Dose Reduction Protocol Research Articles

Hospital-Level Factors Associated With Use of Pediatric Radiation Dose-Reduction Protocols for Head CT: Results From a National Survey

To examine hospital-level factors associated with the use of a dedicated pediatric dose-reduction protocol and protective shielding for head CT in a national sample of hospitals.A mixed-mode (online and paper) survey was administered to a stratified random sample of US community hospitals (N = 751). Respondents provided information on pediatric head CT scanning practices, including use of a dose-reduction protocol. Modified Poisson regression analyses describe the relative risk (RR) of not reporting the use of a pediatric dose-reduction protocol or protective shielding; multivariable analyses adjust for census region, trauma level, children's hospital status, and bed size.Of hospitals that were contacted, 38 were ineligible (no CT scanner, hospital closed, do not scan infants), 1 refused, and 253 responded (35.5% response rate). Across all hospitals, 92.6% reported using a pediatric dose-reduction protocol. Modified Poisson regression showed that small hospitals (0-50 beds) were 20% less likely to report using a protocol than large hospitals (>150 beds) (RR: 0.80, 95% confidence interval [CI]: 0.65-0.99; adjusted for covariates). Teaching hospitals were more likely to report using a protocol (RR: 1.10, 95% CI: 1.02-1.19; adjusted for covariates). After adjusting for covariates, children's hospitals were significantly less likely to report using protective shielding than nonchildren's hospitals (RR: 0.64, 95% CI: 0.56-0.73), though this may be due to more advanced scanner type.Results from this study provide guidance for tailored educational campaigns and quality improvement interventions to increase the adoption of pediatric dose-reduction efforts.

Can a revised paediatric radiation dose reduction CT protocol be applied and still maintain anatomical delineation, diagnostic confidence and overall imaging quality?

To compare multidetector CT (MDCT) radiation doses between default settings and a revised dose reduction protocol and to determine whether the diagnostic confidence can be maintained with imaging quality made under the revised protocol in paediatric head, chest and abdominal CT studies. The study retrospectively reviewed head, chest, abdominal and thoracoabdominal MDCT studies, comparing 231 CT studies taken before (Phase 1) and 195 CT studies taken after (Phase 2) the implemented revised protocol. Image quality was assessed using a five-point grading scale based on anatomical criteria, diagnostic confidence and overall quality. Image noise and dose-length product (DLP) were collected and compared. The relative dose reductions between Phase 1 and Phase 2 were statistically significant in 35%, 51% and 54% (p < 0.001) of head, chest and abdominal CT studies, respectively. There were no statistically significant differences in overall image quality score comparisons in the head (p = 0.3), chest (p = 0.7), abdominal (p = 0.7) and contiguous thoracic (p = 0.1) and abdominal (p = 0.2) CT studies, with the exception of anatomical quality in definition of bronchial walls and delineation of intrahepatic portal branches in thoracoabdominal CTs, and diagnostic confidence in mass lesion in head CTs, liver lesion (>1 cm), splanchnic venous thrombosis, pancreatitis in abdominal CTs, and emphysema and aortic dissection in thoracoabdominal CTs. Paediatric CT radiation doses can be significantly reduced from manufacturer's default protocol while still maintaining anatomical delineation, diagnostic confidence and overall imaging quality. Revised paediatric CT protocol can provide a half DLP reduction while preserving overall imaging quality.

Successful Withdrawal of Omalizumab in a Patient with Severe Asthma: Free IgE as a Possible Biomonitor

To date, the pharmacological activity and clinical benefits of omalizumab have been well described, however several questions still remain unanswered, such as the moment to withdraw the drug as well as the possible biological markers that may be useful to do so. In the present case report, we describe our experience with our dose-reduction protocol in a middle-aged patient and elucidate the usefulness of free IgE levels.

Dose Reduction Efforts for Pediatric Head CT Imaging in Washington State Trauma Centers: Follow-Up Survey Results

To examine variation in pediatric trauma head CT imaging protocols in Washington State trauma centers (TCs) in 2012 and compare to a previous survey conducted in 2008-2009. A mixed-mode (online and paper) survey was sent to all adult and pediatric Washington State TCs (levels 1-5). Respondents provided information about the CT scanner used for pediatric head scans and technical information about pediatric dose reduction protocols. Mean head effective dose and organ dose for a female baby were estimated. Results were compared with previous data. Sixty-one of 76 TCs responded to the 2012 survey (response rate, 80.3%, versus 76% for 2008-2009 survey). In 2012, 91.7% reported having a dedicated pediatric protocol (87.7% in 2008-2009). Protective shielding use ranged from 80% to 100% across both survey years. In 2012, 2.5 times more TCs provided sufficient information to conduct dose calculations than in 2008-2009. Estimated mean CT dose index was 23.1 milliGray (mGy) in 2012, compared with 34.8 mGy in 2008-2009 (P = .01). Estimated mean dose length product was also significantly lower in 2012 than 2008-2009 (307.6 mGy × cm versus 430.1 mGy × cm, respectively; P = .04). Wide variation in mean effective dose was observed for level 3 and 4 TCs in 2012, similar to variation observed in 2008-2009 among level 4 TCs. Mean organ dose was significantly lower in 2012 for eye lens and brain, but higher for thyroid than in 2008-2009 (P < .05). Although most Washington State TCs employ dose reduction protocols for pediatric head CTs, and some measures were lower in 2012, variation in protocols use and estimated dose continues to exist. More complete responses in 2012 suggest improved understanding of the importance of pediatric dose reduction efforts. Education and institutional protocols are necessary to reduce pediatric radiation dose from head CTs.

THU0157 Tripterygium WILFORDII multiglycoside combined regimen as long-term maintenance therapy in chinese rheumatoid arthritis patients

BackgroundLong-term use of traditional and biologic disease-modifying anti-rheumatic drugs (DMARDs) has been applied to achieve the goal of rheumatoid arthritis (RA) treatment. Despite the proven efficacy of DMARDs, there is...

Radiation dose in 320-slice multidetector cardiac CT: A single center experience of evolving dose minimization

BackgroundMinimization of radiation exposure remains an important subject that occurs in parallel with advances in scanner technology. ObjectiveWe report our experience of evolving radiation dose and its determinants after the introduction of 320-multidetector row cardiac CT within a single tertiary cardiology referral service. MethodsFour cohorts of consecutive patients (total 525 scans), who underwent cardiac CT at defined time points as early as 2008, are described. These include a cohort just after scanner installation, after 2 upgrades of the operating system, and after introduction of an adaptive iterative image reconstruction algorithm. The proportions of nondiagnostic coronary artery segments and studies with nondiagnostic segments were compared between cohorts. ResultsSignificant reductions were observed in median radiation doses in all cohorts compared with the initial cohort (P < .001). Median dose-length product fell from 944 mGy · cm (interquartile range [IQR], 567.3–1426.5 mGy · cm) to 156 mGy · cm (IQR, 99.2–265.0 mGy · cm). Although the proportion of prospectively triggered scans has increased, reductions in radiation dose have occurred independently of distribution of scan formats. In multiple regression that combined all groups, determinants of dose-length product were tube output, the number of cardiac cycles scanned, tube voltage, scan length, scan format, body mass index, phase width, and heart rate (adjusted R2 = 0.85, P < .001). The proportion of nondiagnostic coronary artery segments was slightly increased in group 4 (2.9%; P < .01). ConclusionWhile maintaining diagnostic quality in 320-multidetector row cardiac CT, the radiation dose has decreased substantially because of a combination of dose-reduction protocols and technical improvements. Continued minimization of radiation dose will increase the potential for cardiac CT to expand as a cardiac imaging modality.

2078 IS TOTAL ABDOMINAL EXPOSURE DURING NON-CONTRAST COMUTERIZED TOMOGRAPHY (NCCT) NECESSARY AS FOLLOW -UP(F-U) OF PATIENTS WITH URETERAL STONES?!

You have accessJournal of UrologyStone Disease: Basic Research (I)1 Apr 20132078 IS TOTAL ABDOMINAL EXPOSURE DURING NON-CONTRAST COMUTERIZED TOMOGRAPHY (NCCT) NECESSARY AS FOLLOW -UP(F-U) OF PATIENTS WITH URETERAL STONES?! Avi Stein, Yuval Freifeld, ofir Avitan, Roni Molnar, Yoel Mecz, Dmitri Goldin, Tal May, Ilan Klein, Hashul Sharbal, Moad Yichie, Mati Shnap, Nathan Peled, and Yoram Dekel Avi SteinAvi Stein Haifa, Israel More articles by this author , Yuval FreifeldYuval Freifeld Haifa, Israel More articles by this author , ofir Avitanofir Avitan Haifa, Israel More articles by this author , Roni MolnarRoni Molnar Haifa, Israel More articles by this author , Yoel MeczYoel Mecz Haifa, Israel More articles by this author , Dmitri GoldinDmitri Goldin Haifa, Israel More articles by this author , Tal MayTal May Haifa, Israel More articles by this author , Ilan KleinIlan Klein Haifa, Israel More articles by this author , Hashul SharbalHashul Sharbal Haifa, Israel More articles by this author , Moad YichieMoad Yichie Haifa, Israel More articles by this author , Mati ShnapMati Shnap Haifa, Israel More articles by this author , Nathan PeledNathan Peled Haifa, Israel More articles by this author , and Yoram DekelYoram Dekel Haifa, Israel More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.2497AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Ureteral calculi are a common and recurrent clinical emergency in younger patients. The calculi are frequently progressing downstream and some get expelled spontaneously. Repeated NCCT involving radiation exposures are therefore often needed in the course of the same and in recurrent episodes. The issue of X-ray potential accumulated risk has been widely described. We conducted a prospective study in which a batch was formed from the f-u NCCT including only “slices” distal to the original ureteral stone location. The aim of the study was to evaluate the rate of potentially missed findings in this batch compared to the full NCCT and to calculate the radiation exposure which could be saved by using the limited field batch compared to the full study. METHODS 40 patients with single stones in ureters were included. Stone size and locations were described. Patients who had retrograde manipulations were excluded. The full CT and batches were separately interpreted. CTDI was then calculated and translated to msv for all batches and full studies and Rx exposure was then compared calculating the Rx dose which could have been saved if only batches are used for F-U NCCT studies. RESULTS 15/40 patients had stones located at the proximal ureter and 25 in the distal part. The average msv (graph) was 12 for the complete CT and 3.1 for the batches (in average 73% less Rx exposure More radiation was obviously saved in distal stones, which present more frequently . No other pathology was missed by the limited field batch compared to the full F-U NCCT, given that a complete NCCT is performed at presentation. Presence of hydronephrosis can be easily detected by ultrasound. CONCLUSIONS Many patients are referred to repeated FU NCCT. We present a method of limited field NCCT. This, eventually combined with dose reduction protocols, may suggest a significant saving in Rx exposure for patients with ureteral calculi. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e852-e853 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Avi Stein Haifa, Israel More articles by this author Yuval Freifeld Haifa, Israel More articles by this author ofir Avitan Haifa, Israel More articles by this author Roni Molnar Haifa, Israel More articles by this author Yoel Mecz Haifa, Israel More articles by this author Dmitri Goldin Haifa, Israel More articles by this author Tal May Haifa, Israel More articles by this author Ilan Klein Haifa, Israel More articles by this author Hashul Sharbal Haifa, Israel More articles by this author Moad Yichie Haifa, Israel More articles by this author Mati Shnap Haifa, Israel More articles by this author Nathan Peled Haifa, Israel More articles by this author Yoram Dekel Haifa, Israel More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Reduction of coronary artery multi-slice computed tomographic radiation and maintained image interpretability by parameter optimization: the multicenter RAMBO study

Multi-slice computed tomography (MSCT) has proven in several studies to have a high diagnostic accuracy for the detection or exclusion of coronary artery disease. A major concern with coronary MSCT, however, is the associated radiation exposure of patients. Recent studies suggest that use of a 64-slice scanner is associated with a non-negligible lifetime attributable risk of cancer. Several strategies can be used to reduce patient exposure in coronary MSCT. The purpose of this multicenter study was to investigate the effects of the adjustment of tube voltage and current on radiation dose and image interpretability. MSCT with retrospective ECG gating was performed in 315 patients. The dose-length product (DLP) in the patients enrolled with the dose reduction protocol resulted in a 36% overall reduction in the mean radiation dose (911 ± 289 mGy.cm) compared with the standard protocol (1427 ± 226 mGy.cm, p < 0.001). Nevertheless, image interpretability was maintained. This study on coronary MSCT demonstrates that the radiation dose can be significantly reduced by parameter optimization, with maintained image interpretability.

Wax-matrix extended-release niacin vs inositol hexanicotinate: A comparison of wax-matrix, extended-release niacin to inositol hexanicotinate “no-flush” niacin in persons with mild to moderate dyslipidemia

Nicotinic acid (NA), long used for the treatment of dyslipidemia, has shown problems with undesirable side effects and safety issues. Wax-matrix, extended-release niacin (WMER) and inositol hexanicotinate (IHN) have both been formulated to increase patient tolerability. Several trials of WMER demonstrated good efficacy in improving dyslipidemia; however, there are few scientific data on the use of IHN. This study was designed to compare the efficacy and tolerability of WMER and IHN to each other and placebo to help clinicians make an informed choice of NA agents. This was a 6-week blinded, placebo-controlled trial comparing 1500 mg/d of WMER with 1500 mg/d IHN. Subjects with mild-to-moderate dyslipidemia (low-density lipoprotein= 130-190/dL) were randomized, after a 4-week diet lead-in period, to three parallel study arms (40 subjects/arm). Diet, pill compliance, and side effects were monitored as well as lipid and blood chemistry profiles (baseline, 6 weeks). A dose-reduction protocol was included for subjects who did not tolerate the 1500-mg dose of NA. A pharmacokinetic substudy was conducted on subjects from the WMER (n= 5) and IHN (n= 5) groups. WMER demonstrated significant improvements in total cholesterol= -11%, low-density lipoprotein= -18%, high-density lipoprotein=+12%, and non-high-density lipoprotein= -15% (P < .001), whereas IHN and placebo showed no significant improvement in lipids. All groups had good medication compliance and treatment tolerance with only one dropout in the WMER group as the result of flushing. Blood chemistries showed small (24%-27%) mean increases in hepatic transaminases; six subjects completed the study at reduced dosage protocol with good lipid results. Pharmacokinetics demonstrated an intermediate release and absorption rate for WMER over 6 hours and IHN showed no evidence of bioavailability. WMER demonstrated good tolerance and efficacy and extended-release kinetics. IHN was well tolerated but was no better than placebo in lipid improvement and showed no evidence of bioavailability.

Organ-Based Computed Tomographic (CT) Radiation Dose Reduction to the Lenses

Recently, a new specific organ dose adaption and reduction protocol, or SODAR tool (X-CARE, Siemens Healthcare), which reduces dose to the anterior aspect of the body of patients, was installed on our computed tomographic scanner. The purpose of this pilot project was to evaluate image quality and dose distribution in the acquired data with the new protocol. Sixteen consecutive patients were scanned with the new SODAR head protocol. The findings were compared with 16 matched patients who were imaged with the standard computed tomographic head trauma protocol. Image quality was assessed qualitatively using a scale of 1 to 4 (1, excellent; 2, good; 3, fair; 4, nondiagnostic). Additionally, 1-cm regions of interest were placed in the white matter of the cerebral hemispheres, the cerebellar hemispheres, and the brain stem at the level of the pons for a quantitative analysis. The standard deviation of each measurement was recorded as an indicator for image noise. Dose measurement trials were performed using optically stimulated luminescence dosimeters on head phantoms and then on patients. Subjective image quality ranged between 1 and 3; no scan areas were considered nondiagnostic. Overall image quality of the posterior fossa averaged at 1.656 was slightly reduced compared to the cerebral hemispheres (mean, 1.141). The mean standard protocol brain stem image quality was 1.604, with only minimal deterioration to 1.708 in the SODAR group.No significant difference in image noise could be found between the SODAR group with a mean noise of 4.515 and standard images with a mean of 4.721 (P > 0.05).The dose to the anterior aspect of the patient was lowered to 3.2 mGy compared to 4.5 mGy on the lateral aspect of the scan (P > 0.05). To compensate for the photon loss in the posterior aspect, the dose has to be slightly increased to a mean of 6 mGy, but overall, a significant dose reduction with stable image quality could be achieved by reducing the dose length product from 1489 to 1347 mGy·cm using SODAR (P < 0.0001). Using the SODAR protocol resulted not only in an impressive 46% to 59% frontal dose reduction but also in the overall dose reduction. This dose reduction was obtained without sacrificing image quality, providing diagnostic images of the brain while protecting radiosensitive structures like the eye lenses in trauma brain imaging. Future applications will be reducing dose to other radiosensitive structures such as the thyroid gland and breast tissue from potentially harmful low-energy radiation without compromising image quality.

Ureteral Stents: A Risk Factor for Polyomavirus BK Viremia in Kidney Transplant Recipients Undergoing Protocol Screening

Background Polyomavirus BK nephropathy (BKN) remains a common cause of early renal transplant dysfunction and graft loss. To date, little has been reported on the role, if any, of transplant ureteral stents in the development of polyomavirus BK viremia (BVK) and BKN. Methods We performed a single-center, retrospective analysis of renal transplant recipients who underwent renal transplantation followed by monthly BKV screening at Albany Medical Center between January 1, 2006, and December 31, 2009. A transplant ureteral stent was placed at the discretion of the surgeon. The immunosuppression protocol employed for deceased donor and unrelated living -donor recipients was antithymocyte antibody induction with methylprednisolone, mycophenolate mofetil, tacrolimus, and sirolimus. Results During the study period, 186 recipients were identified; 124 (67%) underwent intraoperative transplant ureteral stent placement, while 62 patients (33%) did not undergo stent placement. With our monthly screening protocol, we detected BKV in 32 of the 186 recipients (17%) following transplantation; 27 of the 32 (84%) viremic patients were stent recipients. In all patients who developed BKV, an immunosuppression dose reduction protocol was employed. Ureteral stent placement conferred a statistically significant elevated risk of developing BKV (odds ratio = 3.17, 95% confidence interval 1.16–8.70). Patient gender, age, ethnicity, diabetes status, and retransplant status were not statistically significant factors in the development of BKV. Conclusion Our study demonstrated the elevated risk of BKV in recipients who undergo transplant ureteral stenting. Monthly BK polymerase chain reaction screening appears to be a useful tool for the early detection of BKV in this higher-risk group.

Use of Angiographic CT Imaging in the Cardiac Catheterization Laboratory for Congenital Heart Disease

This study sought to retrospectively evaluate our initial experience using angiographic computed tomography (ACT) in a pediatric cardiac catheterization laboratory. ACT provides cross-sectional CT images from a rotational angiography run using a C-arm mounted flat-panel detector in the interventional suite. A 3-dimensional (3D) angiographic image can be created from the CT volume set and used in real time during the procedure. To our knowledge, its use has never previously been described for congenital heart disease. 3D reconstructions were created and we retrospectively reviewed cases during our first year of ACT use. Images obtained were independently evaluated to determine their diagnostic utility. Radiation dose reduction protocols were defined using phantom testing and radiation dose calculation. ACT was used during 41 cardiac catheterizations in patients at a median age of 5.1 years (range: 0.4 to 58.8 years) for evaluation of: right ventricular outflow tract (RVOT)/central pulmonary arteries (PAs) in 20; cavopulmonary connection (CPC) in 11; pulmonary veins in 5; distal PAs in 4; and other locations in 5. Four subjects had 2 anatomic areas studied by ACT. The mean contrast volume for ACT was 1.2 ± 0.4 ml/kg. Diagnostic-quality imaging was obtained in 71% of cases: 13/20 RVOT/central PAs; 9/11 CPC; 4/5 pulmonary veins; 2/4 distal PAs; and 4/5 others. In 12 cases, ACT contributed to clinical outcomes beyond standard angiography. Radiation dose reduction protocols allowed ACT to be comparable in exposure to a standard biplane cineangiogram. Diagnostic-quality imaging can be obtained using ACT in 71% of cases without a significant increase in contrast or radiation exposure. In certain cases, ACT provides additional anatomic detail and may aid complex catheter manipulations. Future work is needed to continue to define applications of this new technology.

Effect of a Standardized Quality-Improvement Protocol on Radiation Dose in Coronary Computed Tomographic Angiography

Coronary computed tomographic angiography (CCTA) is associated with ionizing radiation, prompting concerns of future cancer risk. Recent studies have reported reduced radiation doses and similar image quality by the selective use of dose reduction techniques, although the clinical penetration of these methods has been limited. In a quality improvement initiative, a comprehensive, standardized radiation dose reduction protocol was implemented, and its effect on radiation dose and image quality was assessed. A total of 449 patients who underwent 64-detector CCTA at 3 centers were prospectively evaluated, and patients were compared before (n = 247) and after (n = 202) the implementation of a standardized body mass index-based and heart rate-based protocol that simultaneously incorporated multiple dose reduction strategies. Median radiation dose decreased from 2.6 mSv (interquartile range 2.0 to 4.2) to 1.3 mSv (interquartile range 0.8 to 1.9) after the implementation of the standardized protocol (p < 0.001). On multivariate analysis, reduction in overall radiation dose was observed by numerous dose reduction techniques, with varying efficacy of dose lowering: prospective (vs retrospective) electrocardiographic gating (-82%), reduced tube voltage (-41% for 100 vs 120 kV), lower tube current (-25% per -100 mA), and reduced overall scan length (-6% per -1 cm) (p < 0.001 for each). No differences were observed between patients before and after the initiation of the protocol for study interpretability (96% vs 96%, p = 0.66). There was an increase in signal-to-noise ratio after implementing the standardized protocol (11 ± 3 vs 12 ± 4, p < 0.01). In conclusion, a quality improvement protocol for CCTA incorporating multiple dose reduction techniques permits significant radiation dose reduction and may improve the safety profile of CCTA.

Radiation dose from coronary CT angiography: Five years of progress

Radiation doses from coronary CT angiography have been scrutinized as a consequence of rising concern over cumulative lifetime radiation dose from diagnostic imaging and potential cancer risk. In response to this, the past 5 years have witnessed progressive refinements in CT technology and new dose reduction protocols, including electrocardiography-based tube current modulation, lower peak tube voltage, prospective or axial scanning, high-pitch spiral scanning, and iterative CT data reconstruction. As a direct result, compared with radiation exposure levels initially reported from 64-detector coronary CT angiography without dose modulation (range, 16-20 mSv), doses have decreased by approximately 50% every 2 years since 2005. Recent high-pitch spiral scan studies have documented doses ≤ 1 mSv. In routine clinical practice, registries show somewhat higher radiation dose levels, but nonetheless a similar rate of improvement with marked dose reduction enabled by dissemination of updated CT scanner technology. The current challenge is to continue the past rate of progress by incorporating research into practice and to facilitate improved technology.

Estimated cumulative radiation dose from PET/CT in children with malignancies: reply to Gelfand et al

Sir, We highly appreciate the comments of Dr. Michael Gelfand and his colleagues [1] regarding our article [2]. We agree that when appropriate administered activities of FDG and appropriate PET/CT protocols are used, the effective dose attributable to the addition of PET/CT to the previously required CT imaging can be much less than the 24.8 mSv stated in our study. In the discussion portion of our manuscript, we specifically pointed out that, while our original CT protocols were adjusted for patient size, we have instituted even more aggressive dose reduction protocols (as shown in Table 3 in our article [2]) that involve reducing kVp as well as the use of tube current modulation (a function that was not available on the original PET/CT scanner used in this study but is now available on the systems in our current clinical practice). We also described one key aspect of our practice, that the CT portion of the exam is used for diagnosis and not just for PET attenuation correction. This aspect itself has a significant impact on the radiation dose delivered to the patient. To obtain diagnostic-quality CT images requires more radiation dose than do images that are only used for attenuation correction. However, our radiologists believe that the information obtained is vital to patient management and so it is our practice to perform these scans at levels consistent with our diagnostic protocols. Further, it should be noted that our estimates of radiation dose were done in a very detailed manner and were not based solely on scanner-reported CTDI values, which represent dose to one of two standardized phantoms (either 16- or 32-cm phantom, depending on the manufacturer), and do not reflect actual patient dose. Instead, we used previously published Monte Carlo simulation results as well as published adjustments for patient size. We believe this provides a much more accurate estimate of actual radiation dose to individual pediatric patients than conventional estimates obtained using CTDIvol and Dose Length Product (DLP) values reported at the scanner. Finally, the point of our study was to review our existing institutional protocols, especially for pediatric patients with malignancies who undergo frequent and repeated PET/CT scanning and to look at not just the effects of an individual scan but at the cumulative impact on these patients, even for protocols that had been only somewhat tailored for children, and to evaluate their impact in terms of the radiation exposure. It should be remembered that many institutions do not have their protocols specifically adjusted for children and that many pediatric patients with malignancies are subjected to repeated studies to monitor disease status. Therefore, protocols should be designed with a balance of radiation exposure and benefit in mind, and both CT and PET/CT studies should be performed with specific pediatric guidelines, thus reducing the overall radiation dose to this patient population.

Effect of a Standardized Radiation Dose Reduction Protocol on Diagnostic Accuracy of Coronary Computed Tomographic Angiography

Although numerous strategies for radiation dose decrease in coronary computed tomographic angiography are effective, their combined impact on diagnostic performance is not known. We therefore assessed the effect of a standardized coronary computed tomographic angiographic protocol on diagnostic accuracy. We evaluated 80 consecutive patients from 3 sites with coronary computed tomographic angiography and quantitative coronary angiography. All sites initially used nonstandardized protocols; 2 sites then initiated a standardized protocol, and 1 site continued its nonstandardized protocol as a time-overlapping control. Two blinded readers interpreted coronary computed tomographic angiographic studies; a third obtained consensus. A blinded core laboratory performed quantitative coronary angiography. Each segment was graded as <50% or > or =50% diameter stenosis. Compared to those using nonstandardized protocols (n = 35), studies using standardized protocols (n = 45) had a trend to increased use of prospective gating (p = 0.09), lower voltage (p <0.01), decreased current (p <0.01), and shorter scan length (p <0.01). Median (interquartile range) radiation dose decreased from 5.7 mSv (4.0 to 10.8) to 2.0 mSv (1.3 to 3.4, p <0.001). There were no significant differences in sensitivity (100%, 20 of 20, vs 100%, 18 of 18, p = 1.0), specificity (93%, 14 of 15, vs 85%, 23 of 27, p = 0.61), or accuracy (97%, 34 of 35, vs 91%, 41 of 45, p = 0.27) by patient; sensitivity (83%, 33 of 40, vs 83%, 25 of 30, p = 0.93), specificity (92%, 86 of 93, vs 92%, 134 of 146, p = 0.85), or accuracy (89%, 119 of 133, vs 90%, 159 of 176, p = 0.80) by artery; or sensitivity (80%, 44 of 55, vs 72%, 26 of 36, p = 0.74), specificity (94%, 332 of 353, vs 94%, 499 of 531, p = 0.96), or accuracy (92%, 376 of 408, vs 93%, 525 of 567, p = 0.80) by segment. In conclusion, a standardized dose-decrease protocol for coronary computed tomographic angiography decreases radiation dose without affecting diagnostic performance.

TH-C-201B-01: Changes in Radiation Dose of Abdominal and Pelvic Computed Tomography Examinations over a Seven Year Period

PURPOSE: Computed tomography (CT) technology has rapidly evolved. Phantom studies show higher radiation doses with increasing detector rows. However scanner-based dose-reduction techniques have also evolved. Given these opposing trends that impact patient dose it is unclear whether doses increased have or decreased over time. Using an automated dose information extraction tool we analyzed trends in radiation doses over time for abdominal and pelvic examinations at our institution. METHOD AND MATERIALS: Radiation dose (total DLP) from 1716 abdominal and pelvic CT examinations performed between 2003 and 2010 were analyzed. Examinations were performed on 6 MDCT scanners ranging from 4 to 64 detectors. Dose data from protocol sheets was extracted using a novel extraction system. RESULTS: Average DLP for CT examinations of the abdomen and pelvis performed in 2003 was 728.9 +/−278 mGy-cm. Average DLP for examinations performed in 2010 was 1034 +/− 458 mGy-cm a 41.8% increase. For a 16 slice scanner in constant use since 2003 average DLP increased from 728.9 +/− 278 mGy-cm in 2003 to 1004 +/− 421 mGy-cm in 2010 a 37.7% increase. For abdominal and pelvic examinations from the year 2010 average DLP for exams performed on 16-slice scanners (2 total) was 1094 +/− 478 mGy-cm. The average DLP for examinations performed on 64-slice scanners (3 total) was 1245 +/− 598 mGy-cm which is an average 13.8% higher dose. CONCLUSIONS: Average CT radiation dose has increased over time. Scanners with greater numbers of detector rows delivered a higher radiation dose. Patient radiation doses for abdominal and pelvic examinations performed on a given scanner also increased over time. The upward trend in dose is likely due to a combination of hardware factors protocol changes and potentially changes in the patient population. Knowledge of these trends is important for effective implementation of dose reduction protocols and quality assurance.

Abstract No. 126: A dose reduction protocol for CT-guided procedures

Abstract No. 126: A dose reduction protocol for CT-guided procedures

Combined Vascular–Excretory Phase MDCT Angiography in the Preoperative Evaluation of Renal Donors

The objective of our study was to test a dose reduction protocol that uses combined vascular-excretory phase scanning achieved by split IV contrast injection and compare it with conventional multiphase MDCT angiography (MDCTA) in evaluating potential renal donors. This study is a review of MDCTA examinations of 54 potential renal donors scanned on 16- and 64-MDCT. The IV bolus was split: 50 mL was administered 3 minutes before scanning and a second injection of 70-100 mL was administered at a rate of 4-6 mL/s, with CT angiography started by bolus tracking. The second vascular (venous) phase was acquired 20 seconds later. Two readers reviewed the two phases, assessed vascular and parenchymal anatomy and variants or abnormalities, graded the added value of the venous phase on a 5-point scale, and took attenuation measurements in Hounsfield units. The operative notes of 39 subjects were reviewed as the reference standard for anatomic findings and compared with CT reports. All of the relevant anatomy findings, according to the operative notes, were accurately depicted by MDCTA, and all were well recognized on the arterial phase. The arterial phase combined information from the arterial, venous, parenchymal, and excretory phases. The venous phase was inferior to the arterial phase in assessing the renal arteries without additional venous, parenchymal, or excretory phase information. The mean renal artery attenuation was 355 HU in the first phase versus 173 HU in the second phase (p<0.0001). The mean renal vein attenuation was not significantly different between the two phases. The parenchymal system and excretory system were equally well depicted in both vascular phases. Split-bolus contrast injection and combined vascular-excretory phase scanning are adequate for studying potential renal donors and result in a marked decrease in multiphase scanning and, thus, in radiation dose.

The FLT3 inhibitor tandutinib (formerly MLN518) has sequence-independent synergistic effects with cytarabine and daunorubicin

AML remains a difficult disease to treat. Despite response to induction chemotherapy, most patients ultimately relapse. Further, among elderly patients, aggressive therapy options are often limited due to other medical conditions and decreased tolerance of these patients to conventional chemotherapy. Internal tandem duplications (ITD) of the FLT3 juxtamembrane domain occur in 20-30% of AML patients and predict poor outcome. First clinical data with the FLT3 inhibitor tandutinib demonstrated antileukemic activity in approximately half of the patients - predominantly with FLT3 ITD-positive AML. But the data also show that optimal use of tandutinib will require combination therapy with cytotoxic agents. Notably, single agent tandutinib has not been associated with myelosuppression, mucositis or cardiac toxicity - the dose limiting toxicities of AML chemotherapy. We determined the feasibility of combining tandutinib with the standard “3+7” induction regimen in AML and show that, in contrast to other structurally unrelated FLT3 inhibitors recently evaluated in clinical trials, the use of tandutinib displayed application sequence independent synergistic antileukemic effects in combination with cytarabine and daunorubicin. Strong synergistic antiproliferative and proapoptotic effects were thereby predominantly seen on FLT3 ITD-positive blasts. Further we demonstrate, that addition of tandutinib may allow dose reduction of chemotherapy without loss of overall antileukemic activity – but with a resultant decrease of potential side effects. This approach might be an interesting novel strategy especially in the treatment of elderly/comorbid patients. Our data provide a rationale for combining tandutinib with induction chemotherapy in intensified as well as in dose reduction protocols for FLT3 ITD-positive AML.