An analytic approach to double dosimetry algorithms in occupational dosimetry using energy dependent organ dose conversion coefficients

Medical staff dose estimation during pediatric cardiac interventional procedures

The purpose of this study is to evaluate the occupational doses (eye lens, extremities and whole body) in paediatric cardiac interventional and diagnostic catheterization procedures performed in a paediatric reference hospital located in Recife, Pernambuco. For eye lens dosimetry, the results show that the left eye receives a higher dose than the right eye, and there is a small difference between the doses received during diagnostic (D) and therapeutic (T) procedures. The extrapolated annual values for the most exposed eye are close to the annual limit. For doses to the hands, it was observed that in a significant number of procedures (37 out of 45 therapeutic procedures, or 82%) at least one hand of the physician was exposed to the primary beam. During diagnostic procedures, the physician's hand was in the radiation field in 11 of the 17 catheterization procedures (65%). This resulted in a 10-fold increase in dose to the hands. The results underscore the need for optimization of radiation safety and continued efforts to engage staff in a radiation safety culture.

Assessment of dosimetric approaches in evaluating radiation exposure for interventional cardiologists in Sri Lanka

Interventional cardiologists face significant radiation exposure during interventional cardiology procedures. Therefore, this study focuses on assessing radiation exposure among interventional cardiologists during their procedures. Specifically, it aims to determine the effectiveness of both single and double dosimeter methods in estimating annual occupational radiation doses. This research holds pioneering significance as it represents the very first study undertaken in Sri Lanka. Thirteen interventional cardiologists performed 486 interventional cardiology procedures over three months in three different healthcare institutes. Active Hp(10) dosimeters were placed to measure radiation exposure. Effective doses were calculated using single and double dosimetric algorithms. Annual occupational doses were assessed on an operator basis. Statistical analyses were conducted to assess algorithmic differences and dose variations using the Kruskal-Wallis test and linear regression. The highest annual occupational dose for each dosimetric algorithm received as 2.00 ± 0.24 mSv, 2.29 ± 0.48 mSv, 3.35 ± 0.71 mSv, and 2.64 ± 0.42 mSv, respectively, and remained below the recommended safety limit of 20 mSv/year. The Kruskal-Wallis test revealed no significant differences in the effective doses among double dosimetric algorithms, as well as between single and double dosimetric algorithms (p > 0.05). Linear regression showed strong correlations among various algorithms, demonstrating consistency. The findings of this study hold significant effects on interventional cardiology practice in Sri Lanka, enhancing radiation safety and monitoring.

Modified design of x-ray protective clothing to enhance radiation protection for interventional radiologists

BACKGROUND

In interventional radiology procedures, the operator typically stands on the right side of the patient's right thigh to manipulate devices through the femoral sheath. Because the standard x-ray protective clothing is designed as sleeveless and scatter radiations from the patient are mainly incident from the left-anterior direction to the operator, the arm hole of the clothing may be a significant unprotected area, contributing to an increase in the operator's organ doses and effective dose.

PURPOSE

This study aimed to compare the organ doses and effective dose received by the interventional radiologist when wearing the standard x-ray protective clothing and when wearing the modified clothing with an additional shoulder guard.

METHODS

The experimental setup aimed to simulate actual clinical practice in interventional radiology. The patient phantom was located at the beam center to generate scatter radiation. An adult female anthropomorphic phantom loaded with 126 nanoDots (Landauer Inc., Glenwood, IL) was used to measure organ and effective doses to the operator. The standard wrap-around type x-ray protective clothing offered 0.25-mm lead-equivalent protection, and the frontal overlap area offered 0.50-mm lead-equivalent protection. The shoulder guard was custom-made with a material providing x-ray protection equivalent to lead of 0.50 mm thickness. The organ and effective doses were compared between the operator wearing the standard protective clothing and the one wearing the modified clothing with a shoulder guard.

RESULTS

After adding the shoulder guard, doses to the lungs, bone marrow, and esophagus decreased by 81.9%, 58.6%, and 58.7%, respectively, and the effective dose to the operator decreased by 47.7%.

CONCLUSIONS

Widespread use of modified x-ray protective clothing with shoulder guards can significantly decrease the overall occupational radiation risk in interventional radiology.

Practical guidelines for personal monitoring and estimation of effective dose and dose to the lens of the eye in interventional procedures

Estimation of effective dose and dose to the lens of the eye for workers involved in interventional procedures is challenging. The interventional procedures in question involve high doses and, due to this, workers need to wear protective garments. As a result, various methodologies have been developed to assess the effective dose and dose to the lens of the eye. In the present study, measurements from four European dosimetry services, over and under protective garments, have been collected and analysed in order to provide practical guidelines based on the routine use of personal dosemeters from staff in interventional workplaces. The advantages and limitations of using one or two dosemeters are discussed.

REDUCTION OF STAFF RADIATION DOSE IN PROSTATIC ARTERY EMBOLISATION

Prostatic artery embolisation (PAE) is used to treat patients with benign prostatic hyperplasia and with lower urinary obstructive tract symptoms. It is an interventional procedure which uses fluoroscopy equipment and can result in exposure to high doses of radiation in patients and staff. We aimed to demonstrate the reduction of radiation doses received by staff during PAE by implementing an optimised protocol called Radiation Exposure Curtailment for Embolisation (RECiFE). This protocol was implemented in cooperation with the medical team and technical team using Siemens Combined Applications to Reduce Exposure (CARE) protocol. The results showed approximately 83% reduction in the radiation doses received by the main physician during PAE. Thus, by adjusting the acquisition parameters of the angiographic equipment and implementing the RECiFE protocol, it is possible to optimise the PAE procedure and reduce the staff radiation dose.

EXPERIMENTAL VALIDATION OF ALGORITHMS USED TO ESTIMATE EFFECTIVE DOSE DURING INTERVENTIONAL RADIOLOGY PROCEDURES

In IR procedures, in order to evaluate the effective dose, the importance of the double dosemeter has been recognised, one worn above and one under the apron. Over the last few decades several algorithms have been developed to combine the readings of the dosemeters, however currently there is no international consensus on which is the best one. In this work, eight irradiations, corresponding to typical interventional radiology procedures, were carried out in order to experimentally verify the accuracy of the algorithms. The patient was substituted by solid water-equivalent (RW3) layers, while effective dose to personnel was calculated by TLDs inside the Alderson Rando phantom. The results show that most of the algorithms, with a few exceptions, are too conservative, however there are many factors which can affect their accuracy, so it is impossible to achieve a high level of precision in the evaluation of the effective dose.

ASSESSMENT ON THE INTERCHANGEABILITY OF PERSONAL EFFECTIVE DOSE ALGORITHMS IN FLUOROSCOPY-GUIDED INTERVENTIONS USING BLAND-ALTMAN ANALYSIS

Long exposure to radiation from fluoroscopy-guided interventions (FGIs) can be detrimental to both patients and radiologists. The effective doses received by the interventional radiology staff after performing 230 FGIs in a year were assessed by using double dosimetry and five various algorithms. The Shapiro-Wilk test revealed normally-distributed data (p < 0.01), while the significant correlation coefficients between the effective doses ranged between 0.88 and 1.00. As for the Bland-Altman analysis, both Niklason and Boetticher algorithms strongly supported the absence of statistical significance between the estimated effective doses. This portrays that the occupational doses received by the interventional radiology staff during FGIs fall within the acceptable limit regardless of the varied algorithms applied. In short, the Niklason and Boetticher algorithms appeared to be the more interchangeable ones for effective evaluation of doses. This is in view of their strong mutual correlations and excellent agreement.

RADIATION DOSES TO ANAESTHETISTS DURING PROSTATIC ARTERY EMBOLIZATION INTERVENTIONAL PROCEDURES

The objective of this study was to assess the radiation doses received by anaesthetists from prostatic artery embolization (PAE) procedures. Ten PAE procedures conducted in a reference hospital in the city of Recife, Brazil were investigated. Occupational dosimetry was performed using thermoluminescent dosemeters which were located next to the eyes, close to the thyroid (over the shielding), on the thorax (under the apron), on the wrist and on the feet of the physician's body. The results showed that the anaesthetist's feet received the highest doses followed by the eyes and the hands. In some complex PAE procedures the doses received by anaesthetists on the lens of the eyes and the effective dose were higher than those received by the main operator due to the anaesthetist's close position to the patient's table and the use of oblique projections. The personal dose equivalent Hp(3) per procedure for the anaesthetist's right eyebrow ranged from 20.2 μSv to 568.3 μSv. This result shows that anaesthetists assisting PAE procedures can exceeds the annual eye lens dose limit of 20 mSv recommended by the ICRP with only one procedure per week if radiation protection measures are not implemented during procedures.

THE CHALLENGES IN THE ESTIMATION OF THE EFFECTIVE DOSE WHEN WEARING RADIOPROTECTIVE GARMENTS

The performance of a single or double dosimetry (SD or DD) algorithm on estimating effective dose wearing radioprotective garments (ERPG) depends on the specific irradiation conditions. This study investigates the photon energies and angles of incidence for which the estimation of ERPG with the personal dose equivalents measured over and under the RPG (Ho and Hu) becomes more challenging. The energy and angular dependences of ERPG, Ho and Hu were Monte Carlo calculated for photon exposures. The personal dosimeter of SCK · CEN was modeled and used to determine Ho and Hu. Different SD and DD algorithms were tested and critical exposure conditions were identified. Moreover, the influence of calibration methods was investigated for the SCK · CEN dosimeter when worn over RPG. We found that the accuracy with which ERPG is calculated using SD and DD is strongly dependent on the energy and angle of incidence of photons. Also, the energy of the photon beam used to calibrate the Ho dosimeter can bias the estimation of ERPG.

Radiation Exposure of Patients and Interventional Radiologists during Prostatic Artery Embolization: A Prospective Single-Operator Study

PURPOSE

To prospectively analyze the radiation exposure of patients and interventional radiologists during prostatic artery embolization (PAE).

MATERIALS AND METHODS

Twenty-five consecutive PAE procedures performed with an Artis zee system in a single center by an interventional radiologist were prospectively monitored. The mean age, weight, and prostate volume of the patients were 65.7 year (range, 43-85 y), 71.4 kg (range, 54-88 kg), and 79 cm³ (range, 36-157 cm³), respectively. In addition to Digital Imaging and Communications in Medicine radiation data, direct measures were also obtained. Radiochromic film was used to evaluate peak skin dose (PSD). The radiologist wore a protective apron and a thyroid collar, and a ceiling-suspended screen and a table curtain were used. To estimate the absorbed doses, nine pairs of dosimeters were attached to the operator's body.

RESULTS

The average fluoroscopy time was 30.9 minutes (range, 15.5-48.3 min). The mean total dose-area product (DAP) was 450.7 Gy·cm² (range, 248.3-791.73 Gy·cm²) per procedure. Digital subtraction angiography was responsible for 71.5% of the total DAP, followed by fluoroscopy and cone-beam computed tomography. The mean PSD was 2,420.3 mGy (range, 1,390-3,616 mGy). The average effective dose for the interventional radiologist was 17 μSv (range, 4-47 μSv); values for the eyes, hands, and feet were obtained, and were all greater on the left side.

CONCLUSIONS

PAE may lead to high x-ray exposures to patients and interventional radiologists.

Radiation Exposure of the Operator During Coronary Interventions (from the RADIO Study)

We sought to compare operator radiation exposure during procedures using right femoral access (RFA), right radial access (RRA), and left radial access (LRA) during coronary angiography (CA) and percutaneous coronary intervention (PCI). Because of an increased incidence of long-term malignancy in interventional cardiologists, operator radiation exposure is of rising concern. This prospective study included all consecutive patients who underwent elective or emergency CA ± PCI from September 2014 to March 2015. The primary end point was operator radiation exposure, quantified as the ratio of operator cumulative dose (CD) and patient radiation reported as dose-area product (DAP) (CD/DAP). Secondary end points included CD, DAP, and fluoroscopy time (FT). Overall 830 procedures (457 CA [55%] and 373 PCI [45%]) were performed, 455 (55%) through RFA, 272 (33%) through RRA, and 103 (12%) through LRA. The CD/DAP was lower in RFA (0.09 μSv/Gycm(2) [0.02 to 0.20]) compared with RRA (0.47 μSv/Gycm(2) [0.25 to 0.75], p <0.001). The LRA showed lower CD/DAP compared with RRA (p <0.001). CD was significantly lower in RFA (3 μSv [1 to 7]) compared with RRA (12 μSv [6 to 29], p <0.001). The LRA showed lower CD compared with RRA (p <0.001). There were no significant differences in DAP among the 3 access sites. FT was similar for the 3 groups (RFA 7 ± 7, RRA 5 ± 5, LRA 6 ± 5 minutes, RFA vs RRA: p = 1, RFA vs LRA: p = 0.16, RRA vs LRA: p = 0.52). In conclusion, the use of RFA during CA ± PCI is associated with significantly lower operator radiation exposure compared with RRA. LRA is associated with significantly lower operator radiation exposure compared with RRA.

A semi‑automated FISH‑based micronucleus‑centromere assay for biomonitoring of hospital workers exposed to low doses of ionizing radiation

The aim of the present study was to perform cytogenetic analysis by means of a semi‑automated micronucleus‑centromere assay in lymphocytes from medical radiation workers. Two groups of workers receiving the highest occupational doses were selected: 10 nuclear medicine technicians and 10 interventional radiologists/cardiologists. Centromere‑negative micronucleus (MNCM‑) data, obtained from these two groups of medical radiation workers were compared with those obtained in matched controls. The blood samples of the matched controls were additionally used to construct a 'low‑dose' (0‑100 mGy) MNCM‑ dose‑response curve to evaluate the sensitivity and suitability of the micronucleus‑centromere assay as an 'effect' biomarker in medical surveillance programs. The physical dosimetry data of the 3 years preceding the blood sampling, based on single or double dosimetry practices, were collected for the interpretation of the micronucleus data. The in vitro radiation results showed that for small sized groups, semi‑automated scoring of MNCM‑ enables the detection of a dose of 50 mGy. The comparison of MNCM‑ yields in medical radiation workers and control individuals showed enhanced MNCM‑ scores in the medical radiation workers group (P=0.15). The highest MNCM‑ scores were obtained in the interventional radiologists/cardiologists group, and these scores were significantly higher compared with those obtained from the matched control group (P=0.05). The higher MNCM‑ scores observed in interventional radiologists/cardiologists compared with nuclear medicine technicians were not in agreement with the personal dosimetry records in both groups, which may point to the limitation of 'double dosimetry' procedures used in interventional radiology/cardiology. In conclusion, the data obtained in the present study supports the importance of cytogenetic analysis, in addition to physical dosimetry, as a routine biomonitoring method in medical radiation workers receiving the highest occupational radiation burdens.

Prostatic artery embolization: radiation exposure to patients and staff

The aim of this study was to evaluate the radiation doses to patients and staff received from the first cases of prostatic artery embolization (PAE) conducted in a public hospital in Recife, Brazil. Five PAE procedures for 5 men diagnosed with benign prostatic hyperplasia were investigated. In order to characterize patient exposure, dosimetric quantities, such as the air kerma-area product (P KA), the cumulative air kerma at the interventional reference point (Ka,r), the number of images, etc, were registered. To evaluate the possibility for deterministic effects, the peak skin dose (PSD) was measured using radiochromic films. For evaluation of personal dose equivalent and effective dose to the medical staff, thermoluminescent dosemeters (TLD-100) were used. The effective dose was estimated using the double dosimetry alghoritm of von Boetticher. The results showed that the mean patient's PSD per procedure was 2674.2 mGy. With regard to the medical staff, the mean, minimum and maximum effective doses estimated per procedure were: 18 μSv, 12 μSv and 21 μSv respectively. High personal equivalent doses were found for the feet, hands and lens of the eye, due to the use of multiple left anterior oblique projections and the improper use of the suspended lead screen and the lead curtain during procedures.

Evaluation of staff, patient and foetal radiation doses due to endoscopic retrograde cholangiopancreatography (ERCP) procedures in a pregnant patient

The use of endoscopic retrograde cholangiopancreatography (ERCP) in pregnant patients is not rare. Most studies on the safety and efficacy of these procedures report short- and long-term pregnancy outcomes and but not foetal absorbed doses. This investigation reports on an ERCP procedure for a 40-y-old woman who was 32-34 weeks pregnant. Thermoluminescent dosemeters (TLD 100) were used to measure doses received by the patient and the staff. Additionally, Monte Carlo calculations were performed using a 3D computational phantom representing a 9-month pregnant patient to estimate the foetal absorbed dose. The results show that the spleen of the mother received the largest absorbed dose of 12.18 mGy since it was closer to the source than other internal organs. For the foetus and uterus, the lowest absorbed dose was found to be 0.01 mGy to the foetal brain, while the largest absorbed dose was estimated to be 0.13 mGy to the placenta.

Radiation exposure to patients and medical staff in hepatic chemoembolisation interventional procedures in Recife, Brazil

The purpose of this study was to evaluate patient and medical staff absorbed doses received from transarterial chemoembolisation of hepatocellular carcinoma, which is the most common primary liver tumour worldwide. The study was performed in three hospitals in Recife, capital of the state of Pernambuco, located in the Brazilian Northeastern region. Two are public hospitals (A and B), and one is private (C). For each procedure, the number of images, irradiation parameters (kV, mA and fluoroscopy time), the air kerma-area product (PKA) and the cumulative air kerma (Ka,r) at the reference point were registered. The maximum skin dose (MSD) of the patient was estimated using radiochromic film. For the medical staff dosimetry, thermoluminescence dosemeters (TLD-100) were attached next to the eyes, close to the thyroid (above the shielding), on the thorax under the apron, on the wrist and on the feet. The effective dose to the staff was estimated using the algorithm of von Boetticher. The results showed that the mean value of the total PKA was 267.49, 403.83 and 479.74 Gy cm(2) for Hospitals A, B and C, respectively. With regard to the physicians, the average effective dose per procedure was 17 µSv, and the minimum and maximum values recorded were 1 and 41 µSy, respectively. The results showed that the feet received the highest doses followed by the hands and lens of the eye, since the physicians did not use leaded glasses and the equipment had no lead curtain.

Assessment of eye and body dose for interventional radiologists, cardiologists, and other interventional staff

A dose limit for the eye of 20 mSv, as proposed by the ICRP, could be exceeded by interventional clinicians. Data on eye dose levels for interventional radiologists and cardiologists provided by medical physicists from hospitals around the UK have been collated. The results indicate that most hospitals would require one or more interventional clinicians to be classified and several would have exceeded a 20 mSv limit. Dose data in the literature have been reviewed to derive factors that might be used to predict eye dose levels based on dose per procedure or kerma-area product workload. These could be used in prior risk assessments to establish monitoring practice. An alternative approach to personnel dose monitoring in radiology applications using a collar dosimeter worn outside the lead apron as the first dosimeter is proposed. The collar dosimeter would provide an assessment of eye dose in terms of Hp(3) and body dose in terms of Hp(10), which could be divided by ten to provide an assessment of effective dose. If Hp(3) exceeded 1 mSv per month, regular monitoring with a head dosimeter would be recommended, and if Hp(10) exceeded 2 mSv per month, then an under-apron dosimeter should also be worn.

Reduction of operator radiation dose by a pelvic lead shield during cardiac catheterization by radial access: comparison with femoral access

OBJECTIVES

This study sought to determine the efficacy of patient pelvic lead shielding for the reduction of operator radiation exposure during cardiac catheterization via the radial access in comparison with the femoral access.

BACKGROUND

Cardiac catheterization via the radial access is associated with significantly increased radiation dose to the patient and the operator. Improvements in radiation protection are needed to minimize this drawback. Pelvic lead shielding has the potential to reduce operator radiation dose.

METHODS

We randomly assigned 210 patients undergoing elective coronary angiography by the same operator to a radial and femoral access with and without pelvic lead shielding of the patient. Operator radiation dose was measured by a radiation dosimeter attached to the outside breast pocket of the lead apron.

RESULTS

For radial access, operator dose decreased from 20.9 ± 13.8 μSv to 9.0 ± 5.4 μSv, p < 0.0001 with pelvic lead shielding. For femoral access, it decreased from 15.3 ± 10.4 μSv to 2.9 ± 2.7 μSv, p < 0.0001. Pelvic lead shielding significantly decreased the dose-area product-normalized operator dose (operator dose divided by the dose-area product) by the same amount for radial and femoral access (0.94 ± 0.28 to 0.39 ± 0.19 μSv × Gy(-1) × cm(-2) and 0.70 ± 0.26 to 0.16 ± 0.13 μSv × Gy(-1) × cm(-2), respectively).

CONCLUSIONS

Pelvic lead shielding is highly effective in reducing operator radiation exposure for radial as well as femoral procedures. However, despite its use, radial access remains associated with a higher operator radiation dose.