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1Nuclear Energy Department, Federal University of Pernambuco, Recife, PE, Brazil. 2IMIP—Institute of Medicine Dr. Fernando Figueira, Recife, PE, Brazil.
Radiation Protection Dosimetry Advance Access published April 12, 2015 Radiation Protection Dosimetry (2015), pp. 1–5

doi:10.1093/rpd/ncv075

RADIATION EXPOSURE TO PATIENTS AND MEDICAL STAFF IN HEPATIC CHEMOEMBOLISATION INTERVENTIONAL PROCEDURES IN RECIFE, BRAZIL H. J. Khoury1,*, W. J. Garzon1, G. Andrade2, N. Lunelli1, R. Kramer1, V. S. M. de Barros1 and A. Huda3 1 Nuclear Energy Department, Federal University of Pernambuco, Recife, PE, Brazil 2 IMIP—Institute of Medicine Dr. Fernando Figueira, Recife, PE, Brazil 3 California State University, Fresno, CA, USA *Corresponding author: [email protected] 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 cm2 for Hospitals A, B and C, respectively. With regard to the physicians, the average effective dose per procedure was 17 mSv, and the minimum and maximum values recorded were 1 and 41 mSy, 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.

INTRODUCTION The transarterial chemoembolisation (TACE) is a widespread procedure in the treatment of unresectable hepatocellular carcinoma and has most widely been applied for patients who are not eligible for surgery. It is an interventional radiology procedure performed using a coaxial catheter system to deliver a local and concentrated dose of chemotherapeutic agents directly into the arterial feeding vessels of the tumour. Despite the benefits, these procedures often expose patients and medical staff to high doses of radiation. Patient radiation dose carries risks of secondary stochastic and deterministic injury(1). The medical staff, during the TACE procedure, remain close to the patient and consequently are also potentially exposed. They could receive doses higher than the occupational limit and, in particular, when the radiation protection devices are not adequate, their risk of exceeding the dose limit to the lens of the eye is significant (1, 2). The aim of this paper was to evaluate the MSD and the dose distribution on patient’s skin and to estimate the effective doses to the medical staff from the procedures performed in Recife, Brazil. MATERIALS AND METHODS This study was performed in three hospitals, located in the city of Recife, two being public hospitals (A and B) and one private (C). The X-ray imaging systems used for this procedure in these hospitals are

Siemens Artis Zee, with a 30`  40 cm rectangular flat panel (Hospital A); a Toshiba angiography system, model DRX-T7345GDS, equipped with image intensifier (Hospital B) and a Phillips Allura FD20 equipped with a flat panel (Hospital C). Initially, the equipment was evaluated, and relevant parameters were tested based on AAPM report No 70(3) and found to be in compliance with manufacturer’s specifications. Patient dosimetry The radiation dose was evaluated in 55 adult patients with ages ranging from 25 to 89 y and a mean age of 62.2 y. For each procedure, the irradiation parameters (kV, mAs, pulse width, etc.), the value of cumulative dose (air kerma at the interventional reference point) and the air kerma –area product (PKA) were recorded. The systems of Institutions A and C are equipped with an internal KAP meter that provides the readout of the cumulative PKA values. For the equipment of Institution B, the Diamentor E2—KAP meter (PTW Freiburg) was coupled at the end of the X-ray tube. The calibration of the PKA meters was based on the PKA value obtained from the product of Ka, measured with a reference ionisation chamber, and of the irradiated area A on a film, exposed at the position of the chamber. The product of such values was then compared with that obtained with the PKA meter, and the calibration coefficients were calculated.

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H. J. KHOURY ET AL.

The air kerma was measured at the centre of the radiation field with the Radcal 10`  6 ion chamber, previously calibrated at the Metrology Laboratory of Ionizing Radiation of the DEN/UFPE (LMRIDEN/UFPE) and positioned under the couch, according to the procedure described in IAEA code of practice(4). The following components affect the uncertainty of the calibration factor of PKA: uncertainty in the calibration factor of the reference ionisation chamber (3 %); uncertainty in the reading of the air kerma values (2.5 %); uncertainty reading of the PKA meter (2.5 %); uncertainty correction factors for standard air density for the reference chamber (kTP , ref ) and for the KAP meter (kTP , PKA.) (1 %); uncertainty in the determination of field area from the film (3 %) and uncertainty due to the effect of field inhomogeneities (4 %). Combining these independent uncertainties leads to a relative expanded uncertainty of 4.3 % for the calibration of KAP meter. The MSD and the dose distribution across the patient’s skin were evaluated using a Gafchromic XR-RV3 Radiochromic films (ISP—international Specialty Products, Wayne, NJ, USA). The films were placed on the couch with the orange side facing up and centred as close as possible to the most irradiated area of the patient’s back. The colour of the film is orange and becomes darkened according to radiation exposure. Darker film represents higher absorbed doses. The radiochromic films were previously calibrated at the Metrology Laboratory of Ionizing Radiation of the DEN/UFPE (LMRI-DEN/UFPE) with X-ray RQR-6 beam quality (80 kV, 10 mA and HVL of 3.01 mm of Al)(4), and the reflective density was measured using a reflectance densitometer X-Rite Series 500 in RGB mode. The film reflective density-to-air kerma calibration curves were constructed with measurements done after 24 h of irradiation. The reflective densities of the films irradiated with the patients were also measured after 24 h of the procedure. This period of time is enough to warrant the stability of the reflective density of the radiochromic films(5). Staff dosimetry Thermoluminescence dosemeters (TLD-100) were used to evaluate the dose of the main physician that does the TACE procedure. A pair of TLD chips were encapsulated in plastic bag and attached to the following positions on the physician’s body: one close to thyroid (above the apron), one at chest level under the apron, next to the eyes, on the wrist and on the feet. Calibration of the dosemeters was performed at the LMRI-DEN/UFPE with the standard N-80 beam quality(6) in terms of personal dose equivalent [Hp(10) and Hp(0.07)], using conversion factors from air kerma to suitable operational quantity(6). The relative uncertainties associated with the reference

quantities Hp(10) and Hp(0.07) are +4.3 %. According to the European Commission assessment, the quantity personal dose equivalent Hp(0.07) can be used for equivalent dose for lens to the eye(7). Hence, the response of the dosemeters used near the eyes was calibrated for Hp(0.07). The TLDs were read using a Victoreen 2800 manual reader. The effective dose to the staff was estimated by the algorithm of von Boetticher(8), using the equation: E ¼ 0:84Hp;u ð10Þ þ 0:051Hp;o ð10Þ;

ð1Þ

where Hp,u(10) is the dosemeter reading at chest level (under apron) and Hp,o(10) is the dosemeter reading at collar level (above the apron). In this calculation, the tissue weighting factors wT used are based on ICRP 103 recommendations(9). This algorithm is independent of the lead apron thickness and gives a good estimation of the effective dose in comparison with the value calculated by Monte Carlo simulation(10). The staff wore a protective apron and thyroid shields with an equivalent thickness of either 0.5 mm or 0.25 mm of lead. Additional lead shields, such as curtains mounted on the patient table or shields suspended from the ceiling, were only available in Institution C; however, only the table lead curtains were used by the staff. RESULTS AND DISCUSSION Patient dosimetry Table 1 presents the average and minimum– maximum values of the irradiation parameters used in the hospitals where the TACE procedures were studied. The results show that, despite the fact that the X-ray equipment of institution A has a flat panel, the current used is high, similar to that used in Institution B where the equipment has an image intensifier. Figure 1 shows the distribution of the values of PKA in terms of box-and-whiskers diagram. This diagram shows the quartiles of the data from each procedure, and its maximum and minimum values. The line in the box represents the median value. The results show that the distribution of PKA varies among patients and hospitals. The average values of PKA found are similar to that found in the literature(11, 12) Table 2 presents the values of the air kerma at the interventional reference point (Ka,r) and the MSD obtained in this study for the procedures performed at the three hospitals. The sources of uncertainty in the MSD values comprise the calibration of the gafchromic films and the readout system. The sources of uncertainty from the component related to calibration consist of: irradiation conditions, calibration of the ionisation chamber and stability of the X-ray machine. The source of the

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RADIATION EXPOSURE TO PATIENTS AND MEDICAL STAFF Table 1. Irradiation parameters used in the three hospitals studied for the TACE procedures. Hospital

Fluoroscopy A

Digital subtraction angiography

B

kV Mean 67 Min– max (66.4–69) mA Mean 148.5 Min– max (137.8– 160) Width time (ms) Mean 12.5 Min– max (12.1–12.7) Fluoroscopy time (min) Mean 20.4 Min– max (2.2– 54.3) Number of images Mean — Min– max

C

A

B

C

78 (70– 83.9)

96.4 (87.5–106)

72.2 (63.5– 82.2)

88.6 (80–90.2)

83.7 (78.3–92.1)

120.7 (104.7–131)

15.82 (11.7–21.9)

528.2 (212.5–798)

500 (350– 540)

626.8 (574–696)

4.8 (3.2– 5.7)

UD

120.7 (87–160)

95.1 (92–95.8)

UD

12 (3.3– 25)

16.4 (10.4–24)











250 (75–530)

UD

214.6 (175–317)

UD, unreported data.

Figure 1. Distribution of PKA across procedures and hospitals.

Figure 2. Distribution of the personal dose equivalent values on different regions of the physicians for the three hospitals.

Table 2. Values of the air kerma at the interventional reference point (Ka,r) and the MSD obtained in this study for the procedures performed at the three hospitals.

readout system includes the reproducibility of the system and the standard deviation of the measurements of reflective density. Combining all the components yields a combined uncertainty of the dose value measured of 3 %. Considering all the patients studied, in 31.5 %, the MSD was .2Gy, which can produce a prompt deterministic skin effect, like erythema(13). Prompt reactions are those that occur ,2 weeks after irradiation. The results also show that the MSD values observed in the patients of the three institutions are very similar. In case of Institution C, the patients

Hospital Ka,r (Gy) Mean Min– max MSD (Gy) Mean Min– max

A

B

C

1.791+0.054 0.276– 5.259



2.645+0.079 1.453–4.501

1.86 þ 0.056 0.33–4.3

1.97+0.059 0.16– 4.6

2.3+0.069 0.36– 4.72

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H. J. KHOURY ET AL. Table 3. Mean, min and max personal dose equivalent values on different regions of the physicians for each hospital. Personal dose equivalent (mSv)

Hospitals A B C

Right eye Mean Min–max

Left eye Mean Min–max

Right hand Mean Min–max

Left hand Mean Min– max

Right foot Mean Min–max

Left foot Mean Min– max

109 (21 –445) 39 (26 –60) 85 (27 –207)

381 (98 –894) 386 (251–598) 497 (311–792)

225 (94–417) 255 (142– 441) 267 (125– 460)

432 (134–956) 1019 (515–1758) 840 (271–2034)

742 (231–2768) 1878 (892–2863) 264 (78 –789)

1207 (339– 3445) 2540 (776– 5135) 628 (69– 1552)

evaluated were more obese than the patients of the other two institutions. This fact explains the higher kV values used in the TACE procedures performed at this institution in comparison with the other two institutions. The co-relation between the values of Ka,r and MSD values presented a correlation coefficient R 2 ¼ 0.8628, indicating that the Ka,r values could be used as an alert indication for the MSD values. Staff dosimetry Figure 2 shows the distribution of the values of the personal dose equivalent for each procedure, measured in the region of the feet, hands and eyes of the principal physician who had performed the procedures assessed in this study. Table 3 presents the range and the mean values of these doses per hospital. One can observe from the results that the left side of the physician receives a higher radiation dose than the right side due to his/her position during the procedure, which is on the right side of the fluoroscopy equipment. On the other hand, in Institution C, the doses on the feet are lower than the other two institutions, due to the presence of the lead curtains mounted on the table. Average doses near the left eye were similar in all three hospitals and are 400 mSv per procedure. Considering the new dose threshold established for the lens of the eye tissue reactions(14), a physician who performs liver chemoembolisation procedures would reach the annual limit of equivalent dose in the eyes with just one procedure per week. The eye doses found in this paper are 52.2 % higher than those reported in the literature where the physicians use leaded glasses(15). The range and the mean values of the effective dose calculated using the algorithm of von Boetticher for each procedure are: Institution A (range: 7–41 mSv, mean 17.6 mSv); Institution B (16 –25 mSv, mean 20.1 mSv) and Institution C (12– 148 mSv, mean 80 mSv). In Institution C, some procedures were done by a

resident and this explains the highest effective dose values found. Considering the worst mean effective dose value found, it can be inferred that the physician could perform up to 4 weekly procedures to not exceed the annual limit established for effective dose, which is 20 mSv. CONCLUSION The patient skin dose in the liver chemoembolisation procedures might be higher than the threshold for deterministic effects, and skin injuries are possible in these examinations although variable individual radiosensitivity can influence the outcome. For economic reasons, the additional lead shields, such as curtains mounted on the patient table and shields suspended from the ceiling, are not available in all the hospitals and, sometimes, when available, are not used by the physicians. Training in radiation protection is necessary for the physicians to contribute to a culture of radiation protection. Based on the findings of this study, it is recommended that data of Ka,r and MSD that are relevant to the estimation of the risk of deterministic effect be documented in the medical record for interventional procedures ACKNOWLEDGEMENTS The authors thank the hospitals for allowing the measurements and also the Brazilian funding agencies CNPq and FACEPE. FUNDING The authors received funding from CNPq- Conselho Nacional de Desenvolvimento Cientifico e TecnologicoGrant Number 305903/2011-0. REFERENCES 1. Hidajat, N., Wust, P., Felix, R. and Schro¨der, R. J. Radiation exposure to patient and staff in hepatic

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