Low-dose Fluoroscopy Research Articles

Radiating for Two: Quantifying Radiation Exposure to Pregnant Urologists During Percutaneous Nephrolithotomy.

Current occupational recommendations limit fetal radiation dose to 1 mSv. With increased gender diversity in urology, understanding radiation exposure during pregnancy is crucial. The purpose of this study was to determine surgeon uterine radiation dose during percutaneous nephrolithotomy (PCNL) and compare effectiveness of several radiation reduction strategies in a cadaver model. Two cadavers were used to simulate the surgeon and patient in a PCNL model. An ion chamber was placed behind the surgeon's anterior uterine wall to measure radiation dose. Three radiation reduction methods were compared: pulsed fluoroscopy (1, 4, 8, 15, 30 pps), low-dose (LD) fluoroscopy, and surgeon shielding (none, 0.35, 0.50, 0.70 mm lead equivalents). The average radiation dose/second was recorded for 20 trials per combination. Assuming 5 minutes of fluoroscopy per PCNL, the number of cases required to exceed the fetal occupational limit was determined. Decreasing pulse frequency from 30 to 1 pps reduced dose by 96% (p<0.001). The LD setting decreased dose by 56% (p<0.001). A 0.35 mm lead apron resulted in a 94% dose reduction (p<0.001), and the 0.50 and 0.70 mm lead aprons further reduced dose by 12% and 47%, respectively. At conventional fluoroscopy settings of automatic exposure control and 30 pps, a surgeon could perform 12 PCNLs using no lead or 189 PCNLs using a 0.35 mm lead apron before reaching the 1 mSv limit. In addition to shielding, employing 1 pps with LD further decreased radiation exposure, allowing over 6000 cases to be performed with <1 mSv uterine radiation exposure. Within the limitations of this cadaver study, these data support that high volume pregnant surgeons employing active radiation reduction techniques such as pulsed, LD fluoroscopy and appropriate shielding can maintain surgical volume with relatively low risk. Fetal dosimeter use with monthly monitoring is still encouraged to confirm safety throughout pregnancy.

More is less: image enhancement technology reduces radiation exposure during anterior lumbar interbody fusion

BACKGROUND CONTEXTFluoroscopy and radiation exposure occur during anterior lumbar interbody fusion (ALIF). Image enhancement technology is available that can potentially reduce radiation exposure. PURPOSEThe purpose of this study is to evaluate radiation exposure and fluoroscopy times comparing standard fluoroscopy (FL) with a low dose image enhancement platform (LD). STUDY DESIGNRetrospective review of prospectively maintained database. PATIENT SAMPLEConsecutive patients undergoing ALIF with either standard fluoroscopy or low dose image enhancement technology. OUTCOME MEASURESRadiation dispersion and fluoroscopy times in ALIF patients with standard fluoroscopy and low dose image enhancement technology. METHODSA retrospective review of a prospective database on consecutive patients who have undergone ALIF, stratified into 2 groups: subjects with standard fluoroscopy (FL), and low dose fluoroscopy with image enhancement technology (LD). RESULTSA total of 487 ALIF patients were included (FL: 372 vs. LD: 115). LD patients were significantly older (66 vs. 60 years), with more deformity cases (28% vs. 12%), and less degenerative cases (71% vs. 87%), all p<.05; no differences in sex, BMI, or the number of levels operated on between groups. Fluoroscopy time (sec) was significantly higher in LD (51.4 vs. 45.5), with a statistically significant reduction in radiation (mGy) compared to FL (23.3 vs. 48.2), both p<.05. Furthermore, the results showed that radiation dispersion is increasingly reduced as fluoroscopy time increases in LD compared to FL (12%, 56%, and 65% reduction in radiation dispersion for fluoroscopy time <30 sec, between 30 to 60 sec, and >60 sec, respectively). CONCLUSIONSThe use of low dose fluoroscopy with image enhancement technology significantly reduces the cumulative dose of radiation during ALIF compared to standard dose fluoroscopy. Also, radiation dispersion increasingly decreases as fluoroscopy time increases using low dose image enhancement technology. Low dose image enhancement technology improves the safety profile of ALIF for patients and operating room staff.

Near-zero fluoroscopy technique for cardiac electronic device implantation: long-term outcomes

Abstract Introduction Radiation hazards are a major concern for both patients and staff. We have previously described a near-zero fluoroscopy technique for cardiac electronic device implantation. In this study, we aimed to investigate the long-term safety of this technique and compare outcomes and procedural metrics with a conventional approach in a larger population. Methods Low-dose fluoroscopy technique. Radiation exposure during fluoroscopy is directly proportional to the time the unit is activated. Typically, the pedal switch is depressed for at least a few seconds per imaging sequence in order to visualize "live" movements of either the leads during their positioning or the needle during a fluoroscopy-guided puncture of the subclavian vein. Our technique consists of setting a low frame rate per second (0.5-3.75fps) and momentarily triggering the foot pedal switch only to obtain screenshots of the position of the leads/needle. Use of live electrograms to assist spatial awareness of lead position (e.g. Atrial, Coronary Sinus, Ventricular signals) acts as an adjunct to guidance. Study design We included consecutive patients undergoing permanent pacemaker (PPM) or cardiac defibrillator (ICD) implant at our center from July 2018 to December 2022 using the near-zero fluoroscopy technique. Procedures were performed by three operators (AC, MD, MF). Cumulative radiation dose was measured using dose-area product (DAP). We assessed procedure success and complication rate during long-term follow-up. We compared the procedural metrics and outcomes with a cohort of patients with PPM or ICD implanted in our centre by senior operators, using a traditional fluoroscopic approach. Propensity score was adopted to match baseline characteristics between the study and control group. Results The total population consisted of 412 patients (74.2±13.9 years, 60.9% male). We included 206 who underwent PPM or ICD implantation using the low-dose fluoroscopy technique, and 206 matched-control. A PPM or ICD was successfully implanted in all patients. Fluoroscopy time and DAP were significantly lower in the low-dose fluoroscopy group, mean 2.3±2.0 seconds versus 258.4±252.1 seconds (P&amp;lt;0.001) and 3.4±3.5 µGym2 versus 29.8±55.4 µGym2 (P&amp;lt;0.001), respectively. Mean procedure time was 49.0±20.8 minutes in the low fluoroscopy group and 65.7±26.8 minutes in the control group (P&amp;lt;0.001). Median frame per second setting was 0.5 in the low-dose cohort. After a mean follow-up of 441±470 days, the rate of complications was identical across groups (2.4%, p = 1.0). Conclusion This near-zero dose fluoroscopy technique is effective and safe, enabling a 10x reduction in radiation exposure during device implant. Modification of traditional implant and imaging techniques can provide material reductions in fluoroscopy dose to even below that for a standard PA chest radiograph.

Case Report: Endovascular technique for intravascular foreign body retrieval in severely preterm neonate

Background Intravascular foreign bodies (IFB) in severely preterm neonates present critical clinical challenges. Traditional surgical removals are often risky and may not be feasible in these patients. This case report aims to detail a successful endovascular approach for IFB retrieval in a severely preterm neonate. Case This is a case report of a 14-day old, male 30-week gestation neonate with a retained umbilical catheter fragment. The baby was referred after an unsuccessful explorative laparotomy by a paediatric surgery team. The endovascular procedure was performed using a 4 French (Fr) vertebra catheter and a One Snare wire in the right femoral region under low-dose fluoroscopy. The IFB was successfully removed. Post-procedure, the patient’s leukocyte count normalized, and he transitioned from ventilator support to a nasal cannula and eventually to room air within three days. The neonate could also tolerate oral intake, signalling a rapid recovery and low morbidity. Conclusions This case report highlights the potential of endovascular approaches for IFB retrieval as viable alternatives to traditional surgeries, especially in neonates where surgical options are limited or have failed. Further research is needed to standardize such minimally invasive techniques in neonatal care.

Transseptal Puncture Guided by Three-Dimensional Electroanatomical Mapping: Early Experience Using a Simplified Approach in Adults with Congenital Heart Disease.

The widespread use of three-dimensional (3D) mapping systems and echocardiography in the field of cardiac electrophysiology has made it possible to perform transseptal punctures (TSP) with low or no fluoroscopy. However, such attempts in adults with congenital heart disease (ACHD) who have previously undergone surgical or interventional treatment are limited. Therefore, we sought to explore the feasibility and safety of an approach to perform zero- or low-fluoroscopy TSP in ACHD patients undergoing left atrial cardiac ablation procedures. This study included 45 ACHD patients who underwent TSP for ablation of left-sided tachycardias (left atrium or pulmonary venous atrium). Computed tomography (CT) of the heart was performed in all patients prior to ablation. 3D mapping of the right-sided heart chambers before TSP was used to superimpose the registered anatomy, which was subsequently used for the mapping-guided TSP technique. TSP was performed with zero-fluoroscopy in 27 patients, and the remaining 18 patients had a mean fluoroscopy exposure of 315.88 ± 598.43 μGy.m2 and a mean fluoroscopy duration of 1.9 ± 5.4 min. No patient in this cohort experienced TSP-related complications. Our study describes a fluoroscopy-free or low-dose fluoroscopy approach for TSP in ACHD patients undergoing catheter ablation of left-sided tachyarrhythmias who had been previously treated surgically or interventionally due to congenital heart defects. By superimposing 3D electroanatomic mapping with cardiac CT anatomy, this protocol proved to be highly effective, feasible and safe.

PD22-10 HOW SAFE ARE PREGNANT SURGEONS DURING PERCUTANEOUS NEPHROLITHOTOMY?

You have accessJournal of UrologyCME1 Apr 2023PD22-10 HOW SAFE ARE PREGNANT SURGEONS DURING PERCUTANEOUS NEPHROLITHOTOMY? Toby Clark, Kye Park, Nicole Mack, Cliff De Guzman, Matthew Buell, Akin S. Amasyali, Rose Leu, Kanha Shete, Ala'a Farkouh, Elizabeth Baldwin, and D. Duane Baldwin Toby ClarkToby Clark More articles by this author , Kye ParkKye Park More articles by this author , Nicole MackNicole Mack More articles by this author , Cliff De GuzmanCliff De Guzman More articles by this author , Matthew BuellMatthew Buell More articles by this author , Akin S. AmasyaliAkin S. Amasyali More articles by this author , Rose LeuRose Leu More articles by this author , Kanha SheteKanha Shete More articles by this author , Ala'a FarkouhAla'a Farkouh More articles by this author , Elizabeth BaldwinElizabeth Baldwin More articles by this author , and D. Duane BaldwinD. Duane Baldwin More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003295.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: There has been little study of radiation safety among pregnant healthcare workers, but current occupational recommendations limit fetal dose to 1 mSv. No prior study has investigated surgeon uterine radiation dose during percutaneous nephrolithotomy (PCNL). With the increased gender diversity in urology, understanding radiation exposure to the gravid uterus is essential. The purpose of this study was to determine surgeon uterine radiation dose during PCNL and the efficacy of radiation reduction techniques. METHODS: A coronally bisected cadaver, with an 8-week sized uterus, was positioned standing at bedside, similar to a surgeon performing PCNL. An ion chamber was placed behind the anterior wall of the uterus to measure radiation dose, while a second complete cadaver was positioned prone on the operating table, to produce scatter radiation. Three different methods for reducing uterine exposure were studied: pulsed fluoroscopy (1, 4, 8, 15, 30 pps), low dose (LD) fluoroscopy, and surgeon shielding (none, 0.35, 0.50, 0.70 mm lead equivalents). Using a conventional image intensifier C-arm, 20 trials were conducted for each of 40 comparison groups to determine dose/second. For calculations, PCNL exposure time was assumed to be 5 minutes and the case number prior to reaching the 1 mSv limit was determined. Statistical analysis was performed using the Wilcoxon test, and Kruskal Wallis with Dunn’s test. RESULTS: Decreasing pulse frequency from 30 to 1 pps resulted in a 96% dose reduction (p<0.001). Compared to automatic exposure control (AEC), low-dose settings decreased dose by 56% (p<0.001). Using continuous fluoroscopy with AEC and without shielding resulted in 0.086 mSv per PCNL to the uterus. Addition of a standard (0.35 mm) lead vest resulted in a 94% dose reduction (p<0.001). Compared to the 0.35 mm lead, the 0.50 and 0.70 mm lead vests reduced dose by 12% and 47%, respectively. At AEC (30 pps) with no lead and 0.35 mm lead, a surgeon could perform 12 and 189 PCNLs respectively, prior to reaching the 1 mSv limit. Using a 0.70 mm lead vest at LD and 1 pps, a pregnant surgeon could safely perform 11,700 PCNLs. CONCLUSIONS: Pregnant surgeons performing PCNL with conventional fluoroscopy settings and no lead could reach unsafe fetal exposure levels after 12 cases. In contrast, pregnant surgeons using low dose and pulsed fluoroscopy, together with lead shielding can practice in a high volume endourology setting without exceeding occupational dose limits. Surgeons, especially those considering pregnancy, are strongly encouraged to implement dose reduction strategies. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e668 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Toby Clark More articles by this author Kye Park More articles by this author Nicole Mack More articles by this author Cliff De Guzman More articles by this author Matthew Buell More articles by this author Akin S. Amasyali More articles by this author Rose Leu More articles by this author Kanha Shete More articles by this author Ala'a Farkouh More articles by this author Elizabeth Baldwin More articles by this author D. Duane Baldwin More articles by this author Expand All Advertisement PDF downloadLoading ...

V02-06 ULTRA-LOW DOSE FLUOROSCOPY DURING PCNL: HOW LOW CAN YOU GO?

You have accessJournal of UrologyCME1 Apr 2023V02-06 ULTRA-LOW DOSE FLUOROSCOPY DURING PCNL: HOW LOW CAN YOU GO? Vance Gentry, Kanha Shete, Ala'a Farkouh, Alphie Rotinsulu, Matthew Buell, Rose Leu, Akin S. Amasyali, Matthew Wilson, Joel Pearson, and D. Duane Baldwin Vance GentryVance Gentry More articles by this author , Kanha SheteKanha Shete More articles by this author , Ala'a FarkouhAla'a Farkouh More articles by this author , Alphie RotinsuluAlphie Rotinsulu More articles by this author , Matthew BuellMatthew Buell More articles by this author , Rose LeuRose Leu More articles by this author , Akin S. AmasyaliAkin S. Amasyali More articles by this author , Matthew WilsonMatthew Wilson More articles by this author , Joel PearsonJoel Pearson More articles by this author , and D. Duane BaldwinD. Duane Baldwin More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003232.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Patients diagnosed with renal stones may be subjected to substantial doses of ionizing radiation during diagnosis, treatment, and follow-up. Physicians and other healthcare workers are also exposed to radiation during procedures, such as percutaneous nephrolithotomy (PCNL). This puts both patients and surgeons at the risk of developing radiation-related deleterious outcomes, like malignancies. The purpose of this video is to demonstrate tips and tricks that can be used to reduce radiation exposure during PCNL. METHODS: In this video, we demonstrate techniques to reduce radiation exposure to both patients and surgeons, in an 86-year-old female with a 2 cm renal pelvic and 8 mm lower pole stones who underwent PCNL at an academic center. These steps include planning for surgery, equipment set-up and calibration, use of personal protective equipment (PPE), use of multiple modalities to guide access into the renal pelvis, omitting fluoroscopy from various steps of the surgery, and a low dose CT for follow-up imaging. RESULTS: This video demonstrates a successful PCNL with a total fluoroscopy time of 5.6 seconds. Radiation reduction was achieved preoperatively by reviewing CT scans before surgery to plan access. Intraoperatively all of the following were employed: using a sterile ultrasound to map out a safe zone, relying on tactile feedback instead of fluoroscopy for retrograde glidewire placement into renal pelvis, use of endoscopic combined intrarenal surgery (ECIRS) for renal access, tract dilation, and sheath placement, appropriate use of lead shielding, using pulsed low-dose fluoroscopy, and using laser to guide percutaneous access into the renal pelvis. Post-operatively, ultra-low-dose 7.5 mAs CT scan was used to check for residual stones. CONCLUSIONS: This video has demonstrated many radiation-reducing techniques to both patient and surgeon, all of which can be easily incorporated into daily practice. By following these techniques, we effectively lowered radiation exposure to half the dose of a KUB. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e169 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Vance Gentry More articles by this author Kanha Shete More articles by this author Ala'a Farkouh More articles by this author Alphie Rotinsulu More articles by this author Matthew Buell More articles by this author Rose Leu More articles by this author Akin S. Amasyali More articles by this author Matthew Wilson More articles by this author Joel Pearson More articles by this author D. Duane Baldwin More articles by this author Expand All Advertisement PDF downloadLoading ...

Linear relationship between absorbed radiation dose and pulse rate during fluoroscopy.

To identify the relationship between fluoroscopy pulse rate and absorbed radiation dose. We compared absorbed radiation dose with common proxy measurements such as fluoroscopy time and C-arm reported dose. Using a simulated patient model, 60s fluoroscopy exposures were performed using pulse rates of 30, 8, 4, 2, and 1 pulse(s) per second. Each experiment was performed with both standard and low-dose settings using a GE OEC 9800 plus C-arm. Landauer nanoDot™ OSL dosimeters were used to measure the absorbed radiation dose. Fluoroscopy pulse rate and absorbed radiation dose demonstrated a linear correlation for both standard (R2 = 0.995, p < 0.001) and low-dose (R2 = 0.998, p < 0.001) settings. For any given pulse rate, using the low-dose setting reduced absorbed radiation dose by 58 ± 2.8%. Fluoroscopy time demonstrated a linear relationship with absorbed radiation dose for both standard (R2 = 0.996, p < 0.001) and low-dose (R2 = 0.991, p < 0.001) settings, but did not change with use of the low-dose setting. C-arm reported radiation dose correlated linearly with absorbed dose (R2 = 0.999) but consistently under-estimated measured values by an average of 49 ± 3.5%. Using a combination of 1 pulse-per-second and low-dose fluoroscopy, absorbed dose was reduced by 97.7 ± 0.1% compared to standard dose and 30 pulse-per-second settings. Absorbed radiation dose decreases linearly with fluoroscopy pulse rate during equivalent exposure times. Adjusting fluoroscopy pulse rate and utilizing low-dose settings significantly reduces overall absorbed radiation exposure by up to 98%.

Low-dose fluoroscopy technique drastically decreases patient radiation exposure during percutaneous nephrolithotomy.

Fluoroscopy is essential in percutaneous nephrolithotomy (PCNL) but exposes patients and operating room staff to radiation. We investigated whether a low-dose (LD) protocol could reduce radiation exposure during fluoroscopy-guided access without compromising clinical outcomes. Patients undergoing PCNL with fluoroscopy-guided access at a tertiary care stone center between January 2019 and July 2021 were identified. Prior to September 3, 2020, the Philips Veradius C-arm's default settings were used: standard per-frame dose, 15 pulses per second (PPS) frame rate. After this date, a low-dose protocol was used: reduced per-frame dose, reduced frame rate of 8 PPS for needle puncture and 4 PPS for all other steps. Clinical and radiographical data were retrospectively collected. The primary outcome was cumulative radiation dose. Secondary outcomes were stone-free status (SFS; defined as no fragments ≥ 2mm) and complications. Multivariate regression analysis was performed. 100 patients were identified; 31 were in the LD group. The LD cohort was exposed to a significantly lower mean cumulative radiation dose of 11.68mGy compared to 48.88mGy (p < 0.0001). There were no differences in operative time, fluoroscopy time, stone burden, SFS, or complications. In a multivariable regression model adjusting for several variables, LD protocol was associated with lower radiation dose while skin-to-calyx-distance (STCD) was positively associated with cumulative radiation dose. Low-dose fluoroscopy and decreased frame rate during PCNL decreased radiation exposure fourfold without affecting SFS or complication rates.

MEASURES OF VENTILATION DERIVED FROM RADIOGRAPH VELOCIMETRY CORRELATE WITH SPIROMETRY IN PATIENTS WITH COPD

MEASURES OF VENTILATION DERIVED FROM RADIOGRAPH VELOCIMETRY CORRELATE WITH SPIROMETRY IN PATIENTS WITH COPD

A single phantom, a single statistical method for low-contrast detectability assessment.

The assessment of low-contrast-details is a part of the quality control (QC) program in digital radiology. It generally consists of evaluating the threshold contrast (Cth) detectability details for different-sized inserts, appropriately located in dedicated QC test tools. This work aims to propose a simplified method, based on a statistical model approach for threshold contrast estimation, suitable for different modalities in digital radiology. A home-madelow-contrast phantom, made of a central aluminium insert with a step-wedge, was assembled and tested. The reliability and robustness of the method were investigated for Mammography, Digital Radiography, Fluoroscopy and Angiography. Imageswere analysed using our dedicated software developed on Matlab®. TheCth is expressed in the same unit (mmAl) for all studied modalities. This method allows the collection of Cthinformation from different modalities and equipment by different vendors, and it could be used to define typical values. Results are summarized in detail. For 0.5 diameter detail, Cthresults are in the range of: 0.018-0.023mmAl for 2D mammography and 0.26-0.34mmAl DR images. For angiographic images, for 2.5mm diameter detail, the Cths median values are 0.55, 0.4, 0.06, 0.12mmAl for low dose fluoroscopy, coronary fluorography, cerebral and abdominal DSA, respectively. The statistical method proposed in this study gives a simple approach for Low-Contrast-Details assessment, and the typical values proposed can be implemented in a QA program for digital radiology modalities.

Low-Dose Fluoroscopy Protocol for Diagnostic Cerebral Angiography.

PurposeWe applied a low-dose fluoroscopic protocol in routine diagnostic cerebral angiography and evaluated the feasibility of the protocol.Materials and MethodsWe 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.ResultsAge, 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.ConclusionThe low-dose fluoroscopy protocol is feasible to apply for diagnostic cerebral angiography in that this protocol could significantly reduce the fluoroscopic dose.

Radiation Doses to Staff in a Hybrid Operating Room: An Anthropomorphic Phantom Study with Active Electronic Dosimeters

To quantify the effects of different imaging settings on radiation exposure to the operator and surgical team in a hybrid operating room (OR). Measurements to determine scatter radiation in different imaging and geometry settings using an anthropomorphic phantom were performed in a hybrid OR equipped with a robotic C arm interventional angiography system (Artis Zeego; Siemens Healthcare, Erlangen, Germany). The radiation dose (RD) was measured with seven calibrated Philips DoseAware active electronic dosimeters and a Raysafe Xi survey detector, which were placed at different locations in the hybrid OR. The evaluated set ups included low dose, medium dose, and high dose fluoroscopy for abdomen; fluoroscopy fade; roadmap; and digital subtraction angiography (DSA), all using 20s exposures. The effect of magnification, tube angulation, field size, source to skin distance, and RADPAD protection shields were assessed. Finally RD during cone beam computed tomography (CBCT) was obtained. In the operator position the initial settings with low dose fluoroscopy caused a RD of 1.03μGy. The use of fluorofade did not increase the radiation dose (1.02μGy), whereas the roadmap increased it threefold (2.84μGy). The RD with "normal fluoro" was 4.13μGy and increased to 6.44μGy when high dose fluoroscopy mode was used. Magnification or field size varying from 42cm to 11cm led the RD to change from 0.86μGy to 2.10μGy. Decreasing the field of view to 25% of the initial size halved the RD (0.48μGy). The RDs for the left anterior oblique 30° and right anterior oblique 30° were 3.26μGy and 1.63μGy, respectively. DSA increased the cumulative dose 33 fold but the RADPAD shield decreased the DSA RD to 4.92μGy. The RD for CBCT was 47.2μGy. Radiation exposure to operator and personnel can be significantly reduced during hybrid procedures with proper radiation protection and dose optimisation. A set of six behavioural rules were established.

Staff Doses and Patient Skin Doses in Hybrid Operating Room Procedures – An Anthropomorphic Phantom Study with Active Electronic Dosimeters

Introduction - Fluoroscopically guided hybrid procedures have rapidly increased among vascular surgeons. During these interventions, the personnel are at risk of stochastic or deterministic effect of ionizing radiation. Minimizing the absorbed radiation dose is essential to reduce its harmful effects for the patients and personnel. The aim of our study was to quantify the effects of different imaging settings on the staff dose and patient skin dose with the active electronic dosimeters (AED). Methods - Measurements to determine radiation dose in different imaging and geometry settings were performed in a hybrid operation room (OR) equipped with a robotic C-arm interventional angiography system (Artis Zeego, Siemens Healthcare) with an anthropomorphic adult female phantom (ATOM 702-D, CIRS). Scattered radiation doses were measured with nine calibrated Philips DoseAware AEDs and a Raysafe Xi survey detector (Unfors Raysafe) that were placed at different locations in the OR mimicking the positions of surgeons and nurses during the procedure (Figure 1). Furthermore, a Raysafe R/F detector was placed under the phantom in the primary beam to measure the entrance surface air kerma. The evaluated imaging set-ups contained low-dose, medium-dose, and high-dose fluoroscopy for abdomen, low-dose DSA for abdomen, fluorofade, roadmap, and dyna-CT. The effect of magnification was evaluated with five magnification levels, tube angulation with ±30° settings, and field size, and source-to-skin distance with a few set-ups. We also determined the effects of RADPAD radiation protection shields (Worldwide Innovations and Technologies) on staff doses. Radiation was on for 20 seconds in all the imaging set-ups, except for Dyna-CT. The results are expressed as relative doses (RD) compared to the cumulative dose (1.05 μSv) measured with the AED B (“operating surgeon”) in the reference imaging setting with abdomen low-dose fluoroscopy program (4 pps) and C-arm in posterior-anterior position without magnification. Results - The use of fluorofade did not increase the cumulative dose (RD=1.1) whereas the roadmap increased it threefold (RD=3.1). The RD was 4.5 with normal-fluoro 7.5 pps instead of 4 pps and 7.0 when high-dose-fluoro was used 7.5 pps. The RDs for the magnifications 2,3,4 and 5 were 0.9, 1.0, 2.0, and 2.3 respectively. Decreasing the field-of-view to 25% of the reference field-of-view halved the radiation dose (RD=0.52). The RDs for the LAO 30° and RAO 30° were 1.6 and 2.1, respectively. The RADPAD shield decreased the cumulative dose to fifth (RD=0.23). DSA increased the cumulative dose 33-fold but the RADPAD shield decreased the DSA RD to 6.6. The RD for Dyna CT was 79. The patient skin dose in the reference setting was 229 μGy whereas 58-fold with the DSA. The doses in the AED D (“assisting nurse) were unmeasurable due to low dose in most of the set-ups. The AED F gained 4-fold doses compared to the AED E as the protection shields were on the right side of the table. Conclusion - Radiation exposure to personnel, as well as to the patients, can significantly be reduced in the hybrid OR procedures with optimization. For this purpose, the AEDs offer excellent tools.

Real-time algorithm for Poissonian noise reduction in low-dose fluoroscopy: performance evaluation

BackgroundQuantum noise intrinsically limits the quality of fluoroscopic images. The lower is the X-ray dose the higher is the noise. Fluoroscopy video processing can enhance image quality and allows further patient’s dose lowering. This study aims to assess the performances achieved by a Noise Variance Conditioned Average (NVCA) spatio-temporal filter for real-time denoising of fluoroscopic sequences. The filter is specifically designed for quantum noise suppression and edge preservation. It is an average filter that excludes neighborhood pixel values exceeding noise statistic limits, by means of a threshold which depends on the local noise standard deviation, to preserve the image spatial resolution. The performances were evaluated in terms of contrast-to-noise-ratio (CNR) increment, image blurring (full width of the half maximum of the line spread function) and computational time. The NVCA filter performances were compared to those achieved by simple moving average filters and the state-of-the-art video denoising block matching-4D (VBM4D) algorithm. The influence of the NVCA filter size and threshold on the final image quality was evaluated too.ResultsFor NVCA filter mask size of 5 × 5 × 5 pixels (the third dimension represents the temporal extent of the filter) and a threshold level equal to 2 times the local noise standard deviation, the NVCA filter achieved a 10% increase of the CNR with respect to the unfiltered sequence, while the VBM4D achieved a 14% increase. In the case of NVCA, the edge blurring did not depend on the speed of the moving objects; on the other hand, the spatial resolution worsened of about 2.2 times by doubling the objects speed with VBM4D. The NVCA mask size and the local noise-threshold level are critical for final image quality. The computational time of the NVCA filter was found to be just few percentages of that required for the VBM4D filter.ConclusionsThe NVCA filter obtained a better image quality compared to simple moving average filters, and a lower but comparable quality when compared with the VBM4D filter. The NVCA filter showed to preserve edge sharpness, in particular in the case of moving objects (performing even better than VBM4D). The simplicity of the NVCA filter and its low computational burden make this filter suitable for real-time video processing and its hardware implementation is ready to be included in future fluoroscopy devices, offering further lowering of patient’s X-ray dose.

Low Dose Fluoroscopy During Ureteroscopy Does Not Compromise Surgical Outcomes.

Objective: To evaluate whether reducing the dose of fluoroscopy to ¼ of standard dose during unilateral ureteroscopy for ureteral stone treatment would impact in a reduction of total radiation emitted and whether this strategy would impact operation time, stone-free rate, and complication rate. Methods: From August 2016 to August 2017, patients over 18 years submitted to ureteroscopy for ureteral stone between 5 and 20 mm were prospectively randomized for ¼ dose reduction or standard dose fluoroscopy. Patients with abnormal urinary anatomy such as horseshoe kidney, pelvic kidney, or duplex system were excluded from the study. Results: Ninety-four patients were enrolled. The fluoroscopic dose reduction strategy to ¼ of the standard dose was able to significantly reduce the cumulative radiation emitted by C-arm fluoroscopy and the dose area product (3.6 ± 4.5 mGy vs 16.2 ± 19.3 mGy, p = 0.0001 and 0.23 ± 0.52 mcGycm2vs 1.15 ± 2.74 mcGycm2, p = 0.02, respectively). Fluoroscopy time was similar between groups (74.5 ± 84.8 seconds vs 88.3 ± 90 seconds, p = 0.44). There was no need to increase the fluoroscopy dose during any of the procedures. Surgical outcomes were not affected by fluoroscopic dose reduction strategy. Conclusion: Low dose fluoroscopy reduces the emitted radiation during ureteroscopy without compromising surgical outcomes.

Strategies for radiation exposure-sparing in fluoroscopically guided invasive cardiovascular procedures.

Minimizing radiation exposure during x-ray fluoroscopically guided procedures is critical to patients and to medical personnel. Tableside adjustment of x-ray image acquisition parameters can vary the fluoroscopic radiation exposure rate. To determine the impact of adjusting four tableside controllable image acquisition parameters on x-ray fluoroscopic radiation exposure rate. We made fluoroscopic exposures of a standard radiologic phantom to measure radiation exposure rates as kerma•area product per second of exposure and milligray per x-ray pulse under all possible combinations of detector zoom mode, collimated image field size, fluoroscopy dose mode, and fluoroscopy pulse frequency. Kerma•area product per second was linearly proportional to pulse frequency. Selecting larger detector zoom modes, smaller collimated image field sizes and low dose fluoroscopy mode each decreased exposure rate. We found a > 20-fold variation in dose rates over the range of acquisition parameter combinations. Selecting the most appropriate fluoroscopy acquisition parameters enables physician operators to adjust radiation exposure rates over a large range. Judicious selection of acquisition parameters can reduce patient and medical personnel radiation exposure by as much as 95% compared to "standard" fluoroscopy protocol settings.

54. Spatio-temporal generalisation of Model Observer for Low Contrast Detectability assessment of dynamic angiographic images: comparison with an innovative Statistical method and 2AFC experiments

Purpose Evaluate the feasibility of different less time consuming approaches for protocol optimisation in interventional radiology. Methods A Allura FD20 (Philips, The Netherlands) has been employed in this study. Low Dose Fluoroscopy was selected due to its spatial resolution, characterised by a lower enhancement compared to other modalities. Simulated images have been obtained adding a blurred circular insert to a series of acquired homogeneous images. A total of 3 insert dimensions (1.25, 2, 3 mm of diameter), 25 contrast levels and 4 different visualised frame rate (5, 10, 15 and 30 fps) have been selected to characterise low contrast detectability. A series of 2AFC experiments have been performed by two observers. Two different Model Observers has been considered: Non-PreWhitening Eye filter (NPWE) with spatio-temporal contrast sensitivity function and Channelized Hotelling Observer (CHO) with spatio-temporal Gabor filters. Furthermore, Low Contrast Detectability has been evaluated with a statistical method using uniform images. This analysis has been performed on an averaging of frames depending from the visualised fps. In particular, the averaging process was performed on groups of frames that correspond to the noise integration time of human eye-brain system of 200 ms, e.g. 3 frames with 15 fps. Results Analysis with both Model Observers and 2AFC experiments suffered from the general low quality of the protocol considered (Fig. 1). Nevertheless, a good agreement ( Conclusions The agreement with human observer experiments underlines the feasibility of the proposed generalisations. Thus, they could be introduced for a deeper modalities characterisation, in terms of image quality, or for clinical protocol optimization involving cine images.

Applicability and repeatability in angiography systems of statistical method for the low contrast detectability

Purpose The aim of this study is to evaluate the applicability and repeatability of the Low Contrast Detectability (LCD) statistical method in angiography systems [1] , [2] . Methods A phantom consisting of a square aluminum target and a 5-step-wedge (0.2–1 mmAl) was built according to Radice et al. [2] . Different acquisition protocols were used (low, normal and high dose fluoroscopy; abdomen and cerebtal fluorography), and measurements were repeated for several thicknesses of PolyMethylMethAcrylate (PMMA). A Matlab software automatically calculates LCD values in terms of Pixel Value (PV) and contrast threshold (Ct); it also converts PV in mmAl (Fig. 1), providing the LCD(mmAl) [2] . The short- and long-term repeatability were evaluated by repeating acquisitions five times for every session and monthly (for six months) respectively. Results The Coefficients of Variation CV(%) reported in Table 1 are always higher for LCD(mmAl) than for LCD(PV) and LCD(Ct), especially in case of long-term measurements which consequently are not repeatable. This difference is related to unstable conversion from PV to mmAl; indeed, the image noise makes difficult to select the steps of the wedge. To overcome the problem, it would be possible to extend the step-wedge up to 2 mmAl, to introduce the point (0,0) in the conversion curve and to use only the curves with R2 > 0.8. Conclusions The LCD statistical method is easy to implement and provides consistent results for LCD(PV) and LCD(Ct). However, the LCD(mmAl) values seem to be not repeatable because of the instability of PV-mmAl conversion; the suggested solutions can improve the conversion, leading to more robust LCD (mmAl) values.

OPTIMISATION OF PATIENT DOSE AND IMAGE QUALITY IN FLUOROSCOPICALLY GUIDED CERVICAL SPINE SURGERY: A PHANTOM-BASED STUDY.

The purpose of the current study was to provide useful data, which may help neurosurgeons to manage the patient dose and image quality in spinal surgery procedures, utilising a phantom and a test object. The kerma area product, cumulative dose (CD) and entrance surface dose (ESD) rate on the phantom and image intensifier were measured, for selectable fields of view (FOVs), fluoroscopy modes, two geometric magnifications and various phantom thicknesses. The images were subjectively evaluated regarding low-contrast detectability and high-contrast resolution. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), high-contrast spatial resolution (HCSR) and figure of merit (FOM) values were also estimated. The ESD rates increased with increasing phantom thickness, when using electronic or geometric magnification, continuous or high-definition fluoroscopy (HDF). The observers' evaluation showed relatively slight changes in image quality when pulsed fluoroscopy was used. SNR, CNR and HCSR values decreased with increasing phantom thicknesses, while remained almost constant when using pulsed fluoroscopy. SNR and HCSR improved in HDF, while the CNR remained almost constant only for the FOVs 23 and 17 cm. By applying electronic magnification, this resulted in improved HCSR. FOM values decreased in HDF, with increasing phantom thickness and using electronic magnification. For the 'thinnest' patients, CD may overestimate skin dose by 25% than the actual values. Geometric magnification resulted in improved FOM, especially for low-dose fluoroscopy and FOV 23 cm. The knowledge of the increments in dose values, image quality and FOM indices concerning phantom thickness may help neurosurgeons to optimise spinal surgery procedures by selecting the appropriate operational parameters, which could contribute toward the establishment of a radiation protection culture.