Operator Shielding: How and Why

An investigation of the radiation doses to the lower legs and feet of staff undertaking interventional procedures

OBJECTIVE

Occupational radiation doses from fluoroscopic procedures are some of the highest doses of exposure amongst medical staff using radiography. Protective equipment and dose monitoring are used to minimize and control the risk from these occupational doses. Other studies have considered the effectiveness of this protection, but this study further considers whether protection is adequate for the lower leg and foot and the extent to which these doses can be reduced.

METHODS

Scatter air kerma profiles at toe level were measured with an ionization chamber. Thermoluminescent dosemeters and lower extremity phantoms were used to estimate the dose variation with the height of patient couch. A 7-week period of in situ toe dose monitoring of four radiologists was also undertaken.

RESULTS

The use of protective curtains effectively reduced the exposure to most of the lower extremities. Toe doses were found to be high and increased with increase in couch height. In situ monitoring indicated annual toe doses of 110 mSv for two of the four radiologists monitored.

CONCLUSION

Protective curtains should be used, but they might have limitations with respect to toe doses. Annual toe doses approaching the classification threshold of 150 mSv were measured for two radiologists. Caution should be exercised when there is a gap below curtains and, when possible, staff should step back from the couch. Lower legs and toes should be included in local radiation protection programmes.

ADVANCES IN KNOWLEDGE

Toe doses in interventional radiology may be higher than expected and may have to be included in radiation protection programmes.

How Effective Are Radiation Reducing Gloves in C-arm Fluoroscopy-guided Pain Interventions?

Background

The physician's hands are close to the X-ray field in C-arm fluoroscopy-guided pain interventions. We prospectively investigated the radiation attenuation of Proguard RR-2 gloves.

Methods

In 100 cases, the effective doses (EDs) of two dosimeters without a radiation-reducing glove were collected. EDs from the two dosimeters-one dosimeter wrapped with a glove and the other dosimeter without a glove- were also measured at the side of the table (Group 1, 140 cases) and at a location 20 cm away from the side of the table (Group 2, 120 cases). Mean differences such as age, height, weight, radiation absorbed dose (RAD), exposure time, ED, and ratio of EDs were analyzed.

Results

In the EDs of two dosimeters without gloves, there were no significant differences (39.0 ± 36.3 µSv vs. 38.8 ± 36.4 µSv) (P = 0.578). The RAD (192.0 ± 182.0 radcm²) in Group 2 was higher than that (132.3 ± 103.5 radcm²) in Group 1 (P = 0.002). The ED (33.3 ± 30.9 µSv) of the dosimeter without a glove in Group 1 was higher than that (12.3 ± 8.8 µSv) in Group 2 (P < 0.001). The ED (24.4 ± 22.4 µSv) of the dosimeter wrapped with a glove in Group 1 was higher than that (9.2 ± 6.8 µSv) in Group 2 (P < 0.001). No significant differences were noted in the ratio of EDs (73.5 ± 6.7% vs. 74.2 ± 9.3%, P = 0.469) between Group 1 and Group 2.

Conclusions

Proguard RR-2 gloves have a radiation attenuation effect of 25.8-26.5%. The radiation attenuation is not significantly different by intensity of scatter radiation or the different RADs of C-arm fluoroscopy.

The Radiation Exposure of Radiographer Related to the Location in C-arm Fluoroscopy-guided Pain Interventions

Background

Although a physician may be the nearest to the radiation source during C-arm fluoroscope-guided interventions, the radiographer is also near the fluoroscope. We prospectively investigated the radiation exposure of radiographers relative to their location.

Methods

The effective dose (ED) was measured with a digital dosimeter on the radiographers' left chest and the side of the table. We observed the location of the radiographers in each procedure related to the mobile support structure of the fluoroscope (Groups A, M and P). Data about age, height, weight, sex, exposure time, radiation absorbed dose (RAD), and the ED at the radiographer's chest and the side of the table was collected.

Results

There were 51 cases for Group A, 116 cases for Group M and 144 cases for Group P. No significant differences were noted in the demographic data such as age, height, weight, and male to female ratio, and exposure time, RAD and ED at the side of the table. Group P had the lowest ED (0.5 ± 0.8 µSv) of all the groups (Group A, 1.6 ± 2.3 µSv; Group M, 1.3 ± 1.9 µSv; P < 0.001). The ED ratio (ED on the radiographer's chest/ED at the side of the table) of Group A was the highest, and the ED radio of Group P was the lowest of all the groups (Group A, 12.2 ± 21.5%; Group M, 5.7 ± 6.5%; Group P, 2.5 ± 6.7%; P < 0.001).

Conclusions

Radiographers can easily reduce their radiation exposure by changing their position. Two steps behind the mobile support structure can effectively decrease the exposure of radiographers by about 80%.

Extremity and eye lens dosimetry for medical staff performing vertebroplasty and kyphoplasty procedures

Measurements of doses to hands, legs and eyes are reported for operators in four different hospitals performing vertebroplasty or kyphoplasty. The results confirm that occupational doses can be high for interventional spine procedures. Extremity and eye lens doses were measured with thermoluminescent dosimeters positioned on the ring fingers, wrists, legs and near the eyes of interventional radiologists and neurosurgeons, over a period of 15 months. Doses were generally larger on the left side for all positions monitored. The median dose to the left finger was 225 μSv per procedure, although a maximum of 7.3 mSv was found. The median dose to the right finger was 118 μSv, but with an even higher maximum of 7.7 mSv. A median left eye dose of 34 μSv (maximum 836 μSv) was found, while the legs received the lowest doses with a median of 13 μSv (maximum 332 μSv) to the left leg. Annual dose to the hand assessed by the cumulated doses almost reached the annual dose limit of 500 mSv, while annual dose to the eyes exceeded the eye lens dose limit of 20 mSv yr(-1). Different x-ray systems and radiation protection measures were tested, like the use of lead gloves and glasses, tweezers, cement delivery systems and a magnetic navigation system. These measurements showed that doses can be significantly reduced. The use of lead glasses is strongly recommended for protection of the eyes.

Cone beam CT guidance provides superior accuracy for complex needle paths compared with CT guidance

OBJECTIVE

To determine the accuracy of cone beam CT (CBCT) guidance and CT guidance in reaching small targets in relation to needle path complexity in a phantom.

METHODS

CBCT guidance combines three-dimensional CBCT imaging with fluoroscopy overlay and needle planning software to provide real-time needle guidance. The accuracy of needle positioning, quantified as deviation from a target, was assessed for inplane, angulated and double angulated needle paths. Four interventional radiologists reached four targets along the three paths using CBCT and CT guidance. Accuracies were compared between CBCT and CT for each needle path and between the three approaches within both modalities. The effect of user experience in CBCT guidance was also assessed.

RESULTS

Accuracies for CBCT were significantly better than CT for the double angulated needle path (2.2 vs 6.7 mm, p<0.001) for all radiologists. CBCT guidance showed no significant differences between the three approaches. For CT, deviations increased with increasing needle path complexity from 3.3 mm for the inplane placements to 4.4 mm (p=0.007) and 6.7 mm (p<0.001) for the angulated and double angulated CT-guided needle placements, respectively. For double angulated needle paths, experienced CBCT users showed consistently higher accuracies than trained users [1.8 mm (range 1.2-2.2) vs 3.3 mm (range 2.1-7.2) deviation from target, respectively; p=0.003].

CONCLUSION

In terms of accuracy, CBCT is the preferred modality, irrespective of the level of user experience, for more difficult guidance procedures requiring double angulated needle paths as in oncological interventions.

ADVANCES IN KNOWLEDGE

Accuracy of CBCT guidance has not been discussed before. CBCT guidance allows accurate needle placement irrespective of needle path complexity. For angulated and double-angulated needle paths, CBCT is more accurate than CT guidance.

The Survey about the Degree of Damage of Radiation-Protective Shields in Operation Room

Background

Medical doctors who perform C-arm fluoroscopy-guided procedures are exposed to X-ray radiation. Therefore, radiation-protective shields are recommended to protect these doctors from radiation. For the past several years, these protective shields have sometimes been used without regular inspection. The aim of this study was to investigate the degree of damage to radiation-protective shields in the operating room.

Methods

This study investigated 98 radiation-protective shields in the operation rooms of Konkuk University Medical Center and Jeju National University Hospital. We examined whether these shields were damaged or not with the unaided eye and by fluoroscopy.

Results

There were seventy-one aprons and twenty-seven thyroid protectors in the two university hospitals. Fourteen aprons (19.7%) were damaged, whereas no thyroid protectors (0%) were. Of the twenty-six aprons, which have been used since 2005, eleven (42.3%) were damaged. Of the ten aprons, which have been used since 2008, none (0%) was damaged. Of the twenty-three aprons that have been used since 2009, two (8.7%) of them were damaged. Of the eight aprons used since 2010, one (12.3%) was damaged. Of the four aprons used since 2011, none (0%) of them were damaged. The most common site of damage to the radiation-protective shields was at the waist of the aprons (51%).

Conclusions

As a result, aprons that have been used for a long period of time can have a higher risk of damage. Radiation-protective shields should be inspected regularly and exchanged for new products for the safety of medical workers.

ICRP Publication 117. Radiological protection in fluoroscopically guided procedures performed outside the imaging department

An increasing number of medical specialists are using fluoroscopy outside imaging departments, but there has been general neglect of radiological protection coverage of fluoroscopy machines used outside imaging departments. Lack of radiological protection training of those working with fluoroscopy outside imaging departments can increase the radiation risk to workers and patients. Procedures such as endovascular aneurysm repair, renal angioplasty, iliac angioplasty, ureteric stent placement, therapeutic endoscopic retrograde cholangio-pancreatography,and bile duct stenting and drainage have the potential to impart skin doses exceeding Gy. Although tissue reactions among patients and workers from fluoroscopy procedures have, to date, only been reported in interventional radiology and cardiology,the level of fluoroscopy use outside imaging departments creates potential for such injuries.A brief account of the health effects of ionising radiation and protection principles is presented in Section 2. Section 3 deals with general aspects of the protection of workers and patients that are common to all, whereas specific aspects are covered in Section 4 for vascular surgery, urology, orthopaedic surgery, obstetrics and gynaecology,gastroenterology and hepatobiliary system, and anaesthetics and pain management.Although sentinel lymph node biopsy involves the use of radio-isotopic methods rather than fluoroscopy, performance of this procedure in operating theatres is covered in this report as it is unlikely that this topic will be addressed in another ICRP publication in coming years. Information on radiation dose levels to patients and workers, and dose management is presented for each speciality.

Step back from the patient: reduction of radiation dose to the operator by the systematic use of an automatic power injector for contrast media in an interventional angiography suite

BACKGROUND

During arterial interventional procedures, power injectors allow the operator to step back from the patient or exit the angiography suite during digital subtraction angiography (DSA) acquisitions. Increasing the distance to the radiation source reduces exposure to the operator and staff.

PURPOSE

To systematically investigate the effect of increasing the distance between the radiation source and the operator during DSA acquisitions in a daily clinical setting, regarding radiation exposure to the operator and patient, as well as the duration of the procedure using a power injector to deliver contrast media.

MATERIAL AND METHODS

Patients scheduled for arterial interventional procedures in the pelvis or lower extremities were consecutively included. In phase one (duration 6 weeks, 44 patients) contrast media were injected manually. In phase two (duration until the total dose area product [DAP] was equal to phase 1, 41 patients) the operator used a power injector and exited the suite whenever possible. Patient, procedure, and examination data were recorded. Collective dose to the operator's collar, lead apron, and hands was recorded using thermo luminescent dosimetry (TLD).

RESULTS

Our results showed a dose reduction of 50% to the operator's hands, lead apron, and thyroid collar when using a power injector during DSA, with no significant increase in DAP or procedure time when performing pelvic procedures. For lower extremity procedures there was a small but significant increase in procedure time and DAP. Pelvic procedures yielded substantially higher DAP than lower extremity procedures during both phases.

CONCLUSION

Utilization of a power injector, thus allowing the operator to step back from the patient, facilitates a radiation dose reduction to the operator of approximately 50% with no significant increase in patient dose or procedure time during pelvic procedures.

Radiation safety and education in the applicants of the final test for the expert of pain medicine

Background

The C-arm fluoroscope is known as the most important equipment in pain interventions. This study was conducted to investigate the completion rate of education on radiation safety, the knowledge of radiation exposure, the use of radiation protection, and so on.

Methods

Unsigned questionnaires were collected from the 27 pain physicians who applied for the final test to become an expert in pain medicine in 2011. The survey was composed of 12 questions about the position of the hospital, the kind of hospital, the use of C-arm fluoroscopy, radiation safety education, knowledge of annual permissible radiation dose, use of radiation protection, and efforts to reduce radiation exposure.

Results

In this study, although most respondents (93%) had used C-arm fluoroscopy, only 33% of the physicians completed radiation safety education. Even though nine (33%) had received education on radiation safety, none of the physicians knew the annual permissible radiation dose. In comparing the radiation safety education group and the no-education group, the rate of wearing radiation-protective glasses or goggles and the use of radiation badges or dosimeters were significantly higher in the education group. However, in the use of other protective equipment, knowledge of radiation safety, and efforts to reduce radiation exposure, there were no statistical differences between the two groups.

Conclusions

The respondents knew very little about radiation safety and had low interest in their radiation exposure. To make the use of fluoroscopy safer, additional education, as well as attention to and knowledge of practices of radiation safety are required for pain physicians.