Exposición a radiación ionizante en médicos residentes de ortopedia en un hospital de referencia.

OBJECTIVE: To describe and analyze the exposure to ionizing radiation of orthopedic residents. METHOD: A prospective study was carried out to evaluate the degree of exposure to ionizing radiation with a bandage dosimeter placed under the lead apron for medical residents for 10 months. An online survey measured the degree of knowledge about radiation safety. RESULTS: 54 resident physicians participated. 55.6% report having knowledge of the existence of radiological protection equipment and 40.7% report that they had previous training in its use. 77.8% use the leaded apron and 31.5% use thyroid protection. 81.5% were positioned less than 1 meter from the source of the X-ray production of the arc in C. The total mean radiation exposure was 2.9 ± 2.17 mSv (95% confidence interval: 1.25-14.28; p = 0.424). CONCLUSIONS: Orthopedic residents present radiation doses below the International Commission on Radiological Protection recommended limit. However, there is a lack of knowledge of radiation protection and as well as a lack of interest and ignorance of the adverse effects of radiation.

OBJETIVO: Describir y analizar la exposición a radiación ionizante de los residentes de ortopedia. MÉTODO: Se realizó un estudio prospectivo para evaluar el grado de exposición a radiación ionizante con un dosímetro de placa colocado debajo del mandil plomado a médicos residentes, por 10 meses. Mediante una encuesta en línea se midió el grado de conocimientos sobre seguridad radiológica. RESULTADOS: Participaron 54 médicos residentes. El 55.6% refiere tener conocimiento de la existencia de equipo de protección radiológica y el 40.7% refiere que tuvo entrenamiento previo en su uso. El 77.8% utiliza el mandil plomado y el 31.5% la protección tiroidea. El 81.5% se posicionó a menos de 1 metro de la fuente de producción de rayos X del arco en C. La exposición a la radiación media total fue de 2.9 ± 2.17 mSv (intervalo de confianza del 95%: 1.25-14.28; p = 0.424). CONCLUSIONES: Los médicos residentes de ortopedia presentan dosis de radiación menores que el límite recomendado por la International Commission on Radiological Protection. Sin embargo, existe una falta de conocimientos sobre protección radiológica, así como falta de interés e ignorancia de los efectos adversos de la radiación.

A closer look at the synthesis of 2-[18F]fluoroethyl tosylate to minimize the formation of volatile side-products.

BACKGROUND: 2-[18F]Fluoroethyltosylate ([18F]FEtOTs) is a well-known 18F-fluoroalkylating agent widely used to synthesize radiotracers for positron emission tomography. The widespread use of [18F]FEtOTs is due in part to its low volatility when compared to other halide and sulfonate building blocks. In this work, the radioactive volatile side-products formed during the synthesis of [18F]FEtOTs were identified and characterized for the first time, and an optimization of the reaction conditions to minimize their formation was proposed. RESULTS: In order to characterize the volatiles produced during [18F]FEtOTs synthesis, the reaction mixtures of both cold FEtOTs and [18F]FEtOTs were co-injected onto the HPLC system. The radioactive peaks corresponding to the volatile compounds were collected, analyzed through headspace gas chromatography mass spectrometry sampler (HS-GC-MS) and identified as vinyl fluoride ([19F]VF) and 2-fluoroethanol ([19F]FEOH). By using a rotatable central composite design with a two-level full factorial core of two factors (22), it was determined that temperature and time are independent variables which affect the generation of [18F]VF and [18F]FEOH during the radiosynthesis of [18F]FEtOTs. In addition, in order to reduce the formation of the volatiles ([18F]VF and [18F]FEOH) and increase the yield of [18F]FEtOTs, it was demonstrated that the molar ratio of base to precursor must also be considered. CONCLUSION: [18F]VF and [18F]FEOH are volatile side-products formed during the radiosynthesis of [18F]FEtOTs, whose yields depend on the reaction time, temperature, and the molar ratio of base to precursor. Therefore, special care should be taken during the radiosynthesis and subsequent reactions using [18F]FEOTs in order to avoid environmental contamination and to improve the yield of the desired products.

TIger II vs JUdkins Catheters for Transradial Coronary Angiography (TIJUCA Study): A Randomized Controlled Trial of Radiation Exposure.

BACKGROUND: In high-expertise transradial (TR) centers, the radiation exposure to patients during coronary angiography (CAG) is equivalent to transfemoral use. However, there is no definitive information during TR-CAG regarding the use of a single, dedicated catheter to impart less radiation exposure to patients. OBJECTIVE: We compare the radiation exposure to patients during right TR-CAG with Tiger II catheter (Terumo Interventional Systems) vs Judkins right (JR) 4.0/Judkins left (JL) 3.5 catheters (Cordis Corporation). METHODS: This multicenter, randomized, and prospective trial included 180 patients submitted to right TR-CAG, with the primary objective of observing radiation exposure to patients through the measurement of fluoroscopy time, air kerma (AK), and dose-area product (DAP) using Tiger II (group 1) vs JR 4.0 and JL 3.5 Judkins catheters (group 2). Secondary outcomes included contrast volume usage and the need to use additional catheters to complete the procedure (the crossover technique). RESULTS: Group 1 demonstrated reduced fluoroscopy time (2.47 ± 1.05 minutes in group 1 vs 2.68 ± 1.26 minutes in group 2; P=.01) and non-significant reduction of AK (540.9 ± 225.3 mGy in group 1 vs 577.9 ± 240.1 mGy in group 2; P=.34) and DAP (3786.7 ± 1731.7 µGy•m² in group 1 vs 4058.0 ± 1735.4 µGy•m² in group 2; P=.12). Contrast volume usage (53.46 ± 10.09 mL in group 1 vs 55.98 ± 10.43 mL in group 2; P=.13) and the need for additional catheters (5.56% in group 1 vs 4.44% in group 2; P>.99) were similar between groups. CONCLUSION: The Tiger II catheter was able to reduce radiation exposure to patients submitted to TR-CAG through a significant reduction in fluoroscopy time.

Dual fluoroscopy with live-image digital zooming significantly reduces patient and operating staff radiation during fenestrated-branched endovascular aortic aneurysm repair.

OBJECTIVE: Fenestrated-branched endovascular aneurysm repair (F/B-EVAR) is a complex procedure that generates high radiation doses. Magnification aids in vessel cannulation but increases radiation. The aim of the study was to compare radiation doses to patients and operating room staff from two fluoroscopy techniques, standard magnification vs dual fluoroscopy with live-image digital zooming during F/B-EVAR. METHODS: An observational, prospective, single-center study of F/B-EVAR procedures using Philips Allura XperFD20 equipment (Philips Healthcare, Amsterdam, The Netherlands) was performed during a 42-month period. Intravascular ultrasound, three-dimensional fusion, and extreme collimation were used in all procedures. Intraoperative live-image processing was performed with two imaging systems: standard magnification in 123 patients (81%) and dual fluoroscopy with live-image digital zooming in 28 patients (18%). In the latter, the live "processed" zoomed images are displayed on examination displays and live images are displayed on reference displays. The reference air kerma was collected for each case and represents patient dose. Operating staff personal dosimetry was collected using the DoseAware system (Philips Healthcare). Patient and staff radiation doses were compared using nonparametric tests. RESULTS: Mean age was 71.6 ± 11.4 years. The median body mass index was 27 kg/m2 (interquartile range [IQR], 24.4-30.6 kg/m2) and was the same for both groups. Procedures performed with dual fluoroscopy with digital zooming demonstrated significantly lower median patient (1382 mGy [IQR, 999-2045 mGy] vs 2458 mGy [IQR, 1706-3767 mGy]; P < .01) and primary operator radiation doses (101 µSv [IQR, 34-235 µSv] vs 266 µSv [IQR, 104-583 µSv]; P < .01) compared with standard magnification. Similar significantly reduced radiation doses were recorded for first assistant, scrub nurse, and anesthesia staff in procedures performed with dual fluoroscopy. According to device design, procedures performed with four-fenestration/branch devices generated higher operator radiation doses (262 µSv [IQR, 116.5-572 µSv] vs 171 µSv [IQR, 44-325 µSv]; P < .01) compared with procedures with three or fewer fenestration/branches. Among the most complex design (four-vessel), operator radiation dose was significantly lower with digital zooming compared with standard magnification (128.5 µSv [IQR, 70.5-296 µSv] vs 309 µSv [IQR, 150-611 µSv]; P = .01). CONCLUSIONS: Current radiation doses to patients and operating personnel are within acceptable limits; however, dual fluoroscopy with live-image digital zooming results in dramatically lower radiation doses compared with the standard image processing with dose-dependent magnification. Operator radiation doses were reduced in half during procedures performed with more complex device designs when digital zooming was used.

Aplicación forense de tecnología radiográfica dental portátil en Argentina: estado actual y perspectivas futuras / Forensic application of portable dental radiographic technology in Argentina: current status and future prospects

Objetivos: Mensurar los niveles de radiación de fuga y dispersión emanada a través de los blindajes y estructuras plomadas del tubo de rayos X de la unidad dental portátil NOMAD, controlando la retrodispersión con el uso del escudo protector de acrílico plomado adaptado en el extremo final del tubo localizador plomado. Se midieron las tasas de exposición dispersadas mediante un detector tipo Geiger-Müller y una cámara de ionización con respuesta en el rango de energías aportadas en diagnóstico por imágenes para la medición de la exposición directa y determinación posterior de las dosis. Se utilizó un fantomas diseñado para diagnóstico odontológico, sopesando la radiación en diferentes angulaciones de operación del equipo NOMAD, simulando los gestos posturales de odontólogos, radiólogos y sujetos a identificar. Se controlaron las tasas de exposición para determinar los valores de las dosis aportadas en las zonas significativas corporales más radiosensibles del operador del equipo. Se obtuvo como resultado que la retrodispersión en el cristalino del ojo del operador fue significativamente menor cuando el fantomas estaba acostado, mientras que a nivel de gónadas resultó más baja con el cuerpo sentado. La tasa de dosis máxima de radiación dispersa que impactó en los operadores fue de 350.8 micro Sieverts por hora (uSv/h) en la zona de gónadas, por cada radiografía tomada sin el uso del delantal de goma plomada, reduciéndose a 4.38 micro Sieverts por hora (uSv/h) al utilizarlo (AU)

SU-E-T-383: Pulsed Low Dose Rate Radiotherapy Using Advanced Treatment Methods: A Novel Technique for Patient Re-Irradiation.

PURPOSE: Pulsed low dose-rate radiotherapy (PLDR) re-irradiation has the potential to reduce late normal tissue toxicity while still providing significant tumor control for recurrent cancers. In contrast to conventional treatments delivered at dose-rates of 400-600cGy/min, PLDR treatments deliver 20cGy pulses separated by 3-minute intervals to achieve an effective-dose-rate of 6.7cGy/min. This work aims to investigate the planning strategy and delivery quality of PLDR treatment using IMRT and RapidArc techniques. METHODS: Twenty cases (10 treated with PLDR IMRT, 10 for evaluation purposes) were recruited in this study including prostate, pancreas, lung, head-and-neck, breast and pelvis. IMRT and the RapidArc treatment plans were generated using the Eclipse TPS. For IMRT treatment, each plan consisted of 10 fields to achieve a daily dose of 200cGy. The breast IMRT and the RapidArc plans consisted of two fields/arcs, respectively (40cGy/plan) and were delivered 5 times. The dose contribution from each field to the planning target volume (PTV) was analyzed to evaluate the feasibility for PLDR treatment. Machine-operation- dose-rate and plan quality was also investigated. Dose delivery accuracy was assessed using a cylindrical diode array. RESULTS: Throughout the six treatment sites, the mean PTV dose ranged from 16.1 to 26.1cGy/arc for RapidArc plans and 10.3 to 36.7cGy/field for IMRT plans. For IMRT, the PTV dose contribution from each field strongly depends on the beam arrangement and optimization parameters. With very low dose for a full rotation (∼ 20cGy/arc), the machine-operation-dose-rate of RapidArc plans significantly affects plan quality and deliverability. A machine-operation-dose-rate of 100 MU/min results in superior delivery accuracy (>97.7% gamma-passing-rate for 3%/3mm criteria) for both IMRT and RapidArc plans. CONCLUSIONS: PLDR radiotherapy using IMRT and RapidArc techniques Result in both dosimetric and radiobiological benefits, which may have great potential for those previously-irradiated patients who have historically done poorly.

SU-E-T-464: Impact of the Treatment Margin on Tumor Control and Normal Tissue Complication for Prostate Treatment.

PURPOSE: To investigate the consequence of treatment margin reduction on normal tissue complication probability (NTCP) and tumor control probability (TCP) of prostate external beam treatment. METHODS: Intensity modulated rotational radiotherapy plans were generated for 10 prostate patients with 6 different posterior margin sizes from 5mm to 0. The prescription dose is 80Gy for 40 treatment fractions. The dose distributions were recalculated with consideration of the intrafractional motion and the localization error. The statistical uncertainties of the intrafractional motion and the localization error were derived based on the motion tracking data recorded by the Calypso 4D localization system for a large patient population. The TCP and NTCP were calculated based on the dose volume histograms (DVH) of prostate and rectum for plans with different margins using an equivalent uniform dose (EUD) based biological model. The 50% tumor control dose (TCD50) of 60Gy for prostate and the median toxic dose (TD50) of 55Gy for rectum were used in the calculation. RESULTS: The minimum dose of the prostate and the mean dose of the rectum dropped with the decrease of the treatment margin. When the posterior treatment margin was reduced from 5mm to zero, the EUD of prostate decreased from 83Gy (±0.5Gy) to 81Gy (±0.5Gy) and the TCP dropped from 93.2% (±0.1%) to 91.7% (±0.1%), the EUD of the rectum decreased more significantly from 48.9Gy (±0.4Gy) to 32.5Gy (±0.5Gy) and the NTCP dropped from 13.3% (±1.5%) to 0.03% (± 0.01%). CONCLUSIONS: The treatment margin size affects the dose to the target and the nearby critical structure. More significant impact on NTCP has been observed than on TCP. This gives us some room to consider the quality of the patient's after-treatment life. A wise choice of treatment margin can be made based on physician's opinion and patient's preference on the tumor control and the quality of life.

SU-E-T-201: Safety-Focused Customization of Treatment Plan Documentation.

PURPOSE: Plan report documentation contains numerous details about the treatment plan, but critical information for patient safety is often presented without special emphasis. This can make it difficult to detect errors from treatment planning and data transfer during the initial chart review. The objective of this work is to improve safety measures in radiation therapy practice by customizing the treatment plan report to emphasize safety-critical information. METHODS: Commands within the template file from a commercial planning system (Eclipse, Varian Medical Systems) that automatically generates the treatment plan report were reviewed and modified. Safety-critical plan parameters were identified from published risks known to be inherent in the treatment planning process. Risks having medium to high potential impact on patient safety included incorrect patient identifiers, erroneous use of the treatment prescription, and incorrect transfer of beam parameters or consideration of accessories. Specific examples of critical information in the treatment plan report that can be overlooked during a chart review included prescribed dose per fraction and number of fractions, wedge and open field monitor units, presence of beam accessories, and table shifts for patient setup. RESULTS: Critical information was streamlined and concentrated. Patient and plan identification, dose prescription details, and patient positioning couch shift instructions were placed on the first page. Plan information to verify the correct data transfer to the record and verify system was re-organized in an easy to review tabular format and placed in the second page of the customized printout. Placeholders were introduced to indicate both the presence and absence of beam modifiers. Font sizes and spacing were adjusted for clarity, and departmental standards and terminology were introduced to streamline data communication among staff members. CONCLUSIONS: Plan reporting documentation has been customized to concentrate and emphasize safety-critical information, which should allow for a more efficient, robust chart review process.