Substantial dose reduction using dry deposited underlayer for EUV lithography while maintaining roughness and minimizing defects

Substantial CT radiation dose reduction does not affect the preference for CT over direct digital radiography to diagnose isolated zygomatic fractures – A study in human cadavers

The aim of this study was to assess the potential of a modern x,y,z modulation-based automatic exposure control system (AEC) for dose reduction in pediatric and adult multidetector CT (MDCT) imaging and evaluate the quality of the images obtained. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-, 5-, 10-year old child, and adult were scanned with a MDCT scanner, equipped with a modern AEC system. Dose reduction (%DR) was calculated as the percentage difference of the mean modulated and the preset tube current-time product that is prescribed for standard head and body scan protocols. The effect of the tube potential and the orientation of the topogram acquisition on dose reduction were assessed. Image quality was evaluated on the basis of image noise and signal to noise ratio (SNR). The dose reduction values achieved in pediatric phantoms were remarkably lower than those achieved for the adult. The efficiency of the AEC is decreased at 80 kVp compared to higher tube potentials and for helical scans following an anterior posterior (AP-AEC) compared to a lateral (LAT-AEC) topogram acquisition. In AP-AEC scans, the dose reduction ranged between 4.7 and 34.7% for neonate, 15.4 and 30.9% for 1 year old, 3.1 and 26.7% for 5 years old, 1.2 and 58.7% for 10 years old, and 15.5 and 57.4% for adult. In LAT-AEC scans, the corresponding dose reduction ranged between 11.0 and 36.5%, 27.2 and 35.7%, 11.3 and 35.6%, 0.3 and 67.0%, and 15.0 and 61.7%, respectively. AP-AEC scans resulted in a 17.1% and 19.7% dose increase in the thorax of neonate and the pelvis of the 10-year old phantom, respectively. The variation in the measured noise among images obtained along the scanning z axis was lower in AEC activated compared to fixed milliamperes scans. However, image noise was significantly increased (P<.001) and SNR significantly decreased (P<.001) in most AEC activated compared to fixed milliamperes scans. In conclusion, AEC resulted in a (i) substantial dose reduction, which is less pronounced in children compared to adult, (ii) higher dose reduction in scans following a lateral compared to scans following an anterior-posterior topogram acquisition, (iii) increase of image noise and degradation of SNR in the obtained images compared to the fixed milliamperes technique.

Various studies have demonstrated that additional prefilters and/or reduced tube voltages have the potential to significantly increase the contrast-to-noise ratios at unit dose (CNRDs) and thereby to significantly reduce patient dose in clinical CT. An exhaustive analysis, accounting for a wide range of filter thicknesses and a wide range of tube voltages extending beyond the 70 to 150kV range of today's CT systems, including their specific choice depending on the patient size, is, however, missing. Therefore, this work analyzes the dose reduction potential for patient-specific selectable prefilters combined with a wider range of tube voltages. We do so for soft tissue and iodine contrast in single energy CT. The findings may be helpful to guide further developments of x-ray tubes and automatic filter changers. CT acquisitions were simulated for different patient sizes (semianthropomorphic phantoms for child, adult, and obese patients), tube voltages (35-150kV), prefilter materials (tin and copper), and prefilter thicknesses (up to 5mm). For each acquisition soft tissue and iodine CNRDs were determined. Dose was calculated using Monte Carlo simulations of a computed tomography dose index (CTDI) phantom. CNRD values of acquisitions with different parameters were used to evaluate dosereduction. Dose reduction through patient-specific prefilters depends on patient size and available tube current among others. With an available tube current time product of 1000mAs dose reductions of 17% for the child, 32% for the adult and 29% for the obese phantom were achieved for soft tissue contrast. For iodine contrast dose reductions were 57%, 49%, and 39% for child, adult, and obese phantoms, respectively. Here, a tube voltage range extended to lower kV isimportant. Substantial dose reduction can be achieved by utilizing patient-specific prefilters. Tube voltages lower than 70kV are beneficial for dose reduction with iodine contrast, especially for small patients. The optimal implementation of patient-specific prefilters benefits from higher tube power. Tin prefilters should be available in 0.1mm steps or lower, copper prefilter in 0.3mm steps or lower. At least 10 different prefilter thicknesses should be used to cover the dose optima of all investigated patient sizes and contrast mechanisms. In many cases it would be advantageous to adapt the prefilter thickness rather than the tube current to the patient size, that is, to always use the maximum available tube current and to control the exposure by adjusting the thickness of the prefilter.

Systematic Comparison of Reduced Tube Current Protocols for High-pitch and Standard-pitch Pulmonary CT Angiography in a Large Single-center Population

The emergence of PET/CT multi-modality imaging has provided the ability to sequentially obtain anatomic and functional information using adjacent PET and CT scanners without having to move the patient. To avoid the need for successive PET and CT scans, we have investigated the possibility of acquiring both the anatomic and functional images using the same detection system, based on conventional PET detectors and electronics operated in photon counting mode. The detector consisted of a high-luminosity LSO scintillator individually coupled to an avalanche photodiode to enable low-energy X-ray detection at high-count rate. A simulator was set up to collect tomographic data using a monochromatic 60 keV source (/sup 241/Am) to irradiate a phantom made of tissue-equivalent materials. The measured spatial resolution with this non-optimized setup was nearly 1 mm, demonstrating the capability to provide fairly accurate anatomical localization in CT counting mode. The images obtained showed that the three main constituents of a biological body (bones, water and air) can be clearly identified with a dose significantly lower than with conventional CT operated in current mode. These preliminary results demonstrate the feasibility of dual-modality PET/CT imaging based on PET detectors and electronics, and confirm that substantial dose reduction would be possible by acquiring the CT image in photon counting mode.

Background/purposeTo investigate a quantitative method for assessing image quality of low dose lung computed tomography (CT) and find the lowest exposure dose providing diagnostic images. MethodsAxial volumetric lung CT acquisitions (256 slice scanner) were performed on three different sized anthropomorphic phantoms at different dose levels. The maximum steepness of sigmoid curves fitted to line density profiles was measured at lung-to-pleura interfaces. For each phantom, image sharpness was calculated as the median of 468 measurements from 39 different locations. Diagnostic image quality for the adult and paediatric phantom was rated by three radiologists using 4-point Likert scales. The image sharpness cut-off for obtaining adequate image quality was determined from qualitative ratings. ResultsAdequate diagnostic image quality was reached at a median steepness of 713 HU/mm in the adult phantom with a corresponding CTDIvol of 0.14 mGy and an effective dose of 0.13 mSv at a dose level of 100 kVp and 10 mA. In the paediatric phantom diagnostic image quality was reached at a median steepness of 1139 HU/mm with a corresponding CTDIvol of 0.13 mGy and an effective dose of 0.08 mSv at a dose level of 100 kVp and 10 mA. ConclusionsDetermination of image sharpness on line density profiles can be used as quantitative measure for image quality of lung CT. Sufficient-quality lung CT can be achieved at effective radiation doses of 0.13 mSv (adult phantom) and 0.08 mSv (paediatric phantom). These findings suggest that substantial dose reduction is feasible without compromising diagnostic accuracy.

To evaluate radiation exposure and image quality in thoracic computed tomography (CT) using a new dose-saving algorithm to protect radiosensitive organs. For dose measurements, an Alderson RANDO phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to the International Commission on Radiologic Protection 103. Exposure was performed on a second-generation dual-source CT. The following parameters for thoracic CT were used: 160 effective mAs, 120 kV, scan range of 30 cm, collimation of 128 × 0.6 mm. For the acquisition, the tube current modulation type XCare was used, which reduces the tube current for anterior tube position to minimize direct exposure to anterior located organs. To compare differences, scans with and without XCare were performed. Objective signal-to-noise measurements were evaluated, and the subjective noise perception was rated in a 3-point scale (1: excellent, 3: affecting diagnostic accuracy) in 30 patients with a standard thoracic examination and a follow-up using XCare. A substantial dose reduction in radiosensitive tissues was evident using the dose-saving algorithm XCare. Specifically, reductions of 35.2% for the female breast and 20.1% for the thyroid gland were measured, resulting in a decreasing effective whole-body dose of 8.0% and 14.3% for males and females, respectively. The objective and subjective evaluation of image quality showed no significant differences between both scan protocols (P > 0.05). Mean signal-to-noise ratio was 1.3 ± 0.2 and 1.2 ± 0.2 in scan protocols without and with XCare, respectively. The subjective scores at the level of the pulmonary trunk were 1.2 ± 0.4 and 1.4 ± 0.5 in standard chest scan and scans with the dose-saving algorithm XCare, respectively. The XCare technique protects radiosensitive organs like the female breast and the thyroid gland without affecting image quality. Therefore, this dose-saving algorithm may be used in thoracic CT examinations in male and female patients.

Lung cancer is the leading cause of cancer death for men and women in the industrialized world. It is desirable to detect disease at a stage when it is not causing symptoms and when control or cure is possible. If the screening test detects patients with the disease at an early stage, they can be examined to confirm the diagnosis and intervention can alter the natural history of the disease. The results of screening programs designed to detect early lung cancer using either conventional chest radiograph or sputum cytology are disappointing for a diagnostic screening test. Because of advances in helical CT imaging techniques, screening for lung cancer has been suggested as a possible method of improving outcome. Findings in recent publications suggest that substantial dose reduction is possible in chest CT. The advantages of low-dose CT are more sensitive than chest radiograph for detecting small pulmonary nodules that may be lung cancers, shorter scanning time than conventional chest CT scan without intravenous contrast injection, cheaper cost than standard CT, low radiation dose. However, the true clinical significance of the small tumors found by screening is still unknown, and their effect on mortality awaits future investigation. Furthermore, in addition to detecting an increased number of lung cancers, low-dose CT found at least one indeterminate nodule in many of all screened patients. The majority should be benign but evaluation of all these indeterminate nodules is not a trivial problem in routine practice. In conclusion, lung cancer screening with low-dose CT is a complex subject. The true effectiveness of lung cancer screening (a reduction in mortality from lung cancer) with low-dose CT can be determined through well-designed randomized control trials with enrolment of appropriate subjects. (Tuberc Respir Dis 2004; 57:118-124)

To report the results of treating laryngeal sarcoidosis with intralesional steroids and minimally invasive laser surgery. Sarcoidosis is a rare multisystem inflammatory disorder of unknown cause. Laryngeal involvement is extremely rare, and its optimal management remains controversial. Retrospective medical chart review. Settings Tertiary care center/national referral airway reconstruction center. Ten consecutive patients treated for laryngeal sarcoidosis between 2004 and 2008. Demographic and clinical information including extralaryngeal manifestations obtained from patient records, laryngeal anatomic subsite manifestation of disease, intraoperative findings, and scores from the Medical Research Council (MRC) dyspnea outcome assessment instrument (which was administered preoperatively, at the first postoperative outpatient visit 4-6 weeks later, and at last follow-up). The patients included 9 women and 1 man, a total of 2.8% of the unit's adult surgical airway case mix (10 of 353). Mean (SD) age at presentation was 37 (17) years. All patients presented with dyspnea and dysphonia; 2 required emergency tracheostomy prior to treatment. Six patients presented with isolated laryngeal sarcoid. Supraglottis and arytenoids were affected in all patients. The median number of endoscopic treatments was 2 (range, 1-4). Significant improvement in MRC dyspnea grading was found postoperatively (P < .05), and patients with tracheostomy were successfully decannulated. The mean (SD) follow-up time was 24 (18) months. There were no adverse effects of surgery. Nine patients had a substantial dose reduction or discontinuation of their systemic corticosteroid therapy following endoscopic treatment. Minimally invasive endoscopic surgery with intralesional corticosteroid injection and laser reduction is an effective method of controlling laryngeal sarcoid. It improves symptoms immediately with minimal morbidity and, most importantly, reduces the need for systemic steroid administration in most patients. This study supports early recognition and endoscopic intervention in the management of laryngeal sarcoidosis.

Equations are given for calculating the dose to the surface of the bladder wall for any values of the parameters, urine flow-rate, bladder voiding period and initial content, for any administered radiopharmaceutical with known biokinetics. The necessary relationships which describe the variation in dose to the bladder wall per unit of cumulated activity in contents with increasing volume of contents are given for 31 radionuclides. Two commonly used rental radiopharmaceuticals, 131I Hippuran and 99Tcm DTPA, are used to illustrate the effects of the above three physiological variables on the dose to the bladder wall and it may be concluded that, for radiopharmaceuticals which are rapidly transferred to the bladder, substantial dose reduction can be achieved by optimising these parameters. Thus, where possible, the patient should be well hydrated, the radiopharmaceutical should be administered when the bladder is partly filled and the voiding period should be about 1.5 h.

This study provides a retrospective assessment of doses to 13 organs for the most common radiographic examinations conducted between the 1930s and 2010, taking into account typical technical parameters used for radiography during those years. This study is intended to be a resource on changes in medical diagnostic radiation exposure over time with a specific purpose of supporting retrospective epidemiological studies of radiation health risks. The authors derived organ doses to the brain, esophagus, thyroid, red bone marrow, lungs, breast, heart, stomach, liver, colon, urinary bladder, ovaries, and testes based on 14 common radiographic procedures and compared, when possible, with doses reported in the literature. These dose estimates were based on radiographic exposure parameters described in textbooks widely used by radiologic technologists in training from 1939 to 2010. The derived estimated doses presented here are believed to be representative of typical organs for an average-size adult who might be considered to be similar to the reference person. There were large variations in organ doses noted among the different types of radiographic examinations. Doses were highest in organs within the area imaged and next highest in organs in close proximity to the area imaged. Estimated organ doses have declined substantially [overall 22-fold (±38)] over time as a consequence of changes in technology, imaging protocols and protective measures. For some examinations, only slight differences were observed in doses for the decades of the 1960s, 1970s, and 1980s due to minor changes in technical parameters. Substantial dose reductions were observed in the 1990s and 2000s.

Substantial radiation reduction in pediatric and adult congenital heart disease interventions with a novel X-ray imaging technology

Recent reports have raised general awareness that cardiac computed tomography (CT) has the potential for relatively high effective radiation doses. While the actual amount of risk this poses to the patient is controversial, the increasing concern has led to a great deal of research on new CT techniques capable of imaging the heart at substantially lower radiation doses than was available only a few years ago. Methods of dose reduction include optimised selection of user-defined parameters, such as tube current and voltage, as well as use of new technologies, such as prospective triggering and iterative reconstruction. These techniques have each been shown to lead to substantial reduction in radiation dose without loss of diagnostic accuracy. This article will review the most frequently used and widely available methods for radiation dose reduction in cardiac CT and give practical advice on their use and limitations.

Prolonged Complete Clinical Remission in Patients With Severe Pemphigus Vulgaris After Cycles of Intravenous Cyclophosphamide

Background: Epidural volume extension with saline solution can contribute to enhancement of a small dose intrathecal local anaesthetic. The resultant substantial reduction in local anaesthetic dose produces a sufficient effective block, decreased side effect and less motor blockade. The aim of this study was to evaluate the sensory and motor block characteristics of 10ml epidural saline after intrathecal small dose local anaesthetic and opioid. Setting and Design: This prospective, randomized, double-blind study was conducted in a operation room setting of a university hospital. One hundred and five women (25-40 years) of ASA 1 and 11 physical status electively undergoing caesarean section under regional anaesthesia were investigated.Method and Material: After hospital Ethics Committee approval and written informed consent, 105 women were allocated randomly, into three groups (n=35), received 7mg of spinal hyperbaric 0.5% Bupivacaine (groupB7), 7mg of spinal hyperbaric 0.5% Bupivacaine followed by 10ml of Normal Saline through the epidural catheter, 5 minutes thereafter (group B7EVE) and 10mg of spinal hyperbaric 0.5% Bupivacaine without epidural volume extension (groupB10). All women also received 25mcg of Fentanyl intrathecally. The patients were assessed at 2.5 minutes interval for sensory block level to loss of pain from pin prick and for motor block using modified Bromage scale. We also recorded visual analogue scale, peak sensory block height, highest Modified Bromage scale, motor block recovery, incidences of side effects and ephedrine dose requirement.Result: Demographic data, duration of surgery, VAS, incidence of maternal side effects and ephedrine dose requirement were similar in all the groups. There was no difference in the peak sensory block heights between the groups during the study. The motor score was significantly lower in the group B7-EVE (grade-1 vs grade-3 in groupB7and groupB10, P=0.014). This was associated with a significantly faster motor recovery to Modified Bromage 0 in group B7-EVE (61-80mts vs 121-140mts in group B7 and 141-160mts in groupB10, P=0.0001).Conclusion: This study demonstrates a benefit in using epidural volume extension with 10ml normal saline, as a part of a combined spinal epidural technique by providing a more rapid motor recovery of the lower limbs after elective caesarean section.