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Medical and occupational dose reduction in pediatric barium meal procedures
Radiation Physics and Chemistry (xxxx) xxxx–xxxx
Contents lists available at ScienceDirect
Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem
Medical and occupational dose reduction in pediatric barium meal procedures ⁎
D. Filipovb, H.R. Schelina, , V. Denyaka,c, S.A. Paschukb, J.A. Ledesmaa, A. Legnania, A.P. Bunicka, J. Sauzenb, A. Yaguia, P. Vosiakb a b c
Pelé Pequeno Príncipe Research Institute (IPPPP), Av. Silva Jardim, 1632, Água Verde, Curitiba, PR, 80250-060, Brazil Federal University of Technology, Paraná (UTFPR), Av. Sete de Setembro, 3165, Rebouças, Curitiba, PR, 80230-90, Brazil National Science Center, Kharkov Institute of Physics and Technology, Akademicheskaya 1, Kharkiv 61108, Ukraine
A R T I C L E I N F O
A BS T RAC T
Keywords: Pediatric fluoroscopy Barium mealprocedure Occupational exposure Thermoluminescent dosimeter Dose reduction
Doses received in pediatric Barium Meal procedure can be rather high. It is possible to reduce dose values following the recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP). In the present work, the modifications of radiographic techniques made in a Brazilian hospital according to the EC and the ICRP recommendations and their influence on medical and occupational exposure are reported. The procedures of 49 patients before and 44 after the optimization were studied and air kerma-area product (PK,A) values and the effective doses were evaluated. The occupational equivalent doses were measured next to the eyes, under the thyroid shield and on each hand of both professionals who remained inside the examination room. The implemented modifications reduced by 70% and 60% the PK,A and the patient effective dose, respectively. The obtained dose values are lower than approximately 75% of the results from similar studies. The occupational annual equivalent doses for all studied organs became lower than the limits set by the ICRP. The equivalent doses in one examination were on average below than 75% of similar studies.
1. Introduction The pediatric barium meal (BM) procedure is an examination that employs ionizing radiation and implies radiation exposure of children and staff with doses that can be rather high. It is possible to reduce the dose values optimizing the technical parameters of the equipment that usually is not configured for pediatric imaging. The recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP) for pediatric fluoroscopy can be used as a guideline for such optimization. There are some studies dedicated to BM procedures in pediatric patients, in which air kerma-area product (PK,A) and/or effective dose were determined (Servomaa et al., 2000; Yakoumakis et al., 2014; Canevaro et al., 2004; Chateil et al., 2004; Iacob and Diaconescu, 2004, ; Hiorns et al., 2006; Damilakis et al., 2006; Sorop et al., 2008; Hart et al., 2009; Dimitriadis et al., 2011; Emigh et al., 2013; Sulieman et al., 2014; Wambani et al., 2014). In Brazil, no diagnostic reference levels (DRLs) have been established for fluoroscopy-guided examinations and no experimental data are available for children (Canevaro et al., 2004).
⁎
Despite the importance of occupational exposure monitoring in pediatric BM procedures, the number of such studies is scarce (Damilakis et al., 2006; Coakley et al., 1997; Kemerink et al., 2000; Alejo et al., 2015; Ubeda et al., 2016). In Brazil, as well as for medical exposures, no data were found for occupational exposure. The results of our previous work (Filipov et al., 2015) showed a significant difference between the radiographic techniques used in a Brazilian hospital and the recommendation based on the EC data. In the present work, the modifications of radiographic techniques made in the same hospital according to the EC recommendations and their influence on medical and occupational exposure are reported. 2. Materials and methods This study was performed at the Pequeno Príncipe Hospital, one of the largest pediatric hospitals in Brazil, with 0–16 years old patients, in two phases: before (49 patients) and after (44 patients) the implementation of the optimization. The present study was done with the approval of the Hospital Ethical Committee.
Corresponding author. E-mail address: [email protected] (H.R. Schelin).
http://dx.doi.org/10.1016/j.radphyschem.2017.01.034 Received 30 September 2016; Received in revised form 25 January 2017; Accepted 27 January 2017 0969-806X/ © 2017 Elsevier Ltd. All rights reserved.
Please cite this article as: Filipov, D., Radiation Physics and Chemistry (2017), http://dx.doi.org/10.1016/j.radphyschem.2017.01.034
Radiation Physics and Chemistry (xxxx) xxxx–xxxx
D. Filipov et al.
Table 1 Optimization of the technical parameters. “NSF” is the number of spot films; “FI” is the number of fluoroscopy images; “FT” is the fluoroscopy time; “FS” is the field size on patient. “kVp”, “mAs” are the tube voltage and the current-time product, respectively, used for spot films. Parameter
NSF FI FT (min) FS (cm2) kVp mAs
<1 Before
After
6.0 ± 1.1 6.2 ± 0.7 1.6 ± 0.4 278 ± 46 59.1 ± 0.4 9.3 ± 1.3
5.5 ± 0.5 6.0 ± 1.5 0.8 ± 0.1 225 ± 12 71.2 ± 0.5 4.8 ± 0.6
1–5 y Reduct. (%) 8 3 50 19 −20 48
Before
After
6.8 ± 0.7 5.0 ± 0.0 1.4 ± 0.1 341 ± 27 60.6 ± 0.5 9.5 ± 0.5
6.4 ± 0.7 9.0 ± 0.0 1.0 ± 0.1 234 ± 17 71.9 ± 0.7 4.3 ± 0.4
5–10 y Reduct. (%) 6 −80 29 31 −19 55
Before
After
7.6 ± 0.5 15.0 ± 3.0 1.2 ± 0.2 426 ± 63 62.7 ± 1.0 12.1 ± 0.8
6.3 ± 1.3 8.8 ± 0.9 1.1 ± 0.2 318 ± 25 70.0 ± 0.0 5.2 ± 0.2
> 10 Reduct. (%) 17 41 8 25 −12 57
Before
After
Reduct. (%)
6.9 ± 0.6 4.0 ± 0.0 1.6 ± 0.2 705 ± 99 68.8 ± 2.3 16.0 ± 2.0
5.7 ± 0.9 10.0 ± 0.0 1.1 ± 0.1 360 ± 45 78.8 ± 2.0 5.7 ± 0.8
17 −150 31 49 −15 64
Table 2 PK,A and effective dose (E). Reference
This work
<1 y
Before After
Servomaa et al. (2000) NRPB (2002) Canevaro et al. (2004) Chateil et al. (2004) Iacob and Diaconescu (2004) Hiorns et al. (2006) Damilakis et al. (2006) Sorop et al. (2008) Hart et al. (2009) Dimitriadis et al. (2011) Emigh et al. (2013) Sulieman et al. (2014) Wambani et al. (2014) Yakoumakis et al. (2014)
1–5 y
PK,A (cGy cm2)
PK,A (cGy cm2)
160 ± 10 50 ± 10 135.1 70 205 ± 116 89 ± 39
160 ± 2 70 ± 10 37.6 200 319 ± 171 136 ± 59 125 ± 43 9.5 ± 11.4
6.4 ± 8.6 78.6 44 ± 37 75 221.8 18.2
151 ± 66 130 189.4 82.5
80 173.9
240 284.9
5–10 y
> 10 y
E (mSv)
PK,A (cGy cm2)
E (mSv)
1.14 ± 0.18 0.6 ± 0.1
280 ± 10 80 ± 10 373.1 325 330 ± 335 151 ± 56 270 ± 103 25 ± 26
1.11 ± 0.02 0.3 ± 0.0
1.0 ± 0.4
310 ± 129 240
1.9 0.77 ± 0.02
122.4
1.0 2.8
PK,A (cGy cm2) 610 ± 10 140 ± 30 936.2 560
610 ± 272 25 ± 26 1.4 ± 0.5
515 ± 283 640
0.75 ± 0.02 0.3 3.0
300
500
The fluoroscopy equipment used was the Philips Diagnost 93 overcouch system with a total nominal filtration of 2.5 mm Al. The LiF:Mg,Ti (for patient) and LiF:Mg,Cu,P (for staff) (RadPRO International GmbH, Wermelskirchen, Germany) thermoluminescent dosimeters (TLDs) were used for dose measurement. For each examination there were recorded:
The equivalent doses per procedure (HtProc) and the annual equivalent doses (HtAnn) for each investigated region was then estimated (Filipov et al., 2015).
•
3.1. Optimization
•
3. Results and discussion
Patient's anthropometric information: gender, age, body mass, upper-chest thickness (measured in the supine position).
Table 1 shows the changes made. Some essential in optimization of BM procedure factors (fluoroscopy pulsed mode, removal of antiscattering grid and additional filtration) were not considered. The used equipment did not allow such changes. Only the technical parameters were modified. During the optimization, the X-ray tube was positioned at its maximum distance from the image intensifier (150 cm), which represents an increase of 24%. Regarding the number of images, it was found that the number of spot films could be lower if more medical physicians accepted the fluoroscopy images, even with its relative low quality.
Technical information: kVp, mAs and exposure time of spot films; total fluoroscopy time; number of recorded images (for fluoroscopy and radiography); fluoroscopy mode (pulsed or continuous); use of antiscattering grid; field size on the table; focus-table and focusdetector distances.
The patient PK,A values were calculated from the entrance-surface air kerma (Filipov et al., 2015), obtained with the TLDs. To obtain effective doses, Monte Carlo simulations were performed with the software “CalDose” (Lima et al., 2011) that uses examination tube voltage, total filtration, focus-detector distance, field size and measured PK,A as the entrance parameters. This software has mathematical adult and pediatric human phantoms. In the case of pediatric BM examination, it is only possible to choose the phantoms that represent 5 or 10 years old patients. The equivalent doses of the staff were measured with TLDs positioned on the temples (near both eyes), on the neck lead protector and on the hands. For the analysis of the doses received by the staffs’ thyroids, the attenuation of the protector (with 0.5 mm lead equivalent) was determined and the TLD measurement on the protector was multiplied by the attenuation factor.
Table 3 DRLs - PK,A 75th percentile. (cGy.cm2). Reference This work
Before After
NRPB (2002) Chateil et al. (2004) Hiorns et al. (2006) Hart et al. (2009) Wambani et al. (2014)
2
<1 y
1–5 y
5–10 y
> 10 y
150 55
190 85
190 85
610 185
70 170 8 75 120
200 220 12 130 300
325 240 32 240 400
560 240 32 640 700
Radiation Physics and Chemistry (xxxx) xxxx–xxxx
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Table 4 Estimative of the equivalent doses received by the staffs in each procedure - HtProc. “TF” is the total filtration; “FT” is the fluoroscopy time; “NSF” is the number of spot films; “Thyroid*” means over the lead protector. Reference
HtProc (µSv)
Technical Parameters Thyroid*
This work
Before
After
Coakley et al. (1997)
Kemerink et al. (2000) Damilakis et al. (2006)
Alejo et al. (2015)
Ubeda et al. (2016)
TF: 2.5 mm Al FT: 1.0 min NSF: 6.0 TF: 2.5 mm Al FT: 1.4 min NSF: 6.0 TF: 3.0 mm Al FT: 3.3 min NSF: 4–10 TF and FT: —— NSF: 12 TF: 4.0 mm Al FT: 1.5 min NSF: 3.5 TF: —— FT: 19.7 min NSF: —— TF: —— FT: 15.9 min NSF: ——
Hands
Eyes
Staff 1
Staff 2
Staff 1
Staff 2
Staff 1
Staff 2
52 ± 12
38 ± 11
83 ± 39
45 ± 8
48 ± 9
32 ± 9
28 ± 9
13 ± 5
43 ± 7
19 ± 5
25 ± 6
13 ± 4
1.5 ± 0.4
5.8 ± 1.0
30 ± 25 47
28.5 ± 12.1
0.2–116
one group. Also, in the present study, a rather small amount of patients was investigated, which means that each additional patient may change significantly the PK,A and/or the effective dose values.
According to the EC, a voltage of at least 70 kVp is recommended. This recommendation has been implemented and all examinations were performed with this minimum voltage. Consequently, the mAs was reduced. During this part of the study, the problem was noted: when operators were asked to increase voltage to the minimum of 70 kVp (and hence reducing the mAs), they showed some difficulties in carrying out such operation. They were used to increase the mAs without changing the kVp for larger patients or to improve image quality. The ICRP recommends collimation restricted to the region of interest, with a safety margin, especially in the case of uncooperative patients. The reduction of field size will reduce the amount of direct and scattered radiation and, consequently, the peripheral dose. The reduction of the radiation field was possible when patients were immobilized. A bag of sand (~ 5 kg) was used on the legs of ~55% of the patients.
3.3. Staff dose The distances from Staff 1 and Staff 2 to the central beam were increased, respectively, in 18% and 17%: Staff 1 increased the distance from 55 cm to 65 cm and Staff 2 increased its distance from 60 cm to 70 cm. Other information refers to the number of examinations in which the second professional was involved: Staff 2 participated only in 50% of the procedures in each phase. Table 4 presents the equivalent doses received by the staffs in each procedure. A reduction of ~ 55% at the second phase is noted for both staffs. After the optimization, HtProc obtained by Staffs 1 and 2 remained higher than 60% of the results from the similar studies. At the first phase, they were higher in 90% of the cases. It can also be noted that usually studies of occupational doses do not provide much information about technical parameters of examinations, which makes it difficult to compare.
3.2. Patient dose The results obtained before and after the optimization and in the similar studies are shown in Table 2. Approximately 15% of the results from the other researches showed lower PK,A values than the present study after the optimization in contrast to 60% obtained in the preoptimization phase. Although only the technical parameters were changed, it was possible to reduce, on average, the PK,A and the effective dose values by 70% and 60%, respectively. The DRLs were estimated as a 75th percentile before and after the optimization (Table 3). It was found that, before the optimization, our DRLs were higher than 50% of the other studies. After the optimization, our results were higher only than the obtained by Hiorns et al. (2006), where detailed information about technical parameters is not available. Comparing the both phases, the local DRLs have been reduced about 60%. Observing Tables 2 and 3, a wide variation of the PK,A and the effective doses in the different studies can be seen. This might be explained through the fact that the body size affects the dose received. It seems better to assign patients to narrower age groups that will reduce the effect of an unduly large range of body weights and sizes in
Table 5 HtAnnual for each investigated region (mSv). Before
After
Reduct. (%)
Lens Staff 1 Staff 2 ICRP Limit
Staff 1 Staff 2 ICRP Limit
35.0 ± 0.3 11.0 ± 0.2
18.2 ± 0.2 4.5 ± 0.1 20a
Thyroid (Under Lead Protector) 2.0 ± 0.0 1.1 ± 0.0 0.8 ± 0.0 0.3 ± 0.0 300
48 59
45 63
Hands Staff 1 Staff 2 ICRP Limit a
3
59.9 ± 1.1 15.2 ± 0.1
32.5 ± 0.2 6.8 ± 0.1 500
46 55
Averaged over defined periods of 5 years with no single year exceeding 50 mSv.
Radiation Physics and Chemistry (xxxx) xxxx–xxxx
D. Filipov et al.
children. Br. J. Radiol. 70, 933–936. http://dx.doi.org/10.1259/ bjr.70.837.9486070. Damilakis, J., Stratakis, J., Raissaki, M., Perisinakis, K., Kourbetis, N., Gourtsoyiannis, N., 2006. Normalized dose data for upper gastrointestinal tract contrast studies performed to infants. Med. Phys. 33 (4), 1033–1040. http://dx.doi.org/10.1118/ 1.2181297. Dimitriadis, A., Gialousis, G., Makri, T., Karlatira, M., Karaiskos, P., Georgiou, E., Papaodysseas, S., Yakoumakis, E., 2011. Monte Carlo estimation of radiation doses during paediatric barium meal and cystourethrography examinations. Phys. Med. Biol. 56, 367–382. http://dx.doi.org/10.1088/0031-9155/56/2/006. Emigh, B., Gordon, C.L., Connolly, B.L., Falkiner, M., Thomas, K.E., 2013. Effective dose estimation for pediatric upper gastrointestinal examinations using an anthropomorphic phantom set and metal oxide semiconductor field-effect transistor (MOSFET) technology. Pediatr. Radiol. 43, 1108–1116. http://dx.doi.org/10.1007/ s00247-013-2674-5. European Communities, 1996. European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics. Office for Official Publications of the European Communities, Luxembourg. Filipov, D., Schelin, H.R., Denyak, V., Paschuk, S.A., Porto, L.E., Ledesma, J.A., Nascimento, E.X., Legnani, A., Andrade, M.E.A., Khoury, H.J., 2015. Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures. Rad. Phys. Chem. 116, 267–272. http://dx.doi.org/10.1016/j.radphyschem.2015.05.036. Hart, D., Hillier, M.C., Wall, B.F., 2009. National reference doses for common radiographic, fluoroscopic and dental X-ray examinations in the UK. Br. J. Radiol. 82, 1–12. http://dx.doi.org/10.1259/bjr/12568539. Hiorns, M.P., Saini, A., Marsden, P.J., 2006. A review of current local dose–area product levels for paediatric fluoroscopy in a tertiary referral centre compared with national standards. Why are they so different? Br. J. Radiol. 79, 326–330 http://dx.doi.org/. 1259/bjr/36530782. Iacob, O., Diaconescu, C., 2004. Doses to patients from diagnostic medical radiation exposure in Romania. In: Proceedings of the 11th International Congress of the International Radiation Protection Association. Madrid. ICRP, 2013. Radiological protection in paediatric diagnostic and interventional radiology. Ann. ICRP 42, 2, (ICRP Publication 121). Kemerink, G.J., Borstlap, A.C.W., Frantzen, M.J., Schultz, F.W., Zoetelief, J., van Engelshoven, M.A., 2000. Patient and occupational dosimetry in double contrast barium enema examinations. Br. J. Radiol. 74 (881), 420–428. http://dx.doi.org/ 10.1259/bjr.74.881.740420. Lima, V.J., De, M., Cassola, V.F., Kramer, R., de Oliveira Lira, C.A.B., Khoury, H.J., Vieira, J.W., 2011. Development of 5 and 10 years old pediatric phantoms based on polygon mesh surfaces. Med. Phys. 38 (8), 325–329. http://dx.doi.org/10.1118/ 1.3615623. NRPB, 2002. Doses to patients from medical X-ray examinations in the UK – 2000 review. NRPB-W14, Chilton, UK. Servomaa, A., Komppa, T., Heikkilä, M., Parviainen, T., 2000. Patient doses in paediatric fluoroscopy examinations in Finland. Rad. Prot. Dosim. 90 (1–2), 239–243. Sorop, I., Mossang, D., Iacob, M.R., Dadulescu, E., Iacob, O., 2008. Update of diagnostic medical and x-ray exposures in Romania. J. Radiol. Prot. 28, 563–571 http://dx.doi. org/1088/0952-4746/28/4/008. Sulieman, A., Alzimami, K., Elhag, B., Babikir, E., Alsafi, K., 2014. Evaluation of radiation dose to pediatric patients during certain special procedures. Rad. Phys. Chem. 104, 267–271. http://dx.doi.org/10.1016/j.radphyschem.2013.11.034. Ubeda, C., Vano, E., Miranda, P., Aguirre, D., Riquelme, N., Dalmazzo, D., Galaz, S., 2016. Patient and staff doses in paediatric interventional cardiology derived from experimental measurements with phantoms. Phys. Med. 32, 176–181. http:// dx.doi.org/10.1016/j.ejmp.2015.11.009. Wambani, J.S., Korir, G.K., Tries, M.A., Korir, I.K., Sakwa, J.M., 2014. Patient radiation exposure during general fluoroscopy examinations. J. Appl. Clin. Med. Phys. 15 (2), 262–270. http://dx.doi.org/10.1120/jacmp.v15i2.4555. Yakoumakis, E., Dimitriadis, A., Gialousis, G., Makri, T., Karavasilis, E., Yakoumakis, N., Georgiou, E., 2014. Evaluation of organ and effective doses during paediatric barium meal examinations using PCXMC 2.0 Monte Carlo code. Rad. Prot. Dosim. 1, 1–8. http://dx.doi.org/10.1093/rpd/ncu174.
Table 5 shows the estimated values of the annual equivalent doses, for both phases. It can be seen that, after the optimization, the equivalent doses do not exceed the ICRP limits. Before the optimization, the eyes annual equivalent dose of Staff 1 was 85% higher than the annual limit, and Staff 2 received 70% of this limit. It should be mentioned that the obtained doses were not received by fixed staffs, but by the different professionals remained in the same positions. The other equivalent doses are much lower than the ICRP recommendations. 4. Conclusion The present study aimed to optimize the exposure technique in barium meal procedure according to the EC and the ICRP recommendations for pediatric fluoroscopy and to compare before and after the optimization: a) the value of the PK,A and the effective doses in pediatric patients; b) the equivalent doses in the region of the lens, thyroid and hands of professionals who participated in the procedure. The implemented modifications has reduced by 70% and 60% the PK,A and the effective dose, respectively, in pediatric patients. The obtained dose values are lower than approximately 75% of the results from similar studies. Regarding the occupational exposure, it was found that: a) the optimization made the annual equivalent doses for all studied organs lower than the limits set by the ICRP. b) the equivalent doses in one examination were, on average, below than in 75% of similar studies. Acknowledgments The authors would like to thank the Brazilian agencies CNPq, CAPES, and “Fundação Araucária” for financial support. References Alejo, L., Koren, C., Ferrer, C., Corredoira, E., Serrada, A., 2015. Estimation of eye lens doses received by pediatric interventional cardiologists. Appl. Rad. Isot. 103, 43–47. http://dx.doi.org/10.1016/j.apradiso.2015.05.008. Canevaro, L.V., Oliveira, R.R., Daltro, P.A., 2004. Radiation exposure of children during barium meal and micturatingcystourethrography examinations. In: Proceedings of the 11th International Congress of the International Radiation Protection Association. Madrid. Chateil, J.F., Rouby, C., Brun, M., Labessan, C., Diard, F., 2004. Mesure pratique de l’irradiation en radiopédiatrie: utilisation du produit dose surface en fluorographie numérique et pour les radiographies pulmonaires néonatales. J. Radiol. 85, 619–625 . http://dx.doi.org/10.1016/S0221-0363(04)97638-X. Coakley, K.S., Ratcliffe, J., Masel, J., 1997. Measurement of radiation dose received by the hands and thyroid of staff performing gridless fluoroscopic procedures in
4
Contents lists available at ScienceDirect
Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem
Medical and occupational dose reduction in pediatric barium meal procedures ⁎
D. Filipovb, H.R. Schelina, , V. Denyaka,c, S.A. Paschukb, J.A. Ledesmaa, A. Legnania, A.P. Bunicka, J. Sauzenb, A. Yaguia, P. Vosiakb a b c
Pelé Pequeno Príncipe Research Institute (IPPPP), Av. Silva Jardim, 1632, Água Verde, Curitiba, PR, 80250-060, Brazil Federal University of Technology, Paraná (UTFPR), Av. Sete de Setembro, 3165, Rebouças, Curitiba, PR, 80230-90, Brazil National Science Center, Kharkov Institute of Physics and Technology, Akademicheskaya 1, Kharkiv 61108, Ukraine
A R T I C L E I N F O
A BS T RAC T
Keywords: Pediatric fluoroscopy Barium mealprocedure Occupational exposure Thermoluminescent dosimeter Dose reduction
Doses received in pediatric Barium Meal procedure can be rather high. It is possible to reduce dose values following the recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP). In the present work, the modifications of radiographic techniques made in a Brazilian hospital according to the EC and the ICRP recommendations and their influence on medical and occupational exposure are reported. The procedures of 49 patients before and 44 after the optimization were studied and air kerma-area product (PK,A) values and the effective doses were evaluated. The occupational equivalent doses were measured next to the eyes, under the thyroid shield and on each hand of both professionals who remained inside the examination room. The implemented modifications reduced by 70% and 60% the PK,A and the patient effective dose, respectively. The obtained dose values are lower than approximately 75% of the results from similar studies. The occupational annual equivalent doses for all studied organs became lower than the limits set by the ICRP. The equivalent doses in one examination were on average below than 75% of similar studies.
1. Introduction The pediatric barium meal (BM) procedure is an examination that employs ionizing radiation and implies radiation exposure of children and staff with doses that can be rather high. It is possible to reduce the dose values optimizing the technical parameters of the equipment that usually is not configured for pediatric imaging. The recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP) for pediatric fluoroscopy can be used as a guideline for such optimization. There are some studies dedicated to BM procedures in pediatric patients, in which air kerma-area product (PK,A) and/or effective dose were determined (Servomaa et al., 2000; Yakoumakis et al., 2014; Canevaro et al., 2004; Chateil et al., 2004; Iacob and Diaconescu, 2004, ; Hiorns et al., 2006; Damilakis et al., 2006; Sorop et al., 2008; Hart et al., 2009; Dimitriadis et al., 2011; Emigh et al., 2013; Sulieman et al., 2014; Wambani et al., 2014). In Brazil, no diagnostic reference levels (DRLs) have been established for fluoroscopy-guided examinations and no experimental data are available for children (Canevaro et al., 2004).
⁎
Despite the importance of occupational exposure monitoring in pediatric BM procedures, the number of such studies is scarce (Damilakis et al., 2006; Coakley et al., 1997; Kemerink et al., 2000; Alejo et al., 2015; Ubeda et al., 2016). In Brazil, as well as for medical exposures, no data were found for occupational exposure. The results of our previous work (Filipov et al., 2015) showed a significant difference between the radiographic techniques used in a Brazilian hospital and the recommendation based on the EC data. In the present work, the modifications of radiographic techniques made in the same hospital according to the EC recommendations and their influence on medical and occupational exposure are reported. 2. Materials and methods This study was performed at the Pequeno Príncipe Hospital, one of the largest pediatric hospitals in Brazil, with 0–16 years old patients, in two phases: before (49 patients) and after (44 patients) the implementation of the optimization. The present study was done with the approval of the Hospital Ethical Committee.
Corresponding author. E-mail address: [email protected] (H.R. Schelin).
http://dx.doi.org/10.1016/j.radphyschem.2017.01.034 Received 30 September 2016; Received in revised form 25 January 2017; Accepted 27 January 2017 0969-806X/ © 2017 Elsevier Ltd. All rights reserved.
Please cite this article as: Filipov, D., Radiation Physics and Chemistry (2017), http://dx.doi.org/10.1016/j.radphyschem.2017.01.034
Radiation Physics and Chemistry (xxxx) xxxx–xxxx
D. Filipov et al.
Table 1 Optimization of the technical parameters. “NSF” is the number of spot films; “FI” is the number of fluoroscopy images; “FT” is the fluoroscopy time; “FS” is the field size on patient. “kVp”, “mAs” are the tube voltage and the current-time product, respectively, used for spot films. Parameter
NSF FI FT (min) FS (cm2) kVp mAs
<1 Before
After
6.0 ± 1.1 6.2 ± 0.7 1.6 ± 0.4 278 ± 46 59.1 ± 0.4 9.3 ± 1.3
5.5 ± 0.5 6.0 ± 1.5 0.8 ± 0.1 225 ± 12 71.2 ± 0.5 4.8 ± 0.6
1–5 y Reduct. (%) 8 3 50 19 −20 48
Before
After
6.8 ± 0.7 5.0 ± 0.0 1.4 ± 0.1 341 ± 27 60.6 ± 0.5 9.5 ± 0.5
6.4 ± 0.7 9.0 ± 0.0 1.0 ± 0.1 234 ± 17 71.9 ± 0.7 4.3 ± 0.4
5–10 y Reduct. (%) 6 −80 29 31 −19 55
Before
After
7.6 ± 0.5 15.0 ± 3.0 1.2 ± 0.2 426 ± 63 62.7 ± 1.0 12.1 ± 0.8
6.3 ± 1.3 8.8 ± 0.9 1.1 ± 0.2 318 ± 25 70.0 ± 0.0 5.2 ± 0.2
> 10 Reduct. (%) 17 41 8 25 −12 57
Before
After
Reduct. (%)
6.9 ± 0.6 4.0 ± 0.0 1.6 ± 0.2 705 ± 99 68.8 ± 2.3 16.0 ± 2.0
5.7 ± 0.9 10.0 ± 0.0 1.1 ± 0.1 360 ± 45 78.8 ± 2.0 5.7 ± 0.8
17 −150 31 49 −15 64
Table 2 PK,A and effective dose (E). Reference
This work
<1 y
Before After
Servomaa et al. (2000) NRPB (2002) Canevaro et al. (2004) Chateil et al. (2004) Iacob and Diaconescu (2004) Hiorns et al. (2006) Damilakis et al. (2006) Sorop et al. (2008) Hart et al. (2009) Dimitriadis et al. (2011) Emigh et al. (2013) Sulieman et al. (2014) Wambani et al. (2014) Yakoumakis et al. (2014)
1–5 y
PK,A (cGy cm2)
PK,A (cGy cm2)
160 ± 10 50 ± 10 135.1 70 205 ± 116 89 ± 39
160 ± 2 70 ± 10 37.6 200 319 ± 171 136 ± 59 125 ± 43 9.5 ± 11.4
6.4 ± 8.6 78.6 44 ± 37 75 221.8 18.2
151 ± 66 130 189.4 82.5
80 173.9
240 284.9
5–10 y
> 10 y
E (mSv)
PK,A (cGy cm2)
E (mSv)
1.14 ± 0.18 0.6 ± 0.1
280 ± 10 80 ± 10 373.1 325 330 ± 335 151 ± 56 270 ± 103 25 ± 26
1.11 ± 0.02 0.3 ± 0.0
1.0 ± 0.4
310 ± 129 240
1.9 0.77 ± 0.02
122.4
1.0 2.8
PK,A (cGy cm2) 610 ± 10 140 ± 30 936.2 560
610 ± 272 25 ± 26 1.4 ± 0.5
515 ± 283 640
0.75 ± 0.02 0.3 3.0
300
500
The fluoroscopy equipment used was the Philips Diagnost 93 overcouch system with a total nominal filtration of 2.5 mm Al. The LiF:Mg,Ti (for patient) and LiF:Mg,Cu,P (for staff) (RadPRO International GmbH, Wermelskirchen, Germany) thermoluminescent dosimeters (TLDs) were used for dose measurement. For each examination there were recorded:
The equivalent doses per procedure (HtProc) and the annual equivalent doses (HtAnn) for each investigated region was then estimated (Filipov et al., 2015).
•
3.1. Optimization
•
3. Results and discussion
Patient's anthropometric information: gender, age, body mass, upper-chest thickness (measured in the supine position).
Table 1 shows the changes made. Some essential in optimization of BM procedure factors (fluoroscopy pulsed mode, removal of antiscattering grid and additional filtration) were not considered. The used equipment did not allow such changes. Only the technical parameters were modified. During the optimization, the X-ray tube was positioned at its maximum distance from the image intensifier (150 cm), which represents an increase of 24%. Regarding the number of images, it was found that the number of spot films could be lower if more medical physicians accepted the fluoroscopy images, even with its relative low quality.
Technical information: kVp, mAs and exposure time of spot films; total fluoroscopy time; number of recorded images (for fluoroscopy and radiography); fluoroscopy mode (pulsed or continuous); use of antiscattering grid; field size on the table; focus-table and focusdetector distances.
The patient PK,A values were calculated from the entrance-surface air kerma (Filipov et al., 2015), obtained with the TLDs. To obtain effective doses, Monte Carlo simulations were performed with the software “CalDose” (Lima et al., 2011) that uses examination tube voltage, total filtration, focus-detector distance, field size and measured PK,A as the entrance parameters. This software has mathematical adult and pediatric human phantoms. In the case of pediatric BM examination, it is only possible to choose the phantoms that represent 5 or 10 years old patients. The equivalent doses of the staff were measured with TLDs positioned on the temples (near both eyes), on the neck lead protector and on the hands. For the analysis of the doses received by the staffs’ thyroids, the attenuation of the protector (with 0.5 mm lead equivalent) was determined and the TLD measurement on the protector was multiplied by the attenuation factor.
Table 3 DRLs - PK,A 75th percentile. (cGy.cm2). Reference This work
Before After
NRPB (2002) Chateil et al. (2004) Hiorns et al. (2006) Hart et al. (2009) Wambani et al. (2014)
2
<1 y
1–5 y
5–10 y
> 10 y
150 55
190 85
190 85
610 185
70 170 8 75 120
200 220 12 130 300
325 240 32 240 400
560 240 32 640 700
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Table 4 Estimative of the equivalent doses received by the staffs in each procedure - HtProc. “TF” is the total filtration; “FT” is the fluoroscopy time; “NSF” is the number of spot films; “Thyroid*” means over the lead protector. Reference
HtProc (µSv)
Technical Parameters Thyroid*
This work
Before
After
Coakley et al. (1997)
Kemerink et al. (2000) Damilakis et al. (2006)
Alejo et al. (2015)
Ubeda et al. (2016)
TF: 2.5 mm Al FT: 1.0 min NSF: 6.0 TF: 2.5 mm Al FT: 1.4 min NSF: 6.0 TF: 3.0 mm Al FT: 3.3 min NSF: 4–10 TF and FT: —— NSF: 12 TF: 4.0 mm Al FT: 1.5 min NSF: 3.5 TF: —— FT: 19.7 min NSF: —— TF: —— FT: 15.9 min NSF: ——
Hands
Eyes
Staff 1
Staff 2
Staff 1
Staff 2
Staff 1
Staff 2
52 ± 12
38 ± 11
83 ± 39
45 ± 8
48 ± 9
32 ± 9
28 ± 9
13 ± 5
43 ± 7
19 ± 5
25 ± 6
13 ± 4
1.5 ± 0.4
5.8 ± 1.0
30 ± 25 47
28.5 ± 12.1
0.2–116
one group. Also, in the present study, a rather small amount of patients was investigated, which means that each additional patient may change significantly the PK,A and/or the effective dose values.
According to the EC, a voltage of at least 70 kVp is recommended. This recommendation has been implemented and all examinations were performed with this minimum voltage. Consequently, the mAs was reduced. During this part of the study, the problem was noted: when operators were asked to increase voltage to the minimum of 70 kVp (and hence reducing the mAs), they showed some difficulties in carrying out such operation. They were used to increase the mAs without changing the kVp for larger patients or to improve image quality. The ICRP recommends collimation restricted to the region of interest, with a safety margin, especially in the case of uncooperative patients. The reduction of field size will reduce the amount of direct and scattered radiation and, consequently, the peripheral dose. The reduction of the radiation field was possible when patients were immobilized. A bag of sand (~ 5 kg) was used on the legs of ~55% of the patients.
3.3. Staff dose The distances from Staff 1 and Staff 2 to the central beam were increased, respectively, in 18% and 17%: Staff 1 increased the distance from 55 cm to 65 cm and Staff 2 increased its distance from 60 cm to 70 cm. Other information refers to the number of examinations in which the second professional was involved: Staff 2 participated only in 50% of the procedures in each phase. Table 4 presents the equivalent doses received by the staffs in each procedure. A reduction of ~ 55% at the second phase is noted for both staffs. After the optimization, HtProc obtained by Staffs 1 and 2 remained higher than 60% of the results from the similar studies. At the first phase, they were higher in 90% of the cases. It can also be noted that usually studies of occupational doses do not provide much information about technical parameters of examinations, which makes it difficult to compare.
3.2. Patient dose The results obtained before and after the optimization and in the similar studies are shown in Table 2. Approximately 15% of the results from the other researches showed lower PK,A values than the present study after the optimization in contrast to 60% obtained in the preoptimization phase. Although only the technical parameters were changed, it was possible to reduce, on average, the PK,A and the effective dose values by 70% and 60%, respectively. The DRLs were estimated as a 75th percentile before and after the optimization (Table 3). It was found that, before the optimization, our DRLs were higher than 50% of the other studies. After the optimization, our results were higher only than the obtained by Hiorns et al. (2006), where detailed information about technical parameters is not available. Comparing the both phases, the local DRLs have been reduced about 60%. Observing Tables 2 and 3, a wide variation of the PK,A and the effective doses in the different studies can be seen. This might be explained through the fact that the body size affects the dose received. It seems better to assign patients to narrower age groups that will reduce the effect of an unduly large range of body weights and sizes in
Table 5 HtAnnual for each investigated region (mSv). Before
After
Reduct. (%)
Lens Staff 1 Staff 2 ICRP Limit
Staff 1 Staff 2 ICRP Limit
35.0 ± 0.3 11.0 ± 0.2
18.2 ± 0.2 4.5 ± 0.1 20a
Thyroid (Under Lead Protector) 2.0 ± 0.0 1.1 ± 0.0 0.8 ± 0.0 0.3 ± 0.0 300
48 59
45 63
Hands Staff 1 Staff 2 ICRP Limit a
3
59.9 ± 1.1 15.2 ± 0.1
32.5 ± 0.2 6.8 ± 0.1 500
46 55
Averaged over defined periods of 5 years with no single year exceeding 50 mSv.
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children. Br. J. Radiol. 70, 933–936. http://dx.doi.org/10.1259/ bjr.70.837.9486070. Damilakis, J., Stratakis, J., Raissaki, M., Perisinakis, K., Kourbetis, N., Gourtsoyiannis, N., 2006. Normalized dose data for upper gastrointestinal tract contrast studies performed to infants. Med. Phys. 33 (4), 1033–1040. http://dx.doi.org/10.1118/ 1.2181297. Dimitriadis, A., Gialousis, G., Makri, T., Karlatira, M., Karaiskos, P., Georgiou, E., Papaodysseas, S., Yakoumakis, E., 2011. Monte Carlo estimation of radiation doses during paediatric barium meal and cystourethrography examinations. Phys. Med. Biol. 56, 367–382. http://dx.doi.org/10.1088/0031-9155/56/2/006. Emigh, B., Gordon, C.L., Connolly, B.L., Falkiner, M., Thomas, K.E., 2013. Effective dose estimation for pediatric upper gastrointestinal examinations using an anthropomorphic phantom set and metal oxide semiconductor field-effect transistor (MOSFET) technology. Pediatr. Radiol. 43, 1108–1116. http://dx.doi.org/10.1007/ s00247-013-2674-5. European Communities, 1996. European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics. Office for Official Publications of the European Communities, Luxembourg. Filipov, D., Schelin, H.R., Denyak, V., Paschuk, S.A., Porto, L.E., Ledesma, J.A., Nascimento, E.X., Legnani, A., Andrade, M.E.A., Khoury, H.J., 2015. Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures. Rad. Phys. Chem. 116, 267–272. http://dx.doi.org/10.1016/j.radphyschem.2015.05.036. Hart, D., Hillier, M.C., Wall, B.F., 2009. National reference doses for common radiographic, fluoroscopic and dental X-ray examinations in the UK. Br. J. Radiol. 82, 1–12. http://dx.doi.org/10.1259/bjr/12568539. Hiorns, M.P., Saini, A., Marsden, P.J., 2006. A review of current local dose–area product levels for paediatric fluoroscopy in a tertiary referral centre compared with national standards. Why are they so different? Br. J. Radiol. 79, 326–330 http://dx.doi.org/. 1259/bjr/36530782. Iacob, O., Diaconescu, C., 2004. Doses to patients from diagnostic medical radiation exposure in Romania. In: Proceedings of the 11th International Congress of the International Radiation Protection Association. Madrid. ICRP, 2013. Radiological protection in paediatric diagnostic and interventional radiology. Ann. ICRP 42, 2, (ICRP Publication 121). Kemerink, G.J., Borstlap, A.C.W., Frantzen, M.J., Schultz, F.W., Zoetelief, J., van Engelshoven, M.A., 2000. Patient and occupational dosimetry in double contrast barium enema examinations. Br. J. Radiol. 74 (881), 420–428. http://dx.doi.org/ 10.1259/bjr.74.881.740420. Lima, V.J., De, M., Cassola, V.F., Kramer, R., de Oliveira Lira, C.A.B., Khoury, H.J., Vieira, J.W., 2011. Development of 5 and 10 years old pediatric phantoms based on polygon mesh surfaces. Med. Phys. 38 (8), 325–329. http://dx.doi.org/10.1118/ 1.3615623. NRPB, 2002. Doses to patients from medical X-ray examinations in the UK – 2000 review. NRPB-W14, Chilton, UK. Servomaa, A., Komppa, T., Heikkilä, M., Parviainen, T., 2000. Patient doses in paediatric fluoroscopy examinations in Finland. Rad. Prot. Dosim. 90 (1–2), 239–243. Sorop, I., Mossang, D., Iacob, M.R., Dadulescu, E., Iacob, O., 2008. Update of diagnostic medical and x-ray exposures in Romania. J. Radiol. Prot. 28, 563–571 http://dx.doi. org/1088/0952-4746/28/4/008. Sulieman, A., Alzimami, K., Elhag, B., Babikir, E., Alsafi, K., 2014. Evaluation of radiation dose to pediatric patients during certain special procedures. Rad. Phys. Chem. 104, 267–271. http://dx.doi.org/10.1016/j.radphyschem.2013.11.034. Ubeda, C., Vano, E., Miranda, P., Aguirre, D., Riquelme, N., Dalmazzo, D., Galaz, S., 2016. Patient and staff doses in paediatric interventional cardiology derived from experimental measurements with phantoms. Phys. Med. 32, 176–181. http:// dx.doi.org/10.1016/j.ejmp.2015.11.009. Wambani, J.S., Korir, G.K., Tries, M.A., Korir, I.K., Sakwa, J.M., 2014. Patient radiation exposure during general fluoroscopy examinations. J. Appl. Clin. Med. Phys. 15 (2), 262–270. http://dx.doi.org/10.1120/jacmp.v15i2.4555. Yakoumakis, E., Dimitriadis, A., Gialousis, G., Makri, T., Karavasilis, E., Yakoumakis, N., Georgiou, E., 2014. Evaluation of organ and effective doses during paediatric barium meal examinations using PCXMC 2.0 Monte Carlo code. Rad. Prot. Dosim. 1, 1–8. http://dx.doi.org/10.1093/rpd/ncu174.
Table 5 shows the estimated values of the annual equivalent doses, for both phases. It can be seen that, after the optimization, the equivalent doses do not exceed the ICRP limits. Before the optimization, the eyes annual equivalent dose of Staff 1 was 85% higher than the annual limit, and Staff 2 received 70% of this limit. It should be mentioned that the obtained doses were not received by fixed staffs, but by the different professionals remained in the same positions. The other equivalent doses are much lower than the ICRP recommendations. 4. Conclusion The present study aimed to optimize the exposure technique in barium meal procedure according to the EC and the ICRP recommendations for pediatric fluoroscopy and to compare before and after the optimization: a) the value of the PK,A and the effective doses in pediatric patients; b) the equivalent doses in the region of the lens, thyroid and hands of professionals who participated in the procedure. The implemented modifications has reduced by 70% and 60% the PK,A and the effective dose, respectively, in pediatric patients. The obtained dose values are lower than approximately 75% of the results from similar studies. Regarding the occupational exposure, it was found that: a) the optimization made the annual equivalent doses for all studied organs lower than the limits set by the ICRP. b) the equivalent doses in one examination were, on average, below than in 75% of similar studies. Acknowledgments The authors would like to thank the Brazilian agencies CNPq, CAPES, and “Fundação Araucária” for financial support. References Alejo, L., Koren, C., Ferrer, C., Corredoira, E., Serrada, A., 2015. Estimation of eye lens doses received by pediatric interventional cardiologists. Appl. Rad. Isot. 103, 43–47. http://dx.doi.org/10.1016/j.apradiso.2015.05.008. Canevaro, L.V., Oliveira, R.R., Daltro, P.A., 2004. Radiation exposure of children during barium meal and micturatingcystourethrography examinations. In: Proceedings of the 11th International Congress of the International Radiation Protection Association. Madrid. Chateil, J.F., Rouby, C., Brun, M., Labessan, C., Diard, F., 2004. Mesure pratique de l’irradiation en radiopédiatrie: utilisation du produit dose surface en fluorographie numérique et pour les radiographies pulmonaires néonatales. J. Radiol. 85, 619–625 . http://dx.doi.org/10.1016/S0221-0363(04)97638-X. Coakley, K.S., Ratcliffe, J., Masel, J., 1997. Measurement of radiation dose received by the hands and thyroid of staff performing gridless fluoroscopic procedures in
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