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

Optimizing Image Quality in Cerebral 3D Rotational Angiography: A Study on the Impact of Voxel Size

BACKGROUND AND PURPOSE

3D rotational angiography (3DRA) is a crucial diagnostic tool for assessing neurovascular diseases. Despite its superior spatial resolution, challenges arise in visualizing minute vasculatures. This study investigates the impact of voxel size on the spatial resolution and noise of cerebral 3DRA.

MATERIALS AND METHODS

3DRA data from January 2022 to May 2022 were retrospectively analyzed, including a total of 10 patients with 50 small vessels (<1.0 mm in diameter) analyzed (5 vessels per patient). Using the Artis Q biplane angiography machine, 3DRA data sets were acquired and reconstructed at various voxel sizes ranging from 0.05 mm to 0.30 mm. Quantitative assessment included measurement of vessel visibility (maximum grayscale intensity within the vessel), vessel sharpness (slope of grayscale intensity calculated between 20% and 80% of maximum intensity), and background noise (standard deviation within a nonvascular region). Qualitative assessments-sharpness, noise, and overall image quality-were evaluated by 3 neuroradiologists.

RESULTS

A total of 50 vessels were analyzed quantitatively. Both the maximum intensity and slope of grayscale intensity at vessel walls decreased with increasing voxel size. There was a significant 2.94% increase in vessel intensity for every 0.05 mm decrease in voxel size (P < .001). Background noise significantly decreased as the voxel size increased (P < .001). Qualitatively, as the voxel size decreased, the sharpness of the image improved, and the amount of noise decreased. The overall image quality generally improved with decreasing voxel size. A good interrater agreement was observed among the neuroradiologists (κ = 0.601).

CONCLUSIONS

Voxel size significantly influences 3DRA image quality. Smaller voxel sizes enhance spatial resolution and overall image clarity despite increased noise and reduced field of view. Strategic application of smaller voxel sizes is crucial for detailed vascular assessments, such as aneurysm morphology and fine vascular structures.

Minimizing eye lens radiation exposure using lens tracking in neurointerventional procedures: retrospective clinical and phantom study

BACKGROUND

The eye lens is particularly vulnerable to radiation during endovascular treatments for intracranial aneurysms due to prolonged exposure under high magnification. This study presents a lens tracking method to monitor lens positions during procedures and estimate radiation doses using a phantom.

METHODS

A consecutive series of patients treated between January and March 2023 were retrospectively reviewed. A lens tracking method was used to mark lenses on three-dimensional source images to track their positions on two-dimensional working views. An anthropomorphic head phantom and photoluminescent glass dosimeters were used to estimate lens exposure under simulated conditions. We also evaluated potential radiation reduction with collimation based on the lens position.

RESULTS

Among 42 patients, 20 (48%) had their eye lens in the field of view (FOV). In 10 of these cases, collimation could have prevented direct exposure. The phantom study showed a median lens dose of 7.32 (5.02-9.59) mGy. Lenses within the anterior-posterior (AP) plane FOV received higher doses compared with those outside it (4.32 mGy vs 1.76 mGy, P<0.001). In the lateral plane, lenses outside the FOV showed significant dose differences (left lens: 5.02 mGy vs right lens: 2.45 mGy, P<0.001). Collimation reduced lens doses by 60% in the AP plane and 52% in the lateral plane (P<0.001 and P=0.001, respectively) with greater reductions for lenses initially in the FOV.

CONCLUSION

In this study, lenses were often included in the FOV, thereby receiving higher radiation doses. This underscores the importance of tracking and excluding lenses from the FOV to reduce radiation exposure during procedures.

Effectiveness of wedge filter application in reducing lens radiation dose during diagnostic cerebral angiography: a phantom and prospective study

OBJECTIVE

Diagnostic cerebral angiography poses a risk of direct radiation exposure to the eye lens. This study aimed to evaluate the effectiveness of using a wedge filter to reduce lens exposure during examination.

METHODS

A phantom study was initially conducted to evaluate the efficacy and determine the optimal depth of the wedge filter. Twenty patients with intracranial aneurysms scheduled for diagnostic cerebral angiography were prospectively enrolled. For each patient, the lens dose reduction protocol (involving a wedge filter) was used on one internal carotid artery (ICA), whereas the standard protocol was applied to the other ICA. Photoluminescent glass dosimeters were used to measure the lens dose. Quantitative noise measurements and qualitative analysis were performed to assess image quality.

RESULTS

The phantom study demonstrated that the wedge filter reduced the radiation dose to the eye lens in anteroposterior (25.5% reduction at 4 cm depth) and lateral projections (28.8% reduction at 3 cm depth). In the patient study (20 patients, 60% female, mean age 57.5 years), the lens dose reduction protocol reduced the dose by 47.2% compared with the standard protocol (median 1.06 mGy vs 0.56 mGy, p < 0.001). In both protocols, the left lens dose was significantly higher than the right (standard: 1.37 mGy vs 0.70 mGy, p < 0.001; reduction: 0.75 mGy vs 0.36 mGy, p < 0.001). No significant differences were observed in image noise or quality.

CONCLUSION

The wedge filter significantly reduced the lens radiation dose during cerebral angiography without affecting image quality.

KEY POINTS

Question The radiation dose to the eye lens during cerebral angiography remains unclear; a targeted method is needed to selectively reduce exposure to this radiosensitive organ. Findings This study directly measured eye lens radiation dose and found that using a wedge filter reduces exposure by nearly half while maintaining diagnostic image quality. Clinical relevance Using a wedge filter during routine neuroangiography effectively reduces eye lens radiation exposure with a simple operation, preserving image quality and potentially lowering the risk of radiation-induced cataracts.

Reducing frame rate and pulse rate for routine diagnostic cerebral angiography: ALARA principles in practice

OBJECTIVE

Diagnostic cerebral angiograms (DCAs) are widely used in neurosurgery due to their high sensitivity and specificity to diagnose and characterize pathology using ionizing radiation. Eliminating unnecessary radiation is critical to reduce risk to patients, providers, and health care staff. We investigated if reducing pulse and frame rates during routine DCAs would decrease radiation burden without compromising image quality.

METHODS

We performed a retrospective review of prospectively acquired data after implementing a quality improvement protocol in which pulse rate and frame rate were reduced from 15 p/s to 7.5 p/s and 7.5 f/s to 4.0 f/s respectively. Radiation doses and exposures were calculated. Two endovascular neurosurgeons reviewed randomly selected angiograms of both doses and blindly assessed their quality.

RESULTS

A total of 40 consecutive angiograms were retrospectively analyzed, 20 prior to the protocol change and 20 after. After the intervention, radiation dose, radiation per run, total exposure, and exposure per run were all significantly decreased even after adjustment for BMI (all p<0.05). On multivariable analysis, we identified a 46% decrease in total radiation dose and 39% decrease in exposure without compromising image quality or procedure time.

CONCLUSIONS

We demonstrated that for routine DCAs, pulse rate of 7.5 with a frame rate of 4.0 is sufficient to obtain diagnostic information without compromising image quality or elongating procedure time. In the interest of patient, provider, and health care staff safety, we strongly encourage all interventionalists to be cognizant of radiation usage to avoid unnecessary radiation exposure and consequential health risks.

Clinical Efficiency of an Artificial Intelligence-Based 3D-Angiography for Visualization of Cerebral Aneurysm: Comparison with the Conventional Method

PURPOSE

Artificial intelligence (AI)-based three-dimensional angiography (3D-A) was reported to demonstrate visualization of cerebral vasculature equivalent to that of three-dimensional digital subtraction angiography (3D-DSA). However, the applicability and efficacy of the AI-based 3D‑A algorithm have not yet been investigated for 3D-DSA micro imaging. In this study, we evaluated the usefulness of the AI-based 3D‑A in 3D-DSA micro imaging.

MATERIALS AND METHODS

The 3D-DSA micro datasets of 20 consecutive patients with cerebral aneurysm (CA) were reconstructed with 3D-DSA and 3D‑A. Three reviewers compared 3D-DSA and 3D‑A in terms of qualitative parameters (degrees of visualization of CA and the anterior choroidal artery [AChA]) and quantitative parameters (aneurysm diameter, neck diameter, parent vessel diameter, and visible length of AChA).

RESULTS

Qualitative evaluation of diagnostic potential revealed that visualization of CA and the proximal to middle parts of the AChA with 3D‑A was equal to that with conventional 3D-DSA; in contrast, visualization of the distal part of the AChA was lower with 3D‑A than with 3D-DSA. Further, regarding quantitative evaluation, the aneurysm diameter, neck diameter, and parent vessel diameter were comparable between 3D‑A and 3D-DSA; in contrast, the visible length of the AChA was lower with 3D‑A than with 3D-DSA.

CONCLUSIONS

The AI-based 3D‑A technique is feasible and evaluable visualization of cerebral vasculature with respect to quantitative and qualitative parameters in 3D-DSA micro imaging. However, the 3D‑A technique offers lower visualization of such as the distal portion of the AChA than 3D-DSA.

Reduction of Radiation Dose to Eye Lens in Cerebral 3D Rotational Angiography Using Head Off-Centering by Table Height Adjustment: A Prospective Study

OBJECTIVE

Three-dimensional rotational angiography (3D-RA) is increasingly used for the evaluation of intracranial aneurysms (IAs); however, radiation exposure to the lens is a concern. We investigated the effect of head off-centering by adjusting table height on the lens dose during 3D-RA and its feasibility in patient examination.

MATERIALS AND METHODS

The effect of head off-centering during 3D-RA on the lens radiation dose at various table heights was investigated using a RANDO head phantom (Alderson Research Labs). We prospectively enrolled 20 patients (58.0 ± 9.4 years) with IAs who were scheduled to undergo bilateral 3D-RA. In all patients' 3D-RA, the lens dose-reduction protocol involving elevation of the examination table was applied to one internal carotid artery, and the conventional protocol was applied to the other. The lens dose was measured using photoluminescent glass dosimeters (GD-352M, AGC Techno Glass Co., LTD), and radiation dose metrics were compared between the two protocols. Image quality was quantitatively analyzed using source images for image noise, signal-to-noise ratio, and contrast-to-noise ratio. Additionally, three reviewers qualitatively assessed the image quality using a five-point Likert scale.

RESULTS

The phantom study showed that the lens dose was reduced by an average of 38% per 1 cm increase in table height. In the patient study, the dose-reduction protocol (elevating the table height by an average of 2.3 cm) led to an 83% reduction in the median dose from 4.65 mGy to 0.79 mGy (P < 0.001). There were no significant differences between dose-reduction and conventional protocols in the kerma area product (7.34 vs. 7.40 Gy·cm², P = 0.892), air kerma (75.7 vs. 75.1 mGy, P = 0.872), and image quality.

CONCLUSION

The lens radiation dose was significantly affected by table height adjustment during 3D-RA. Intentional head off-centering by elevation of the table is a simple and effective way to reduce the lens dose in clinical practice.

Comparing Radiation Dose of Cerebral Angiography Using Conventional and High kV Techniques: A Retrospective Study on Intracranial Aneurysm Patients and a Phantom Study

Evaluation of patient radiation dose after the implementation of a high kV technique during a cerebral angiographic procedure is an important issue. This study aimed to determine and compare the patient radiation dose of intracranial aneurysm patients undergoing cerebral angiography using the conventional and high kV techniques in a retrospective study and a phantom study. A total of 122 cases (61 cases with conventional technique and 61 cases with high kV technique) of intracranial aneurysm patients, who underwent cerebral angiographic procedure and met the inclusion criteria, were recruited. The radiation dose and the angiographic exposure parameters were reviewed retrospectively. The radiation dose in the phantom study was conducted using nanoDot^TM optically stimulating luminescence (OSLD), which were placed on the scalp of the head phantom, the back of the neck, and the phantom skin at the position of the eyes. The standard cerebral angiographic procedure using the conventional and high kV techniques was performed following the standard protocol. The results showed that the high kV technique significantly reduced patient radiation dose and phantom skin dose. This study confirms that the implementation of a high kV technique in routine cerebral angiography for aneurysm diagnosis provides an effective reduction in radiation dose. Further investigation of radiation dose in other interventional neuroradiology procedures, particularly embolization procedure, should be performed.

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.

Lens dose reduction with a bismuth shield in neuro cone-beam computed tomography: an investigation on optimum shield device placement conditions

This study aimed to determine the placement distance, number, and position of the bismuth shield for developing a lens protective device for cone-beam computed tomography (CBCT). To determine the dose reduction rate, the lens doses were measured using an anthropomorphic head phantom and a real-time dosimeter. The image quality assessment was determined by analyzing the change in the pixel value, caused by the bismuth shield, and the artifact index was calculated from the pixel value and image noise within various regions of interest in the head phantom. When the distance between the bismuth shield and the subject was increased, the image quality deteriorated less, but there was also a decrease in the lens dose reduction rate. Upon changing the number of bismuth shields from 1-ply to 2-ply, the dose reduction rate increased; however, there was a decrease in the image quality. Additionally, placing the bismuth shield outside of the subject improved the dose reduction rate without deteriorating the image quality. The optimum placement conditions of the bismuth shield were concluded as follows: positioned outside, placed 10 mm from the surface of the subject, and used a 1-ply bismuth shield. When these placement conditions were used, the lens dose reduction rate was 26.9 ± 0.36% (right-left average) for the "bismuth shield: separate". The protective device developed in this study will contribute to radiation dose reduction in CBCT scans.

Artificial Intelligence-Based 3D Angiography for Visualization of Complex Cerebrovascular Pathologies

BACKGROUND AND PURPOSE

By means of artificial intelligence, 3D angiography is a novel postprocessing method for 3D imaging of cerebral vessels. Because 3D angiography does not require a mask run like the current standard 3D-DSA, it potentially offers a considerable reduction of the patient radiation dose. Our aim was an assessment of the diagnostic value of 3D angiography for visualization of cerebrovascular pathologies.

MATERIALS AND METHODS

3D-DSA data sets of cerebral aneurysms (n _CA = 10), AVMs (n _AVM = 10), and dural arteriovenous fistulas (dAVFs) (n _dAVF = 10) were reconstructed using both conventional and prototype software. Corresponding reconstructions have been analyzed by 2 neuroradiologists in a consensus reading in terms of image quality, injection vessel diameters (vessel diameter [VD] 1/2), vessel geometry index (VGI = VD1/VD2), and specific qualitative/quantitative parameters of AVMs (eg, location, nidus size, feeder, associated aneurysms, drainage, Spetzler-Martin score), dAVFs (eg, fistulous point, main feeder, diameter of the main feeder, drainage), and cerebral aneurysms (location, neck, size).

RESULTS

In total, 60 volumes have been successfully reconstructed with equivalent image quality. The specific qualitative/quantitative assessment of 3D angiography revealed nearly complete accordance with 3D-DSA in AVMs (eg, mean nidus size_{3D angiography/3D-DSA}= 19.9 [SD, 10.9]/20.2 [SD, 11.2] mm; r = 0.9, P = .001), dAVFs (eg, mean diameter of the main feeder_{3D angiography/3D-DSA}= 2.04 [SD, 0.65]/2.05 [SD, 0.63] mm; r = 0.9, P = .001), and cerebral aneurysms (eg, mean size_{3D angiography/3D-DSA}= 5.17 [SD, 3.4]/5.12 [SD, 3.3] mm; r = 0.9, P = .001). Assessment of the geometry of the injection vessel in 3D angiography data sets did not differ significantly from that of 3D-DSA (vessel geometry index_AVM: r = 0.84, P = .003; vessel geometry index_dAVF: r = 0.82, P = .003; vessel geometry index_CA: r = 0.84, P <.001).

CONCLUSIONS

In this study, the artificial intelligence-based 3D angiography was a reliable method for visualization of complex cerebrovascular pathologies and showed results comparable with those of 3D-DSA. Thus, 3D angiography is a promising postprocessing method that provides a significant reduction of the patient radiation dose.

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.

Low-Dose Fluoroscopy Protocol for Diagnostic Cerebral Angiography

PURPOSE

We applied a low-dose fluoroscopic protocol in routine diagnostic cerebral angiography and evaluated the feasibility of the protocol.

MATERIALS AND METHODS

We retrospectively reviewed a total of 60 patients who underwent diagnostic cerebral angiography for various neurovascular diseases from September to November 2019. Routine protocols were used for patients in the first phase and low-dose protocols in the second phase. We compared radiation dose, fluoroscopy time, and complications between groups.

RESULTS

Age, diseases, and operators were not significantly different between the two groups. The mean fluoroscopy dose significantly decreased by 52% in the low-dose group (3.09 vs. 6.38 Gy·cm2 ); however, the total dose was not significantly different between the two groups (34.07 vs. 33.70 Gy·cm2 ). The total fluoroscopic time was slightly longer in the low-dose group, but the difference was not statistically significant (12.2. vs. 12.5 minutes). In all patients, angiography was successfully performed without complications.

CONCLUSION

The low-dose fluoroscopy protocol is feasible to apply for diagnostic cerebral angiography in that this protocol could significantly reduce the fluoroscopic dose.

Comparison of Transfemoral Cerebral Angiography and Transradial Cerebral Angiography Following a Shift in Practice During Four Years at a Single Center in China

Background

Cerebral angiography, or intra-arterial digital subtraction angiography (DSA), is a fluoroscopic imaging technique. In China, until recently, transfemoral access (TFA) has been used, rather than transradial access (TRA). This retrospective study aimed to compare transfemoral cerebral angiography (TFCA) with transradial cerebral angiography (TRCA) consecutively performed by the same operator, at a single center in China, to determine whether there were benefits from the shift from TFA to TRA in terms of efficiency, safety, and feasibility.

Material/Methods

A review of 1,048 cerebral angiograms in 980 patients was performed by a single operator from June 2014 to May 2018, including the TFA group (n=513) and the transradial access (TRA) group (n=535), and 39 patients underwent both TFA and TRA. The total procedure time, duration of fluoroscopy, catheterization success rate, image quality, length of stay in hospital, complications of the procedure, and patient preference were compared between the groups.

Results

Compared with TFCA, TRCA resulted in significantly shorter total procedure time, a higher catheterization success rate, better image quality, and shorter duration of hospital stay (P<0.05). There was no significant difference between the TFA and TRA groups for cardiovascular, cerebral, and access site complications. Patients in the TRA group showed a significantly reduced fluoroscopy time at the early stages of operator training (P<0.05). Patient preference included TRA (76.74%), TFA (16.28%), and no preference (6.89%).

Conclusions

During four years at a single center, and with a single operator, TRCA was safe, feasible, and more rapid when compared with TFCA.

Evaluation of an Artificial Intelligence-Based 3D-Angiography for Visualization of Cerebral Vasculature

PURPOSE

The three-dimensional digital subtraction angiography (3D DSA) technique is the current standard and is based on both mask and fill runs to enable the subtraction technique. Artificial intelligence (AI)-based 3D angiography (3DA) was developed to reduce radiation dosage because only one contrast-enhanced run of the C‑arm system is required for reconstruction of DSA-like 3D volumes. The aim was the evaluation of this algorithm regarding its diagnostic information.

METHODS

3D DSA datasets without pathologic findings were reconstructed both with subtraction technique and with the AI-based algorithm. Corresponding reconstructions were evaluated by 2 neuroradiologists with respect to image quality (IQ), visualization of major segments of the circle of Willis (ICA = C4-C7; OphA; ACA = A1-A2, MCA = M1-M2; VA = V4; BA; AICA; SUCA; PCA = P1-P2), identifiability of perforators (lenticulostriate/thalamoperforating arteries) and vessel diameters (ICA = C4; MCA = M1; BA; PCA = P1).

RESULTS

In total 15 datasets were successfully reconstructed as 3D DSA and 3DA with diagnostic image quality. All major segments of the circle of Willis and perforators were comparably visualized with 3DA. Quantitative analysis of vessel diameters in 3D DSA and 3DA datasets was equivalent and did not show relevant differences (r_ICA = 0.901, p = 0.001; r_M1 = 0.951, p = 0.001; r_BA = 0.906, p = 0.001; r_P1 = 0.991, p = 0.001).

CONCLUSIONS

The use of 3DA demonstrated reliable visualization of cerebral vasculature with respect to quantitative and qualitative parameters. Therefore, 3DA is a promising method that might help to reduce patient radiation.

Estimated radiation dose according to the craniocaudal angle in cerebral digital subtraction angiography: Patient and phantom study

BACKGROUND AND PURPOSE

Routine use of cranial angulation with 15-20 degrees, craniocaudal angled (CC) view, for cerebral digital subtraction angiography (DSA) helps minimize bone subtraction artifacts with less overlapping of the vessels, however, it may increase the radiation dose. We designed the phantom and patient studies to determine the effect of the angulation to the radiation dose and the feasibility of true posteroanterior angled (PA) view, in cerebral DSA.

MATERIALS AND METHODS

In the phantom study, frontal DSA was simulated with variable angulations. In the patient study with thirty-one subjects, one internal carotid arteriogram was obtained with the CC view and the other, PA view in every patient. The dose-area product (DAP) and reference air-kerma (AK) were measured and compared between the angles. A qualitative analysis was performed to assess the diagnostic performance of the DSA over the angles.

RESULTS

The phantom study confirmed that the greater craniocaudal angles caused higher radiation exposure. Especially, the radiation dose (AK) of the CC view was 5.4% higher than that of the PA view. In the patient study, the radiation dose of the PA view was significantly lower compared to the CC view (1.44 vs. 1.63 mGy, AK). In 4 patients, the dose particularly jumped when applying the CC view as the copper filter was automatically removed. The diagnostic ability of the DSA with the PA view tended to be higher without significance.

CONCLUSIONS

In a daily routine cerebral angiography, a simple modification of the angle may help to minimize the radiation dose.

Equivalent thicknesses of beam hardening filters consisting of aluminium, copper, Al/Cu and Al/Gold combinations and plumbiferous acrylic for 40 to 150 kVp diagnostic spectra

PURPOSE

Beam hardening filters used to reduce patient doses typically consist of aluminium, copper, or a combination of both. Optically transparent filters containing lead in plumbiferous acrylic became available. One vendor also uses a combination of aluminium and gold. Data is provided to compare filter thicknesses in terms of half-value layer (HVL) for clinically relevant kVp.

METHODS

Equivalent filter thicknesses were defined by identical kVp and 1st HVL. Equivalent copper filter thicknesses were calculated for aluminium and typical filters found in radiographic and interventional systems. A verified semi-empirical spectrum calculation programme and National Institute of Standards and Technology (NIST) mass attenuation coefficients were applied. Lead acrylic filters were simulated by a two-component model of acrylic plus lead with mass thicknesses determined by matching 1 HVLs in Al at RQR5 using filter specifications.

RESULTS

Coefficients are provided to convert mm Cu to mm Al and vice versa for tube potentials from 40 to 150 kVp. 1 mm Al corresponds to 27.8 ± 1 μm Cu over the entire energy range simulated. Using this simple model as opposed to simulations of all individual filters made from Al/Cu combinations (1 and 2 mm Al, 1 Al + 0.1 and 0.2 Cu, 1.5 Al plus 0.3 and 0.6 Cu, 2 Al plus 0.1 Cu) for the entire energy range results in differences in equivalent Cu thicknesses below 4 μm Cu (3 μm for 50-150 kVp). kVp dependence is larger for filters containing larger Z elements. 1 mm Al plus 10 μm gold used by Shimadzu corresponds to 75-80 μm Cu, depending on kVp; plumbiferous acrylic with nominal filtrations of 1 Al plus 0.1 Cu, and 1 Al plus 0.2 Cu corresponded to 124-132 μm, and 206-232 μm Cu, respectively.

CONCLUSIONS

Experimental verification of the equivalence of aluminium and combined aluminium plus copper filters showed excellent agreement between calculated copper equivalent thickness and measurements with copper filters for clinical beams from 40 to 150 kVp.

Age of Data in Contemporary Research Articles Published in Representative General Radiology Journals

Objective

To analyze and compare the age of data in contemporary research articles published in representative general radiology journals.

Materials and Methods

We searched for articles reporting original research studies analyzing patient data that were published in the print issues of the Korean Journal of Radiology (KJR), European Radiology (ER), and Radiology in 2017. Eligible articles were reviewed to extract data collection period (time from first patient recruitment to last patient follow-up) and age of data (time between data collection end and publication). The journals were compared in terms of the proportion of articles reporting the data collection period to the level of calendar month and regarding the age of data.

Results

There were 50, 492, and 254 eligible articles in KJR, ER, and Radiology, respectively. Of these, 44 (88%; 95% confidence interval [CI]: 75.8-94.8%), 359 (73%; 95% CI: 68.9-76.7%), and 211 (83.1%; 95% CI: 78-87.2%) articles, respectively, provided enough details of data collection period, revealing a significant difference between ER and Radiology (p = 0.002). The age of data was significantly greater in KJR (median age: 826 days; range: 299-2843 days) than in ER (median age: 570 days; range: 56-4742 days; p < 0.001) and Radiology (median age: 618; range: 75-4271 days; p < 0.001).

Conclusion

Korean Journal of Radiology did not fall behind ER or Radiology in reporting of data collection period, but showed a significantly greater age of data than ER and Radiology, suggesting that KJR should take measures to improve the timeliness of its data.

Increase in fluoroscopic radiation dose in successive sessions of multistage Onyx embolization of brain arteriovenous malformations compared with the first session

BACKGROUND AND PURPOSE

Onyx embolization is a treatment for brain arteriovenous malformations (AVMs). However, multistage embolization usually involves the presence of radiodense Onyx cast from the previous sessions, which may influence the fluoroscopic radiation dose. We compared the fluoroscopic dose between the initial and final embolization sessions.

MATERIALS AND METHOD

From January 2014 to September 2016, 18 patients underwent multistage Onyx embolization (more than twice) for brain AVMs. The total fluoroscopic duration (minutes), dose-area product (DAP, Gy×cm²), and cumulative air kerma (CAK, mGy) of both the frontal and lateral planes were obtained. We compared the frontal and lateral fluoroscopic dose rates (dose/time) of the final embolization session with those of the initial session. The relationship between the injected Onyx volume and radiation dose was tested.

RESULTS

The initial and final procedures on the frontal plane showed significantly different fluoroscopic dose rates (DAP: initial 0.668 Gy×cm²/min, final 0.848 Gy×cm²/min, P=0.02; CAK: initial 12.7 mGy/min, final 23.1 mGy/min, P=0.007). Those on the lateral plane also showed a similar pattern (DAP: initial 0.365 Gy×cm²/min, final 0.519 Gy×cm²/min, P=0.03; CAK: initial 6.2 mGy/min, final 12.9 mGy/min, P=0.01). The correlation between the cumulative Onyx volume (vials) and radiation dose ratio of both planes showed an increasing trend (rho 0.4325-0.7053; P=0.0011-0.0730).

CONCLUSION

Owing to the automatic exposure control function during fluoroscopy, successive Onyx embolization procedures increase the fluoroscopic radiation dose in multistage brain AVM embolization because of the presence of radiodense Onyx mass.