Significant Reduction In Radiation Exposure Research Articles

The impact of clinical audits on patient radiation exposure for device procedures

Abstract Background Clinical audits aim to ensure ideal use of ionizing radiation in clinical practice. Since it became mandatory by Swiss law in 2018, such an audit also took place in our Cardiac Pacing and Electrophysiology Division at the University Heart Center. Purpose To establish local diagnostic reference levels (DRLs) for specific procedures and to examine if patient radiation exposure was reduced after the clinical audit. Methods Retrospective cohort study including patients from October 2018 to October 2020 who underwent device implantation, including pacemakers, implantable cardioverter defibrillators (ICD), cardiac resynchronization therapy (CRT), or lead extraction / device explantation. Main measures to reduce radiation exposure after the audit were lower pulsed fluoroscopy frame rates and dose characteristics at baseline. Patient radiation exposure was evaluated with the dose-area product (DAP), cumulative dose, fluoroscopy time, and the number of cine acquisitions. Secondary endpoints included the effective dose, the acute procedural success rate and 30-day complications. Data were collected from a dose management system and cross-checked for accuracy with the patient information system. The third quartiles were set as local DRLs. Data before and after the clinical audit were compared. Results A total of 541 patients (45.7 % before the audit, 54.3% after the audit) were included. 28.3% had a conventional pacemaker, 22.0% a leadless pacemaker, 21.1% an ICD, and 17.2% a CRT implantation. Lead extraction / device explantation was undergone by 11.5% of patients. The local DRLs (including all procedures before and after the audit) for the DAP were significantly lower as compared to national DRLs (6.2 dGy.cm2 versus 300 dGy.cm2 for conventional pacemakers; 7.6 dGy.cm2 versus 200 dGy.cm2 for ICDs, 203 dGy.cm2 versus 570 dGy.cm2 for CRTs). After the audit, DAP (Figure 1), cumulative dose, effective dose and the number of cine acquisition significantly decreased for conventional pacemakers (p-value ≤ 0.04), whereas no significant differences were observed for the other procedures. The acute procedural success rate (98.4 vs 98.9%) and the 30-day complications (4.0 vs 7.8%) were not significantly different before and after the audit. Conclusions The clinical audit in our institution led to a significant reduction of radiation exposure for patients during pacemaker implantations. Regarding DRLs, local values were far below national DRLs, which suggests that national DRLs need to be updated more regularly. Our study highlights the importance of clinical audits and the need for more research in this field.

Protecting Our Own: A Method for Reducing Breast Radiation Exposure in Healthcare Workers.

Standard lead aprons do not protect the female breast adequately from radiation exposure, which has been associated with breast cancer in healthcare workers. A novel lead shield was designed to reduce radiation to the breast, axilla, and thyroid (BAT). A procedure room was simulated with an anthropomorphic phantom representing the operator. Dosimeters were positioned on the outer quadrant of each breast, the chest, the thyroid, and deep inside of a phantom acrylic female torso with neck and head. Standard lead vest plus a thyroid shield was used as control and compared to standard lead vest plus BAT shield. Three operator and two image receptor positions were tested. The reductions in radiation exposure were calculated. The standard vest plus BAT shield provided significant reductions in radiation exposure for all anatomic locations compared to control. When averaging all operator positions, the BAT provided reductions of 91% (p < 0.0001) for near breast. Reductions for far breast, chest, thyroid, and deep tissues were 76% (p = 0.016), 94% (p < 0.0001), 52% (p = 0.026), and 60% (p = 0.004). With operator 90° to the table using a cross-table lateral beam, the BAT provided a 97.7% reduction in radiation to the near breast and significant reduction in radiation to the chest, thyroid, and deep tissues. The BAT shield reduces radiation exposure to the breast, chest, thyroid and deep hematopoietic tissues. Such shields could benefit healthcare workers to reduce the risk of breast cancer and other radiation-associated cancers.

Modeling of Integral Radiobiological Criteria for Simultaneous Irradiation of Multiple Targets with Different Absorbed Total Doses

Purpose: The paper is devoted to the comparison of simultaneous (SIB) and sequential (SEQ) radiation therapy of primary-multiple tumors with different absorbed total doses based on the modeling of integral radiobiological criteria. The research is aimed at optimization of treatment of rare primary-multiple tumors, development of optimal approaches based on the analysis of the effectiveness of different irradiation options. Material and methods: This research considers a system of primary-multiple targets, using a gynecologic tumor including vagina (adenosquamous carcinoma), endometrium (moderately differentiated adenocarcinoma with foci of squamous metaplasia), and lymph nodes as an example, to which certain equivalent total doses of irradiation must be delivered (EQD2&gt;=74.8 Gy for vagina, EQD2&gt;=85 Gy for endometrium). Different scenarios of two-stage and one-stage irradiation, including different combinations and doses for each target, are studied in the simulation. Results: Comparison of treatment plans for the triple target system shows that, performing sequential radiotherapy SEQ is characterized by higher levels of equivalent total dose delivered to the target volumes taking into account the total irradiation time and, consequently, to the critical organ volumes, especially in the rectum and sigmoid colon. In case of simultaneous irradiation SIB, the duration of treatment is five weeks instead of seven weeks, which reduces the value of the equivalent total dose to the target by 7-10 Gy. The value of the absorbed single dose delivered to the target volume is up to 3 Gy, which can be attributed to moderate hypofractionation. Levels of radiation exposure for critical organs in this case are much lower than when two-stage irradiation is used. Conclusion: Simultaneous integrated boost radiation therapy allows a significant reduction in radiation exposure to critical organs compared to sequential radiation therapy (reduction to single systems).

P352 Comparison of Radiation Dose, Image Quality, and Diagnostic Performance between Hybrid Iterative Reconstruction and Deep Learning Reconstruction for CT Enterography of IBD

Abstract Background CT enterography (CTE) is recommended as one of the preferred methods for patients with inflammatory bowel disease (IBD), especially in primary hospitals that lack MRI equipment. However, the potential risk of radiation derived from using CTE during the life-long follow-up is an important issue for these patients. This study aimed to compare the radiation dose, image quality, and diagnostic performance of CTE for IBD using hybrid iterative reconstruction (HIR) and deep learning reconstruction (DLR). Methods We prospectively collected data on low dose CTE reconstructed by HIR and DLR in patients with IBD between February 2023 and September 2023, and retrospectively enrolled IBD patients who underwent conventional dose CTE reconstructed by HIR between June 2019 and June 2022 as controls. The CTE examinations were performed within 2 weeks of bowel histologic evaluation (the reference standard of bowel inflammation). The objective and subjective image quality and the image features were evaluated by two IBD radiologists. The radiation dose, image quality, and diagnostic performance was compared between the two dose protocols. Results The preliminary study included 36 patients in the low dose group with HIR and DLR and 40 patients in the conventional dose group with HIR. There were no significant differences in demographic data of patients between the two groups (all P&amp;gt;0.05). The sensitivity, specificity, and diagnostic accuracy for detecting active inflammation were 71.4% (43.3%), 83.3% (80.0%), and 75.0% (52.5%) for the low dose group with DLR (HIR), respectively, and 84.4%, 62.5%, and 80% for the conventional dose HIR group. Low dose group with DLR resulted in significantly increased objective and subjective image quality and diagnostic confidence for active inflammation compared to low dose group with HIR (all P&amp;lt;0.05), with no inferiority to conventional dose group with HIR (all P&amp;gt;0.05). The dichotomous inter-reader reliability (k) for the entire group was 0.88. Low dose group resulted in a significant reduction in radiation exposure (mean [± SD], 2.20 ± 0.29 mSv) compared to conventional dose group (4.85 ± 1.96 mSv; P&amp;lt;0.001). Conclusion Low dose CTE with DLR significantly improved image quality compared to low dose CTE with HIR, and maintained similarly high diagnostic performance as conventional dose CTE with HIR. Importantly, the low dose CTE with DLR significantly reduced the radiation dose, improving the safety of CTE application in the life-long follow-up of patients with IBD.

Photon-counting detector CT allows significant reduction in radiation dose while maintaining image quality and noise on non-contrast chest CT

PurposeTo investigate if clinical non-contrast chest CT studies obtained with PCD CT using much lower radiation exposure can achieve the same image quality as with the currently established EID protocol. Materials/methodsA total of seventy-one patients were identified who had a non-contrast chest computed tomography (CT) done on PCD CT and EID CT scanners within a 4-month interval. Five fellowship trained chest radiologists, blinded to the scanner details were asked to review the cases side-by-side and record their preference for images from either the photon-counting-detector (PCD) CT or the energy-integrating detector (EID) CT scanner. ResultsThe median CTDIvol for PCD-CT system was 4.710 mGy and EID system was 7.80 mGy (p < 0.001). The median DLP with the PCD-CT was 182.0 mGy.cm and EID system was 262.60 mGy.cm (p < 0.001). The contrast to noise ratio (CNR) was superior on the PCD-CT system 59.2 compared to the EID-CT 53.3; (p < 0.001). Kappa-statistic showed that there was poor agreement between the readers over the image quality from the PCD and EID scanners (κ = 0.19; 95 % CI: 0.12 – 0.27; p < 0.001). Chi-square analysis revealed that 3 out of 5 readers showed a significant preference for images from the PCDCT (p ≤ 0.012). There was no significant difference in the preferences of two readers between EID-CT and PCD-CT images. ConclusionThe first clinical PCD-CT system allows a significant reduction in radiation exposure while maintaining image quality and image noise using a standardized non-contrast chest CT protocol.

Combining conventional technique with fluoroscopy integration module in accessory pathway ablation.

Accessory pathway (AP) ablation is a straightforward approach with high success rates, but the fluoroscopy time (FT) is significantly longer in conventional technique. Electroanatomical mapping systems (EMS), reduce the FT, but anatomical and activation mapping may prolong the procedure time (PT). The fluoroscopy integration module (FIM) uses prerecorded fluoroscopy images and allows ablation similar to conventional technique without creating an anatomical map. In this study, we investigated the effects of combining the FIM with traditional technique on PT, success, and radiation exposure. A total of 131 patients who had undergone AP ablation were included in our study. In 37 patients, right and left anterior oblique (RAO-LAO) images were acquired after catheter placement and integrated with the FIM. The ablation procedure was then similar to the conventional technique, but without the use of fluoroscopy. For the purpose of acceleration, anatomical and activation maps have not been created. Contact-force catheters were not used. 94 patients underwent conventional ablation using fluoroscopy only. FIM into AP ablation procedures led to a significant reduction in radiation exposure, lowering FT from 7.4 to 2.8 min (p < .001) and dose-area product from 12.47 to 5.8 μGym² (p < .001). While the FIM group experienced a reasonable longer PT (69 vs. 50 min p < .001). FIM reduces FT regardless of operator experience and location of APs CONCLUSION: Combining FIM integration with conventional AP ablation offers reduced radiation exposure without compromising success rates and complication.

The Role of Ultrasound in Epicutaneo-Caval Catheter Insertion in Neonates: Systematic Review, Meta-Analysis and Future Perspectives.

Chest and abdominal X-rays after the insertion of an epicutaneo-caval catheter in infants are the standard method of checking the tip location in many neonatal intensive care units. The role of ultrasound in the tip location of the epicutaneo-caval catheter in neonates has been the subject of many recent studies. This systematic review investigates the accuracy of epicutaneo-caval catheter tip location by comparing ultrasound and conventional radiology. We performed a systematic literature search in multiple databases. The selection of studies yielded nineteen articles. The systematic review and meta-analysis were performed according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analysis). The analyses showed that ultrasound is a better imaging technique for epicutaneo-caval catheter tip location in the neonatal intensive care unit than conventional radiology. By improving operator training and selecting a standardized echography protocol, ultrasound could become the gold standard for visualizing the epicutaneo-caval catheter tip in the neonatal intensive care unit. This would have some important benefits: (1) increased accuracy in tip location (2); a more rapid use of the central venous access (3); and a significant reduction in radiation exposure.

Deep learning–based scan range optimization can reduce radiation exposure in coronary CT angiography

ObjectivesCardiac computed tomography (CT) is essential in diagnosing coronary heart disease. However, a disadvantage is the associated radiation exposure to the patient which depends in part on the scan range. This study aimed to develop a deep neural network to optimize the delimitation of scan ranges in CT localizers to reduce the radiation dose.MethodsOn a retrospective training cohort of 1507 CT localizers randomly selected from calcium scoring and angiography scans and acquired between 2010 and 2017, optimized scan ranges were delimited by two radiologists in consensus. A neural network was trained to reproduce the scan ranges and was tested on two randomly selected and independent validation cohorts: an internal cohort of 233 CT localizers (January 2018–June 2020) and an external cohort from a nearby hospital of 298 CT localizers (July 2020–December 2020). Localizers where a bypass surgery was visible were excluded. The effective radiation dose to the patient was simulated using a Monte Carlo simulation. Scan ranges of radiographers, radiologists, and the network were compared using an equivalence test; likewise, the reduction in effective dose was tested using a superior test.ResultsThe network replicated the radiologists’ scan ranges with a Dice score of 96.5 ± 0.02 (p < 0.001, indicating equivalence). The generated scan ranges resulted in an effective dose reduction of 10.0% (p = 0.002) in the internal cohort and 12.6% (p < 0.001) in the external cohort compared to the scan ranges delimited by radiographers in clinical routine.ConclusionsAutomatic delimitation of the scan range can result in a radiation dose reduction to the patient.Clinical relevance statementFully automated delimitation of the scan range using a deep neural network enables a significant reduction in radiation exposure during CT coronary angiography compared to manual examination planning. It can also reduce the workload of the radiographers.Key Points• Scan range delimitation for coronary computed tomography angiography could be performed with high accuracy by a deep neural network.• Automated scan ranges showed a high agreement of 96.5% with the scan ranges of radiologists.• Using a Monte Carlo simulation, automated scan ranges reduced the effective dose to the patient by up to 12.6% (0.9 mSv) compared to the scan ranges of radiographers in clinical routine.Graphical abstract

Significant Reduction of Radiation Exposure Using Specific Settings of the O-Arm for Percutaneous Cementoplasty in Accordance With the ALARA Principle.

Three-dimensional (3D) navigation has become routinely used in spine surgery, allowing more accurate and safe procedures. However, radiation exposure related to the use of imaging is an unresolved issue, and information about it is relatively scarce. The "as low as reasonably achievable" (ALARA) principle aims to reduce the radiation exposure for the patients as low as possible. The objective of this study was to compare the effective dose related to the use of the O-arm in standard settings with adapted features for dose reduction during percutaneous cementoplasty. From March 2021 to October 2022, all consecutive patients who underwent navigated percutaneous cementoplasty with the use of the O-arm were prospectively included. Demographic, operative, irradiation, and radiological data were collected. The main outcome was the effective dose (E) in millisievert (mSv). Secondary outcomes were the absolute risk of cancer (AR) in percent equivalent to a whole-body exposition, operative time, and radiological results according to Garnier. In group A, patients were operated on with standard settings of the O-arm, whereas in group B, navigation on the field of view, collimation, and low-dose settings were used. A total of 70 patients were included in the study: 43 in group A and 27 in group B. Also, 109 vertebrae were operated: 59 in group A and 50 in group B. Mean E was significantly higher in group A than in group B (9.94 and 4.34 mSv, respectively; P < 0.01). The 3D-related E followed the same trend (7.82 and 3.97 mSv, respectively), as did 2-dimensional-related E (2.12 and 0.37 mSv, respectively; P < 0.01). Average AR was also significantly higher in group A than in group B (5.10-4% and 2.10-4% respectively; P < 0.01). Operative time was similar in both groups, but the rate of satisfactory radiological results was higher in group A than in group B (95% and 84%, respectively; P = 0.11), and we found similar rates of cement leakage (22% and 24%, respectively; P = 0.71). The application of settings of the O-arm in accordance with the ALARA principle helped to significantly reduce the radiation exposure and should be routinely used for O-arm-assisted cementoplasty procedures. This study details technical aspects and settings that may help users of the O-arm to decrease radiation exposure to patients and surgeons alike, especially in cementoplasty procedures, as well as in other procedures performed under O-arm guidance.

Overhead arm support reduces radiation exposure during complex endovascular aortic repair

BackgroundComplex endovascular aortic surgery has been associated with increased fluoroscopic radiation exposure. The radiation dosage necessary for visualization is dependent on the amount of tissue penetration required. Elevation of a patient’s arms above their head during endovascular surgery could improve visualization by removing the arms from the field of view. Furthermore, it might reduce the radiation dose required. In the present study, we sought to determine the effect of arm elevation on radiation exposure during endovascular treatment of thoracoabdominal aneurysms. MethodsAll patients enrolled in a single-institution, physician-sponsored investigational device exemption study for endovascular treatment of thoracoabdominal aneurysms (fenestrated/branched endovascular aortic repair [F/BEVAR]) from 2012 to 2022 were assessed. The first 30 patients treated were excluded to account for the learning curve required with treatment. Patients treated after December 2020 were positioned with their arms elevated above their head using an overhead arm support (OAS). These patients were compared with those who had undergone F/BEVAR before the practice change. The radiation dose, fluoroscopy time, and contrast volume used were compared. A subgroup analysis was performed to assess the effect for patients with brachial access. ResultsA total of 145 patients were included in the present study, of whom 43 (30%) had undergone F/BEVAR with their arms supported overhead. No differences were identified in age, body mass index, aneurysm size, or prior aortic intervention between the groups with and without the use of the OAS. A history of dissection (23% vs 7.8%; P = .01) was more frequent for the patients treated with their arms elevated. Arm elevation was associated with a significant reduction in the mean radiation exposure (2261 vs 3100 mGy; P = .01). No differences were observed in the fluoroscopy time or contrast volume used between the two groups. In addition, no patient experienced palsy of the brachial plexus. Of the 145 patients, 55 (38%) had required brachial arterial access, limiting their ability to elevate both arms. In the subgroup analysis, the patients without brachial access continued to show a significant reduction in radiation exposure with arm elevation (2159 vs 3179 mGy; P < .01). ConclusionsElevation of a patient’s arms above their head using an OAS during F/BEVAR offered a low-cost, simple strategy that resulted in a 30% reduction in radiation exposure without added complications. This technique improved visualization and reduced radiation exposure for patients and physicians and should be included in abdominal aortic and visceral procedures work to improve patient and surgeon safety.

Robotics Reduces Radiation Exposure in Minimally Invasive Lumbar Fusion Compared With Navigation.

Retrospective cohort. To compare robotics and navigation for minimally invasive elective lumbar fusion in terms of radiation exposure and time demand. Although various studies have been conducted to demonstrate the benefits of both navigation and robotics over fluoroscopy in terms of radiation exposure, literature is lacking in studies comparing robotics versus navigation. Patients who underwent elective one-level or two-level minimally invasive transforaminal lumbar interbody fusion (TLIF) by a single surgeon using navigation (Stryker SpineMask) or robotics (ExcelsiusGPS) were included (navigation 2017-2019, robotics 2019-2021, resulting in prospective cohorts of consecutive patients for each modality). All surgeries had the intraoperative computed tomography workflow. The two cohorts were compared for radiation exposure [fluoroscopy time and radiation dose: image capture, surgical procedure, and overall) and time demand (time for setup and image capture, operative time, and total operating room (OR) time]. A total of 244 patients (robotics 111, navigation 133) were included. The two cohorts were similar in terms of baseline demographics, primary/revision surgeries, and fusion levels. For one-level TLIF, total fluoroscopy time, total radiation dose, and % of radiation for surgical procedure were significantly less with robotics compared with navigation (20 vs. 25s, P <0.001; 38 vs. 42mGy, P =0.05; 58% vs. 65%, P =0.021). Although time for setup and image capture was significantly less with robotics (22 vs. 25min, P <0.001) and operative time was significantly greater with robotics (103 vs. 93min, P <0.001), there was no significant difference in the total OR time (145 vs. 141min, P =0.25). Similar findings were seen for two-level TLIF as well. Robotics for minimally invasive TLIF, compared with navigation, leads to a significant reduction in radiation exposure both to the surgeon and patient, with no significant difference in the total OR time.

Sustained radiation reduction following initial quality improvement intervention in a paediatric cardiac catheterisation laboratory.

As part of a quality improvement project beginning in October 2011, our centre introduced changes to reduce radiation exposure during paediatric cardiac catheterisations. This led to significant initial decreases in radiation to patients. Starting in April 2016, we sought to determine whether these initial reductions were sustained. After a 30-day trial period, we implemented (1) weight-based reductions in preset frame rates for fluoroscopy and angiography, (2) increased use of collimators and safety shields, (3) utilisation of stored fluoroscopy and virtual magnification, and (4) hiring of a devoted radiation technician. We collected patient weight (kg), total fluoroscopy time (min), and procedure radiation dosage (cGy-cm2) for cardiac catheterisations between October, 2011 and September, 2019. A total of 1889 procedures were evaluated (196 pre-intervention, 303 in the post-intervention time period, and 1400 in the long-term group). Fluoroscopy times (18.3 ± 13.6 pre; 19.8 ± 14.1 post; 17.11 ± 15.06 long-term, p = 0.782) were not significantly different between the three groups. Patient mean radiation dose per kilogram decreased significantly after the initial quality improvement intervention (39.7% reduction, p = 0.039) and was sustained over the long term (p = 0.043). Provider radiation exposure was also significantly decreased from the onset of this project through the long-term period (overall decrease of 73%, p < 0.01) despite several changes in the interventional cardiologists who made up the team over this time period. Introduction of technical and clinical practice changes can result in a significant reduction in radiation exposure for patients and providers in a paediatric cardiac catheterisation laboratory. These reductions can be maintained over the long term.

A simple, reliable and accurate approach for assessing [131I]-capsule activity leading to significant reduction of radiation exposure of medical staff during radioiodine therapy

PurposeAccording to German law, the [131I]-capsule activity has to be checked in the context of radioiodine therapy (RIT) immediately before application. The measurement leads to significant radiation exposure of the medical personnel, especially of their hands. We aimed to establish a method for estimating [131I]-capsule activity by measuring the dose rate (DR) at contact of the delivered lead closed container carrying the [131I]-capsules and to evaluate radiation exposure in comparison to conventional [131I]-capsule measurement using a dose calibrator. MethodsDR on the surface of the closed lead container was measured at two locations and correlated linearly with the [131I]-capsule activity measured in a dose calibrator to create calibrating curves. The hand and whole body (effective) doses were determined with official dose meters during validation of our method in clinical practice. ResultsThe determination coefficients (R2) of linear calibration curves were greater than 0.9974. The total relative uncertainty for estimating [131I]-capsule activity with our method was <±7.5% which is lower than the uncertainty of the nominal activity and quite close to the threshold limit for the maximum allowed uncertainty of ± 5% for measuring activity in radioactive drugs. The reduction of the hand dose caused by our method was 97% compared with the conventional measurements of the [131I]-capsules in a dose calibrator. ConclusionMeasuring DR on the surface of the closed lead containers enables the [131I]-capsules activity to be estimated simply, reliably and with sufficient accuracy leading to significant reduction of the radiation exposure for the medical staff.

Low-Dose CT for Renal Calculi Detection Using Spectral Shaping of High Tube Voltage.

To investigate reduction of radiation exposure in unenhanced CT in suspicion of renal calculi using a tin-filtered high tube voltage protocol compared to a standard low-dose protocol without spectral shaping. A phantom study using 7 human renal calculi was performed to test both protocols. 120 consecutive unenhanced CT examinations performed due to suspicion of renal calculi were included in this retrospective, monocentric study. 60 examinations were included with the standard-dose protocol (SP) (100 kV/130 mAs), whereas another 60 studies were included using a low-dose protocol (LD) applying spectral shaping with tin filtration of high tube voltages (Sn150 kV/80 mAs). Image quality was assessed by two radiologists in consensus blinded to technical parameters using an equidistant Likert scale ranging from 1-5 with 5being the highest score. Quantitative image quality was assessed using regions of interest in abdominal organs, muscles, and adipose tissue to analyze image noise and signal-to-noise ratios (SNR). Commercially available dosimetry software was used to determine and compare effective dose (ED) and size-specific dose estimates (SSDEmean). All seven renal calculi of the phantom could be detected with both protocols. There was no difference regarding calcluli size between the two protocols except for the smallest one. The smallest concretion measured 1.5 mm in LD and1.0 mm in SP (ground truth 1.5 mm). CTDIvol was 3.36 mGy in LD (DLP: 119.3 mGycm) and 8.27 mGy in SP (DLP: 293.6 mGycm). The mean patient age in SP was 47 ± 17 years and in LD 49 ± 13 years. Ureterolithiasis was found in 33 cases in SP and 32 cases in LD. The median concretion size was 3 mm in SP and 4 mm in LD. The median ED in LD was 1.3 mSv (interquartile range (IQR) 0.3 mSv) compared to 2.3 mSv (IQR 0.9 mSv) in SP (p < 0.001). The SSDEmean of LD was also significantly lower compared to SP with 2.4 mGy (IQR 0.4 mGy) vs. 4.8 mGy (IQR 2.3 mGy) (p < 0.001). The SNR was significantly lower in LD compared to SP (p < 0.001). However, there was no significant difference between SP and LD regarding the qualitative assessment of image quality with a median of 4 (IQR 1) for both groups (p = 0.648). Tin-filtered unenhanced abdominal CT for the detection of renal calculi using high tube voltages leads to a significant reduction of radiation exposure and yields high diagnostic image quality without a significant difference compared to the institution's standard of care low-dose protocol without tin filtration. · Tin-filtered CT for the detection of renal calculi significantly reduces radiation dose.. · The application of tin filtration provides comparable diagnostic image quality to that of SP protocols.. · An increase in image noise does not hamper diagnostic image quality.. · Gassenmaier S, Winkelmann MT, Magnus J et al. Low-Dose CT for Renal Calculi Detection Using Spectral Shaping of High Tube Voltage. Fortschr Röntgenstr 2022; 194: 1012 - 1019.

Comparison of radiation exposure and surgery time between an intraoperative CT with automatic surface registration and a preoperative CT with manual surface registration in navigated spinal surgeries

This retrospective matched case-control study was conducted to compare two CT based surgery techniques for navigated screw placement in spinal surgery, whether a reduction of radiation exposure and surgery time could be achieved. We matched cases treated with an intraoperative CT (iCT), regarding the type and number of implants, with cases treated with a preoperative CT (pCT) of one main surgeon. Outcome measures were radiation exposure due to intraoperative control x-rays, radiation exposure due to CT images, and the duration of surgery. The required radiation exposure could be significantly reduced in the iCT group. For the intraoperative control X-rays by 69% (median (MED) 88.50/standard deviation (SD) 107.84 and MED 286.00/SD 485.04 for iCT and pCT respectively-in Gycm2; p < 0.001) and for the CT examinations by 25% (MED 317.00/SD 158.62 and MED 424.50/SD 225.04 for iCT and pCT respectively-in mGycm; p < 0.001) with no significant change in surgery time. The correlation between the number of segments fused and the necessary surgery time decreased significantly for the iCT group (Pearson product-moment-correlation: r = 0.569 and r = 0.804 for iCT and pCT respectively; p < 0.05). The results show that spinal navigation using an intraoperative CT with automatic registration compared to a preoperative CT and intraoperative manual surface registration, allows a significant reduction of radiation exposure, without prolonged surgery time. A significant benefit regarding cut-to-suture-time can be gained with surgeries of a larger scale.

Low-dose coronary calcium scoring CT using a dedicated reconstruction filter for kV-independent calcium measurements.

In this prospective, pilot study, we tested a kV-independent coronary artery calcium scoring CT protocol, using a novel reconstruction kernel (Sa36f). From December 2018 to November 2019, we performed an additional research scan in 61 patients undergoing clinical calcium scanning. For the standard protocol (120 kVp), images were reconstructed with a standard, medium-sharp kernel (Qr36d). For the research protocol (automated kVp selection), images were reconstructed with a novel kernel (Sa36f). Research scans were sequentially performed using a higher (cohort A, n = 31) and a lower (cohort B, n = 30) dose optimizer setting within the automatic system with customizable kV selection. Agatston scores, coronary calcium volumes, and radiation exposure of the standard and research protocol were compared. A phantom study was conducted to determine inter-scan variability. There was excellent correlation for the Agatston score between the two protocols (r = 0.99); however, the standard protocol resulted in slightly higher Agatston scores (29.4 [0-139.0] vs 17.4 [0-158.2], p = 0.028). The median calcium volumes were similar (11.5 [0-109.2] vs 11.2 [0-118.0] mm3; p = 0.176), and the number of calcified lesions was not significantly different (p = 0.092). One patient was reclassified to another risk category. The research protocol could be performed at a lower kV and resulted in a substantially lower radiation exposure, with a median volumetric CT dose index of 4.1 vs 5.2mGy, respectively (p < 0.001). Our results showed that a consistent coronary calcium scoring can be achieved using a kV-independent protocol that lowers radiation doses compared to the standard protocol. KEY POINTS: • The Sa36f kernel enables kV-independent Agatston scoring without changing the original Agatston weighting threshold. • Agatston scores and calcium volumes of the standard and research protocols showed an excellent correlation. • The research protocol resulted in a significant reduction in radiation exposure with a mean reduction of 22% in DLP and 25% in CTDIvol.

Optimal Protocol of Myocardial Perfusion Imaging for Reduction of Radiation Exposure.

The Japanese Circulation Society (JCS) 2021 guideline on radiation safety in cardiology was updated based on the eight best practices for myocardial perfusion single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI), which was determined by panels of international atomic energy agency (IAEA) nuclear cardiology protocols cross-sectional study (INCAPS). Although the guideline recommends to avoid too much 201Tl or 201Tl/99mTc dual-isotope protocol, the utilization rate of 201Tl for SPECT-MPI in Japan is considerably high compared to other countries. In Japan, protocols using 99mTc should be appropriately promoted based on the guideline to reduce radiation exposure in SPECT-MPI. Among the eight practices, stress-only imaging is considered to be a useful strategy that contributes to a significant reduction in radiation exposure, and hybrid assessment in combination with rest computed tomography (CT)-MPI is one of the practical application methods.

ULTRA-LOW-DOSE COMPUTED TOMOGRAPHY IN UROLITHIASIS-EFFECT OF AN ADDITIONAL TIN FILTER ON IMAGE QUALITY AND RADIATION DOSE.

To compare radiation dose and image quality of three CT-scanners using optimal dose protocols in patients with suspected urolithiasis regarding additional hardware (tin filter) and software (iterative reconstruction). Examinations from a single-source CT-scanner (A2) and a dual-source CT-scanner (DSCT) (A1) were compared to a tin filter DSCT (B) regarding dose-length product (DLP) and volume-weighted CT dose-index (CTDIvol). DLP of B was 51 and 53% lower in comparison to A1 and A2 (78.62, 159.20 and 165.80mGy·cm, respectively; P<0.0001). CTDIvol of B was 53% and 56% significantly lower compared to A1 and A2, respectively (1.52 vs. 3.22 vs. 3.46mGy; P<0.0001). Image quality in B proved to be similar to A1 and A2 (3.57, 3.51 and 3.60, respectively; P>0.05). Inter-rater agreement regarding image quality was good for all CT-scanners (κ=0.62). Modern CTs with a built-in tin filter allow a significant reduction of radiation exposure in patients with suspected urolithiasis by optimizing the X-ray spectrum.

RADIATION EXPOSURE IN ACCESSORY PATHWAY ABLATION PROCEDURES IN CARDIAC ELECTROPHYSIOLOGY: A RETROSPECTIVE ANALYSIS

Background. Radiofrequency catheter ablation (CA) has been the treatment of choice in patients with accessory pathway (AP)-mediated tachycardias. Most of these procedures are done under fluoroscopic guidance, leading to significant radiation exposure to the patient and the laboratory personnel. In this analysis, we have looked at the amount of radiation exposure in AP CA procedures performed without the support of a three-dimensional electroanatomic mapping system. We have analyzed changes in exposure indices over the study period and the impact of change in fluoroscopy frame rate (FFR). Objectives. The objectives of this study are to quantify radiation exposure in accessory pathway ablation procedures; to analyze the radiation exposure trend over time; and to evaluate the effect of fluoroscopy frame rate reduction on the radiation exposure indices in these procedures. Methods. All the AP ablation procedures performed at our institute from January 2016 to December 2019 were retrospectively analyzed. The collected data were age, sex, location of APs based on successful site of ablation on fluoroscopy, procedure time, fluoroscopy time, and dose-area product (DAP). Effective dose (ED) was estimated from DAP. The data of procedures performed before January 2018 (“pre” group) were compared with those of the procedures performed after that date (“post” group). Pre-group procedures were performed at an FFR of 7.5 frames per second (fps), and post-group procedures – at an FFR of 3.75 fps. Results. The total number of procedures included in the analysis was 635. The mean age of the patients was 39±14 years, and 401 of them (63%) were males. The most common location of the APs was left lateral (38%). Procedure time and radiation indices showed a significant decrease over the study period (p &lt; 0.001). Post group procedures had significantly shorter procedure time and lower radiation exposure than pre group procedures. Conclusions. A decrease in the FFR was associated with a significant reduction in radiation exposure in AP ablation procedures

A standardized stepwise zero-fluoroscopy approach with transesophageal echocardiography guidance for atrial fibrillation ablation.

There is growing interest in performing fluoroless radiofrequency ablation (RFA) for atrial fibrillation (AF) due to the increasing awareness of risk associated with radiation exposure of patients and professional staff. The present study aimed to evaluate the feasibility, safety, and efficacy of a stepwise transesophageal echocardiography (TEE)-guided zero-fluoroscopy approach (ZFA) for RFA. Consecutive patients (n = 111) referred for AF-ablation were prospectively enrolled with intention to RFA with ZFA. Procedural outcomes were compared with historical controls (HCs) after 1:1 propensity score matching. ZFA success was considered when no X-ray was utilized to perform the whole procedure. ZFA success was achieved in 80 (72%) procedures. BMI > 35kg/m2 resulted in the only independent predictor of ZFA failure (OR = 6.10, 95% CI 1.15-46.49, p = 0.04). In comparison to HCs, a significant reduction in radiation exposure was observed in the ZFA group: fluoroscopy time (3 vs. 63s, p < 0.001), total emitted fluoroscopy dose (0.2 vs. 6.0mGy, p < 0.001), dose area product (0.04 vs. 1.4Gy*cm2, p < 0.001), and effective dose (0.8 vs. 27.2mSv*100, p < 0.001). Complete pulmonary vein isolation was achieved in all procedures. No difference was observed between the groups in in-hospital complication rate (0.9% vs. 1.8%, p = 0.99). This is the largest study proving procedural feasibility, safety, and efficacy of TEE-guided AF-ablation with a complete or near-complete avoidance of radiological exposure, without using intracardiac echocardiography.