Dose Reduction Strategies Research Articles

TH‐A‐214‐11: Dose to Implantable Cardiac Devices from Cone Beam CT

Purpose: To quantify the cumulative dose contribution to implantable cardiac rhythm management devices (ICRMDs) from cone beam CT (CBCT) for patients undergoing radiotherapy and to investigate dose reduction strategies. Methods: An implantable pacemaker (IP) and implantable cardioverter‐defibrillator (ICD) with internal MOSFET dosimeters were used to measure the cumulative CBCT dose to the IP and ICD. Specifically, the MOSFET threshold voltage shifts resulting from standard clinical CBCT imaging protocols were recorded and compared to shifts caused by peripheral megavoltage dose associated with 6 MV IMRT treatment delivery. The dose assessments were performed on an anthropomorphic phantom with the IP or ICD placed in the left clavicular area both inside and outside of the CBCT field of view (FOV). Two dose reduction strategies were evaluated: the use of a 2 mm copper plate to shield the device during imaging and the use of partial‐angle scanning. Results: The average internal IP and ICD doses due to standard clinical CBCT imaging protocols with the device inside the FOV were in the 2.2 – 4.3 cGy and 0.8 – 1.9 cGy range, respectively, but could reach as high as 11.2 cGy per scan. Five centimeters outside the FOV, the dose can reach up to 10% of the in‐field dose in the cranio‐caudal direction and up to 70% in the medio‐ lateral direction. Copper shielding resulted in a 3‐fold reduction in total CBCT dose and a posterior 180 degree scan reduced the dose by a factor of 8 in comparison to a full 360 degree scan. Conclusions: The CBCT imaging dose to ICRMDs can be substantial and needs to be accounted for. Use of a MOSFET dosimeter during the first treatment fraction is an effective way of obtaining a reasonable upper limit of the average cumulative ICRMD dose. Partial posterior scans can greatly reduce this dose.

SU‐E‐I‐80: Dose Metrics, the Relationship, and Reduction Strategies for Interventional Procedures

Purpose: Interventional Radiological (IR) procedures result in the highest individual doses in most radiology practices. Recently FDA unveiled initiative to reduce unnecessary radiation exposure from medical imaging. To achieve this goal, the understanding of dose metrics and their relationships from IR procedures is a must. This study aims to summarize dose metrics, investigate the relationship and develop strategies for IR dose reduction and overdose alert. Methods: A Rando phantom was used to investigate entrance skin dose (ESD) in two Siemens flat panel fluoroscopy systems (Artis and Atris Biplane) using typical protocols for neuro, chest and abdominal interventional procedures. Fluoroscopy time, dose‐area product (DAP), and reference dose were recorded from consoles. Exposure rate and cumulative dose at different surface (skin) locations of the imaged areas were measured with a RadCal dosimeter and a Unfors Patient Skin Dosimeter (PSD, with 4 sensors). The relationships among dose metrics were then analyzed for different clinical settings and dose reduction/overdose alert strategies were discussed. Results: Linear relationships among different dose metrics are observed for fixed clinical setting (SID, image area, fluoroscopy mode, etc). With changes in clinical settings, the linear relationship changes accordingly, which causes difficulty in directly predicting ESD by any single dose metric. However, combining different settings may give a reasonable estimation of patient skin dose during IR procedure. Conclusions: Considering different clinical settings, ESD can be estimated from dose metrics in the current fluoroscopy systems and used as indicator of patient dose during IR procedures. This information and related strategies may potentially reduce the risk of patient overdose.

An education and training programme for radiological institutes: impact on the reduction of the CT radiation dose

To establish an education and training programme for the reduction of CT radiation doses and to assess this programme's efficacy. Ten radiological institutes were counselled. The optimisation programme included a small group workshop and a lecture on radiation dose reduction strategies. The radiation dose used for five CT protocols (paranasal sinuses, brain, chest, pulmonary angiography and abdomen) was assessed using the dose-length product (DLP) before and after the optimisation programme. The mean DLP values were compared with national diagnostic reference levels (DRLs). The average reduction of the DLP after optimisation was 37% for the sinuses (180 vs. 113 mGycm, P < 0.001), 9% for the brain (982 vs. 896 mGycm, P < 0.05), 24% for the chest (425 vs. 322 mGycm, P < 0.05) and 42% for the pulmonary arteries (352 vs. 203 mGycm, P < 0.001). No significant change in DLP was found for abdominal CT. The post-optimisation DLP values of the sinuses, brain, chest, pulmonary arteries and abdomen were 68%, 10%, 20%, 55% and 15% below the DRL, respectively. The education and training programme for radiological institutes is effective in achieving a substantial reduction in CT radiation dose.

Marked Reduction of Effective Radiation Dose in Patients Undergoing CT Coronary Angiography using Prospective ECG Gating

Coronary CT angiography (CCTA) is a rapidly evolving technology which can characterise and image sub clinical atherosclerotic plaque and visualise anatomy and quantitate stenosis. Concern about radiation exposure has limited the uptake of this technology. The aim of this study was to review the radiation dose data in 2298 consecutive patients referred to a single centre in an Australian outpatient setting over 27 months using all available radiation dose reduction strategies. Prospective ECG gating ("step and shoot") was used preferentially in 2025 patients with a mean effective dose of 3.39 ± 1.84 mSv (range 0.86-12.6 mSv). For clinical reasons only 273 patients required retrospective ECG gating, mean dose 19.21 ± 5.58 mSv (range 2.4-34.9 mSv) resulting in an 85.7% reduction in dose for the majority of patients with the low dose technique. In conclusion, most patients referred for routine CCTA can be studied with a radiation dose comparable to invasive X-ray angiography and less than radionuclide myocardial perfusion imaging.

Radioiodine therapy of benign non-toxic goitre. Potential role of recombinant human TSH

This review provides an update on recombinant human TSH (rh-TSH) augmented radioiodine ( 131I) therapy and outlines its potential role in the treatment of symptomatic benign multinodular non-toxic goitre. In some countries, 131I has been used for three decades to reduce the size of nodular goitres. The feasibility of 131I therapy depends on an adequate thyroid 131I uptake. Based on a two-fold increase in thyroid 131I uptake, superiority studies have convincingly demonstrated that the absorbed thyroid 131I dose can be increased without increasing the administered 131I activity, resulting in a 35–56% amplification of goitre reduction at one-year post radioiodine compared to conventional (without rh-TSH) 131I therapy. Although patient satisfaction is not improved at one-year, this approach facilitates tracheal decompression and is particularly promising in large goitres. The majority of multinodular non-toxic goitre patients may not require amplified goitre reduction. But as an alternative strategy, rh-TSH allows up to 80% reduction of the therapeutic 131I activity while still achieving goitre reduction comparable to that of conventional 131I therapy and maintaining high patient satisfaction. The dose-reduction (equality) strategy is attractive in terms of minimizing post-therapeutic restrictions and in reducing the potential risk of radiation-induced malignancy. Adverse effects like temporary thyroid swelling and thyroid hormone excess are to a large extent dose-dependent and generally 0.1 mg rh-TSH or less is well tolerated. Based on these results we conclude that rh-TSH augmented 131I therapy is a promising new therapeutic principle allowing the tailoring of an optimal 131I therapy on the individual level.

Variation in Pediatric Head CT Imaging Protocols in Washington State

To examine variation in pediatric trauma head CT imaging protocols in Washington state. A web-based survey was sent to trauma-designated hospitals in Washington state. Respondents were queried about pediatric head trauma volumes, type of CT scanners, and technical information about the CT imaging protocols. Variation in pediatric trauma volumes, CT dose reduction strategies, and effective dose by trauma center levels was examined. Mean head effective dose and organ dose for a female baby were estimated. We achieved a 76% overall response rate. Of the 2,215 children who received head CT scans, 36.3% (n=805) received head CT imaging at level 4 trauma center facilities, followed by level 1 trauma center (31.4%; n=695), level 3 trauma center (19.7%; n=436), level 2 trauma center (12%; n=267), and Level 5 (0.5%; n=12) facilities. Most responding trauma center facilities (44/47) reported having a pediatric specific imaging head CT protocols. However, compared to levels 1 and 2 trauma centers together, a greater proportion of levels 3, 4 & 5 trauma center facilities collectively lacked dose reduction strategies (0% vs. 25-57%), tended to have higher mAs (169 ± 113 vs. 110 ± 36), and were later adopters of dose reduction strategies on the CT scanners. There was more than a 10-fold variation in estimated median effective dose for a baby within level 4 trauma center facilities (3.5 ± 0.84 mSv, range 0.60 to 9.60 mSv). There is both within and between trauma center level variation in pediatric head CT imaging protocols and radiation dose in Washington state.

565 ASSESMENT OF PEDIATRIC RADIATION EXPOSURE DURING URETEROSCOPY

You have accessJournal of UrologyPediatrics: Imaging/Infections & Vesicoureteral Reflux1 Apr 2011565 ASSESMENT OF PEDIATRIC RADIATION EXPOSURE DURING URETEROSCOPY Paul Kokorowski, Jeanne Chow, Keith Strauss, Melanie Pennison, and Caleb Nelson Paul KokorowskiPaul Kokorowski Boston, MA More articles by this author , Jeanne ChowJeanne Chow Boston, MA More articles by this author , Keith StraussKeith Strauss Boston, MA More articles by this author , Melanie PennisonMelanie Pennison Boston, MA More articles by this author , and Caleb NelsonCaleb Nelson Boston, MA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.1375AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Pediatric patients are more sensitive to ionizing radiation than adults. The ′as low as reasonably achievable′ (ALARA) principle requires efforts to minimize exposure to the patient, but little is known about radiation exposure during urologic procedures in children, including ureteroscopy (URS) for urolithiasis. The aim of this study was to measure radiation exposure during pediatric URS and identify opportunities for quality improvement. METHODS We performed a prospective direct observation of URS procedures as part of a quality improvement initiative. Information regarding pre-operative patient characteristics, operative factors, fluoroscopy unit settings and radiation exposure were recorded. Primary outcomes were total fluoroscopy time (min) and patient skin entrance dose (SED, in mGy). Specific modifiable factors were identified from observations as targets for potential quality improvement. Univariate tests of association were used to identify specific patient and operative factors associated with primary outcomes. RESULTS Direct observation was performed on 48 consecutive ureteroscopic procedures at a single institution. 34 procedures were included in our analysis after excluding two procedures for arterio-venous malformations, one terminated procedure, and 11 non-pediatric patients (≥21 years of age). Median patient age was 16.5 years old (range 7.4 to 19.2). 21% (7/34) procedures resulted in failure to treat a stone due to spontaneous passage or difficult access. Median total fluoroscopy time was 2.85 min (range 0.4–6.7) and median SED was 42.7mGy (range 2.23–223.4).For reference purposes, SED for chest x-ray in a 15 year old is ∼0.16 mGy. There was considerable variability across multiple examined factors and thus no single factor was significantly associated with fluoroscopy time and only source to skin distance (SSD) was associated with skin entrance dose (p=0.02). However, several other modifiable factors including fluoroscopic image rate and field of view demonstrated opportunities for dose reduction. CONCLUSIONS Pediatric patients receive considerable radiation exposure during ureteroscopic procedures. No specific modifiable factors were consistently predictive of total fluoroscopy time and only SSD was associated with skin entry dose. Large variations limited the power to detect differences. Multiple potential methods for potential radiation reduction were identified and future efforts will focus on implementing dose reduction strategies consistent with the ALARA principle. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e228 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Paul Kokorowski Boston, MA More articles by this author Jeanne Chow Boston, MA More articles by this author Keith Strauss Boston, MA More articles by this author Melanie Pennison Boston, MA More articles by this author Caleb Nelson Boston, MA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Estimation of radiation exposure of different dose saving techniques in 128-slice computed tomography coronary angiography

To estimate the effective dose of cardiac CT with different dose saving strategies dependent on varying heart rates. For dose measurements, an Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a 128-slice single source scanner providing a rotation time of 0.30s and standard protocols with 120 kV and 160 mAs/rot. Protocols were evaluated without ECG-pulsing, with two different ECG-pulsing techniques, and automated exposure control with a simulated heart rate of 60 and 100 beats per minute. Depending on different dose saving techniques and heart rate, the effective whole-body dose of a cardiac scan ranged from 2.8 to 9.5 mSv and from 4.3 to 16.0 mSv for males and females, respectively. The radiation-sensitive breast tissue in the primary scan range results in an increased female dose of 66.7 ± 6.0%. Prospective triggering has the greatest potential to reduce the effective dose to 27.8%, compared to a comparable scan protocol with retrospective ECG-triggering with no ECG-pulsing. Furthermore, the heart rate influences the radiation exposure by increasing significantly at lower heart rates. Due to this broad variability in radiation exposure of a cardiac CT, the radiologist and the CT technician should be aware of the different dose reduction strategies.

Direct Quantification of Breast Dose During Coronary CT Angiography and Evaluation of Dose Reduction Strategies

The purpose of this study was to quantify the absorbed radiation dose received by the adult female breast during coronary CT angiography (CTA) and to evaluate the effectiveness of various dose reduction strategies. An adult female thoracic anthropomorphic phantom was scanned using eight different clinical coronary CTA protocols that varied in detector configuration (320 × 0.5 mm or 64 × 0.5 mm), x-ray tube activation (full R-R, 65% R-R, or 70-80% R-R), use of tube current modulation, and use of breast shields. Direct dosimetry measurements were performed using Gafchromic film to determine the absorbed breast dose. Retrospective helical data acquisition using a 64-detector array and a full cardiac cycle without dose modulation or breast shielding is associated with an average absorbed breast dose of 82.9 mGy. Optimization of coronary CTA technique using a 320-detector array and a 70-80% cardiac phase reduces the absorbed breast dose by 78.9% to 17.5 mGy, whereas breast shields used in isolation reduces breast dose by up to 46.8%. The implementation of clinically validated coronary CTA protocols using large-area detector acquisition and prospective ECG gating with limited x-ray tube activation results in substantial breast dose savings of up to 78.9% and should be used whenever possible in combination with bismuth breast shields to achieve further dose reduction.

Successful Efavirenz Dose Reduction Guided by Therapeutic Drug Monitoring

There are potential benefits to individualizing dosage in patients treated with efavirenz (EFV). We tested a simplified algorithm based on a Bayesian pharmacokinetic approach for guiding dose reduction in patients with EFV concentrations above the 75th percentile (P75) with documented virological efficacy. We designed a prospective, open-label, multicentre study. All consenting participants with EFV concentrations above P75 on standard dosage were included in a dose-reduction cycle. Primary end point was the number of patients who reached plasma concentrations within target (1,000-4,000 ng/ml) after, at most, two cycles of dose reduction at 3 and 6 months. CYP2B6 genetic characterization was performed. Seventy-two patients were screened and 13 fulfilled selection criteria. These patients, with undetectable viraemia on a stable 600 mg EFV-based regimen, had a median (interquartile range) EFV plasma level of 8,112 ng/ml (5,993-10,278) at baseline; 38% (between P75 and P95) qualified for a 400 mg EFV dose, and 62% (above P95) qualified for a 200 mg EFV dose. After one to two dose-reduction cycles, all patients reached targets for EFV plasma concentration at 24 weeks. The predictive dose reduction based on genetic profile differed from dose reduction according to therapeutic drug monitoring (TDM) in three patients. All patients maintained viral suppression at 6 months. A standardized TDM-guided EFV dose-reduction strategy over a 24-week period was successful, safe and yielded EFV plasma concentrations within the recommended therapeutic range. In addition to improving neuropsychiatric tolerability, EFV dose reduction has the potential to substantially decrease treatment cost.

CT radiation dose and radiation reduction strategies

CT radiation dose and radiation reduction strategies

Homicide and Associated Steroid Acute Psychosis: A Case Report

We report the case of an old man treated with methylprednisolone for chronic lymphoid leukemia. After two months of treatment, he declared an acute steroid psychosis and beat his wife to death. Steroids were stopped and the psychotic symptoms subsided, but his condition declined very quickly. The clinical course was complicated by a major depressive disorder with suicidal ideas, due to the steroid stoppage, the leukemia progressed, and by a sudden onset of a fatal pulmonary embolism. This clinical case highlights the importance of early detection of steroid psychosis and proposes, should treatment not be stopped, a strategy of dose reduction combined with a mood stabilizer or antipsychotic treatment. In addition have been revised the risks of the adverse psychiatric effects of steroids.

Coronary computed tomography angiography in coronary artery disease.

To investigate the research directions of coronary computed tomography (CT) angiography in the diagnosis of coronary artery disease (CAD) based on a systematic review of the literature. A search of articles on coronary CT angiography in the diagnosis of CAD was performed during a 6-year-period between 2005 and 2010 from five main radiology journals namely, Radiology, American Journal of Roentgenology, European Radiology, European Journal of Radiology and British Journal of Radiology. Analysis of the references was focused on the research directions of coronary CT angiography with regard to the type of studies in terms of diagnostic value, application of dose-reduction strategies and resultant effective radiation doses with use of these techniques. One hundred and forty two studies were identified which met the selection criteria and were included in the analysis. 64-slice CT (single source and dual-source CT) dominated 78% of the coronary CT angiography studies. Prior to 2007, research was focused on the diagnostic value of coronary CT angiography, but since 2008 more attention has been paid to radiation dose reduction. Radiation dose was reported in 64 studies, representing 45% of total studies published in the five radiology journals. Various dose-saving strategies have been implemented and prospective electrocardiography-triggering and high pitch techniques were found to be the most effective approaches for radiation dose reduction, with the corresponding mean effective dose being 3.5 ± 1.9 mSv and 1.7 ± 0.6 mSv, respectively. This review shows that the current research in coronary CT angiography has shifted from the previous focus on diagnostic accuracy in CAD to more emphasis on radiation dose reduction.

Managing Radiation Use in Medical Imaging: A Multifaceted Challenge

This special report aims to inform the medical community about the many challenges involved in managing radiation exposure in a way that maximizes the benefit-risk ratio. The report discusses the state of current knowledge and key questions in regard to sources of medical imaging radiation exposure, radiation risk estimation, dose reduction strategies, and regulatory options.

Strategies to reduce radiation dose in cardiac PET/CT

Abstract Background Our aim was to investigate CT dose reduction strategies on a hybrid PET/CT scanner for cardiac applications. Materials Image quality and dose estimation of different CT scanning protocols for CT coronary angiography (CTCA), and CT-based attenuation correction for PET imaging were investigated. Fifteen patients underwent CTCA, perfusion PET imaging at rest and under stress, and FDG PET for myocardial viability. These patients were divided into three groups based on the CTCA technique performed: retrospectively gated helical (RGH), ECG tube current modulation (ETCM), and prospective gated axial (PGA) acquisitions. All emission images were corrected for photon attenuation using CT images obtained by default setting and an ultra-low dose CT (ULDCT) scan. Results Radiation dose in RGH technique was 22.2±4.0 mSv. It was reduced to 10.95±0.82 and 4.13±0.31 mSv using ETCM and PGA techniques, respectively. Radiation dose in CT transmission scan was reduced by 96.5% (from 4.53±0.5 to 0.16±0.01 mSv) when applying ULDCT as compared to the default CT. No significant difference in terms of image quality was found among various protocols. Conclusion The proposed CT scanning strategies, i.e. ETCM or PGA for CTCA and ULDCT for PET attenuation correction, could reduce radiation dose up to 47% without degrading imaging quality in an integrated cardiac PET/CT coronary artery examination.

Die Computertomographie bei der Bildgebung von Kindern mit kongenitalen Herzvitien

Congenital heart diseases are the most common congenital abnormalities of development. In general, echocardiography and cardiac catheter angiography are considered the gold standard for the evaluation of congenital heart disease. Cardiac magnetic resonance imaging has become an important supplementary imaging modality because of its ability to provide an accurate morphological and functional evaluation. The role of cardiac computed tomography in the imaging of patients with congenital heart disease is becoming increasingly more important due to the development of low radiation dose protocols and improvements in the spatial and temporal resolution. In the preoperative depiction and follow-up after surgical repair of congenital heart diseases, cardiac computed tomography provides detailed information of the heart, the venous and arterial pulmonary circulation as well as systemic arteries. This article reviews the technical aspects of cardiac CT and the modification of examination protocols according to the expected pathology and patient age. The potentials and limitations of the various radiation dose reduction strategies are outlined.

Dose Reduction Strategies for Thoracic Multidetector Computed Tomography

This review will summarize the current background knowledge about radiation exposure related to thoracic computed tomography (CT). It will also review the historical development in this area. This will be followed by a summary of current efforts to reduce dose with respect to predefined clinical indications. Finally, the review will indicate future strategies for further dose reduction in thoracic CT imaging and give practical recommendations for everyday use.

Improving safety in the electrophysiology laboratory using a simple radiation dose reduction strategy: a study of 1007 radiofrequency ablation procedures

BackgroundThe use of fluoroscopic screening involves exposure to ionising radiation for both patients and operators.ObjectiveTo assess the effects of radiation dose reduction manoeuvres (DRM) during radiofrequency ablation (RFA) procedures.DesignProspective study...

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.

Kardiale Niedrigdosis-Computertomographie

Cardiac CT has evolved to a robust and accurate imaging modality in the cardiac diagnostic armamentarium. However, technical developments had been accompanied with an overall increase in radiation exposure. In the last years, several technical developments and algorithms aimed at the reduction of radiation exposure in cardiac CT. The most relevant dose reduction strategies will be highlighted in this article including appropriate indications for cardiac CT, different ECG synchronization techniques, reduction of tube voltage, and high-pitch CT studies.