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Stephen Balter

Publications and source records attributed to Stephen Balter.

14 recordsLinked to original sources
PubMed2006

A multicenter, randomized, dose-finding study of gamma intracoronary radiation therapy to inhibit recurrent restenosis after stenting.

OBJECTIVES: The objective of this double-blind, randomized study was to determine the safety and efficacy of intracoronary radiation therapy (ICRT) with a dose of 17 Gray (Gy) compared to the currently recommended dose prescription of 14 Gy for the treatment of in-stent restenosis within bare metal stents. BACKGROUND: While gamma ICRT for in-stent restenosis has been proven efficacious, the optimal dose is unknown, and radiation failure due to recurrent neointimal hyperplasia remains a significant clinical problem for some patients. A higher radiation dose may improve outcomes, but may potentially increase adverse events. METHODS: Following coronary intervention, 336 patients with in-stent restenosis were randomly assigned to receive ICRT with either 14 Gy or 17 Gy at 2 mm from an 192-iridium source. RESULTS: At 8-month follow up, fewer patients in the 17 Gy group underwent target lesion revascularization (TLR = 15.2% versus 27.2%; p = 0.01), target vessel revascularization (21.3% versus 33.1%; p = 0.02), or reached the composite endpoint of death, myocardial infarction, thrombosis, or TLR (17.1% versus 28.4%; p = 0.02). There were no differences in late thrombosis or mortality between treatment groups. There was a strong trend toward reduced in-lesion late loss (0.36 +/- 0.63 mm vs. 0.51 +/- 0.64 mm; p = 0.09) and a significantly lower rate of binary restenosis (23.9% versus 38.1%; p = 0.031) in the high dose group. CONCLUSIONS: Gamma ICRT with 17 Gy is safe and, compared to 14 Gy, reduces recurrent stenosis and clinical events at 8-month follow up. An increase in the currently recommended gamma radiation dose prescription from 14 Gy to 17 Gy should be strongly considered.

Aged↗
PubMed2004

Occupational hazards of interventional cardiologists: prevalence of orthopedic health problems in contemporary practice.

Invasive cardiologists generally consider radiation to be the chief occupational hazard. Heavy leaded aprons worn to reduce this risk may be associated with orthopedic complications. This study was designed to characterize the prevalence of these occupational health problems. The Interventional Committee of the Society for Cardiac Angiography and Interventions (SCAI) sent to its Internet-registered members a Web-based survey. Inquiries included age, years of invasive practice, and diagnostic/interventional cases/year. Questions (yes/no) focused on orthopedic (spine, hips, knees, and ankles) and radiation-associated problems (cataracts and cancers). The survey was sent to over 1,600 members with 424 responses. Responders were on average busy and experienced, performing catheterization > 10 years in 62% of cases and > 20 years in 24% others. Average annual diagnostic-only case load was > 200/year in 72%, > 300/year in 43%, and > 500/year in 18% of responders. Reported annual interventional caseload was > 100/year in 83%, > 200/year in 37%, and > 300/year in 15% of operators. Orthopedic problems included spine problems in 42% of responders (of these, 70% were lumbosacral and 30% cervical). Hip, knee, or ankle problems were noted in 28% of operators. Spine problems were related to the annual procedural caseload and the number of years in practice. Over one-third reported spine problems had caused them to miss work. The results of the radiation queries were inconclusive. These results document that interventional cardiologists commonly suffer orthopedic disease, frequently leading to lost work days.

Adult↗
PubMed2004

Radiation doses in interventional radiology procedures: the RAD-IR Study. Part III: Dosimetric performance of the interventional fluoroscopy units.

PURPOSE: To present the physics data supporting the validity of the clinical dose data from the RAD-IR study and to document the performance of dosimetry-components of these systems over time. MATERIALS AND METHODS: Sites at seven academic medical centers in the United States prospectively contributed data for each of 12 fluoroscopic units. All units were compatible with International Electrotechnical Commission (IEC) standard 60601-2-43. Comprehensive evaluations and periodic consistency checks were performed to verify the performance of each unit's dosimeter. Comprehensive evaluations compared system performance against calibrated ionization chambers under nine combinations of operating conditions. Consistency checks provided more frequent dosimetry data, with use of each unit's built-in dosimetry equipment and a standard water phantom. RESULTS: During the 3-year study, data were collected for 48 comprehensive evaluations and 581 consistency checks. For the comprehensive evaluations, the mean (95% confidence interval range) ratio of system to external measurements was 1.03 (1.00-1.05) for fluoroscopy and 0.93 (0.90-0.96) for acquisition. The expected ratio was 0.93 for both. For consistency checks, the values were 1.00 (0.98-1.02) for fluoroscopy and 1.00 (0.98-1.02) for acquisition. Each system was compared across time to its own mean value. Overall uncertainty was estimated by adding the standard deviations of the comprehensive and consistency measurements in quadrature. The authors estimate that the overall error in clinical cumulative dose measurements reported in RAD-IR is 24%. CONCLUSION: Dosimetric accuracy was well within the tolerances established by IEC standard 60601-2-43. The clinical dose data reported in the RAD-IR study are valid.

Fluoroscopy↗
PubMed2003

Radiation doses in interventional radiology procedures: the RAD-IR study: part I: overall measures of dose.

PURPOSE: To determine patient radiation doses for interventional radiology and neuroradiology procedures, to identify procedures associated with higher radiation doses, and to determine the effects of various parameters on patient doses. MATERIALS AND METHODS: A prospective observational study was performed at seven academic medical centers. Each site contributed demographic and radiation dose data for subjects undergoing specific procedures in fluoroscopic suites equipped with built-in cumulative dose (CD) and dose-area-product (DAP) measurement capability compliant with International Electrotechnical Commission standard 60601-2-43. The accuracy of the dosimetry was confirmed by comprehensive measurements and by frequent consistency checks performed over the course of the study. RESULTS: Data were collected on 2,142 instances of interventional radiology procedures, 48 comprehensive physics evaluations, and 581 periodic consistency checks from the 12 fluoroscopic units in the study. There were wide variations in dose and statistically significant differences in fluoroscopy time, number of images, DAP, and CD for different instances of the same procedure, depending on the nature of the lesion, its anatomic location, and the complexity of the procedure. For the 2,142 instances, observed CD and DAP correlate well overall (r = 0.83, P <.000001), but correlation in individual instances is poor. The same is true for the correlation between fluoroscopy time and CD (r = 0.79, P <.000001). The correlation between fluoroscopy time and DAP (r = 0.60, P <.000001) is not as good. In 6% of instances (128 of 2,142), which were principally embolization procedures, transjugular intrahepatic portosystemic shunt (TIPS) procedures, and renal/visceral artery stent placements, CD was greater than 5 Gy. CONCLUSIONS: Most procedures studied can result in clinically significant radiation dose to the patient, even when performed by trained operators with use of dose-reducing technology and modern fluoroscopic equipment. Embolization procedures, TIPS creation, and renal/visceral artery stent placement are associated with a substantial likelihood of clinically significant patient dose. At minimum, patient dose data should be recorded in the medical record for these three types of procedures. These data should include indicators of the risk of deterministic effects as well as the risk of stochastic effects.

Adolescent↗
PubMed2003

Radiation doses in interventional radiology procedures: the RAD-IR study: part II: skin dose.

PURPOSE: To determine peak skin dose (PSD), a measure of the likelihood of radiation-induced skin effects, for a variety of common interventional radiology and interventional neuroradiology procedures, and to identify procedures associated with a PSD greater than 2 Gy. MATERIALS AND METHODS: An observational study was conducted at seven academic medical centers in the United States. Sites prospectively contributed demographic and radiation dose data for subjects undergoing 21 specific procedures in a fluoroscopic suite equipped with built-in dosimetry capability. Comprehensive physics evaluations and periodic consistency checks were performed on each unit to verify the stability and consistency of the dosimeter. Seven of 12 fluoroscopic suites in the study were equipped with skin dose mapping software. RESULTS: Over a 3-year period, skin dose data were recorded for 800 instances of 21 interventional radiology procedures. Wide variation in PSD was observed for different instances of the same procedure. Some instances of each procedure we studied resulted in a PSD greater than 2 Gy, except for nephrostomy, pulmonary angiography, and inferior vena cava filter placement. Some instances of transjugular intrahepatic portosystemic shunt (TIPS) creation, renal/visceral angioplasty, and angiographic diagnosis and therapy of gastrointestinal hemorrhage produced PSDs greater than 3 Gy. Some instances of hepatic chemoembolization, other tumor embolization, and neuroembolization procedures in the head and spine produced PSDs greater than 5 Gy. In a subset of 709 instances of higher-dose procedures, there was good overall correlation between PSD and cumulative dose (r = 0.86; P <.000001) and between PSD and dose-area-product (r = 0.85, P <.000001), but there was wide variation in these relationships for individual instances. CONCLUSIONS: There are substantial variations in PSD among instances of the same procedure and among different procedure types. Most of the procedures observed may produce a PSD sufficient to cause deterministic effects in skin. It is suggested that dose data be recorded routinely for TIPS creation, angioplasty in the abdomen or pelvis, all embolization procedures, and especially for head and spine embolization procedures. Measurement or estimation of PSD is the best method for determining the likelihood of radiation-induced skin effects. Skin dose mapping is preferable to a single-point measurement of PSD.

Fluoroscopy↗
PubMed2002

Comparison of four techniques to estimate radiation dose to skin during angiographic and interventional radiology procedures.

PURPOSE: Four techniques used to estimate radiation risk were compared to determine whether commonly used dosimetry measurements permit reliable estimates of skin dose. Peak skin dose (PSD) is known to be the most reliable estimate of risk to skin. The purpose of this study is to determine peak skin dose with use of real-time software measurements and to correlate other measures of dose with PSD. MATERIALS AND METHODS: Two hundred twelve patients undergoing arch aortography and bilateral carotid arteriography (referred to as "carotid"), abdominal aortography and bilateral lower extremity runoff ("runoff"), or tunneled chest wall port placement ("port") were studied. Fluoroscopy time, dose-area product (DAP), and cumulative dose at the interventional reference point were recorded for all procedures; PSD was recorded for a subset of 105 procedures. The dose index, defined as the ratio between PSD and cumulative dose, was also determined. RESULTS: In general, correlation values for comparisons between fluoroscopy time and the other measures of dose (r =.29 to.78) were lower than values for comparisons among DAP, cumulative dose, and PSD (r =.52 to.94). For all procedures, pair-wise correlations between DAP, cumulative skin dose, and PSD were statistically significant (P <.01) The ratio between PSD and cumulative skin dose (dose index) was significantly different for ports versus other procedures (carotid, Z = 4.62, P <.001; runoff, Z = 4.52, P <.001), but carotid and runoff procedures did not differ significantly in this regard (Z = 0.746, P =.22). Within each individual procedure type, the range of values for the dose index varied 156.7-fold for carotid arteriography, 3.2-fold for chest ports, and 175-fold for aortography and runoff. CONCLUSION: Fluoroscopy time is a poor predictor of risk because it does not correlate well with PSD. Cumulative dose and DAP are not good analogues of PSD because of weak correlations for some procedures and because of wide variations in the dose index for all procedures.

Computer Systems↗
PubMed2002

Minimizing radiation-induced skin injury in interventional radiology procedures.

Skin injury is a deterministic effect of radiation. Once a threshold dose has been exceeded, the severity of the radiation effect at any point on the skin increases with increasing dose. Peak skin dose is defined as the highest dose delivered to any portion of the patient's skin. Reducing peak skin dose can reduce the likelihood and type of skin injury. Unfortunately, peak skin dose is difficult to measure in real time, and most currently available fluoroscopic systems do not provide the operator with sufficient information to minimize skin dose. Measures that reduce total radiation dose will reduce peak skin dose, as well as dose to the operator and assistants. These measures include minimizing fluoroscopy time, the number of images obtained, and dose by controlling technical factors. Specific techniques-dose spreading and collimation-reduce both peak skin dose and the size of skin area subjected to peak skin dose. For optimum effect, real-time knowledge of skin-dose distribution is invaluable. A trained operator using well-maintained state-of-the art equipment can minimize peak skin dose in all fluoroscopically guided procedures.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

Influence of flat-panel fluoroscopic equipment variables on cardiac radiation doses.

PURPOSE: To assess the influence of physician-selectable equipment variables on the potential radiation dose reductions during cardiac catheterization examinations using modern imaging equipment. MATERIALS: A modern bi-plane angiography unit with flat-panel image receptors was used. Patients were simulated with 15-30 cm of acrylic plastic. The variables studied were: patient thickness, fluoroscopy pulse rates, record mode frame rates, image receptor field-of-view (FoV), automatic dose control (ADC) mode, SID/SSD geometry setting, automatic collimation, automatic positioning, and others. RESULTS: Patient radiation doses double for every additional 3.5-4.5 cm of soft tissue. The dose is directly related to the imaging frame rate; a decrease from 30 pps to 15 pps reduces the dose by about 50%. The dose is related to [(FoV)(-N )] where 2.0 < N < 3.0. Suboptimal positioning of the patient can nearly double the dose. The ADC system provides three selections that can vary the radiation level by 50%. For pediatric studies (2-5 years old), the selection of equipment variables can result in entrance radiation doses that range between 6 and 60 cGy for diagnostic cases and between 15 and 140 cGy for interventional cases. For adult studies, the equipment variables can produce entrance radiation doses that range between 13 and 130 cGy for diagnostic cases and between 30 and 400 cGy for interventional cases. CONCLUSIONS: Overall dose reductions of 70-90% can be achieved with pediatric patients and about 90% with adult patients solely through optimal selection of equipment variables.

Acrylic Resins↗