Computed tomography urography in macroscopic hematuria: a retrospective study with implications for standard care pathway.

Effective Radiation Dose in CT Colonography: Is There a Downward Trend?

Is Thoracic CT Performed Often Enough?

Currently, computed tomographic (CT) imaging of the heart is mainly used for the quantification of coronary artery calcification as an indirect measure of coronary plaque burden1,2 and, less frequently, for minimally invasive coronary angiography.3 CT imaging of the heart and coronary arteries without unsharpness due to motion artifact first became possible with the introduction of electron beam computed tomography (EBCT) in 1983.4 More recently, so-called multislice spiral computed tomographic (MSCT) scanners with gantry rotation speeds fast enough to produce diagnostic images of the heart under certain conditions have become widely available.5 As a consequence, cardiac CT imaging, most often performed for the purpose of calcium scoring,2 is increasingly applied to the general public. In many centers, patients have access to such studies without physician referral. This has created concerns for public health because of the radiation dose associated with CT imaging.6–8 Many clinicians and researchers working with patients with cardiovascular diseases may yet be unfamiliar with the radiation doses that are received during various cardiac CT imaging protocols and how they differ between the various scanner types that are currently used. To further complicate matters, radiation dose estimates can be expressed in various ways. For these reasons, the doses reported in previous publications on cardiac CT have varied widely, and it is not always clear what parameters were being reported.3,9–11 The purpose of this article is to discuss the current concepts of radiation dose measurement and estimation in CT imaging and to provide comparative estimates for radiation doses received during cardiac examinations with use of EBCT or MSCT. This information may be helpful to physicians who perform calcium scoring, counsel patients contemplating cardiac calcium scoring, or are considering referring their patients for such studies. EBCT scanners acquire 1 scan at a time, using …

BACKGROUND: In accordance with the requirements of the IAEA basic safety standards and the International Commission on Radiation Protection, comparing the radiation dose for patients undergoing computed tomography (CT) in diagnostic and treatment clinics with national or international DRLs is important for controlling medical radiation doses. The search for ways to improve DRLs calculations determines the relevance of such studies. AIM: To analyze the dependence of effective doses (EDs) in CT of different body parts on patients weight and to calculate the standard ED for the patient (70 and 80 kg). MATERIALS AND METHODS: CT acquisition protocols in 209 patients were single phase (SP) CT, while 114 patients underwent multi-phase (MP) CT. ED was calculated according to the normalized coefficients for each body area. The values of standard ED was calculated by data approximation using linear function of ED relatively body weight for each type CT scanner and body area scanned. RESULTS: The increase in ED following a CT examination was proportional to the body weight of patients. For SP and MP CT scans, the standard EDs were calculated according to all body areas. The mean ED, median ED, and DRLs (mSv) in these groups was slightly higher than standard ED (mSv) if the criterion was 70 kg and were close to standard ED if the criterion was 80 kg. These values give a basis for improving the guidelines concerning the recommended limits of radiation doses for CT in individual patients according to indications and body parts studied. CONCLUSIONS: In the study, a methodology for assessing and comparing the dose of CT-radiation at two hospitals in the two CT scanners, considering weight of a standard patient, is described. Our results show that the calculation and analysis of the standard ED of CT-examining areas of the body instead of mean ED and median ED help to compare the radiation exposure in different medical facilities more properly. Given the recent sharp increase in the number of CT studies, not exceeding the standard ED for patients with CT will reduce the long-term consequences in the form of oncological pathology among the population.

CT Imaging: Radiation Risk Reduction—Real-Life Experience in a Metropolitan Outpatient Imaging Network

MULTIVARIATE ANALYSIS OF CLINICAL PARAMETERS OF SYNCHRONOUS PRIMARY SUPERFICIAL BLADDER CANCER AND UPPER URINARY TRACT TUMOR

INTEREST IN THE USE OF COMPUTED TOMOGRAPHY (CT) for cardiac evaluation has increased rapidly since the introduction of 64-slice scanners. Reflecting this, the installation base of CT scanners in US cardiology practices has tripled in the past 2 years. Reports of the high diagnostic performance of coronary CT angiography (CTA), and especially its high negative predictive value in populations with low-to-intermediate prevalence of coronary disease, have been tempered by a concern about its high radiation dose to patients and the attendant risk of cancer. Despite a number of single-center studies that have reported a wide range of effective doses for coronary CTA, the existing literature does not adequately answer the questions of what radiation doses patients actually receive in clinical practice, and what factors are associated with higher radiation dose. Such information should help practitioners develop protocols that are in accordance with the goal of maintaining radiation exposure to patients as low as reasonably achievable (the ALARA principle). The Prospective Multicenter Study On Radiation Dose Estimates Of Cardiac CT Angiography In Daily Practice I (PROTECTION I), an observational study of worldwide cardiac CTA practice in 2007 reported by Hausleiter and colleagues in this issue of JAMA, represents an effort to fill this gap. The primary outcome measure used to quantify radiation dose in PROTECTION I is the dose-length product (DLP), a CT-specific term unfamiliar to many physicians. The DLP is a reflection of the total amount of radiation deposited over the entire set of images comprising a patient’s CT series, reported in mGy cm. Better known is the effective dose, a measure applicable beyond the confines of CT and reported in millisieverts (mSv). Effective dose weights the concentrations of energy deposited in each organ from a radiation exposure using factors reflecting the type of radiation and the relative detriment to each organ of potential radiation-associated mutagenic changes. Although effective dose can be compared between different types of exposures, the factors used in its determination to weight each organ are approximate population averages, and therefore it is imprecise to report the effective dose of an individual patient’s study. Thus, in characterizing the amount of radiation from a single CTA study, DLP is a more objective physical metric than effective dose, and the reason PROTECTION I is replete with DLP data. However, effective dose is appropriate to refer to in a population of patients and is especially useful for comparing between different types of exposures in populations with similar age and sex distributions. As in numerous previous studies, effective dose of CTA is estimated in PROTECTION I by multiplying a median DLP by a conversion factor suggested by the European Commission. Hausleiter et al present a number of interesting and surprising findings about radiation dose from cardiac CTA. The estimated overall median effective dose for CTA, excluding calcium scoring when performed as part of the same study, was 12 mSv, somewhat less than the value reported in several earlier studies using 64-slice scanners. A few factors may account for this. Although the conversion factor used in PROTECTION I to estimate effective dose from DLP was derived using single-slice scanners and chest rather than cardiac scan sequences, this factor is the most current available. The value is approximately 20% lower than that used in previous studies, and thus would be expected to result in effective doses that are correspondingly lower. Additionally, as pointed out by Hausleiter et al, invitation of study sites on the basis of previous publications may have introduced a bias favoring more expert centers, which would be expected to be more proficient in managing radiation dose. Indeed, dosereduction techniques were used in at least 80% of patients undergoing 64-slice CTA for coronary assessment. Consistent with the suggestion of lower dose in centers with greater expertise, Raff et al recently reported a reduction in median effective dose of CTA from 25 mSv in the initial month to 13 mSv in the ninth month of a statewide quality improvement program in Michigan, with no change in image quality. This program used a collaborative

Practical Strategies to Reduce Pediatric CT Radiation Dose

Estimates of individual patient risk, and epidemiologic studies assessing potential late effects, must use patient size–specific dose estimates—they cannot use only scanner output (volume CT dose index or dose-length product).

Radiation Dose and Stochastic Risk From Exposure to Medical Imaging

Computed tomography (CT) utilization has increased rapidly over the past 15years. CT is the most common source for radiation exposure. The objective was to measure the effective dose of radiation delivered during routine head and abdominal CT examinations at a children's hospital. This was a retrospective study of emergency department (ED) patients<20years of age who underwent head or abdominal CT scans in 2012 at a single children's hospital. The authors abstracted the dose-length product from the CT scanners and calculated the effective radiation dose delivered. Patient demographics were abstracted from the medical record. The relationship between effective dose and age, patient weight, and reason for examination were evaluated. A total of 478 subjects were included: 255 underwent head CT, and 223 underwent abdominal CT. The median age was 8.1years (interquartile range= 2.71 to 14.40years) and 56.9% were male. The median effective dose for head CT was 2.68 mSv (95% confidence interval [CI]=2.54 to 2.84 mSv) and decreased as age increased. For abdominal CT, the median effective dose was 5.06 mSv (95% CI=4.58 to 6.03 mSv) and increased as age increased (3.67 to 11.12 mSv, p<0.001). For abdominal CT, 8% of 5- to 10-year-olds, 28% of those 10 to 15years, and 60% of patients over age 15 years received effective doses over 10 mSv. The amount of radiation delivered to pediatric patients during routine CT examinations of the head and abdomen was low. Regardless, a large proportion of older patients were exposed to elevated effective doses of radiation during abdominal CT.

Objective To investigate the clinical feature,pathologic characteristics and prognosis of non-muscle invasive urothelial bladder tumor in young and old patients.Methods From January 2000 to March 2011,the clinicial data of 48 young patients (age ≤ 40 years) with non-muscle invasive urothelial bladder tumor and 50 patients randomly selected with non-muscle invasive urothelial tumor (age ≥ 60 years) were analyzed and compared retrospectively.There were 38 male and 10 female with a median age of 35.4 years (range,18 to 40).There were 34 male and 16 female with a median age of 68.5 years (range,68.5 to 87).All patients had postoperative intravesical instillation for one year.Young patients presented with gross hematuria mostly,which were similmar with old patients.Solitary tumor were 45 cases and 40 cases,and the multiple tumors were 3 cases and 10 cases in the young and old groups,respectively.Of the young group,40 patients were treated by transurethral resection of bladder tumor,and 8 patients by partial cystectomy.Of the old group,35 patients were treated by transurethral resection of bladder tumor,and 15 patients by partial cystectomy.Results According to 2004 WHO classification of papillary urothelial tumor,lower grade tumor were more frequentto occur in young group than in old group.There was significant difference in incidence of PUNLMP between young group and old group (16/48,33.3％ and 8/50,16.0％,P ＜ 0.05).There was significant difference in incidence of high grade bladder cancer between young group and old group (7/48,14.6％ and 17/50,34.0％,P ＜0.05).The incidence of PTa tumor was 70.8％ and 44.0％ in the young and old groups,respectively (P ＜ 0.05).Median follow up was 34 months (range,6 to 132) in young group and 35 months (range,6 to 130) in old group,respectively.Five-year recurrence rate was 36.7％ and 64.3％ respectively (P ＜ 0.05).Conclusions Non-muscle invasive urothelial bladder tumor in young patients had a better prognosis than those in the old group,with lower grade and stage at diagnosisand lower recurrence rate. Key words: Non-muscle invasive urothelial tumor; Bladder; Prognosis

Computed tomography (CT) has been a boon for medical care. By generating detailed anatomical pictures, the technology can improve diagnoses, limit unneeded medical procedures, and enhance treatment. However, CT scans also dose patients with ionizing radiation, a known human carcinogen, posing a potential downside for public health. Mounting health worries over radiation risks are now driving efforts to limit avoidable CT scans and to reduce radiation doses where possible. “There’s a national focus on this issue right now,” says Marilyn Goske, a professor of radiology at Cincinnati Children’s Hospital Medical Center and chairwoman of the Image Gently campaign, a pediatric education and awareness campaign from the Alliance for Radiation Safety in Pediatric Imaging. In December 2011 the Institute of Medicine (IOM) published a report concluding that ionizing radiation contributes more to the development of breast cancer than any other type of routine environmental exposure.1 About half the U.S. annual exposure to ionizing radiation comes from natural sources, including cosmic rays, but most of the rest comes from medical imaging and from CT scans in particular.1 The IOM cited research by Amy Berrington de Gonzalez, a senior investigator in the Radiation Epidemiology Branch of the National Cancer Institute (NCI), whose calculations suggest that the CT scans performed in the United States in 2007 might produce up to 29,000 cancers in the future, about 6% of them in the breast and the remainder in the lungs, brain, and other organs.2 But the spotlight on CT safety has also drawn a backlash from those who say the risks are overblown. On 13 December 2011 the American Association of Physicists in Medicine (AAPM) issued a statement claiming that risks from CT imaging are “too low to be detectible and may be non-existent.”3 The AAPM added that “speculative predictions about cancer incidence and death” should be discouraged because they generate sensationalist media coverage that deters some patients who need CT scans from having them. Donald Miller, acting chief of the Diagnostic Devices Branch of the U.S. Food and Drug Administration (FDA) Center for Devices and Radiological Health, cites 2 basic principles for decreasing CT radiation risks. One is justification, which refers to prescribing a CT exam only when it is medically necessary. The other is optimization, which refers to adjusting and operating a CT scanner so that images adequate for diagnosis are obtained at the lowest possible dose. Justification is more difficult to address, Miller says, because it involves case-by-case decisions made by individual clinicians. More attention has been paid to optimization, he says, but both principles are equally important.

Computed tomography (CT) coronary angiography has become a highly accurate noninvasive approach for delineation of the presence and severity of coronary atherosclerosis [1–9]. Cardiac CT is optimally suited for the evaluation of patients with a low or intermediate risk of coronary disease, allowing the non-invasive rule-out of coronary disease at relatively low cost and risk [10–18]. However, the appropriate radiation dose remains an important issue in cardiac CT. On one hand, a too low radiation dose may result in a high level of image noise and therefore in non-diagnostic images. On the other hand, using higher radiation exposure levels may put patients at unnecessary risk of radiation damage [19–26]. Effective strategies to reduce radiation dose, such as prospective gating, heart rate control, ECG-correlated modulation of the tube current, and tube voltage below 100 kV, are becoming more and more applied in the clinical situation [27–31]. Recently, Buechel et al. [32] evaluated a large group of 612 patients referred for CT coronary angiography by 64-slice computed tomography. Intravenous metoprolol (2 to 30 mg) was administered if necessary to achieve a target heart rate below 65 beats/min. Using prospective ECG-triggering a mean effective radiation dose of 1.8 ± 0.6 mSv was obtained with a diagnostic image quality in 96.2% of segments. The authors concluded that low-dose CT coronary angiography by prospective ECG-triggering is feasible in the vast majority of an every-day population, whereby a heart rate below 62 beats/min favors diagnostic image quality. Blankstein et al. [33] investigated the effective radiation dose and image quality of 100 kV versus 120 kV tube voltage among patients referred for cardiac dual source CT imaging in 294 consecutive patients. They convincingly demonstrated that use of low kV resulted in a substantial reduction of radiation dose without compromising image quality. The effective radiation dose for the 100 and 120 kV scans was 8.5 and 15.4 mSv, respectively. In the recently published PROTECTION II trial, Hausleiter et al. [34] studied 400 non-obese patients undergoing CT angiography with either 100 or 120 kV CT coronary angiography. The study specifically examined the impact of a reduction in tube voltage to 100 kV using 64-slice CT angiography systems from three different manufacturers. It was demonstrated that a further 31% reduction in radiation exposure could be obtained with 100 kV tube voltage settings while image quality was preserved. Zhang et al. [35] prospectively evaluated image quality parameters, contrast volume and radiation dose at the 100 kV tube voltage setting during CT coronary angiography using a 320-row computed tomography scanner. The effective radiation dose was 2.12 ± 0.19 mSv for 100 kV, being a reduction of 54% compared to 4.61 ± 0.82 mSv for 120 kV. Diagnostic image quality was achieved in 98.2% of coronary segments with 100 kV and 98.6% of coronary segments with 120 kV. Therefore, the 100 kV setting allowed significant reductions in contrast material volume and effective radiation dose while maintaining adequate diagnostic image quality. In the current issue of the International Journal of Cardiovascular Imaging, Wang et al. [36] investigated the feasibility of a body mass index-adapted low-dose 80 kV scan protocol using prospectively ECG-triggered high-pitch spiral coronary CT angiography in 106 patients referred for coronary CT angiography to rule out coronary artery disease. The image quality and dose performance were compared with 100 and 120 kV tube settings. The authors demonstrated that an adequate diagnostic image quality was obtained in more than 98% of coronary segments using the 80, 100, and 120 kV tube voltage settings (p = 0.482). Image noise was significantly higher with 80 kV compared to 100 and 120 kV tube voltage settings. The effective dose using 80 kV (0.36 ± 0.03 mSv) was significantly lower than that using 100 kV (0.86 ± 0.08 mSv), or the 120 kV tube voltage setting (1.77 ± 0.18 mSv). Use of a tube voltage of 80 kV for patients with a body mass index ≤ 22.5 kg/m² resulted in a further dose reduction of 58% and 80% compared with 100 and 120 kV protocols, while maintaining diagnostic image quality. Particularly in patients with slim body shape, a further reduction of tube voltage to 80 kV may be advisable. The authors concluded that 80 kV high-pitch spiral coronary CT angiography is feasible for patients with body mass index ≤ 22.5 kg/m². The authors also suggested that the amount of contrast material could be decreased, reducing contrast media-associated nephropathy and avoiding the obscuration of calcification caused by excessively high Hounsfield value. To further reduce the high image noise, they introduced iterative reconstruction in clinical routine practice. Consequently, the authors propose a combination of a low kV scan protocol, reduced contrast material injection protocol, and iterative reconstruction for an acceptable low radiation dose together with preserved image quality. The above-mentioned findings by Wang et al. [36] have been underscored by Abada et al. [37], who used a 64-slice CT 80 kV tube voltage setting in 11 patients with body weight < 60 kg. The authors reported a dose reduction by up to 88% without a negative influence on image quality. Achenbach et al. [38] reported a case of 74-year-old patient with 63 kg body weight using 80 kV tube voltage and showed adequate diagnostic image quality and a dose reduction of 80% compared with a standard 120 kV tube voltage setting. In summary, the study by Wang et al. [36] validly demonstrates that further reduction in tube current may be feasible for reducing radiation exposure in patients undergoing CT coronary angiography.

BackgroundRegular disease monitoring with low-dose high-resolution (LD-HR) computed tomography (CT) scans is necessary for the clinical management of people with cystic fibrosis (pwCF). The aim of this study was to compare the image quality and radiation dose of LD-HR protocols between photon-counting CT (PCCT) and energy-integrating detector system CT (EID-CT) in pwCF.MethodsThis retrospective study included 23 pwCF undergoing LD-HR chest CT with PCCT who had previously undergone LD-HR chest CT with EID-CT. An intraindividual comparison of radiation dose and image quality was conducted. The study measured the dose-length product, volumetric CT dose index, effective dose and signal-to-noise ratio (SNR). Three blinded radiologists assessed the overall image quality, image sharpness, and image noise using a 5-point Likert scale ranging from 1 (deficient) to 5 (very good) for image quality and image sharpness and from 1 (very high) to 5 (very low) for image noise.ResultsPCCT used approximately 42% less radiation dose than EID-CT (median effective dose 0.54 versus 0.93 mSv, p < 0.001). PCCT was consistently rated higher than EID-CT for overall image quality and image sharpness. Additionally, image noise was lower with PCCT compared to EID-CT. The average SNR of the lung parenchyma was lower with PCCT compared to EID-CT (p < 0.001).ConclusionIn pwCF, LD-HR chest CT protocols using PCCT scans provided significantly better image quality and reduced radiation exposure compared to EID-CT.Relevance statementIn pwCF, regular follow-up could be performed through photon-counting CT instead of EID-CT, with substantial advantages in terms of both lower radiation exposure and increased image quality.Key PointsPhoton-counting CT (PCCT) and energy-integrating detector system CT (EID-CT) were compared in 23 people with cystic fibrosis (pwCF).Image quality was rated higher for PCCT than for EID-CT.PCCT used approximately 42% less radiation dose and offered superior image quality than EID-CT.Graphical