Diagnostic reference levels during fluoroscopically guided interventions using mobile C-arms in operating rooms: A national multicentric survey

A French survey on practices of identifying and monitoring patients undergoing interventional radiology procedures

PURPOSE

To take stock of practices in France in terms of the criteria and methods for detecting and monitoring patients at-risk who have undergone interventional procedures.

MATERIALS AND METHODS

A questionnaire was sent to all members of the Imaging-Section at the SFPM. The questions concerned the type and value of alert thresholds reached during interventional procedures requiring the expertise of a medical physicist, thresholds leading to systematic patient follow-up, established follow-up procedures and also organizational questions. Data were collected for 4 interventional specialties, independently.

RESULTS

Twenty French centers participated in the study for one or more interventional specialties. Only 2 centers used different thresholds for different interventional specialties. The dosimetric indicators most often used for alert thresholds were a combination of Dose-Area-Product (DAP) plus Air-Kerma (AK; 35 %) and AK alone (30 %). For DAP, the predominant alert threshold values were 300 Gy.cm2 (23 %) and 500 Gy.cm2 (18 %), and 3 Gy (41 %) and 5 Gy (23 %) for AK. The most commonly-used dosimetric indicator for patient follow-up was peak skin dose (80 %) alone or in combination with another dosimetric indicator. The most common follow-up threshold values were 3 Gy (50 %) and 5 Gy (33 %). Previous examinations in the same anatomical region were taken into account over periods of 2 months (30 %) and 3 months (30 %) and the most common type of follow-up was the patient consultation alone or combined with self-monitoring.

CONCLUSION

This national survey study showed that at-risk patients were monitored in all centers, that there were heterogeneities between centers in the way patients are identified and monitored.

Scoring the Clinical Application of a Novel Scale in a Hybrid Operating Room for Neurosurgery

OBJECTIVE

The lack of clarity regarding the application performance of a hybrid operating room (HOR) and the uncertainty of surgical scheduling often lead to its inefficient application. This study aimed to review the clinical application of our neurosurgical HOR and propose a scale to score cases clearly.

METHODS

We reviewed the operating procedures and duration of stay in 1865 HOR cases. The actual procedures of each case were summarized into 5 application types, and numerical assignment was used to distinguish the dependence of each type on our HOR: surgical procedures combined with interventional procedures (4 points, the highest dependence), surgical procedures combined with imaging procedures (3 points), interventional procedures (2 points), imaging procedures (1 point), and surgical procedures (0 points, the lowest dependence).

RESULTS

A novel scale that could score 1865 cases into those 5 grades was developed. The percentages by grade were as follows: 4 points, 4.24%; 3 points, 4.88%; 2 points, 20.75%; 1 point, 69.38%; and 0 points, 0.75%. The cumulative usage time was 4241.9 h, the duration of which was as follows: 4 points, 16.17%; 3 points, 15.50%; 2 points, 31.32%; 1 point, 35.62%; and 0 points, 1.39%.

CONCLUSIONS

The HOR serves as a multifunctional room to treat neurosurgical diseases. The scale helps to quickly prioritize cases that rely more on HOR, providing guidelines for surgical scheduling. Although our HOR is unsuitable for emergency cases, it clearly shows the application performance of our HOR to provide a reference for promoting its efficient application.

Typical dose values for intra-operative fluoroscopy during orthopaedic trauma surgery at Larnaca general hospital in cyprus: A five-year retrospective study

The purpose of this study was to establish typical dose values at orthopaedic operating rooms of the Larnaca General Hospital (LGH). Kerma area product (KAP), fluoroscopy time (FT) and cumulative air-kerma (Ka,r) measurements were collected for 821 patients who underwent common and reproducible trauma surgery over a five-year period, with three mobile C-arm systems; two equipped with an image-intensifier and one with a flat-panel detector. Dose indices were automatically extracted from radiation dose structured reports or DICOM meta-data files archived in the PACS, using custom-made software. The procedures were categorised based on the anatomical area and included foot/ankle, tibia/fibula, knee (distal femur, tibia plateau), femur/trochanter, hip, hand, radius/ulna, elbow, and humerus. The medians of KAP, FT and Ka,r were defined as typical dose values. Variations in dose values among the C-arm systems or different surgical operations involving femur/hip, tibia/fibula, and humerus were analysed as secondary outcomes. For the procedures on upper extremities, the typical dose values ranged between 20.1-197 mGycm2 for KAP, 4.50-14.5 s for FT and 0.07-0.71 mGy for Ka,r, whilst for the procedures on lower extremities ranged between 46.6-202 mGycm2 for KAP, 4.86-24.0 s for FT and 0.16-0.74 mGy for Ka,r. The largest values were reported for dynamic hip screw (889 mGycm2, 14.3 s, 3.10 mGy), and femur/trochanter intramedullary (long/short nail: 2007/1326 mGycm2, 52.3/36.0 s, 6.53/4.05 mGy) nailing, respectively. A decrease of up to 65 %, and 74 % was found in median KAP, and Ka,r, and an increase of up to 119 % (except knee's) in median FT values for the procedures performed with the flat-panel systems. Additionally, when comparing surgical operations, only femur/trochanter long/short and tibia intramedullary nailing demonstrated a significant increase in median KAP, FT and Ka,r values compared to dynamic hip screw and fixation with a locking plate, respectively. The typical dose values reported could be used as a guide to appropriate levels of intra-operative fluoroscopy in orthopaedic trauma surgery at LGH, and to encourage further optimisation by providing a baseline for audit of local practice in the absence of national reference doses. These values could also contribute to the establishment of the first national DRLs for orthopaedic trauma surgery.

Optimization of radiation doses for open lumbar spinal fusion using C-arm fluoroscopy and impact on radiation-induced cancer: a pilot study

PURPOSE

Intraoperative fluoroscopy use is essential during spinal fusion procedures. The amount of radiation dose should always be minimized. This study aimed to determine the feasibility of halving the frame rate from 12.5 to 6.25 frames per second (fps) and to quantify the reduction in the risk of developing radiation-induced cancer.

METHODS

This pilot study included 34 consecutive patients operated for open lumbar posterolateral fusion (PLF) with or without transforaminal lumbar interbody fusion (TLIF). C-arm modes were changed from half-dose (12.5 frames per second (fps), group I) to quarter-dose (6.25 fps, group II). Age, body mass index, surgical procedure, number of treated levels, and complications were collected. Kerma area product (KAP), cumulative air kerma (CAK), and fluoroscopy time were compared. Effective dose and radiation-induced cancer risk were estimated.

RESULTS

Eighteen and 16 patients were, respectively, included in group I and II. Demographic, surgical data, and fluoroscopy time were similar in both groups. However, CAK, KAP, and effective dose were significantly lower in group II, respectively, 0.56 versus 0.41 mGy (p = 0.03), 0.09 versus 0.06 Gy cm2 (p = 0.04), and 0.03 versus 0.02 mSv (p = 0.04). Radiation-induced cancer risk decreased by 47.7% from 1.49 × 10-6 to 7.77 × 10-7 after optimization. No complications were recorded in either group.

CONCLUSION

This study demonstrates the feasibility of setting 6.25 fps for TLIF with and without PLF. By halving the fps, radiation-induced cancer risk could be almost divided by two, without compromising surgical outcome. Finally, after optimization, the risk of developing radiation-induced cancer was less than one in a million.

Radiation exposure of patients during endourological procedures

PURPOSE

Considering the existing gaps in the literature regarding patient radiation dose (RD) and its associated risks, a systematic review of the literature on RD was conducted, focusing on percutaneous nephrolithotomy (PCNL), extracorporeal shock wave lithotripsy (SWL), and ureteroscopy (URS).

METHODS

Two authors conducted a literature search on PubMed, Web of Science, and Google Scholar to identify studies on RD during endourological procedures. Two thousand two hundred sixty-six articles were screened. Sixty-five publications met the inclusion criteria using the PRISMA standards.

RESULTS

RD was generally highest for PCNL, reaching levels up to 33 mSv, 28,700 mGycm2, and 430.8 mGy. This was followed by SWL, with RD reaching up to 7.32 mSv, 13,082 mGycm2, and 142 mGy. URS demonstrated lower RD, reaching up to 6.07 mSv, 8920 mGycm2, and 46.99 mGy. Surgeon experience and case load were inversely associated with RD. Strategies such as optimizing fluoroscopy settings, implementing ultrasound (US), and following the ALARA (As Low As Reasonably Achievable) principle minimized RD.

CONCLUSIONS

This is the first systematic review analyzing RD, which was generally highest during PCNL, followed by SWL and URS. There is no specific RD limit for these procedures. Implementation of strategies such as optimizing fluoroscopy settings, utilizing US, and adhering to the ALARA principle proved effective in reducing RD. However, further research is needed to explore the factors influencing RD, assess their impact on patient outcomes, and establish procedure-specific reference levels for RD.

Technical note: Workload and transmission data for mobile C-arm fluoroscopy in gastrointestinal endoscopy

BACKGROUND

Mobile C-arms may be used in fixed locations, and it is recommended that qualified experts evaluate structural shielding.

PURPOSE

To assess clinical workload distributions for mobile C-arms used in gastrointestinal endoscopy and determine the Archer equation parameters for the C-arm beam spectra.

METHODS

Consecutive (30 months) gastrointestinal endoscopic procedures on two Cios Alpha systems (Siemens) were retrospectively analyzed. X-ray tube voltage, tube current-time product, reference point air kerma (Ka,r), air kerma-area product (PKA), and fluoroscopic time were examined. The primary beam half-value layer (HVL) was measured with an ionization chamber and aluminum 1100 plates. Stray radiation fraction at 1 m from a scattering source (ACR R/F phantom) was directly measured. Monte Carlo (Geant4) simulation was performed to calculate the transmission of broad X-ray beams through lead, concrete, gypsum, and steel, with X-ray HVLs matching those of the C-arm X-ray beam. The transmission data were fitted to the Archer equation.

RESULTS

The number of procedures (3509) was equivalent to 13.48 procedures per room per week. Dose quantities were 54.8 mGy (Ka,r), 18.3 Gy∙cm2 (PKA), and 7.8 min (fluoroscopic time) per procedure. X-ray beam irradiation events were recorded for 2906 (82.8%) procedures with 160,009 events, whose mA-minute weighted tube voltage was 91.0 kV and the workload was 0.68 mA-minute per procedure. The two rooms had a significant difference in the number of procedures per week, 17.3 (29) [mean (maximum)] and 9.6 (16), respectively. The stray radiation fraction was 9.7×10-4 (80 kV) and 1.25×10-3 (120 kV). Transmission fitting parameters were provided for the tube voltage (on average, 90 kV; high end, 120 kV) of the C-arm.

CONCLUSIONS

This work provides workload and transmission data for mobile C-arm fluoroscopy in gastrointestinal endoscopy, which indicates a need for structural shielding evaluation of the procedure rooms.

Proposing national diagnostic reference levels for electrophysiology studies and catheter ablation procedures in Bulgaria

INTRODUCTION

The implementation of diagnostic reference levels (DRLs) is an essential tool for optimisation of the routine practice, better management of patient exposure while maintaining sufficient image quality. National DRLs for electrophysiology (EP) procedures are not available in our country.

PURPOSE

The main purpose of the study was to propose, for first time in Bulgaria, national DRLs (NDRLs) for EP studies and ablation procedures of two different levels of complexity. The proposed DRLs can be later used to establish NDRLs by the national authority with regulatory functions related to medical exposure.

METHOD

A retrospective study was done with the three highest volume Bulgarian EP centers, where over 95% of all cardiac ablations were performed. Data were extracted from the electronic registry for invasive electrophysiology BG-EPHY. Independently of the proposed NDRLs, we also compared the air kerma-area product (KAP) between the participating centers for procedures of the same level of complexity.

RESULTS

The proposed NDRL in terms of KAP were: 5.2 Gy.cm2 for diagnostic EP studies, 25.5 Gy.cm2 for simple ablations, and 52.1 Gy.cm2 for complex ablations. There was a significant variation in KAP for procedures with the same degree of complexity within each center.

CONCLUSION

This study is the first to propose NDLRs for EP studies and ablation procedures of two levels of complexity in Bulgaria. The results identified EP procedures requiring further optimization of patient protection and provided a basis for future comparisons and standardization with further investigations on the topic. The proposed NDRLs are recommended to be used for better management of radiation exposure during EP procedures of different levels of complexity.

Current status of diagnostic reference levels in interventional cardiology

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

Diagnostic Reference Levels for Fluoroscopy-guided Gastrointestinal Procedures in Japan from the REX-GI Study: A Nationwide Multicentre Prospective Observational Study

BACKGROUND

Diagnostic reference levels (DRLs) are required to optimize medical exposure. However, data on DRLs for interventional fluoroscopic procedures are lacking, especially in gastroenterology. This study aimed to prospectively collect currently used radiation doses and help establish national DRLs for fluoroscopy-guided gastrointestinal procedures in Japan.

METHODS

This multicentre, prospective, observational study collected actual radiation dose data from endoscopic retrograde cholangiopancreatography (ERCP), interventional endoscopic ultrasound (EUS), balloon-assisted enteroscopy (BAE), enteral metallic stent placement, and enteral tube placement from May 2019 to December 2020. The study outcomes were fluoroscopy time (FT: min), air kerma at the patient entrance reference point (Ka,r: mGy), air kerma area product (PKA: Gycm2), and radiation dose rate (RDR: mGy/min). Additionally, the basic settings of fluoroscopy equipment and the factors related to each procedure were investigated. This study was registered in the UMIN Clinical Trial Registry (UMIN 000036525).

FINDINGS

Overall, 12959 fluoroscopy-guided gastrointestinal procedures were included from 23 hospitals in Japan. For 11162 ERCPs, the median/third quartile values of Ka,r (mGy), PKA (Gycm2), and FT (min) were 69/145 mGy, 16/32 Gycm2, and 11/20 min, respectively. Similarly, these values were 106/219 mGy, 23/41 Gycm2 and 17/27 min for 374 interventional EUSs; 53/104 mGy, 16/32 Gycm2 and 10/15 min for 523 metallic stents; 56/104 mGy, 28/47 Gycm2, and 12/18 min for 599 tube placements; and 35/81 mGy, 16/43 Gycm2 and 7/15 min for 301 BAEs, respectively. For the overall radiation dose rate, the median/third quartile values of RDR were 5.9/9.4 (mGy/min). The RDR values at each institution varied widely.

INTERPRETATION

This study reports the current radiation doses of fluoroscopy-guided gastrointestinal procedures expressed as DRL quantities. This will serve as a valuable reference for national DRL values.

FUNDING

This work was supported by a clinical research grant from the Japanese Society of Gastroenterology.