Radiation dose in neuroangiography using image noise reduction technology: a population study based on 614 patients

Effective and organ doses in patient undergoing interventional neuroradiology procedures: A multicentre study

PURPOSE

Radiation doses to adult patients submitted to cerebral angiography and intracranial aneurysms treatments were assessed by using DICOM Radiation Dose Structured Reports (RDSR) and Monte Carlo simulations. Conversion factors to estimate effective and organ doses from Kerma-Area Product (PKA) values were determined.

METHODS

77 cerebral procedures performed with five angiographic equipment installed in three Italian centres were analyzed. Local settings and acquisition protocols were considered. The geometrical, technical and dosimetric data of 16,244 irradiation events (13305 fluoroscopy, 2811 digital subtraction angiography, 128 cone-beam CT) were extracted from RDSRs by local dose monitoring systems and were input in MonteCarlo PCXMC software to calculate effective and organ doses. Finally, conversion factors to determine effective and organ doses from PKA were determined. Differences between centres were assessed through statistical analysis and accuracy of dose calculation method based on conversion factors was assessed through Bland-Altman analysis.

RESULTS

Large variations in PKA (14-561 Gycm2) and effective dose (1.2-73.5 mSv) were observed due to different degrees of complexity in the procedures and angiographic system technology. The most exposed organs were brain, salivary glands, oral mucosa, thyroid and skeleton. The study highlights the importance of recent technology in reducing patient exposure (about fourfold, even more in DSA). No statistically significant difference was observed in conversion factors between centres, except for some organs. A conversion factor of 0.09 ± 0.02 mSv/Gycm2 was obtained for effective dose.

CONCLUSIONS

Organ and effective doses were assessed for neuro-interventional procedures. Conversion factors for calculating effective and organ doses from PKA were provided.

Radiation Dose and Fluoroscopy Time of Extracranial Carotid Artery Stenting : Elective vs. Emergency Treatment Including Combined Mechanical Thrombectomy in Tandem Occlusion

PURPOSE

Fluoroscopically guided endovascular carotid artery stenting (CAS) of extracranial carotid stenosis (ECS) is a reasonable alternative to carotid endarterectomy in selected patients. Diagnostic reference levels (DRL) for this common neurointervention have not yet been defined and respective literature data are sparse. We provide detailed dosimetrics for useful expansion of the DRL catalogue.

METHODS

A retrospective single-center study of patients undergoing CAS between 2013 and 2021. We analyzed dose area product (DAP) and fluoroscopy time considering the following parameters: indications for CAS, semielective/elective versus emergency including additional mechanical thrombectomy (MT) in extracranial/intracranial tandem occlusion, etiology of ECS (atherosclerotic vs. radiation-induced), periprocedural features, e.g., number of applied stents, percutaneous transluminal angioplasty (PTA) and MT maneuvers, and dose protocol. Local DRL was defined as 75% percentile of the DAP distribution.

RESULTS

A total of 102 patients were included (semielective/elective CAS n = 75, emergency CAS n = 8, CAS + MT n = 19). Total median DAP was 78.2 Gy cm2 (DRL 117 Gy cm2). Lowest and highest median dosimetry values were documented for semielective/elective CAS and CAS + MT (DAP 49.1 vs. 146.8 Gy cm2, fluoroscopy time 27.1 vs. 43.8 min; p < 0.005), respectively. Dosimetrics were significantly lower in patients undergoing 0-1 PTA maneuvers compared to ≥ 2 maneuvers (p < 0.05). Etiology of ECS, number of stents and MT maneuvers had no significant impact on dosimetry values (p > 0.05). A low-dose protocol yielded a 33% reduction of DAP.

CONCLUSION

This CAS study suggests novel local DRLs for both elective and emergency cases with or without intracranial MT. A dedicated low-dose protocol was suitable for substantial reduction of radiation dose.

Current status of diagnostic reference levels in interventional cardiology

Interventional cardiology provides indisputable benefits for patients but uses a substantial amount of ionising radiation. The diagnostic reference level (DRL) is the tool recommended by the International Commission on Radiological Protection to optimise imaging procedures. In this work, a review of studies dealing with radiation dose or recommending DRL values for interventional cardiology since 2010 is presented, providing quantitative and qualitative results. There are many published papers on coronary angiography (CA) and percutaneous coronary intervention. The DRL values compiled for different continental regions are different: the DRL for CA is about 35 Gy cm²for Europe and 83 Gy cm²for North America. These differences emphasise the need to establish national DRLs considering different social and/or economic factors and the harmonisation of the survey methodology. Surveys with a large amount of data collected with the help of dose management systems provide more reliable information with less chance of statistical bias than those with a small amount of data. The complexity of procedures and improvements in technology are important factors that affect the radiation dose delivered to patients. There is a need for additional data on structural and electrophysiological procedures. The analysis of paediatric procedures is especially difficult because some studies present results split into age bands and others into weight bands. Diagnostic procedures are better described, but there is a great variety of therapeutic procedures with different DRL values (up to a factor of nine) and these require a dedicated review.

Radiation dose reduction during adrenal vein sampling using a new angiographic imaging technology

To compare the patient radiation doses during angiographic selective adrenal vein sampling (AVS) before and after an imaging technology upgrade. In this retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), fluoroscopy time and contrast agent dosage were recorded from 70 patients during AVS. 35 procedures were performed before and 35 after an imaging processing technology upgrade. Mean values were calculated and compared using an unpaired student’s t-test. DSA image quality was assessed independently by two blinded readers using a four-point Likert scale (1 = poor; 4 = excellent) and compared using Wilcoxon signed-rank test. After the technology upgrade we observed a significant reduction of 35% in AK (1.7 ± 0.7 vs. 1.1 ± 0.7 Gy, p = 0.01) and a significant reduction of 28% in DAP (235.1 ± 113 vs. 170.1 ± 94 Gy*cm², p = 0.01) in comparison to procedures before the upgrade. There were no significant differences between the number of exposure frames (143 ± 86 vs. 132 ± 61 frames, p = 0.53), fluoroscopy time (42 ± 23 vs. 36 ± 18 min, p = 0.22), or the amount of contrast medium used (179.5 ± 84 vs. 198.1 ± 109 ml, p = 0.41). There was also no significant difference regarding image quality (3 (2–4) vs. 3 (2–4), p = 0.67). The angiographic imaging technology upgrade significantly decreases the radiation dose during adrenal vein sampling without increasing time of fluoroscopy or contrast volume and without compromising image quality.

Occlusion Type, Number of Recanalization Passages and Dose Program Determine Radiation Dose in Endovascular Stroke Thrombectomy

PURPOSE

Identification of independent treatment factors associated with high radiation exposure during endovascular mechanical thrombectomy (EMT) in acute ischemic stroke.

METHODS

This retrospective analysis included all patients treated by means of EMT during the 2‑year period 2017-2018 in a comprehensive stroke center. The EMT were performed by four internal and three external certified neuroradiologists in a clinic overlapping on call system. Radiation exposure as the dependent variable (dose area product DAP, Gy ⋅ cm²) was dichotomized in < 100 Gy ⋅ cm² and ≥ 100 Gy ⋅ cm². Independent variables were age (< 75 years vs. ≥ 75 years), time of intervention (during vs. beyond workday), treating neuroradiologist (internal vs. external), occlusion type ("mono" vs. "tandem"), reperfusion success (TICI 0-2A vs. TICI 2B/3), recanalization attempts (≤ 2 vs. > 2) and dose protocol (normal dose in 2017 vs. low dose in 2018).

RESULTS

The EMT treatment of 208 patients (111 female, 97 male, mean age 71.6 years) was analyzed. Median DAP was 86.6 Gy ⋅ cm² and could be reduced from 104.8 Gy ⋅ cm² (N = 105 in 2017) to 73.3 Gy ⋅ cm² (N = 103 in 2018) with LD program. Univariable and multivariable binary logistic regression analysis revealed a significantly increased radiation exposure (≥ 100 Gy ⋅ cm²) in tandem occlusion type (P < 0.001), > 2 recanalization attempts (P < 0.001) and normal dose protocol (P = 0.002).

CONCLUSION

Low dose programs can significantly reduce the radiation exposure in EMT. High radiation exposure is significantly associated with more than two recanalization attempts and in cases of tandem occlusions.

New imaging technology system reduces patient radiation dose during peripheral arterial endovascular interventions

BACKGROUND

Radiation exposure and imaging quality are among the main concerns in endovascular procedures. The Clear VD11 PURE platform technology system (Siemens Healthineers, Erlangen, Germany) has been reported to lower the radiation dose and improve image quality. In the present study, we evaluated whether the radiation dose during peripheral arterial endovascular procedures had decreased after implementation of this new imaging system.

METHODS

The patient characteristics (age, gender, body mass index [BMI]), procedure type (diagnostic, balloon angioplasty, atherectomy, stenting), body location (aortoiliac, superficial femoral artery, tibial artery), reference air kerma (RAK), kerma area product (KAP), and fluoroscopy time (FT) were recorded during peripheral artery interventions performed 1 year before (group A) and 1 year after (group B) the CLEAR system upgrade. The procedures were performed in an Artis zeego hybrid room (Siemens Healthineers) with the same providers. A general linear model was used to estimate the average difference between groups adjusted by procedure type and patient age, gender, and BMI. Additionally, to control for variations in case complexity, groups A and B were matched by age, gender, BMI, lesion location, and intervention type. Propensity score matching and a paired t test were used to compare the KAP, RAK, and FT stratified by single intervention procedures.

RESULTS

A total of 487 endovascular procedures were performed: 209 in group A and 278 in group B. A total of 111 single intervention procedures from each group were matched (1:1), with a mean age of 61 ± 8 years and a BMI of 26.5 ± 4 kg/m². The median KAP, RAK, and FT for group A were 28.8 Gy · cm² (interquartile range [IQR], 24-34 Gy · cm²), 146 mGy (IQR, 123-173 mGy), and 12 minutes (IQR, 10-14 minutes), respectively. The median KAP, RAK, and FT for group B were 18.3 Gy · cm² (IQR, 16-22 Gy · cm²), 71.2 mGy (IQR, 60-85 mGy), and 10.4 minutes (IQR, 9-12 minutes), respectively. The KAP, RAK, and FT were significantly decreased in group B by 24% (P = .005), 41% (P < .001), and 22% (P = .002), respectively, compared with the values for group A. Stratified by single intervention procedures, the KAP and RAK had decreased significantly in group B (36% [P = .002] and 51% [P < .001], respectively) compared with group A. The FT decrease of 13% in group B was not statistically significant (P = .20).

CONCLUSIONS

Use of the Clear VD11 PURE platform system (Siemens Healthineers) reduced the patient radiation dose by 51% during endovascular peripheral interventions. The similar FTs for the matched single intervention procedures before and after the upgrade indicated consistent case complexity and surgeon practice. This platform appears to be an effective system for lowering the radiation dose.

Radiation Dose and Fluoroscopy Time of Endovascular Coil Embolization in Patients with Carotid Cavernous Fistulas

Carotid cavernous fistulas (CCFs) are abnormal connections between the cavernous sinus and the internal and/or external carotid artery. Endovascular therapy is the gold standard treatment. In the current retrospective single-center study we report detailed dosimetrics of all patients with CCFs treated by endovascular coil embolization between January 2012 and August 2021. Procedural and dosimetric data were compared between direct and indirect fistulas according to Barrow et al., and different DSA protocol groups. The local diagnostic reference level (DRL) was defined as the 3rd quartile of the dose distribution. In total, thirty patients met the study criteria. The local DRL was 376.2 Gy cm². The procedural dose area product (DAP) (p = 0.03) and the number of implanted coils (p = 0.02) were significantly lower in direct fistulas. The median values for fluoroscopy time (FT) (p = 0.08) and number of DSA acquisitions (p = 0.84) were not significantly different between groups. There was a significantly positive correlation between DAP and FT (p = 0.003). The application of a dedicated low-dose protocol yielded a 32.6% DAP reduction. In conclusion, this study provides novel DRLs for endovascular CCF treatment using detachable coils. The data presented in this work might be used to establish new specific DRLs.

Predictors of radiation dose for uterine artery embolisation are angiography system-dependent

This study sought to achieve radiation dose reductions for patients receiving uterine artery embolisation (UAE) by evaluating radiation dose measurements for the preceding generation (Allura) and upgraded (Azurion) angiography system. Previous UAE regression models in the literature could not be applied to this centre's practice due to being based on different angiography systems and radiation dose predictor variables. The aims of this study were to establish whether radiation dose is reduced with the upgraded angiography system and to develop a regression model to determine predictors of radiation dose specific to the upgraded angiography system. A comparison between Group I (Allura,n= 95) and Group II (Azurion,n= 95) demonstrated a significant reduction in kerma-area product (KAP) and Ka, r (reference air kerma) by 63% (143.2 Gy cm²vs 52.9 Gy cm²;P< 0.001,d= 0.8) and 67% (0.6 Gy vs 0.2 Gy;P< 0.001,d= 0.8), respectively. The multivariable linear regression (MLR) model identified the UAE radiation dose predictors for KAP on the upgraded angiography system as total fluoroscopy dose, Ka, r, and total uterus volume. The predictive accuracy of the MLR model was assessed using a Bland-Altman plot. The mean difference was 0.39 Gy cm²and the limits of agreement were +28.49 and -27.71 Gy cm², and thus illustrated no proportional bias. The resultant MLR model was considered system-dependent and validated the upgraded angiography system and its advance capabilities to significantly reduce radiation dose. Interventional radiologist and interventional radiographer familiarisation of the system's features and the implementation of the newly established MLR model would further facilitate dose optimisation for all centres performing UAE procedures using the upgraded angiography system.

Low-Dose Three-Dimensional Rotational Angiography for Evaluating Intracranial Aneurysms: Analysis of Image Quality and Radiation Dose

Objective

This study aimed to evaluate the image quality and dose reduction of low-dose three-dimensional (3D) rotational angiography (RA) for evaluating intracranial aneurysms.

Materials and Methods

We retrospectively evaluated the clinical data and 3D RA datasets obtained from 146 prospectively registered patients (male:female, 46:100; median age, 58 years; range, 19–81 years). The subjective image quality of 79 examinations obtained from a conventional method and 67 examinations obtained from a low-dose (5-seconds and 0.10-µGy/frame) method was assessed by two neurointerventionists using a 3-point scale for four evaluation criteria. The total image quality score was then obtained as the average of the four scores. The image quality scores were compared between the two methods using a noninferiority statistical testing, with a margin of -0.2 (i.e., score of low-dose group – score of conventional group). For the evaluation of dose reduction, dose-area product (DAP) and air kerma (AK) were analyzed and compared between the two groups.

Results

The mean total image quality score ± standard deviation of the 3D RA was 2.97 ± 0.17 by reader 1 and 2.95 ± 0.20 by reader 2 for conventional group and 2.92 ± 0.30 and 2.95 ± 0.22, respectively, for low-dose group. The image quality of the 3D RA in the low-dose group was not inferior to that of the conventional group according to the total image quality score as well as individual scores for the four criteria in both readers. The mean DAP and AK per rotation were 5.87 Gy-cm² and 0.56 Gy, respectively, in the conventional group, and 1.32 Gy-cm² (p < 0.001) and 0.17 Gy (p < 0.001), respectively, in the low-dose group.

Conclusion

Low-dose 3D RA was not inferior in image quality and reduced the radiation dose by 70%–77% compared to the conventional 3D RA in evaluating intracranial aneurysms.

Radiation Dose and Fluoroscopy Time of Endovascular Treatment in Patients with Intracranial Lateral Dural Arteriovenous Fistulae

Purpose

Intracranial lateral dural arteriovenous fistula (LDAVF) represents a specific subtype of cerebrovascular fistulae, harboring a potentially life-threatening risk of brain hemorrhage. Fluoroscopically guided endovascular embolization is the therapeutic gold standard. We provide detailed dosimetry data to suggest novel diagnostic reference levels (DRL).

Methods

Retrospective single-center study of LDAVFs treated between January 2014 and December 2019. Regarding dosimetry, the dose area product (DAP) and fluoroscopy time were analyzed for the following variables: Cognard scale grade, endovascular technique, angiographic outcome, and digital subtraction angiography (DSA) protocol.

Results

A total of 70 patients (19 female, median age 65 years) were included. Total median values for DAP and fluoroscopy time were 325 Gy cm² (25%/75% percentile: 245/414 Gy cm²) and 110 min (68/142min), respectively. Neither median DAP nor fluoroscopy time were significantly different when comparing low-grade with high-grade LDAVF (Cognard I + IIa versus IIb–V; p > 0.05, each). Transvenous coil embolization yielded the lowest dosimetry values, with significantly lower median values when compared to a combined transarterial/transvenous technique (DAP 290 Gy cm² versus 388 Gy cm², p = 0.031; fluoroscopy time 85 min versus 170 min, p = 0.016). A significant positive correlation was found between number of arterial feeders treated by liquid embolization and both DAP (r_s = 0.367; p = 0.010) and fluoroscopy time (rs = 0.295; p = 0.040). Complete LDAVF occlusion was associated with transvenous coiling (p = 0.001). A low-dose DSA protocol yielded a 20% reduction of DAP (p = 0.021).

Conclusion

This LDAVF study suggests several local DRLs which varied substantially dependent on the endovascular technique and DSA protocol.

High filtration in interventional practices reduces patient radiation doses but not always scatter radiation doses

OBJECTIVES

In fluoroscopy-guided interventional practices, new dose reduction systems have proved to be efficient in the reduction of patient doses. However, it is not clear whether this reduction in patient dose is proportionally transferred to operators' doses. This work investigates the secondary radiation fields produced by two kinds of interventional cardiology units from the same manufacturer with and without dose reduction systems.Methods:Data collected from a large sample of clinical procedures over a 2-year period (more than 5000 procedures and 340,000 radiation events) and the DICOM radiation dose structured reports were analysed.

RESULTS

The average cumulative H_p(10) per procedure measured at the C-arm was similar for the standard and the dose reduction systems (452 vs 476 μSv respectively). The events analysis showed that the ratio H_p(10)/KAP at the C-arm was (mean ± SD) 5 ± 2, 10 ± 4, 14 ± 4 and 14 ± 6 μSv·Gy^-1·cm^-2 for the beams with no added filtration, 0.1, 0.4 and 0.9 mm Cu respectively and suggested that the main cause for the increment of the ratio H_p(10)/KAP vs the "standard system" is the use of higher beam filtration in the "dose reduction" system.

CONCLUSION

Dose reduction systems are beneficial to reduce KAP in patients and their use should be encouraged, but they may not be equally effective to reduce occupational doses. Interventionalists should not overlook their own personal protection when using new technologies with dose reduction systems.

ADVANCES IN KNOWLEDGE

Dose reduction technology in interventional systems may increase scatter dose for operators. Personal protection should not be overlooked with dose reduction systems.

Radiation dose reduction capabilities of a new C-arm system with optimized hard- and software

PURPOSE

To assess the radiation dose reduction capabilities and the image quality of a new C-arm system in comparison to a standard C-arm system.

METHOD

Prospective, randomized, IRB approved two-arm trial design. 49 consecutive patients with primary or secondary liver cancer were treated with transarterial chemoembolization (TACE) on two different angiography units. 28 patients were treated on a conventional angiography unit B, 21 patients on unit A which provides improved hardware and optimized image processing algorithms. Dose area product (DAP) and fluoroscopy time were recorded. DSA image quality of all procedures was assessed on a four-rank-scale by two independent and blinded readers.

RESULTS

Both cohorts showed no significant differences with regard to patient characteristics, tumor burden and fluoroscopy time. The new system resulted in a statistically significant reduction of cumulative DAP of 72% compared to the old platform (median 76 vs. 269 Gy*cm2). Individually, Fluoro-DAP and DSA-DAP decreased by 48% and 77% (p = 0.012 and p < 0.01), respectively. No statistically significant differences in DSA image quality were found between the two imaging platforms.

CONCLUSIONS

The new C-arm system significantly reduced radiation exposure for TACE procedures without increased radiation time or negative impact on DSA image quality. The combination of optimized hardware and software yields the highest radiation dose reduction and is of utmost importance for patients and interventionalists.

Typical values related to the complexity of interventional treatment of acute ischemic stroke

BACKGROUND AND PURPOSE

Interventional Neuroradiology (INR) procedures are often complex, requiring prolonged high-dose exposures. This leads to increased radiation exposure to both patient and operating staff. The purpose of this study is to identify parameters related to the complexity of acute ischemic stroke (AIS) procedures that increase patient exposure and derive DRLs according to ICRP 135.

METHODS

Data from 145 patients treated for AIS between 2017 and 2019 in a Hub Stroke center were retrospectively analyzed. Dosimetric parameters, demographic and clinical data were collected for each patient. The INR operator and the fluoroscopy system used were included.

RESULTS

A multivariable analysis was performed to identify which parameters significantly influence the dosimetric data. Thrombus location and the use of stent retriever were noted as the most likely parameters of complex INR procedures. Male sex is an indicator of complex procedure only with regards to the Kerma area product and the air kerma. Patient age significantly affects the exposure time alone. Senior or more experienced operator's data demonstrated reduced patient's exposure time and therefore the KAP and Kar values. The type of X-ray equipment influenced the outcome of the procedure in terms of number of images acquired. Typical values obtained are 168 Gycm², 0.68 Gy, 19 min and 181 images.

CONCLUSION

Typical values derived in this study promote patient dose optimization, when considering the complexity of INR procedures. The clinical variables related to the complexity of procedure that mainly affect the dosimetric data in our experience are thrombus location and use of stent retrievers.

Fluoroscopically-guided interventions with radiation doses exceeding 5000 mGy reference point air kerma: a dosimetric analysis of 89,549 interventional radiology, neurointerventional radiology, vascular surgery, and neurosurgery encounters

PURPOSE

To quantify and categorize fluoroscopically-guided procedures with radiation doses exceeding 5000 mGy reference point air kerma (Ka,r). Ka,r > 5000 mGy has been defined as a "significant radiation dose" by the Society of Interventional Radiology. Identification and analysis of interventions with high radiation doses has the potential to reduce radiation-induced injuries.

MATERIALS AND METHODS

Radiation dose data from a dose monitoring system for 19 interventional suites and 89,549 consecutive patient encounters from January 1, 2013 to August 1, 2019 at a single academic institution were reviewed. All patient encounters with Ka,r > 5000 mGy were included. All other encounters were excluded (n = 89,289). Patient demographics, medical specialty, intervention type, fluoroscopy time (minutes), dose area product (mGy·cm2), and Ka,r (mGy) were evaluated.

RESULTS

There were 260 (0.3%) fluoroscopically-guided procedures with Ka,r > 5000 mGy. Of the 260 procedures which exceeded 5000 mGy, neurosurgery performed 81 (30.5%) procedures, followed by interventional radiology (n = 75; 28.2%), neurointerventional radiology (n = 55; 20.7%), and vascular surgery (n = 49; 18.4%). The procedures associated with the highest Ka,r were venous stent reconstruction performed by interventional radiology, arteriovenous malformation embolization performed by neurointerventional radiology, spinal hardware fixation by neurosurgery, and arterial interventions performed by vascular surgery. Neurointerventional radiology had the highest mean Ka,r (7,799 mGy), followed by neurosurgery (7452 mGy), vascular surgery (6849 mGy), and interventional radiology (6109 mGy). The mean Ka,r for interventional radiology performed procedures exceeding 5000 mGy was significantly lower than that for neurointerventional radiology, neurosurgery, and vascular surgery.

CONCLUSIONS

Fluoroscopically-guided procedures with radiation dose exceeding 5000 mGy reference point air kerma are uncommon. The results of this study demonstrate that a large proportion of cases exceeding 5000 mGy were performed by non-radiologists, who likely do not receive the same training in radiation physics, radiation biology, and dose reduction techniques as radiologists.

Feasibility of low-dose digital subtraction angiography protocols for the endovascular treatment of intracranial dural arteriovenous fistulas

BACKGROUND

Among neurointerventional procedures, the embolization of complex shunt lesions usually requires more radiation dose. We aimed to evaluate the procedural outcome and safety in using low-dose DSA protocols for intracranial dural arteriovenous fistula (AVF) embolization treatment.

METHODS

Between January 2014 and July 2018, 55 patients with dural AVFs who underwent endovascular treatment were included in the study. The low-dose group (n = 27) included from January 2016 used various low-dose DSA protocols made by modifying the thickness of the copper filter or the detector entrance dose. We compared radiation dose metrics, such as air-kerma, kerma-air product (KAP), and fluoroscopy time, as well as clinical and imaging outcomes with the conventional-dose group (n = 28) included before January 2016.

RESULTS

The total KAP was 40.1% lower in the low-dose group (87.9 vs. 146.7 Gy cm², p = 0.002). The average number of DSA runs (25.1 vs. 25.5, p = 0.86) and fluoroscopy times (77.4 vs. 69.7 min, p = 0.48) were similar between the groups. An immediate favorable occlusion rate (total or near total occlusion) was achieved in 41 (74.5%) patients. Ten patients (18.2%) underwent additional procedures due to residual (n = 6) and/or recurrent (n = 5) lesions. At a median of 10 months follow-up, 45 patients (86.5%) had achieved favorable occlusion. Treatment outcomes showed no significant between-group differences. There was one case (1.8%) of procedure-related complications in the low-dose group. All but one patient showed favorable clinical outcomes (modified Rankin score ≤ 2).

CONCLUSION

The low-dose protocols were feasible by showing significant radiation dose reduction and acceptable procedural outcome.

The role of a commercial radiation dose index monitoring system in establishing local dose reference levels for fluoroscopically guided invasive cardiac procedures

PURPOSE

The primary goal was to evaluate local dose level for fluoroscopically guided invasive cardiac procedures in a high-volume activity catheterization laboratory, using automatic data registration with minimal impact on operator workload. The secondary goal was to highlight the relationship between dose indices and acquisition parameters, in order to establish an effective strategy for protocols optimization.

METHODS

From September 2016 to December 2018, a dosimetric survey was conducted in the 2 rooms of the catheterization laboratory of our institution. Data collection burden was minimized using a commercial Radiation Dose Index Monitoring System (RDIMs) that analyzes dicom files automatically sent by the x-ray equipment. Data were combined with clinical information extracted from the HIS records reported by the interventional cardiologist. Local dose levels were established for different invasive cardiac procedures.

RESULTS

A total of 3029 procedures performed for 2615 patients were analyzed. Median KAP were 21 Gycm² for invasive coronary angiography (ICA) procedures, 61 Gycm² for percutaneous coronary intervention (PCI) procedures, 59 Gycm² for combined (ICA+PCI) procedures, 87 Gycm² for structural heart intervention (TAVI) procedures. A significant dose reduction (51% for ICA procedures and 58% for PCI procedures) was observed when noise reduction acquisition techniques were applied.

CONCLUSIONS

RDIMs are effective tools in the establishment of local dose level in interventional cardiology, as they mitigate the burden to collect and register extensive dosimetric data and exposure parameters. Systematic review of data support the multi-disciplinary team in the definition of an effective strategy for protocol management and dose optimization.

Radiation Dose Reduction Using a Novel Fluoroscopy System in Patients Undergoing Diagnostic Invasive Coronary Angiography

BACKGROUND

Invasive coronary angiography (ICA) still causes a significant amount of radiation exposure for patients and operators. In February 2017, the Azurion system was introduced, a new-generation fluoroscopy image acquisition and processing system. Radiation exposure in patients undergoing ICA was assessed comparing the novel Azurion 7 F12 angiography system to its predecessor Allura Xper in a randomized manner.

METHODS

Radiation exposure was prospectively analyzed in 238 patients undergoing diagnostic ICA. Patients were randomly assigned to the novel Azurion system (119 patients) or its predecessor Allura Xper system (119 patients). In each patient, 8 predefined standard projections (5 left coronary artery, 3 right coronary artery) were performed. Image quality was quantified by grading of the images on the basis of a 5-point grading system.

RESULTS

Radiation dose area product was significantly lower in the Azurion group 109 (interquartile range [IQR 75-176] cGy cm) compared with the Allura Xper group 208 [IQR 134-301] cGy cm (P<0.001). Body mass index (26.6 [IQR 23.9-29.7] kg/m vs. 26.2 [IQR 24.2-29.4] kg/m; P=0.607), body surface area (1.96 [IQR 1.81-2.11] m vs. 1.90 [IQR 1.77-20.4] m; P=0.092), and procedure duration (1.5 [IQR 1.2-2.3] min vs. 1.6 [IQR 1.2-2.5] min; P=0.419) were similar in both groups. Images from the Azurion system were at least of equal quality compared with Allura Xper (image quality grade 4.82±0.45 vs. 4.75±0.52, P=0.43).

CONCLUSION

Use of the novel Azurion 7 F12 angiography system resulted in a significant reduction of dose area product in patients undergoing diagnostic ICA by 56%.

Radiation dose reduction and static image quality assessment using a channelized hotelling observer on an angiography system upgraded with clarity IQ

The goal of this paper was the comparison of radiation dose and imaging quality before and after the Clarity IQ technology installation in a Philips AlluraXper FD20/20 angiography system using a Channelized Hotelling Observer model (CHO). The core characteristics of the Allura Clarity IQ technology are its real-time noise reduction algorithms (NRT) combined with state-of-the-art hardware; this technology allows to implement acquisition protocols able to significantly reduce patient entrance dose. To measure the system performances in terms of image quality we used a contrast detail phantom in a clinical scatter condition. A Leeds TO10 phantom has been imaged between two 10 cm thick homogeneous solid water slabs. Fluoroscopy images were acquired using a cerebral protocol at 3 dose levels (low, medium and high) with a field- of view (FOV) of 31 cm. Cineangiography images were acquired using a cerebral protocol at 2 fps. Thus, 4 acquisitions were obtained for the conventional technology and 4 acquisitions were taken after the Clarity IQ upgrade, for a total of 8 different image sets. A validated 40 Gabor channels CHO with an internal noise model compared the image sets. Human observers' studies were carried out to tune the internal noise parameter. We showed that the CHO did not detect any significant difference between any of the image sets acquired using the two technologies. Consequently, this x-ray imaging technology provides a non-inferior image quality with an average patient dose reduction of 57% and 28% respectively in cineangiography and fluoroscopy. The Clarity IQ installation has certainly allowed a considerable improvement in patient and staff safety, while maintaining the same image quality.

Multicenter Assessment of Radiation Exposure during Pediatric Cardiac Catheterizations Using a Novel Imaging System

Objectives

To quantify radiation exposure during pediatric cardiac catheterizations performed by multiple operators on a new imaging platform, the Artis Q.zen (Siemens Healthcare, Forchheim, Germany), and to compare these data to contemporary benchmark values.

Background

The Artis Q.zen has been shown to achieve significant radiation reduction during select types of pediatric cardiac catheterizations in small single-center studies. No large multicenter study exists quantifying patient dose exposure for a broad spectrum of procedures.

Methods

Retrospective collection of Air Kerma (AK) and dose area product (DAP) for all pediatric cardiac catheterizations performed on this new imaging platform at four institutions over a two-year time period.

Results

A total of 1,127 pediatric cardiac catheterizations were analyzed. Compared to dose data from earlier generation Artis Zee imaging systems, this study demonstrates 70–80% dose reduction (AK and DAP) for similar patient and procedure types. Compared to contemporary benchmark data for common interventional procedures, this study demonstrates an average percent reduction in AK and DAP from the lowest dose saving per intervention of 39% for AK and 27% for DAP for transcatheter pulmonary valve implantation up to 77% reduction in AK and 70% reduction in DAP for atrial septal defect closure.

Conclusion

Use of next-generation imaging platforms for pediatric cardiac catheterizations can substantially decrease patient radiation exposure. This multicenter study defines new low-dose radiation measures achievable on a novel imaging system.

Significant Radiation Dose Reduction Using a Novel Angiography Platform in Patients Undergoing Cryoballoon Pulmonary Vein Isolation

OBJECTIVES

Cryoballoon pulmonary vein isolation (cPVI) in patients with atrial fibrillation requires fluoroscopic guidance, causing a relevant amount of radiation exposure. Strategies to reduce radiation exposure in electrophysiologic procedures and specifically cPVI are of great importance. The aim of this study was to evaluate a possible reduction of radiation dose using the novel Azurion 7 F12 x-ray system compared with its predecessor Allura FD10.

METHODS

In February 2017, the Philips Azurion angiography system was introduced, combining the Allura Clarity radiation dose reduction technology with a more powerful generator, improved image resolution, and a large screen display. In 173 patients undergoing cPVI by a single experienced operator in our institution between December 2016 and April 2018, dose area products (cGy×cm) and image quality were compared using Azurion 7 F12 or Allura FD10 angiography system.

RESULTS

A significant reduction in total radiation dose expressed as a dose area products of 524 (332; 821) cGy×cm on the Allura system compared with 309 (224; 432) cGy×cm on the Azurion system was observed (P<0.001). The number of imaging scenes recorded were 14.7 versus 13.9, and mean overall imaging quality scores (grading 4.85±0.4 with Azurion vs. 4.80±0.4 with Allura, P=0.38) and scores based on specific quality parameters were similar in both groups.

CONCLUSION

Use of the new Azurion 7 F12 angiography system substantially reduced radiation doses compared with the previous generation reference system, Allura Clarity, without compromising imaging quality in patients undergoing cryoballoon pulmonary vein isolation.

Feasibility of ultra-low radiation dose digital subtraction angiography: Preliminary study in a simplified cerebral angiography phantom

INTRODUCTION

The objective of this article is to evaluate the feasibility of cerebral digital subtraction angiography (DSA) using ultra-low radiation dose settings in a simplified cerebral angiography phantom.

MATERIALS AND METHODS

We created a silicone phantom capable of producing a simplified cerebral DSA. A total of 18 DSA sets were obtained with gradual six-step reduction of the detector entrance dose (DED) from 1.82 to 0.08 μGy per frame, while standard, postprocessing algorithm (PPA) and copper filter (0.3 mm) with PPA (CwP) algorithm reconstruction protocols were applied. We quantitatively compared their signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) and qualitatively analyzed the images' qualities in terms of image sharpness, contrast, and noise as investigated by five observers.

RESULTS

The SNR and CNR, which decreased with lowering of the DED in the standard protocol group, were significantly compensated by using the PPA. The values were approximately double in the PPA (11.5 ± 2.9) and CwP (11.0 ± 2.5) groups compared with the standard (5.4 ± 1.1) group in the DED of 0.24 μGy per frame as well as in the other values. The total scores of the observers according to the protocols showed a tendency to decrease as the DED lowered. On average, the PPA (96.3 ± 34.6) and CwP (91.3 ± 29.9) groups yielded higher results than the standard protocol (83.7 ± 46.7).

CONCLUSION

Given that the current DED ranges from 1.82 to 3.60 μGy per frame for routine cerebral DSA, our results indicate that DED can be decreased to 15%-30% of the current dose level in vessels 2-4 mm in diameter if image-improvement algorithms are applied.

Image Quality of Low-Dose Cerebral Angiography and Effectiveness of Clinical Implementation on Diagnostic and Neurointerventional Procedures for Intracranial Aneurysms

BACKGROUND AND PURPOSE

Awareness of the potential for exposure to high doses of radiation from interventional radiologic procedures has increased. The purpose of this study was to evaluate image quality and dose reduction of low-dose cerebral angiography during diagnostic and therapeutic procedures for intracranial aneurysms.

MATERIALS AND METHODS

A retrospective review of 1137 prospectively collected patients between January 2012 and June 2014 was performed. Beginning in April 2013, a dose-reduction strategy was implemented. Subjective image-quality assessment of 506 standard and 540 low-dose cerebral angiography images was performed by 2 neuroradiologists using a 5-point scale and was tested using noninferiority statistics. Radiation dose-area product and air kerma of 1046 diagnostic and 317 therapeutic procedures for intracranial aneurysms were analyzed and compared between groups before (group 1) and after (group 2) clinical implementation of a dose-reduction strategy.

RESULTS

The image quality of the low-dose cerebral angiography was not inferior on the basis of results from the 2 readers. For diagnostic cerebral angiography, the mean dose-area product and air kerma were 140.8 Gy×cm² and 1.0 Gy, respectively, in group 1 and 82.0 Gy×cm² and 0.6 Gy in group 2 (P < .001, P < .001). For the neurointerventional procedure, the mean dose-area product and air kerma were 246.0 Gy×cm² and 3.7 Gy, respectively, in group 1 and 169.8 Gy×cm² and 3.3 Gy in group 2 (P < .001, P = .291).

CONCLUSIONS

With low-dose cerebral angiography, image quality was maintained, and implementation of dose-reduction strategies reduced radiation doses in patients undergoing diagnostic and neurointerventional procedures for intracranial aneurysms.

A new imaging technology to reduce the radiation dose during uterine fibroid embolization

BACKGROUND

Uterine fibroid embolization (UFE) is a minimally invasive imaging-guided treatment using radiation exposure.

PURPOSE

To compare the patients' radiation exposure during UFE before and after introduction of a new X-ray imaging platform.

MATERIAL AND METHODS

Forty-one patients were enrolled in a prospective, comparative two-arm project before and after introduction of a new X-ray imaging platform with reduced dose settings, i.e. novel real-time image processing techniques (AlluraClarity). Demographic, pre-interventional imaging, and procedural data, including dose area product (DAP) and estimated organ dose on the ovaries and uterus, were recorded and angiographic quality of overall procedure was assessed.

RESULTS

There were no significant differences in demographic characteristics and preoperative fibroid and uterine volumes in the two groups. The new imaging platform led to a significant reduction in mean total DAP (102 vs. 438 Gy.cm²; P < 0.001), mean fluoroscopy DAP (32 vs. 138 Gy.cm²; P < 0.001), mean acquisition DAP (70 vs. 300 Gy.cm²; P < 0.001), and acquisition DAP estimated organ dose in ovaries (42 vs. 118 mGy; P < 0.001) and uterus (40 vs. 118 mGy, P < 0.001), without impairment of the procedure and angiographic image quality.

CONCLUSION

A substantial 77% reduction of DAP values and 64% and 66% reduction in organ dose on ovaries and uterus, respectively, was demonstrated with the new imaging platform, while maintaining optimal imaging quality and efficacy.

Evaluation of patient and staff exposure with state of the art X-ray technology in cardiac catheterization: A randomized controlled trial

INTRODUCTION

Cardiac catheterization procedures result in high patient radiation exposure and corresponding staff doses are reported to be among the highest for medical staff. The purpose of current randomized controlled study was to quantify the potential radiation dose reduction for both patient and staff, enabled by recent X-ray technology. This technology is equipped with advanced image processing algorithms, real-time dose monitoring, and an acquisition chain optimized for cardiac catheterization applications.

METHODS

A total of 122 adult patients were randomly assigned to one of two cath labs, either the reference X-ray modality (Allura Xper FD10, Philips Healthcare, the Netherlands) or the new X-ray system (AlluraClarity FD20/10 Philips Healthcare, the Netherlands). Exposure parameters and staff dosimeter readings were recorded for each exposure. Technical measurements were performed to define the radiation scatter behavior.

RESULTS

With the newer equipment, patient radiation dose is reduced (as total dose-area product) by 67% based on geometric means with 95%CI of 53%, 77% for diagnostic and interventional procedures. The C-arm and leg dosimeter readings were both reduced with 65% (P < 0.001), while for the collar and chest dosimeter readings no statistically significant reduction was noticed.

CONCLUSION

The new x-ray and image processing technology, significantly reduces patient dose in coronary angiographies, and PCIs by 67%. In general, scatter dose was also reduced, yet for some dosimeters the reduction was limited and not statistically significant. This study clearly indicates that the scatter behavior is highly dependent on C-arm rotation, operator movement and height, dosimeter position, beam filtration, clinical procedure type and system geometry.

Reduction in Radiation Dose in a Pediatric Cardiac Catheterization Lab Using the Philips AlluraClarity X-ray System

The objective of this study was to compare radiation doses and imaging quality using Philips AlluraClarity (Philips Healthcare, Best, The Netherlands) X-ray system and an older generation reference system. AlluraClarity is a new generation fluoroscopy system designed to reduce radiation without compromising image quality, but reports of its use in pediatric patients are limited. Dose area products (DAP, mGy cm²) and DAP/kg were compared in patients catheterized using Allura Xper and AlluraClarity systems over a year of use for each. Randomly selected studies from each system were assessed for image quality. The 430 patients imaged with Clarity were larger than the 332 imaged with Xper (median BSA: 0.74 vs. 0.64 m², p = 0.06), and median total fluoroscopic times (TFT) were similar (15.8 vs. 16.1 min, p = 0.37). Median DAPs were 8661 mGy cm² (IQR: 18,300 mGy cm²) and 4523 mGy cm² (IQR: 11,596 mGy cm²) with Xper and Clarity, respectively (p < 0.001). There was a reduction in median DAP in all procedure categories. After adjustment for BSA, TFT, and procedure type, using Clarity was associated with a 57.5% (95% CI 51.5-62.8%, p < 0.001) reduction in DAP for all procedures. Reductions did not significantly differ by weight (<10 kg, 10-40 kg, ≥ 40 kg). There was an adjusted percent reduction in DAP for each procedure category ranging from 39.0% (95% CI 25.6-50.1%, p < 0.001) for cardiac biopsies with or without coronary angiography to 67.6% (95% CI 61.2-72.8%, p < 0.001) for device occlusions. Mean overall imaging quality scores (4.3 ± 0.8 with Clarity vs. 4.4 ± 0.6 with Xper, p = 0.62) and scores based on specific quality parameters were similar in the two groups. Use of AlluraClarity substantially reduced radiation doses compared to the older generation reference system without compromising imaging quality in a pediatric cardiac catheterization lab.

Noise reduction angiographic imaging technology reduces radiation dose during bronchial artery embolization

PURPOSE

Comparison of radiation doses in patients undergoing angiographic bronchial artery embolization (BAE) before and after a noise reduction imaging technology upgrade.

METHODS

We performed a retrospective study of 70 patients undergoing BAE. Procedures were performed before (n=32) and after (n=38) the technology upgrade containing additional filters and improved image-processing. Cumulative air kerma (AK), cumulative dose area product (DAP), number of exposure frames, total fluoroscopy time and amount of contrast agent were recorded. Mean values were calculated and compared using two-tailed t-tests. DSA image quality was assessed independently by two blinded readers and compared using the Wilcoxon signed-rank test.

RESULTS

Using the new technology resulted in a significant reduction of 59% in DAP (149.2 (103.1-279.1) vs. 54.8 (38.2-100.7) Gy*cm², p<0.001) and a significant reduction of 60% for AK (1.3 (0.6-1.9) vs. 0.5 (0.3-0.9) Gy, p<0.001) in comparison to procedures before the upgrade. There was no significant difference between the number of exposure frames in both groups (251±181 vs. 254±133 frames, p=0.07), time of fluoroscopy (28.8 (18.5-50.4) vs. 28.1 (23.3-38.7) min, p=0.73), or the amount of contrast agent used (139.5±70.8 vs. 163.1±63.1ml, p=0.11). No significant difference regarding image quality could be detected (3 (2,3) vs. 3 (2-4), p=0.64).

CONCLUSIONS

The new angiographic noise reduction technology significantly decreases the radiation dose during bronchial artery embolization without compromising image quality or increasing time of fluoroscopy or contrast volume.

Modern Fixed Imaging Systems Reduce Radiation Exposure to Patients and Providers

High-definition fluoroscopic imaging is required to perform endovascular procedures safely and precisely, especially in complex cases, resulting in longer procedures and increased radiation exposure. This is of importance for training institutions as trainees, even with sound instruction in as low as reasonably achievable (ALARA) principles, tend to have high radiation exposures. Recently, there was an upgrade in the imaging system allowing for comparison of radiation exposure to patients and providers. We performed an analysis of consecutive endovascular aneurysm repair (EVAR) and superficial femoral artery (SFA) interventions in the years 2013 to 2014. We recorded body mass index (BMI) and fluoroscopy time (FT) and subsequently matched 1:1 based on BMI, FT, or both. We determined radiation dose using air kerma (AK) and also recorded individual surgeons’ badge readings. Allura Xper FD20 was upgraded to AlluraClarity with ClarityIQ. We identified a total of 77 EVARs (52 pre and 25 post) and 134 SFA interventions (99 pre and 35 post). Unmatched results for EVAR were BMI pre 26.2 versus post 25.8 (kg/m2, P = .325), FT 28.1 versus 21.2 (minutes, P = .051), and AK 1178.5 versus 581 (mGy, P < .001), respectively. After matching, there was a 53.2% reduction in AK (846.1 vs 395.9 mGy; P = .004) for EVAR. Unmatched results for SFA interventions were BMI pre 28.1 versus post 26.6 ( P = .327), FT 18.7 versus 16.2 ( P = .282), and AK 285.6 versus 106.0 ( P < .001), respectively. After matching, there was a 57.0% reduction in AK (305.0 vs 131.3, P < .001). The total deep dose equivalent from surgeons’ badge readings decreased from 39.5 to 17 mrem ( P = .029). Aortic and peripheral endovascular interventions can be performed with reduced radiation exposure to patients and providers, employing modern fixed imaging systems with advanced dose reduction technology. This is of particular importance in the light of the increasing volume and complexity of endovascular and hybrid procedures as well as the prospect of decades of radiation exposure during training and practice.

Image noise reduction technology allows significant reduction of radiation dosage in cardiac device implantation procedures

BACKGROUND

Novel x-ray systems with real-time image noise reduction technology (INRT) to reduce radiation dose during fluoroscopy and cine acquisition have become available. This study evaluated the reduction of radiation dose in device implantation with INRT.

METHODS

Radiation dose data from 132 consecutive new device implantation procedures (102 pacemaker [PM] or implantable cardioverter defibrillator [ICD] and 30 cardiac resynchronization therapy [CRT] devices) performed between January 2015 and December 2015 on an angiography system with INRT (Allura ClarityIQ) were collected. For comparison, radiation dose data from 147 consecutive device implantation procedures (121 PM/ICDs and 26 CRT devices) performed between June 2013 and September 2014 on a C-arm system with continuous and pulsed fluoroscopy option (4 frames/second) were evaluated. Total dose area product (DAP), fluoroscopy DAP, and cine DAP were evaluated.

RESULTS

Patient age, gender and body weight, procedure, and fluoroscopy times were similar between systems. In PM/ICD cases, DAP of INRT and C-arm system was similar (423 ± 381 cGycm²  vs 417 ± 517 cGycm) due to pulsed fluoroscopy with the C-arm system (78% of time) and sparse use of cine. In CRT procedures requiring higher image quality (82% use of continuous fluoroscopy with C-arm system), DAP of INRT was significantly lower (1,544 ± 834 cGycm vs 7,252 ± 6,431 cGycm, P < 0.001) due to less fluoroscopy DAP (1,414 ± 757 cGycm vs 5,854 ± 6,767 cGycm) and less cine DAP (130 ± 106 cGycm vs 1,399 ± 1,342 cGycm). Considering all procedures, total DAP was reduced by 60% using INRT.

CONCLUSION

Novel INRT results in a substantial lowering of radiation dose in device implantation, in particular, in complex CRT implantation procedures requiring high image quality.

Characteristics of a New X-Ray Imaging System for Interventional Procedures: Improved Image Quality and Reduced Radiation Dose

Purpose

To compare image quality and radiation exposure between a new angiographic imaging system and the preceding generation system during uterine artery embolization (UAE).

Materials and Methods

In this retrospective, IRB-approved two-arm study, 54 patients with symptomatic uterine fibroids were treated with UAE on two different angiographic imaging systems. The new system includes optimized acquisition parameters and real-time image processing algorithms. Air kerma (AK), dose area product (DAP) and acquisition time for digital fluoroscopy (DF) and digital subtraction angiography (DSA) were recorded. Body mass index was noted as well. DF image quality was assessed objectively by image noise measurements. DSA image quality was rated by two blinded, independent readers on a four-rank scale. Statistical differences were assessed with unpaired t tests and Wilcoxon rank-sum tests.

Results

There was no significant difference between the patients treated on the new (n = 36) and the old system (n = 18) regarding age (p = 0.10), BMI (p = 0.18), DF time (p = 0.35) and DSA time (p = 0.17). The new system significantly reduced the cumulative AK and DAP by 64 and 72%, respectively (median 0.58 Gy and 145.9 Gy*cm² vs. 1.62 Gy and 526.8 Gy*cm², p < 0.01 for both). Specifically, DAP for DF and DSA decreased by 59% (75.3 vs. 181.9 Gy*cm², p < 0.01) and 78% (67.6 vs. 312.2 Gy*cm², p < 0.01), respectively. The new system achieved a significant decrease in DF image noise (p < 0.01) and a significantly better DSA image quality (p < 0.01).

Conclusions

The new angiographic imaging system significantly improved image quality and reduced radiation exposure during UAE procedures.

Electronic supplementary material

The online version of this article (doi:10.1007/s00270-017-1821-z) contains supplementary material, which is available to authorized users.

Flexible lateral isocenter: A novel mechanical functionality contributing to dose reduction in neurointerventional procedures

Aim of the study

A new functionality that enables vertical mobility of the lateral arm of a biplane angiographic machine is referred to as the flexible lateral isocenter. The aim of this study was to analyze the impact of the flexible lateral isocenter on the air-kerma rate under experimental conditions.

Material and methods

An anthropomorphic head-and-chest phantom with anteroposterior (AP) diameter of the chest varying from 22 cm to 30 cm simulated human bodies of different body constitutions. The angulation of the AP arm in the sagittal plane varied from 35 degrees to 55 degrees for each AP diameter. The air-kerma rate (mGy/min) values were read from the system dose display in two settings for each angle: flexible lateral isocenter and fixed lateral isocenter.

Results

The air-kerma rate was significantly lower for all AP diameters of the chest of the phantom when the flexible lateral isocenter was used: (a) For 22 cm, the p value was 0.028; (b) For 25 cm, the p value was 0.0169; (c) For 28 cm, the p value was 0.01005 and (d) For 30 cm, the p value was 0.01703.

Conclusion

Our results show that the flexible lateral isocenter contributes significantly to the reduction of the air-kerma rate, and thus to a safer environment in terms of dose lowering both for patients and staff.

Radiation Dose Reduction without Compromise to Image Quality by Alterations of Filtration and Focal Spot Size in Cerebral Angiography

Objective

Different angiographic protocols may influence the radiation dose and image quality. In this study, we aimed to investigate the effects of filtration and focal spot size on radiation dose and image quality for diagnostic cerebral angiography using an in-vitro model and in-vivo patient groups.

Materials and Methods

Radiation dose and image quality were analyzed by varying the filtration and focal spot size on digital subtraction angiography exposure protocols (1, inherent filtration + large focus; 2, inherent + small; 3, copper + large; 4, copper + small). For the in-vitro analysis, a phantom was used for comparison of radiation dose. For the in-vivo analysis, bilateral paired injections, and patient cohort groups were compared for radiation dose and image quality. Image quality analysis was performed in terms of contrast, sharpness, noise, and overall quality.

Results

In the in-vitro analysis, the mean air kerma (AK) and dose area product (DAP)/frame were significantly lower with added copper filtration (protocols 3 and 4). In the in-vivo bilateral paired injections, AK and DAP/frame were significantly lower with filtration, without significant difference in image quality. The patient cohort groups with added filtration (protocols 3 and 4) showed significant reduction of total AK and DAP/patient without compromise to the image quality. Variations in focal spot size showed no significant differences in radiation dose and image quality.

Conclusion

Addition of filtration for angiographic exposure studies can result in significant total radiation dose reduction without loss of image quality. Focal spot size does not influence radiation dose and image quality. The routine angiographic protocol should be judiciously investigated and implemented.

Radiation Dose Reduction during Uterine Fibroid Embolization Using an Optimized Imaging Platform

PURPOSE

To assess radiation dose reduction during uterine fibroid embolization (UFE) using an optimized angiographic processing and acquisition platform.

MATERIALS AND METHODS

Radiation dose data for 70 women (mean age, 46 y; range, 34-67 y) who underwent UFE were retrospectively analyzed. Twenty-one patients underwent UFE using the baseline fluoroscopic and angiographic image acquisition platform, and 49 underwent UFE after implementing an optimized imaging platform in otherwise identical angiography suites. Cumulative kerma-area product (CKAP), cumulative air kerma (CAK), total fluoroscopy time, and image exposure number were collected for each procedure. Image quality was assessed by 3 interventional radiologists blinded to the platform used for image acquisition and processing.

RESULTS

Patients undergoing UFE using the new x-ray fluoroscopy platform had significantly lower CKAP and CAK indicators than patients for whom baseline settings were used. Mean CKAP decreased by 60% from 438.5 Gy · cm² (range, 180.3-1,081.1 Gy · cm²) to 175.2 Gy · cm² (range, 47.1-757.0 Gy · cm²; P < .0001). Mean CAK decreased by 45% from 2,034.2 mGy (range, 699.3-5,056.0 mGy) to 1,109.8 mGy (range, 256.6-4,513.6 mGy; P = .001). No degradation of image quality was identified through qualitative evaluation.

CONCLUSIONS

Significant reduction in patient radiation dose indicators can be achieved with use of an optimized image acquisition and processing platform.

Spot fluoroscopy: a novel innovative approach to reduce radiation dose in neurointerventional procedures

Background

Increased interest in radiation dose reduction in neurointerventional procedures has led to the development of a method called “spot fluoroscopy” (SF), which enables the operator to collimate a rectangular or square region of interest anywhere within the general field of view. This has potential advantages over conventional collimation, which is limited to symmetric collimation centered over the field of view.

Purpose

To evaluate the effect of SF on the radiation dose.

Material and Methods

Thirty-five patients with intracranial aneurysms were treated with endovascular coiling. SF was used in 16 patients and conventional fluoroscopy in 19. The following parameters were analyzed: the total fluoroscopic time, the total air kerma, the total fluoroscopic dose-area product, and the fluoroscopic dose-area product rate. Statistical differences were determined using the Welch’s t-test.

Results

The use of SF led to a reduction of 50% of the total fluoroscopic dose-area product (CF = 106.21 Gycm², SD = 99.06 Gycm² versus SF = 51.80 Gycm², SD = 21.03 Gycm², p = 0.003884) and significant reduction of the total fluoroscopic dose-area product rate (CF = 1.42 Gycm²/min, SD = 0.57 Gycm²/s versus SF = 0.83 Gycm²/min, SD = 0.37 Gycm²/min, p = 0.00106). The use of SF did not lead to an increase in fluoroscopy time or an increase in total fluoroscopic cumulative air kerma, regardless of collimation.

Conclusion

The SF function is a new and promising tool for reduction of the radiation dose during neurointerventional procedures.

The Effect of a New Angiographic Imaging Technology on Radiation Dose in Visceral Embolization Procedures

PURPOSE

To evaluate the impact of a new angiographic imaging technology on radiation dose during visceral embolization procedures involving both fluoroscopy and digital subtraction angiography.

MATERIAL AND METHODS

A retrospective analysis from a single-center consecutive series of patients was performed comparing 2 angiographic imaging systems. The AlluraClarity (CIQ; Philips Healthcare, Best, the Netherlands) was used in 100 patients (n = 59 male, mean age: 70.6 years) from July 2013 to April 2014 and compared to the former AlluraXper (AX) technology used in 139 patients (n = 71 male, mean age: 70.1 years) from May 2011 to June 2013. Patients were categorized according to body mass index (BMI [kg/m²])-group 1: BMI <25, group 2: BMI ≥25 and <30, and group 3: BMI ≥30. Fluoroscopy time, the total dose of iodinated contrast administered, and procedural AirKerma (Ka, r [mGy]) were obtained.

RESULTS

Mean BMI was 26.4 ± 5.0 kg/m² in the CIQ and 26.4 ± 7.1 kg/m² in the AX group ( P = .93). Fluoroscopy time and the amount of contrast media were equally distributed. Ka, r was 1342.9 mGy versus 2214.8 mGy ( P < .001, t test) when comparing CIQ to AX. Comparing CIQ to AX, BMI subgroup analysis revealed a mean Ka, r of 970.1 to 1586.1 mGy ( P = .003, t test), 1484.7 to 2170.1 mGy ( P = .02, t test), and 1848.8 to 3348.9 mGy ( P = .001, t test) in BMI groups 1, 2, and 3, respectively.

CONCLUSION

The CIQ technology significantly reduced mean radiation dose by 39.4% for visceral embolization procedures when compared to fluoroscopy time and contrast media dose. This dose relationship was consistent across all BMI groups.

Comprehensive assessment of patient image quality and radiation dose in latest generation cardiac x-ray equipment for percutaneous coronary interventions

This study aimed to determine whether a reduction in radiation dose was found for percutaneous coronary interventional (PCI) patients using a cardiac interventional x-ray system with state-of-the-art image enhancement and x-ray optimization, compared to the current generation x-ray system, and to determine the corresponding impact on clinical image quality. Patient procedure dose area product (DAP) and fluoroscopy duration of 131 PCI patient cases from each x-ray system were compared using a Wilcoxon test on median values. Significant reductions in patient dose ([Formula: see text]) were found for the new system with no significant change in fluoroscopy duration ([Formula: see text]); procedure DAP reduced by 64%, fluoroscopy DAP by 51%, and "cine" acquisition DAP by 76%. The image quality of 15 patient angiograms from each x-ray system (30 total) was scored by 75 clinical professionals on a continuous scale for the ability to determine the presence and severity of stenotic lesions; image quality scores were analyzed using a two-sample [Formula: see text]-test. Image quality was reduced by 9% ([Formula: see text]) for the new x-ray system. This demonstrates a substantial reduction in patient dose, from acquisition more than fluoroscopy imaging, with slightly reduced image quality, for the new x-ray system compared to the current generation system.

Assessment of the occupational eye lens dose for clinical staff in interventional radiology, cardiology and neuroradiology

In accordance with recommendations by the International Commission on Radiological Protection, the current European Basic Safety Standards has adopted a reduced occupational eye lens dose limit of 20 mSv yr^-1. The radiation safety implications of this dose limit is of concern for clinical staff that work with relatively high dose x-ray angiography and interventional radiology. Presented in this work is a thorough assessment of the occupational eye lens dose based on clinical measurements with active personal dosimeters worn by staff during various types of procedures in interventional radiology, cardiology and neuroradiology. Results are presented in terms of the estimated equivalent eye lens dose for various medical professions. In order to compare the risk of exceeding the regulatory annual eye lens dose limit for the widely different clinical situations investigated in this work, the different medical professions were separated into categories based on their distinct work pattern: staff that work (a) regularly beside the patient, (b) in proximity to the patient and (c) typically at a distance from the patient. The results demonstrate that the risk of exceeding the annual eye lens dose limit is of concern for staff category (a), i.e. mainly the primary radiologist/cardiologist. However, the results also demonstrate that the risk can be greatly mitigated if radiation protection shields are used in the clinical routine. The results presented in this work cover a wide range of clinical situations, and can be used as a first indication of the risk of exceeding the annual eye lens dose limit for staff at other medical centres.

Reduced Patient Radiation Exposure during Neurodiagnostic and Interventional X-Ray Angiography with a New Imaging Platform

BACKGROUND AND PURPOSE

Advancements in medical device and imaging technology as well as accruing clinical evidence have accelerated the growth of the endovascular treatment of cerebrovascular diseases. However, the augmented role of these procedures raises concerns about the radiation dose to patients and operators. We evaluated patient doses from an x-ray imaging platform with radiation dose-reduction technology, which combined image noise reduction, motion correction, and contrast-dependent temporal averaging with optimized x-ray exposure settings.

MATERIALS AND METHODS

In this single-center, retrospective study, cumulative dose-area product inclusive of fluoroscopy, angiography, and 3D acquisitions for all neurovascular procedures performed during a 2-year period on the dose-reduction platform were compared with a reference platform. Key study features were the following: The neurointerventional radiologist could select the targeted dose reduction for each patient with the dose-reduction platform, and the statistical analyses included patient characteristics and the neurointerventional radiologist as covariates. The analyzed outcome measures were cumulative dose (kerma)-area product, fluoroscopy duration, and administered contrast volume.

RESULTS

A total of 1238 neurointerventional cases were included, of which 914 and 324 were performed on the reference and dose-reduction platforms, respectively. Over all diagnostic and neurointerventional procedures, the cumulative dose-area product was significantly reduced by 53.2% (mean reduction, 160.3 Gy × cm²; P < .0001), fluoroscopy duration was marginally significantly increased (mean increase, 5.2 minutes; P = .0491), and contrast volume was nonsignificantly increased (mean increase, 15.3 mL; P = .1616) with the dose-reduction platform.

CONCLUSIONS

A significant reduction in patient radiation dose is achievable during neurovascular procedures by using dose-reduction technology with a minimal impact on workflow.

Radiation Exposure during Neurointerventional Procedures in Modern Biplane Angiographic Systems: A Single-Site Experience

Background and Purpose

Per the ALARA principle, reducing the dose delivered to both patients and staff must be a priority for endovascular therapists, who should monitor their own practice. We evaluated patient exposure to radiation during common neurointerventions performed with a recent flat-panel detector angiographic system and compared our results with those of recently published studies.

Methods

All consecutive patients who underwent a diagnostic cerebral angiography or intervention on 2 modern flat-panel detector angiographic biplane systems (Innova IGS 630, GE Healthcare, Chalfont St Giles, UK) from February to November 2015 were retrospectively analyzed. Dose-area product (DAP), cumulative air kerma (CAK) per plane, fluoroscopy time (FT), and total number of digital subtraction angiography (DSA) frames were collected, reported as median (interquartile range), and compared with the previously published literature.

Results

A total of 755 consecutive cases were assessed in our institution during the study period, including 398 diagnostic cerebral angiographies and 357 interventions. The DAP (Gy × cm²), fontal and lateral CAK (Gy), FT (min), and total number of DSA frames were as follows: 43 (33-60), 0.26 (0.19-0.33), 0.09 (0.07-0.13), 5.6 (4.2-7.5), and 245 (193-314) for diagnostic cerebral angiographies, and 66 (41-110), 0.46 (0.25-0.80), 0.18 (0.10-0.30), 18.3 (9.1-30.2), and 281 (184-427) for interventions.

Conclusion

Our diagnostic cerebral angiography group had a lower median and was in the 75th percentile of DAP and FT when compared with the published literature. For interventions, both DAP and number of DSA frames were significantly lower than the values reported in the literature, despite a higher FT. Subgroup analysis by procedure type also revealed a lower or comparable DAP.

Can image enhancement allow radiation dose to be reduced whilst maintaining the perceived diagnostic image quality required for coronary angiography?

OBJECTIVE

The aim of this research was to quantify the reduction in radiation dose facilitated by image processing alone for percutaneous coronary intervention (PCI) patient angiograms, without reducing the perceived image quality required to confidently make a diagnosis.

METHODS

Incremental amounts of image noise were added to five PCI angiograms, simulating the angiogram as having been acquired at corresponding lower dose levels (10-89% dose reduction). 16 observers with relevant experience scored the image quality of these angiograms in 3 states-with no image processing and with 2 different modern image processing algorithms applied. These algorithms are used on state-of-the-art and previous generation cardiac interventional X-ray systems. Ordinal regression allowing for random effects and the delta method were used to quantify the dose reduction possible by the processing algorithms, for equivalent image quality scores.

RESULTS

Observers rated the quality of the images processed with the state-of-the-art and previous generation image processing with a 24.9% and 15.6% dose reduction, respectively, as equivalent in quality to the unenhanced images. The dose reduction facilitated by the state-of-the-art image processing relative to previous generation processing was 10.3%.

CONCLUSION

Results demonstrate that statistically significant dose reduction can be facilitated with no loss in perceived image quality using modern image enhancement; the most recent processing algorithm was more effective in preserving image quality at lower doses. Advances in knowledge: Image enhancement was shown to maintain perceived image quality in coronary angiography at a reduced level of radiation dose using computer software to produce synthetic images from real angiograms simulating a reduction in dose.

Analysis of Radiation Doses and Dose Reduction Strategies During Cerebral Digital Subtraction Angiography

OBJECTIVE

Adverse effects of increased use of cerebral digital subtraction angiography (DSA) include radiation-induced skin reactions and increased risk of malignancy. This study aimed to identify a method for reducing radiation exposure during routine cerebral DSA.

METHODS

A retrospective review of 138 consecutive adult patients who underwent DSA with a biplane angiography system (Artis Zee, Siemens, Germany) from September 2015 to February 2016 was performed. In January 2016, the dose parameter was reset by the manufacturer from 2.4 μGy to 1.2 μGy. Predose (group 1) and postdose parameter reduction (group 2) groups were established. Angiograms and procedure examination protocols were reviewed according to patient age, gender, and diagnosis and angiography techniques were reviewed on the basis of the following radiation dose parameters: fluoroscopy time, reference point air kerma (Ka,r; in mGy), and kerma-area product (PKA; in μGym²).

RESULTS

The mean Ka,r values in groups 1 and 2 were 1841.5 mGy and 1274.8 mGy, respectively. The mean PKA values in groups 1 and 2 were 23212.5 μGym² and 14854.0 μGym², respectively. Ka,r and PKA values were significantly lower in group 2 compared with group 1 (P < 0.001). Among individual factors, young age was a determining factor for reduced fluoroscopy time (P < 0.001), Ka,r (P = 0.047), and PKA (P = 0.022).

CONCLUSIONS

Increased awareness of radiation risks, as well as the establishment of strategies to reduce radiation dose, led to lower radiation doses for DSA. The use of appropriate examinations and low-dose parameters in fluoroscopy contributed significantly to the radiation dose reductions.

Impact of new X-ray technology on patient dose in pacemaker and implantable cardioverter defibrillator (ICD) implantations

PURPOSE

New X-ray technology providing new image processing techniques may reduce radiation exposure. The aim of this study was to quantify this radiation exposure reduction for patients during pacemaker and implantable cardioverter defibrillator (ICD) implantation.

METHODS

In this retrospective study, 1185 consecutive patients who had undergone de novo pacemaker or ICD implantation during a 2-year period were included. All implantations in the first year were performed using the reference technology (Allura Xper), whereas in the second year, the new X-ray technology (AlluraClarity) was used. Radiation exposure, expressed as the dose area product (DAP), was compared between the two time periods to determine the radiation exposure reduction for pacemaker and ICD implantations without cardiac resynchronization therapy (CRT) and with CRT. Procedure duration and contrast volume were used as measures to compare complexity and image quality.

RESULTS

The study population consisted of 591 patients who had undergone an implantation using the reference technology, and 594 patients with the new X-ray technology. The two groups did not differ in age, gender, or body mass index. The DAP decreased with 69 % from 16.4 ± 18.5 to 5.2 ± 6.6 Gy cm2 for the non-CRT implantations (p < 0.001). The DAP decreased with 75 % from 72.1 ± 60.0 to 17.8 ± 17.4 Gy cm2 for the CRT implantations (p < 0.001). Nevertheless, procedure duration and contrast volume did not differ when using the new technology (p = 0.09 and p = 0.20, respectively).

CONCLUSIONS

Introduction of new X-ray technology resulted in a radiation exposure reduction of more than 69 % for patients during pacemaker and ICD implantation while image quality was unaffected.

Radiation dose reduction during transjugular intrahepatic portosystemic shunt implantation using a new imaging technology

OBJECTIVE

To compare patient radiation dose in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) implantation before and after an imaging-processing technology upgrade.

METHODS

In our retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), total fluoroscopy time and contrast agent were collected from an age- and BMI-matched collective of 108 patients undergoing TIPS implantation. 54 procedures were performed before and 54 after the technology upgrade. Mean values were calculated and compared using two-tailed t-tests. Two blinded, independent readers assessed DSA image quality using a four-rank likert scale and the Wilcoxcon test.

RESULTS

The new technology demonstrated a significant reduction of 57% of mean DAP (402.8 vs. 173.3Gycm², p<0.001) and a significant reduction of 58% of mean AK (1.7 vs. 0.7Gy, p<0.001) compared to the precursor technology. Time of fluoroscopy (26.4 vs. 27.8min, p=0.45) and amount of contrast agent (109.4 vs. 114.9ml, p=0.62) did not differ significantly between the two groups. The DSA image quality of the new technology was not inferior (2.66 vs. 2.77, p=0.56).

CONCLUSIONS

In our study the new imaging technology halved radiation dose in patients undergoing TIPS maintaining sufficient image quality without a significant increase in radiation time or contrast consumption.