component therapy, the evaluation of ex vivo purging programs, and in marrow expansion for transplantation.

Performance of a plastic suspended screen solar air heater

A 104 m 2 inflated plastic air heater with black plastic suspended screens as extra absorbing surfaces was tested and compared against an air heater without the screens. There was a definite improvement in collector performance with the addition of one or two suspended screens. The increase in efficiency more than offsets the cost of the screens.