Explore the vast range of titles available.

Objectives Shaping the energy spectrum of the X-ray beam has been shown to be beneficial in low-dose CT. This study’s aim was to investigate dose and image quality of tin filtration at 100 kV for pre-operative planning in low-dose paranasal CT imaging in a large patient cohort. Methods In a prospective trial, 129 patients were included. 64 patients were randomly assigned to the study protocol (100 kV with additional tin filtration, 150mAs, 192x0.6-mm slice collimation) and 65 patients to the standard low-dose protocol (100 kV, 50mAs, 128 × 0.6-mm slice collimation). To assess the image quality, subjective parameters were evaluated using a five-point scale. This scale was applied on overall image quality and contour delineation of critical anatomical structures. Results All scans were of diagnostic image quality. Bony structures were of good diagnostic image quality in both groups, soft tissues were of sufficient diagnostic image quality in the study group because of a high level of noise. Radiation exposure was very low in both groups, but significantly lower in the study group (CTDI vol 1.2 mGy vs. 4.4 mGy, p  < 0.001). Conclusions Spectral optimization (tin filtration at 100 kV) allows for visualization of the paranasal sinus with sufficient image quality at a very low radiation exposure. Key Points • Spectral optimization (tin filtration) is beneficial to low-dose parasinus CT • Tin filtration at 100 kV yields sufficient image quality for pre-operative planning • Diagnostic parasinus CT can be performed with an effective dose <0.05 mSv

Endoscopic retrograde cholangiopancreatography (ERCP) is associated with radiation exposure to the endoscopist and staff that may be significant in high-volume centers. We investigated whether a radiation-attenuating drape over the fluoroscopy image intensifier reduces radiation exposure during ERCP. We performed a prospective, randomized, double-blind trial of 100 therapeutic ERCPs at a tertiary-care university center. Procedures were randomly assigned to groups receiving lead-free radiation-attenuating drapes (n=50) or identical sham drapes (n=50). The drapes were suspended around the fluoroscopy image intensifier during ERCP. The primary end point was the effective dose of radiation measured at the endoscopist's eye and neck, and at the assisting nurse's neck. The cumulative annual radiation exposure was also estimated. Fluoroscopy time, absorbed radiation dose, and dose area product were similar in the study groups. Mean effective dose for sham vs. radiation-attenuating drape was 0.21±0.27 vs. 0.02±0.02 mSv at the endoscopist's eye, 0.35±0.44 vs. 0.03±0.03 mSv at the endoscopist's neck, and 0.27±0.34 vs. 0.02±0.02 mSv at the nurse's neck (P<0.0001 for all comparisons). The relative risk reduction in radiation was 90%, 91%, and 93% at the three sites. At a high-volume center in which an endoscopist performs 500 therapeutic ERCPs per year, the estimated cumulative annual effective dose at the endoscopist's eye level is 126 mSv with conventional protection and 12 mSv with a radiation-attenuating drape, with the recommended limit being 20 mSv. The addition of a radiation-attenuating drape around the image intensifier during ERCP significantly decreases radiation exposure to endoscopists and staff by ∼90%.

Recent technological advances in myocardial perfusion imaging may warrant the use of lower injected activity. We evaluated whether quantitative measures of stress myocardial perfusion defects using Tc-99m sestamibi and low-energy high-resolution (LEHR) collimators are equivalent to lower dose SPECT-CT with cardiac multifocal collimators and software (IQ·SPECT). 93 patients underwent one-day rest-stress gated SPECT-CT. Following conventional rest imaging, 925-1100 MBq (25-30 mCi) of Tc-99m sestamibi was injected during stress testing. Stress SPECT-CT images were acquired two ways: with LEHR (13 minutes) and IQ·SPECT (7 minutes). Low-dose IQ·SPECT stress was simulated by subsampling the full-dose data to half-, quarter-, and eighth-count levels. Abnormalities were quantified using the total perfusion deficit (TPD) score and dose-specific databases. The mean ± SD of the differences between LEHR and IQ·SPECT TPD scores were −1.01 ± 5.36%, −0.10 ± 5.81%, 1.78 ± 4.81%, and 1.75 ± 6.05% at full, half, quarter, and eighth doses, respectively. Differences were statistically significant for quarter and eighth doses. Correlation between LEHR and IQ·SPECT was excellent at all doses (R ≥ 0.93). Bland-Altman plots demonstrated minimal bias. With IQ·SPECT, quantitative stress SPECT-CT imaging is possible with half of the standard injected activity in half the time. Los recientes avances tecnológicos en la imagen de perfusión miocárdica (MPI) pueden justificar el uso de una menor actividad inyectada. Nosotros evaluamos si las mediciones cuantitativas de los defectos de perfusión en estrés usando Tc-99m sestamibi y colimadores de baja energía y alta resolución (LEHR) son equivalentes a dosis menores en SPECT-CT con colimadores multifocales y programa de procesamiento cardiacos (IQ·SPECT). 93 pacientes sometidos a gated SPECT-CT reposo – estrés en un solo día. Después de la imagen convencional de reposo, se inyectaron 925-1100 MBq (25-30 mCi) de Tc-99m sestamibi durante la prueba de estrés. Las imágenes de estrés con SPECT-CT se adquirieron de dos formas: con LEHR (13 min) y con IQ·SPECT (7 min). La dosis baja con IQ·SPECT fue simulada haciendo un submuestreo de los datos de la dosis completa a niveles de la mitad, la cuarta y la octava parte de las cuentas. Las anormalidades se cuantificaron usando el déficit total de perfusión (TPD) y bases de datos específicas por dosis. Las medias ± DE de las diferencias de los valores de TPD entre LEHR y IQ·SPECT fueron −1.01 ± 5.36%, −0.10 ± 5.81%, 1.78 ± 4.81% y 1.75 ± 6.05% a dosis completa, media, cuarta y octava parte, respectivamente. Las diferencias fueron estadísticamente significativas para la cuarta y octava parte de dosis. La correlación entre LEHR con IQ·SPECT fue excelente con todas la dosis (R > 0.93). Las gráficas de Bland-Altman demostraron mínimo sesgo. Con IQ·SPECT, el estrés cuantitativo mediante la imagen de SPECT-CT es posible realizarlo con la mitad de la actividad estándar inyectada y en la mitad de tiempo. 最近心脏灌注显像(MPI)的技术进步使得在较低注射剂量的条件下MPI成像变得可行。 本文评估:采用Tc-99m甲氧基异丁基异腈显影剂和低能量高分辨率准直器定量测定负荷状态下心肌血流灌注缺损(LEHR方法), 是否等效于采用心脏多焦点准直器和软件进行的较低剂量SPECT-CT的测定结果 (IQ·SPECT方法)。 对入选的93个病人均采用负荷一日法/静息门控SPECT-CT 显影方案。 按照常规的方法进行静息图像的采集后, 在运动过程中静脉注射 925-1100 MBq(25-30mCi) 的 Tc-99m (甲氧基异丁基异腈)。 负荷SPECT-CT 图像是以两种方式采集:13分钟的LEHR和7分钟的 IQ·SPECT。 低剂量的负荷 IQ·SPECT是用全剂量样本的子样本来模拟, 分别是半剂量、 四分之一剂量和八分之一剂量。 用血流灌注缺损总积分(TPD)和剂量特征化数据库对心肌灌注异常进行定量。 分别采用LEHR与IQ·SPECT方法时, TPD积分差值的平均值±标准方差是 −1.01 ±5.36%, −0.10 ± 5.81%, 1.78 ± 4.81% 和 1.75 ± 6.05%, 分别对应于全剂量、半剂量、 四分之一剂量和八分之一剂量。在四分之一和八分之一剂量时采用LEHR与IQ·SPECT方法测定的TPD差值在统计学上有显著性差异。在所有剂量段时采用LEHR与 IQ·SPECT 方法测定的TPD都有很好的相关性(R ≥ 0.93)。Bland-Altman图形表明了最小偏差。 采用IQ·SPECT方法, 将图像采集时间和显影剂注射剂量都减半应用于负荷SPECT-CT成像是可行的。

Published data relating to arterial access site selection and radiation exposure during coronary procedures suggest radial access may lead to increased radiation exposure, but this is based on poorly controlled studies. We sought to measure radiation exposure to patients and operators during elective coronary angiography (CA) according to access site, with other procedure related variables controlled for. We also investigated the specific effect of operator expertise in relation to radiation exposure. 100 consecutive patients undergoing first time elective CA were recruited prospectively. An expert transradial (TR) and an expert transfemoral (TF) operator performed 25 cases each via their default route. A trainee cardiologist with intermediate experience in both access sites performed 25 cases via each route. Angiographic projections were standardised and optimised radiation protection was utilised for all procedures. The primary endpoints were operator and patient exposure, quantified by effective dose (ED) and dose area product (DAP) respectively. Secondary endpoints included fluoroscopy time (FT) and time to patient ambulation. The trainee operator recorded higher values for radiation exposure in radial and femoral cases when compared to the expert operators. There were no significant differences in radiation exposure during CA to operator or patient according to access site when standardised by operator experience. For the trainee, ED for TR and TF procedures was 8.8 ± 4.3 μSv and 8.5 ± 6.5 μSv (P = .86) and DAP was 25.4 ± 4.8 Gycm2 vs 25.2 ± 8.3 Gycm2 (P = .9). For the expert TR and TF operators, ED was 6.4 ± 4.7 μSv vs 6.1 ± 5.6 μSv (P = .85) and DAP was 21.7 ± 6.5 Gycm2 vs 22.4 ± 8.0 Gycm2, (P = .74). There was no significant difference in FT in relation to access site. Time to ambulation was significantly longer with TF access. The use of TR access has no adverse effect on radiation exposure or FT for diagnostic CA, but does allow for quicker ambulation compared to TF access. The magnitude of radiation exposure is related to operator expertise for both access sites. The results of previous studies reflect the effect of uncontrolled patient and operator variables and not access site selection.

Objective To examine whether students use or avoid newly shaded areas created by shade sails installed at schools.Design Cluster randomised controlled trial with secondary schools as the unit of randomisation.Setting 51 secondary schools with limited available shade, in Australia, assessed over two spring and summer terms.Participants Students outside at lunch times.Intervention Purpose built shade sails were installed in winter 2005 at full sun study sites to increase available shade for students in the school grounds.Main outcome measure Mean number of students using the primary study sites during weekly observations at lunch time.Results Over the study period the mean change in students using the primary study site from pre-test to post-test was 2.63 (95% confidence interval 0.87 to 4.39) students in intervention schools and −0.03 (−1.16 to 1.09) students in control schools. The difference in mean change between groups was 2.67 (0.65 to 4.68) students (P=0.011).Conclusions Students used rather than avoided newly shaded areas provided by purpose built shade sails at secondary schools in this trial, suggesting a practical means of reducing adolescents’ exposure to ultraviolet radiation.Trial registration Exempt.

Background Hydrogel spacer is an innovative method to protect the rectal wall during prostate cancer radiotherapy. Clinical effects are not well known. Methods Patients have been surveyed before, at the last day, and 2–3 months after radiotherapy using a validated questionnaire (Expanded Prostate Cancer Index Composite). Median dose to the prostate in the spacer subgroup (SP) was 78 Gy in 2 Gy fractions. The results were independently compared with two matched-pair subgroups (treated conventionally without spacer): 3D conformal 70.2 Gy in 1.8 Gy fractions (3DCRT) and intensity-modulated radiotherapy (IMRT) 76 Gy in 2 Gy fractions. There were 28 patients in each of the three groups. Results Baseline mean bowel bother scores were 96 points in all subgroups. Similar mean changes (SP 16, 3DCRT 14, IMRT 17 points) were observed at the end of radiotherapy. The smallest difference resulted in the spacer subgroup 2–3 months after radiotherapy (SP 2, 3DCRT 8, IMRT 6 points). Bowel bother scores were only significantly different in comparison to baseline levels in the spacer subgroup. The percentage of patients reporting moderate/big bother with specific symptoms did not increase for any item (urgency, frequency, diarrhoea, incontinence, bloody stools, pain). Conclusion Moderate bowel quality-of-life changes can be expected during radiotherapy irrespective of spacer application or total dose. Advantages with a spacer can be expected a few weeks after treatment.

Space radiation is a notable hazard for long-duration human spaceflight 1 . Associated risks include cancer, cataracts, degenerative diseases 2 and tissue reactions from large, acute exposures 3 . Space radiation originates from diverse sources, including galactic cosmic rays 4 , trapped-particle (Van Allen) belts 5 and solar-particle events 6 . Previous radiation data are from the International Space Station and the Space Shuttle in low-Earth orbit protected by heavy shielding and Earth’s magnetic field 7 , 8 and lightly shielded interplanetary robotic probes such as Mars Science Laboratory and Lunar Reconnaissance Orbiter 9 , 10 . Limited data from the Apollo missions 11 – 13 and ground measurements with substantial caveats are also available 14 . Here we report radiation measurements from the heavily shielded Orion spacecraft on the uncrewed Artemis I lunar mission. At differing shielding locations inside the vehicle, a fourfold difference in dose rates was observed during proton-belt passes that are similar to large, reference solar-particle events. Interplanetary cosmic-ray dose equivalent rates in Orion were as much as 60% lower than previous observations 9 . Furthermore, a change in orientation of the spacecraft during the proton-belt transit resulted in a reduction of radiation dose rates of around 50%. These measurements validate the Orion for future crewed exploration and inform future human spaceflight mission design. Measurements from the heavily shielded Orion spacecraft during the uncrewed Artemis I mission show dose-rate reductions due to shielding and orientation for Van Allen belt crossings and quantify the interplanetary cosmic-ray radiation in a human-rated spacecraft.

Endovascular operators experience elevated rates of occupational orthopedic injuries and persistent radiation exposure with current lead shielding. Novel shielding systems eliminate the need to wear lead aprons while also mitigating occupational radiation exposure, but real-world evidence of their efficacy remains needed. This study evaluated consecutive endovascular procedures requiring fluoroscopy at U.S. and international institutions following installation of a commercially available portable shielding system consisting of interlocking radiation-attenuating acrylic and soft shielding components. Live dosimeters were placed at the left shoulder of the main and assistant operators for quantification of radiation exposure. In total, 1,712 endovascular procedures performed by 671 operators at 153 sites (19% non-U.S.). In 1,712 (99.4%), radiation exposure was recorded. A majority of procedures (83.6%) were coronary interventions including diagnostic angiography (43.8%), nonchronic total occlusion PCI (27.6%), and chronic total occlusion PCI (6.7%). Median fluoroscopy time was 7.7 mins (IQR 3.9 to 15.3 min), and median radiation exposure to the main operator and first assistant was 2 μSv and 1 μSv. This was comparable to historical measurements of under-lead radiation exposure. In conclusion, the Rampart system effectively reduced radiation exposure in real-world practice, enabling a safe lead-free procedure lab.

Healthcare professionals using fluoroscopic imaging systems rank among the most highly exposed workers to ionising radiations, yet current radiation protection detectors fail to provide accurate measurements in these scenarios. The pulsed structure of the X-ray beam produced by these medical devices poses significant challenges to conventional instruments in measuring and characterising time-structured radiation fields. Furthermore, radiation protection detectors consistently overestimate staff exposure at these low energies (< 100 keV) due to the inherent limitations of the dosimetric system currently in-use. In this study, we present a new hybrid pixel detector, originally developed for particle tracking and timing measurements in high-energy physics experiments at CERN, to overcome the above-mentioned challenges. By integrating single-photon energy measurement and precise timing capabilities, the detector enables highly accurate dose quantification across a broad range of diagnostic X-ray conditions while simultaneously resolving the spectral structure of radiation fields. Our findings demonstrate the detector’s suitability for advanced dosimetry assessment in clinical environments. It uniquely measures photon fluence and energy spectra in clinical X-ray fields, enabling accurate, pulse-independent determination of any exposure-related quantity. By giving access to fundamental radiation field parameters, this work lays the foundation for next-generation detectors that enhance staff safety and advance radiation epidemiology.

In this article, we propose an innovative approach to reduce radiation dose absorption inside human head tissues by shrinking the multiple-input multiple-output (MIMO) terminal geometric area. Initially, we employ COMSOL software to design a MIMO mobile terminal antenna that meets 2G, 3G, 4G, and 5G communication requirements. Through adding the decoupling unit, its geometric area reduces from 58 × 120 mm² to 44 × 80 mm², and its simulations and measurements indicate that the miniaturized MIMO mobile terminal antenna exhibits good radiation performance. Subsequently, we construct a head model based on standard anatomical features, including the scalp, skull, cerebrum, cerebellum, and brainstem. A comparative analysis of the specific absorption rate (SAR) across various cranial tissues, conducted before and after the antenna’s miniaturization, reveals significant reductions: maximum decreases of 85.51% in the scalp, 85.62% in the skull, 89.02% in the cerebrum, 93.04% in the cerebellum, and 88.02% in the brainstem. These findings suggest a significant decrease in the risk of electromagnetic exposure to human subjects by miniaturization. The miniaturization of the MIMO mobile terminal antenna could effectively mitigate the absorption of radiation by head tissues, thereby presenting a novel strategy for electromagnetic radiation protection.