Effect of the learning process on procedure times and radiation exposure for CT fluoroscopy-guided percutaneous biopsy procedures

Reducing Time and Patient Radiation of Computed Tomography-guided Thoracic Needle Biopsies With Single-rotation Axial Acquisitions: An Alternative to "CT Fluoroscopy"

PURPOSE

To investigate the effect on procedure time and patient radiation indices of replacing helical acquisitions for needle guidance during thoracic needle biopsy (TNB) with intermittent single-rotation axial acquisitions.

MATERIALS AND METHODS

This retrospective intervention study included 215 consecutive TNBs performed by a single operator from 2014 to 2018. Characteristics of patients, lesions, and procedures were compared between TNBs guided only by helical acquisitions initiated in the control room (helical group, n=141) and TNBs guided in part by intermittent single-rotation axial computed tomography controlled by foot pedal (single-rotation group, n=74). Procedure time and patient radiation indices were primary outcomes, complications, and radiologist radiation dose were secondary outcomes.

RESULTS

Patient, lesion, and procedural characteristics did not differ between helical and single-rotation groups. Use of single-rotation axial acquisitions decreased procedure time by 10.5 minutes (95% confidence interval [CI]: 8.2-12.8 min) or 27% (95% CI: 22%-32%; P<0.001). Patient dose in cumulative volume computed tomography dose index decreased by 23% (95% CI: 12%-33%) or 8 mGy (95% CI: 4.3-31.6 mGy; P=0.01). Dose-length product decreased by 50% (95% CI: 40%-60%) or 270 mGy cm (95% CI: 195-345 mGy cm; P<0.001). No operator radiation exposure was detected. Rate of diagnostic result, pneumothorax, hemoptysis, and hemorrhage did not differ between groups.

CONCLUSIONS

Replacing helical acquisitions with intermittent single-rotation axial acquisitions significantly decreases TNB procedure time and patient radiation indices without adversely affecting diagnostic rate, procedural complications, or operator radiation dose.

Cutting Staff Radiation Exposure and Improving Freedom of Motion during CT Interventions: Comparison of a Novel Workflow Utilizing a Radiation Protection Cabin versus Two Conventional Workflows

This study aimed to evaluate the radiation exposure to the radiologist and the procedure time of prospectively matched CT interventions implementing three different workflows—the radiologist—(I) leaving the CT room during scanning; (II) wearing a lead apron and staying in the CT room; (III) staying in the CT room in a prototype radiation protection cabin without lead apron while utilizing a wireless remote control and a tablet. We prospectively evaluated the radiologist’s radiation exposure utilizing an electronic personal dosimeter, the intervention time, and success in CT interventions matched to the three different workflows. We compared the interventional success, the patient’s dose of the interventional scans in each workflow (total mAs and total DLP), the radiologist’s personal dose (in µSV), and interventional time. To perform workflow III, a prototype of a radiation protection cabin, with 3 mm lead equivalent walls and a foot switch to operate the doors, was built in the CT examination room. Radiation exposure during the maximum tube output at 120 kV was measured by the local admission officials inside the cabin at the same level as in the technician’s control room (below 0.5 μSv/h and 1 mSv/y). Further, to utilize the full potential of this novel workflow, a sterile packed remote control (to move the CT table and to trigger the radiation) and a sterile packed tablet anchored on the CT table (to plan and navigate during the CT intervention) were operated by the radiologist. There were 18 interventions performed in workflow I, 16 in workflow II, and 27 in workflow III. There were no significant differences in the intervention time (workflow I: 23 min ± 12, workflow II: 20 min ± 8, and workflow III: 21 min ± 10, p = 0.71) and the patient’s dose (total DLP, p = 0.14). However, the personal dosimeter registered 0.17 ± 0.22 µSv for workflow II, while I and III both documented 0 µSv, displaying significant difference (p < 0.001). All workflows were performed completely and successfully in all cases. The new workflow has the potential to reduce interventional CT radiologists’ radiation dose to zero while relieving them from working in a lead apron all day.

First experience of efficacy and radiation exposure in 320-detector row CT fluoroscopy-guided interventions

OBJECTIVE

We investigated the efficacy and exposure to radiation in 320-detector row computed tomography fluoroscopy-guided (CTF-guided) interventions.

METHODS

We analysed 231 320-detector row CTF-guided interventions (207 patients over 2 years and 6 months) in terms of technical success rates, clinical success rates, complications, scanner settings, overall radiation doses (dose-length product, mGy*cm), patient doses of peri-interventional CT series, and interventional CT (including CTF), as a retrospective cohort study. The relationships between patient radiation dose and interventional factors were assessed using multivariate analysis.

RESULTS

Overall technical success rate was 98.7% (228/231). The technical success rates of biopsies, drainages, and aspirations were 98.7% (154/156), 98.5% (66/67), and 100% (8/8), respectively. The clinical success rate of biopsies was 93.5% (146/156). All three major complications occurred in chest biopsies. The median total radiation dose was 522.4 (393.4-819.8) mGy*cm. Of the total radiation dose, 87% was applied during the pre- and post-interventional CT series. Post-interventional CT accounted for 24.4% of the total radiation dose. Only 11.4% of the dose was applied by CTF-guided intervention. Multilinear regression demonstrated that male sex, body mass index, drainage, intervention time, and helical scan as post-interventional CT were significantly associated with higher dose.

CONCLUSION

The 320-detector row CTF interventions achieved a high success rate. Dose reduction in post-interventional CT provides patient dose reduction without decreasing the technical success rates.

ADVANCES IN KNOWLEDGE

This is the first study on the relationship between various interventional outcomes and patient exposure to radiation in 320-detector row CTF-guided interventions, suggesting a new perspective on dose reduction.

Radiology Trainee vs Faculty Radiologist Fluoroscopy Time for Imaging-Guided Procedures: A Retrospective Study of 17,966 Reports Over a 5.5-Year Period

To evaluate differences in fluoroscopy time (FT) for common vascular access and gastrointestinal procedures performed by radiology trainees vs faculty radiologists. Report information was extracted for all 17,966 index fluoroscopy services performed by trainees or faculty, or both from 2 university hospitals over 66 months. Various vascular access procedures (eg, peripherally inserted central catheters [PICCs] and ports) and gastrointestinal fluoroscopy procedures (eg, upper gastrointestinal and contrast enema studies) were specifically targeted. Statistical analysis was performed. FT was recorded in 17,549 of 17,966 reports (98%) The 1393 procedures performed by nonphysician providers or transitional year interns were excluded. Residents, fellows, and faculty were primary operators in 5066, 6489, and 4601 procedures, respectively. Average FT (in seconds) for resident and fellow services, respectively, was less than that of faculty only for PICCs (75 and 101 vs 148, P < 0.01). For all other procedures, average FT of trainee services was greater than that for faculty. This was statistically significant (P < 0.05) for fellows vs faculty port placement (121 vs 87), resident vs faculty small bowel series (130 vs 96), and both resident and fellow vs faculty esophagram procedures (143 and 183 vs 126 ). FT for residents was significantly less than that for fellows only for PICCs (75 vs 101, P < 0.01). For most, but not all, fluoroscopy procedures commonly performed by radiology trainees, FT is greater than that for procedures performed by faculty radiologists. Better awareness and understanding of such differences may aid training programs in developing benchmarks, protocols, and focused teaching in the safe use of fluoroscopy for patients and operators.

A Review of Radiation Protection Requirements and Dose Estimation for Staff and Patients in CT Fluoroscopy

The combination of fluoroscopically guided interventional procedures with computed tomography (CTF) has become widespread around the world. The benefits of CTF include the ability to obtain a real-time visualization of the entire body, increased target accuracy and improved visualization of biopsy needles. Modern CTF units work with variable frame rates for image selection, and therefore the dose distributions for patients and staff can considerably vary, creating growing concern in terms of the occupational exposure of interventionists and the drawback of a higher exposure of the patient. A literature review of the latest CTF publications is summarized in this article. A wide range of CTF studies reveal different treatment methods used in clinical practice, and therefore the differences in the exposures between them; as well as in the radiation protection tools and dose monitoring. Further optimization of radiation protection methods, harmonization of exposure patterns as well as training and education of CTF staff on the basis of the information in the survey, are strongly recommended.

Comparison of CT Fluoroscopy-Guided Manual and CT-Guided Robotic Positioning System for In Vivo Needle Placements in Swine Liver

PURPOSE

To compare CT fluoroscopy-guided manual and CT-guided robotic positioning system (RPS)-assisted needle placement by experienced IR physicians to targets in swine liver.

MATERIALS AND METHODS

Manual and RPS-assisted needle placement was performed by six experienced IR physicians to four 5 mm fiducial seeds placed in swine liver (n = 6). Placement performance was assessed for placement accuracy, procedure time, number of confirmatory scans, needle manipulations, and procedure radiation dose. Intra-modality difference in performance for each physician was assessed using paired t test. Inter-physician performance variation for each modality was analyzed using Kruskal-Wallis test.

RESULTS

Paired comparison of manual and RPS-assisted placements to a target by the same physician indicated accuracy outcomes was not statistically different (manual: 4.53 mm; RPS: 4.66 mm; p = 0.41), but manual placement resulted in higher total radiation dose (manual: 1075.77 mGy/cm; RPS: 636.4 mGy/cm; p = 0.03), required more confirmation scans (manual: 6.6; RPS: 1.6; p < 0.0001) and needle manipulations (manual: 4.6; RPS: 0.4; p < 0.0001). Procedure time for RPS was longer than manual placement (manual: 6.12 min; RPS: 9.7 min; p = 0.0003). Comparison of inter-physician performance during manual placement indicated significant differences in the time taken to complete placements (p = 0.008) and number of repositions (p = 0.04) but not in other study measures (p > 0.05). Comparison of inter-physician performance during RPS-assisted placement suggested statistically significant differences in procedure time (p = 0.02) and not in other study measures (p > 0.05).

CONCLUSIONS

CT-guided RPS-assisted needle placement reduced radiation dose, number of confirmatory scans, and needle manipulations when compared to manual needle placement by experienced IR physicians, with equivalent accuracy.

Radiation exposure in CT-guided interventions

PURPOSE

To investigate radiation exposure in computed tomography (CT)-guided interventions, to establish reference levels for exposure, and to discuss strategies for dose reduction.

MATERIALS AND METHODS

We analyzed 1576 consecutive CT-guided procedures in 1284 patients performed over 4.5 years, including drainage placements; biopsies of different organs; radiofrequency and microwave ablations (RFA/MWA) of liver, bone, and lung tumors; pain blockages, and vertebroplasties. Data were analyzed with respect to scanner settings, overall radiation doses, and individual doses of planning CT series, CT intervention, and control CT series.

RESULTS

Eighty-five percent of the total radiation dose was applied during the pre- and post-interventional CT series, leaving only 15% applied by the CT-guided intervention itself. Single slice acquisition was associated with lower doses than continuous CT-fluoroscopy (37 mGy cm vs. 153 mGy cm, p<0.001). The third quartile of radiation doses varied considerably for different interventions. The highest doses were observed in complex interventions like RFA/MWA of the liver, followed by vertebroplasty and RFA/MWA of the lung.

CONCLUSIONS

This paper suggests preliminary reference levels for various intervention types and discusses strategies for dose reduction. A multicenter registry of radiation exposure including a broader spectrum of scanners and intervention types is needed to develop definitive reference levels.

Low-dose techniques in CT-guided interventions

Computed tomography (CT)-guided interventions such as biopsy, drainage, and ablation may be significant sources of radiation exposure in both patients and radiologists. Simple CT techniques to reduce radiation dose may be employed without increasing the procedure time or significantly degrading image quality. To develop low-dose protocols, it is important to understand the key concepts of delivered radiation dose to patients and physicians during CT-guided interventions. Patient dose estimates are easily followed and are provided at CT workstations. Familiarity with dose estimates, which are expressed as CT dose index and dose-length product, is also important. Methods to reduce radiation exposure in patients and physicians include performing proper preprocedure planning and paying careful attention to technique during the planning stage, making use of personal protective equipment, performing CT fluoroscopy intermittently instead of in real time, and optimizing needle visualization. Representative examples of these techniques have resulted in dose reductions of as much as 89%. Alternative imaging technologies that do not use ionizing radiation, such as virtual and ultrasonographic guidance, may also be used to reduce radiation dose. Understanding dose contribution strategies to reduce radiation dose provides a safer, more efficient environment for patients and the radiology team.

[Vertebroplasty and kyphoplasty under dual guidance (CT and fluoroscopy): radiation dose to radiologist. A comparative study]

OBJECTIVES

The goals of this study is to evaluate and compare the irradiation received by the practitioner when performing percutaneous vertebroplasty or kyphoplasty guided by CT and fluoroscopy, for precise anatomical sites.

METHODS

For each intervention, radiothermoluminescent dosimeters were carefully positioned on both orbitals, both hands, and both ankles of the practitioner.

RESULTS

Twenty-four vertebroplasties were performed in 18 patients and nine kyphoplasties on seven patients. The anatomical site that is most exposed to radiation is the right hand. The two other sites subjected to irradiation are the left hand and the left orbital. This study demonstrates a significant correlation between the irradiation dose and fluoroscopy duration, reflecting both the quantity of primary-beam radiation and backscattered radiation.

CONCLUSION

The radiation dose to radiologist is more important for kyphoplasty procedures than vertebroplasty.

Dual guidance (CT and fluoroscopy) vertebroplasty: radiation dose to radiologists. How much and where?

OBJECTIVE

The goal of this study was to evaluate the radiation received by the practitioner when performing percutaneous vertebroplasty guided by CT and fluoroscopy for specific anatomical sites: orbits, hands, ankles, and thorax (under lead-lined apron).

MATERIALS AND METHODS

Twenty-four vertebroplasties were performed on 18 patients.

RESULTS

The anatomical site that was most exposed to radiation was the right hand (0.37 mSv on average). This study demonstrates a significant correlation between the irradiation dose and fluoroscopy duration, reflecting both the quantity of primary-beam radiation and backscattered radiation. The right hand (P = 0.03), left hand (P = 0.02), and the left orbit (P < 0.0001) are the anatomical zones that are the most affected by the combination of these two types of radiation, with cumulative irradiation doses of 0.45, 0.2, and 0.14 mSv, respectively. There was a significant correlation between the patient weight and radiation of the left hand (P = 0.03), the left orbit (P = 0.03), and the thorax (P = 0.02), confirming the major influence of backscattered radiation.

CONCLUSIONS

The most irradiated anatomical sites limiting the number of interventions are the left orbit and the right hand.

A review of radiology staff doses and dose monitoring requirements

Studies of radiation doses received during X-ray procedures by radiology, cardiology and other clinical staff have been reviewed. Data for effective dose (E), and doses to the eyes, thyroid, hands and legs have been analysed. These data have been supplemented with local measurements to determine the most exposed part of the hand for monitoring purposes. There are ranges of 60-100 in doses to individual tissues reported in the literature for similar procedures at different centres. While ranges in the doses per unit dose-area product (DAP) are between 10 and 25, large variations in dose result from differences in the sensitivity of the X-ray equipment, the type of procedure and the operator technique, but protection factors are important in maintaining dose levels as low as possible. The influence of shielding devices is significant for determining the dose to the eyes and thyroid, and the position of the operator, which depends on the procedure, is the most significant factor determining doses to the hands. A second body dosemeter worn at the level of the collar is recommended for operators with high workloads for use in assessment of effective dose and the dose to the eye. It is proposed that the third quartile values from the distributions of dose per unit DAP identified in the review might be employed in predicting the orders of magnitude of doses to the eye, thyroid and hands, based on interventional operator workloads. Such dose estimates could be employed in risk assessments when reviewing protection and monitoring requirements. A dosemeter worn on the little finger of the hand nearest to the X-ray tube is recommended for monitoring the hand.

[Percutaneous abdominopelvic interventional procedures using real-time CT fluoroscopy guidance at 21 mAs: an analysis of 99 consecutive cases]

PURPOSE

The purpose of our study was to retrospectively evaluate the efficacy, the limitations and the complications of real-time CT fluoroscopy (Carevision) as an adjunct to CT guidance for percutaneous abdominopelvic interventional procedures. Materials and methods. During a 28 month period, 99 patients (55 men, 44 women) with a mean age of 59 years had percutaneous abdominopelvic interventional procedure under CT guidance using CT fluoroscopy. Sixty-four patients had a percutaneous drainage of an abdominopelvic fluid collection with a Seldinger technique using an 8.5- to 14-F drainage catheter and 35 patients had a percutaneous biopsy using an 18-G automatic core biopsy needle.

RESULTS

In all cases, the quality of the real-time CT fluoroscopic images allowed to securely monitor needle advancement towards the target lesion and to confirm correct position of the needle tip. The diameters of target lesions ranged from 1.5 to 10 cm, with a mean value of 4.75 cm. No immediate complications were observed. The real-time CT fluoroscopy times ranged from 25 to 242 sec, with a mean time of 117 sec. All percutaneous procedures (100%) were successfully performed.

CONCLUSION

Our initial clinical experience suggests that real-time CT fluoroscopy allows to perform effective and secure percutaneous abdominopelvic interventional procedures. However, because of substantial radiation exposure, its use has to be limited to specific et selected cases.

Dose reduction during CT fluoroscopy: phantom study of angular beam modulation

PURPOSE

To prospectively evaluate, in a phantom, the dose reductions achievable by using angular beam modulation (ABM) during computed tomographic (CT) fluoroscopy-guided thoracic interventions.

MATERIALS AND METHODS

To enable measurement of organ doses and effective patient dose, a female Alderson-Rando phantom was equipped with thermoluminescent dosimeters (TLDs) in 41 positions, with three TLDs in each position. Additionally, the local dose was assessed in 22 locations above the phantom to estimate the radiation exposure to the radiologist's hand and the patient's skin dose during thoracic interventions. Radiation exposure was performed with a 64-section multidetector CT scanner in the CT fluoroscopy mode, simulating a CT fluoroscopy-guided chest intervention. Effective dose, breast dose, and the dose to the radiologist's hand during the simulated chest intervention were measured with and without ABM. Image noise as an indicator for image quality was compared for both settings. Statistical significance of the measured dose reductions and the image noise was tested by using the paired-samples t test, with P < .05 indicating a significant difference.

RESULTS

ABM significantly reduced the effective patient dose by 35%, the skin dose by 75%, the breast dose by 47% (P < .001 for all), and the physician's hand dose by between 27% (scattered radiation, P = .007) and 72% (direct radiation, P < .001). No significant difference was found in a comparison of the image noise with and that without ABM.

CONCLUSION

ABM leads to significant dose reductions for both patients and personnel during CT fluoroscopy-guided thoracic interventions, without impairing image quality.

Effects of radiologists' skill and experience on patient doses in interventional examinations

In this study, effects of radiologists' skill and experience on patient doses were investigated. Dose-area product and entrance surface doses of two groups of patients, one examined by a number of junior radiologists and another one by a senior radiologist, have been compared for the diagnostic interventional examinations of cerebral and lower limbs. Collimation of the X-ray beam and shortening the fluoroscopy times by the senior radiologist considerably reduced the patient doses for interventional cerebral examinations.

CT fluoroscopy: novel application for the treatment of ventricular pathologies

INTRODUCTION

Recent advances in multidetector CT imaging (MDCT) provide real-time "fluoroscopic-like" capabilities with excellent spatial resolution. MDCT fluoroscopy expands our ability to perform image-guided interventions in anatomically complex locations. Although MDCT fluoroscopy is currently used at our institution for a variety of procedures ranging from spinal nerve blocks to RFA ablation, we believe these same techniques can be used to navigate within the ventricles of the central nervous system to treat conditions requiring placement of intraventricular catheters, depth electrodes, or potentially stents for the relief of CSF outlet obstruction.

METHODS

Using three fresh, unfrozen human cadavers, we studied the feasibility of using MDCT fluoroscopy for intraventricular catheter placement and to stent the aqueduct of Sylvius.

RESULTS

The ventricles were entered via a single needle pass and catheters were placed over the wire. Contrast agent was then injected to visualize the distribution. To stent the aqueduct of Sylvius, a wire was passed into the 4th ventricle and a coronary stent was then inserted over the wire and deployed.

CONCLUSION

Based on our success with these procedures, we believe this technique can be used to limit complications and improve efficacy of a number of neurosurgical procedures.

Minimal access thoracic surgery in the pediatric population

Thoracoscopy was initially described for use in children to obtain pulmonary biopsy samples in the immunocompromised patient. With refinements in technique, development of better instrumentation, and advances in pediatric anesthesia, there are now many diagnostic and therapeutic indications for the use of thoracoscopy in children. One of the most common indications includes pleural debridement for empyema. Many centers consider this the optimal approach for biopsy of mediastinal lesions and excision of bronchogenic or duplication cysts. The technique is useful for pleural disorders, such as spontaneous pneumothorax and chylothorax. Thoracoscopy has been used to achieve exposure for spinal diskectomy in children with thoracic scoliosis, and newer techniques are being developed in performing anatomic lobectomies, repair of esophageal atesias, and closure of diaphragmatic hernias. The role of the robot in pediatric thoracoscopy is still in the early stages of definition.

Radiation dose to the radiologist's hand during continuous CT fluoroscopy-guided interventions

Computed tomography fluoroscopy (CT fluoroscopy) enables real-time image control over the entire body with high geometric accuracy and, for the most part, without significant interfering artifacts, resulting in increased target accuracy, reduced intervention times, and improved biopsy specimens [1--4]. Depending on the procedure being used, higher radiation doses than in conventional CT-supported interventions might occur. Because the radiologist is present in the CT room during the intervention, he is exposed to additional radiation, which is an important aspect. Initial experience with CT fluoroscopically guided interventions is from the work of Katada et al. in 1994 [5] and only relatively few reports on radiation aspects in CT fluoroscopy are found in the literature [1, 2, 6--11]. To date, there are no reported injuries to patients and radiologists occurring with CT fluoroscopy. The time interval since the wide use of CT fluoroscopy is too short to have data on late effects to the operator using CT fluoroscopy on a daily basis. In addition, the spectrum of CT fluoroscopically guided interventional procedures will expand and more sophisticated procedures requiring longer fluoroscopy times will be performed. Thus, effective exposure reduction is very important. The purpose of our study was to assess the radiation dose to the operator's hand by using data from phantom measurements. In addition, we investigated the effect of a lead drape on the phantom surface adjacent to the scanning plane, the use of thin radiation protective gloves, and the use of different needle holders.

Accuracy and complications in computed tomography fluoroscopy-guided needle biopsies of lung masses

The aim of this study was to determine the diagnostic accuracy and frequency of complications of lung biopsy procedures with or without CTF guidance of needle insertion. Records and images of 99 consecutive percutaneous coaxial cutting needle lung biopsy procedures performed on 85 patients were reviewed retrospectively. Fifty-seven and 42 procedures had been done with and without CTF guidance, respectively. Histological results were compared to diagnosis after surgery or after a follow-up period of 12 months. Diagnostic accuracy and the occurrence of pneumothorax and/or bleeding related to the procedures were registered. The level of accuracy of the diagnosis was comparable. The diagnostic accuracy was 96% (50/52) and 95% (34/36) sensitivity 95% (35/37) and 93% (26/28), specificity 100% (15/15) and 100% (8/8) with CTF and conventional CT techniques, respectively. There were fewer post procedure pneumothoraces using the CTF than conventional technique [26% (15/57) vs. 38% (16/42)], but the difference was not statistically significant (P = 0.274). The insertion of a chest tube was required in only one (2%) procedure using the CTF technique, while this was needed in four (10%) using the conventional technique. Small or large hemorrhages occurred in 23% of the procedures, with no apparent difference between the two groups. In conclusion, CTF-guided biopsy of lung lesions provides high diagnostic accuracy, comparable to that of conventional CT-guided procedures, with a low rate of complications, even for small tumors.

Treatment of small hepatocellular carcinoma with acetic acid percutaneous injection

Percutaneous ablation using acetic acid is an attractive method because of its low morbidity and low number of sessions required to induce complete tumor necrosis. Moreover, the real-time fluoroscopy CT scan could improve the technique by improving distribution of the necrotizing agent within the tumor.

AIM

To determine the feasibility and the long-term results of the acetic acid percutaneous injection under CT fluoroscopy guidance in a series of cirrhotic patients with small hepatocellular carcinoma in a single French center.

METHODS

One hundred and two patients with hepatocellular carcinoma were evaluated for treatment between 1999 and 2000. The selection criteria for fluoroscopy CT scan-directed percutaneous acetic acid ablation were: 1) one to three nodules<5 centimeters; 2) Child-Pugh class<13; 3) prothrombin index > 40% and platelet count > 50000 per mm(3) and 4) contraindication to both resection and liver transplantation. Post treatment follow-up included ultrasonography, magnetic resonance and alphafetoprotein levels every 3 months. Recurrence and survival rates were estimated using the Kaplan-Meier method.

RESULTS

Forty-nine patients (48%) could benefit from a curative treatment, most of them (37/49) being eligible for fluoroscopy CT scan-directed percutaneous acetic acid. The mean follow up was 24.4 +/- 2.7 months. Complete tumor necrosis was achieved in 28 patients (76%) after a mean of 1.6 sessions. In these 28 patients, the recurrence rates were 34% and 48% and survival rates were 76% and 70%, at 24 and 36 months, respectively. No serious complications occurred during or after the treatment.

CONCLUSIONS

Percutaneous ablation using acetic acid using CT fluoroscopy guidance may be considered as a short term efficient, low risk treatment and can be applied even in patients with ascites or severe hemostatic abnormalities. However, the high rate of recurrence and the early occurrence of multifocal hepatocellular carcinoma underline the limits of this method as well as of all other percutaneous strategies.

Learning curve of a new hospital laboratory. The monitoring of computer-generated turnaround time of laboratory tests in an emergency department

Learning curves have been described for different health technologies, mainly new surgical or diagnostic procedures, but learning curves for a new hospital's laboratory procedures have not been systematically studied. To monitor the timeliness (turnaround time) of stat tests from the Emergency Department as a marker of laboratory quality and to address the issue of a learning curve for procedures performed in a new hospital laboratory, we employed a computerized system for collecting data of turnaround time (from order entry to result verification) on stat tests from the Emergency Department of a newly opened (July 24, 2000) 471-bed general hospital. The data collection operates without user intervention. We evaluated the turnaround times of stat complete blood count and biochemistry tests from August 2000 to December 2001. Results show that it took 6 to 12 months before the turnaround times reached a plateau, we believe that this is the learning curve of a new hospital laboratory. Computer-generated turnaround times for Emergency Department stat tests appear to be a useful tool for monitoring the quality of laboratory tests and can demonstrate the learning curve of a new hospital laboratory.

CT arthrography of the glenohumeral joint: CT fluoroscopy versus conventional CT and fluoroscopy--comparison of image-guidance techniques

PURPOSE

To compare examination time with radiologist time and to measure radiation dose of computed tomographic (CT) fluoroscopy, conventional CT, and conventional fluoroscopy as guiding modalities for shoulder CT arthrography.

MATERIALS AND METHODS

Glenohumeral injection of contrast material for CT arthrography was performed in 64 consecutive patients (mean age, 32 years; age range, 16-74 years) and was guided with CT fluoroscopy (n = 28), conventional CT (n = 14), or conventional fluoroscopy (n = 22). Room times (arthrography, room change, CT, and total examination times) and radiologist times (time the radiologist spent in the fluoroscopy or CT room) were measured. One-way analysis of variance and Bonferroni-Dunn posthoc tests were performed for comparison of mean times. Mean effective radiation dose was calculated for each method with examination data, phantom measurements, and standard software.

RESULTS

Mean total examination time was 28.0 minutes for CT fluoroscopy, 28.6 minutes for conventional CT, and 29.4 minutes for conventional fluoroscopy; mean radiologist time was 9.9 minutes, 10.5 minutes, and 9.0 minutes, respectively. These differences were not statistically significant. Mean effective radiation dose was 0.0015 mSv for conventional fluoroscopy (mean, nine sections), 0.22 mSv for CT fluoroscopy (120 kV; 50 mA; mean, 15 sections), and 0.96 mSv for conventional CT (140 kV; 240 mA; mean, six sections). Effective radiation dose can be reduced to 0.18 mSv for conventional CT by changing imaging parameters to 120 kV and 100 mA. Mean effective radiation dose of the diagnostic CT arthrographic examination (140 kV; 240 mA; mean, 25 sections) was 2.4 mSv.

CONCLUSION

CT fluoroscopy and conventional CT are valuable alternative modalities for glenohumeral CT arthrography, as examination and radiologist times are not significantly different. CT guidance requires a greater radiation dose than does conventional fluoroscopy, but with adequate parameters CT guidance constitutes approximately 8% of the radiation dose.

Evaluation of patient and staff doses during various CT fluoroscopy guided interventions

As CT scanners are more routinely used as a guidance tool for various types of interventional radiological procedures, concern has grown for high patient and staff doses. CT fluoroscopy provides the physician immediate feedback and can be a valuable tool to dynamically assist various types of percutaneous interventions. However, the fixed position of the scanning plane in combination with high exposure factors may lead to high cumulative patient skin doses that can reach deterministic threshold limits. The staff is also exposed to a considerable amount of scatter radiation while standing next to the patient during the procedures. Although some studies have been published dealing with this subject, data of patient skin doses determined by direct in vivo dosimetry remains scarce. The purpose of this study is to quantify and to evaluate both patient and staff doses by direct thermoluminescent dosimetry during various clinical CT fluoroscopy guided procedures. Patient doses were quantified by determining the entrance skin dose with direct thermoluminescent dosimetry and by estimating the effective dose (E). Staff doses were quantified by determining the entrance skin dose at the level of the eyes, thyroid, and both the hands with direct thermoluminescent dosimetry. For a group of 82 consecutive patients, the following median values were determined (data per procedure): patient E (19.7 mSv), patient entrance skin dose (374 mSv), staff entrance skin dose at eye level (0.21 mSv), thyroid (0.24 mSv), at the left hand (0.18 mSv), and at the right hand (0.76 mSv). The maximum recorded patient entrance skin dose stayed well below the deterministic threshold level of 2 Gy. Poor correlation between both patient/staff doses and integrated procedure mAs emphasizes the need for in vivo measurements. CT fluoroscopy doses are markedly higher than classic CT-scan doses and are comparable to doses from other interventional radiological procedures. They consequently require adequate radiation protection management. An important potential for dose reduction exists by limiting the fluoroscopic screening time and by reducing the tube current (mA) to a level sufficient to provide adequate image quality.

Radiation doses in interventional radiology procedures: the RAD-IR study: part I: overall measures of dose

PURPOSE

To determine patient radiation doses for interventional radiology and neuroradiology procedures, to identify procedures associated with higher radiation doses, and to determine the effects of various parameters on patient doses.

MATERIALS AND METHODS

A prospective observational study was performed at seven academic medical centers. Each site contributed demographic and radiation dose data for subjects undergoing specific procedures in fluoroscopic suites equipped with built-in cumulative dose (CD) and dose-area-product (DAP) measurement capability compliant with International Electrotechnical Commission standard 60601-2-43. The accuracy of the dosimetry was confirmed by comprehensive measurements and by frequent consistency checks performed over the course of the study.

RESULTS

Data were collected on 2,142 instances of interventional radiology procedures, 48 comprehensive physics evaluations, and 581 periodic consistency checks from the 12 fluoroscopic units in the study. There were wide variations in dose and statistically significant differences in fluoroscopy time, number of images, DAP, and CD for different instances of the same procedure, depending on the nature of the lesion, its anatomic location, and the complexity of the procedure. For the 2,142 instances, observed CD and DAP correlate well overall (r = 0.83, P <.000001), but correlation in individual instances is poor. The same is true for the correlation between fluoroscopy time and CD (r = 0.79, P <.000001). The correlation between fluoroscopy time and DAP (r = 0.60, P <.000001) is not as good. In 6% of instances (128 of 2,142), which were principally embolization procedures, transjugular intrahepatic portosystemic shunt (TIPS) procedures, and renal/visceral artery stent placements, CD was greater than 5 Gy.

CONCLUSIONS

Most procedures studied can result in clinically significant radiation dose to the patient, even when performed by trained operators with use of dose-reducing technology and modern fluoroscopic equipment. Embolization procedures, TIPS creation, and renal/visceral artery stent placement are associated with a substantial likelihood of clinically significant patient dose. At minimum, patient dose data should be recorded in the medical record for these three types of procedures. These data should include indicators of the risk of deterministic effects as well as the risk of stochastic effects.

Image-guided percutaneous approach is superior to the thoracoscopic approach in the diagnosis of pulmonary nodules in children

BACKGROUND/PURPOSE

Image-guided, percutaneous techniques are increasingly used in diagnosis of pulmonary disease in children. The aim of this study was to determine the diagnostic accuracy and clinical outcomes of thoracoscopic versus percutaneous lung biopsy in children.

METHODS

Sixty-three consecutive patients from January 1996 to December 2000 who had a thoracoscopic lung biopsy, a percutaneous ultrasound scan, or computed tomography (CT)-guided lung biopsy for well-defined and ill-defined lesions were analyzed.

RESULTS

Twenty-eight patients had a thoracoscopic lung biopsy (TLB), and 35 patients had a percutaneous image-guided lung biopsy (PLB). Age ranged from 6 months to 17 years (median, 8 years). There was no significant difference between groups with regard to age, depth of lung nodule biopsied, or prebiopsy diagnoses. Seventeen patients (60%) of TLB and 23 (65%) of PLB had well-defined pulmonary nodules suspicious for malignancy at the time of biopsy. Adequate tissue for pathologic diagnosis was obtained in 28 (100%) of TLB versus 26 (80%) of PLB patients. However, 8 (28%) thoracoscopic cases needed to be converted to an open procedure. In 3 (8.5%) PLB cases the percutaneous biopsy was insufficient, and a thoracoscopic or open biopsy was required. The median hospital stay was 3 days for TLB and 4 to 6 hours for PLB (P =.023). There were no complications in the PLB group. Five (18%) of TLB patients suffered a persistent air leak treated with continued chest tube drainage, and one patient died of other causes with a persistent air leak.

CONCLUSIONS

Percutaneous lung biopsy has a significantly shorter hospital stay and a lower complication rate than thoracoscopic lung biopsy. The authors propose that the percutaneous technique should be considered as the initial approach for children with pulmonary nodules.

Robotically driven interventions: a method of using CT fluoroscopy without radiation exposure to the physician

Radiation exposure to physicians' hands during interventional procedures with computed tomography (CT) fluoroscopic guidance may be high. A robot was developed that could hold, orient, and advance a needle, with CT fluoroscopic guidance. This robot could be either computer or joystick controlled. Twenty-three robotically guided percutaneous interventions were performed without complication. Physician radiation exposure was negligible during the CT fluoroscopy-guided procedures.

CT fluoroscopy-guided intervention: marked reduction of scattered radiation dose to the physician's hand by use of a lead plate and an improved I-I device

PURPOSE

To estimate the effects of a lead plate, three types of needle holders, tube current, and slice thickness on decreasing the radiation dose to the physician's hand during interventional procedures with computed tomographic (CT) fluoroscopic guidance. The needle holders (I-I devices), which were developed by the authors, maintained the distance between the physician's hand and the CT plane at 7 cm, 10 cm, and 15 cm, respectively.

MATERIALS AND METHODS

The dose rate (mSv/tube current/CT fluoroscopy time) was measured in 55 cases, which were divided into six groups. In group A (n = 14), the current was 135 kV, there was a 5-mm slice thickness, and a 7-cm I-I device was used without the lead plate. Group B (n = 11) entailed a 120-kV current, a 5-mm slice thickness, and a 7-cm I-I device without the lead plate. Group C (n = 8) entailed a 120-kV current, 5-mm slice thickness, and 7-cm I-I device with the lead plate. Group D (n = 9) entailed a 120-kV current, 5-mm slice thickness, and 10-cm I-I device with the lead plate. Group E (n = 7) entailed a 120-kV current, 5-mm slice thickness, and 15-cm I-I device with the lead plate. Group F (n = 6) entailed a 120-kV current, 1-mm slice thickness and 10-cm I-I device with the lead plate. To compare the effects of tube voltage, lead plate use, slice collimation, and I-I devices, differences were compared between groups A and B, B and C, D and F, and among groups C, D, and E.

RESULTS

The dose rates of groups A, B, C, D, E, and F were 126.3, 75.2, 17.8, 13.9, 2.8, and 4.1 mSv/mA/sec x 100,000, respectively. There were significant differences in dose rates between groups A and B (t-test, P =.037), B and C (Student t-test, P =.002), D and F (Mann-Whitney test, P =.011), and among groups C, D, and E (Kruskal-Wallis test, P =.016).

CONCLUSION

The lead plate, the improved I-I devices, use of a 120 kV (vs 135 kV) current, and 1-mm (vs 5 mm) collimation were all useful in decreasing the dose rate.