The Current Use and Effectiveness of Bismuth Shielding in Computed Tomography: A Systematic Review
DOI:
https://doi.org/10.17140/ROJ-2-113Keywords:
Computed tomography, Bismuth shielding, Automated exposure control (AEC)Abstract
Background: The increased use of computed tomography (CT) has raised concerns regarding
the radiation dose received by radiosensitive organs. It is important that practical and reliable
dose reduction strategies are implemented to reduce patient radiation exposure.
Aims: The purpose of this article is to evaluate the current clinical use and effectiveness of
bismuth shielding as a dose reduction technique and assess its impact on image quality, in an
attempt to develop a recommendation for dose reduction in CT.
Methods: A systematic review of current literature was conducted using the PubMed and Scopus
databases. A total of 50 relevant articles were thoroughly assessed and evaluated.
Results: This review found that whilst bismuth shielding proves to provide significant dose reductions
to radiosensitive organs, numerous concerns exist including wasted radiation, reduced
image quality and unpredictable results when combined with AEC. Alternative methods such
as tube current modulation and iterative reconstruction algorithms can provide equivalent dose
savings at superior image quality, without the limitations of bismuth shields.
Conclusion: Until these alternative methods become available in all departments, bismuth
shielding remains a viable dose reduction strategy.
References
Sarma C, Hilbrum ME, Conner KE, Stevens SM, Woller SC, Elliott CG. Radiation and chest CT scan examinations: What do we know? Chest. 2012; 142(3): 750-760. doi: 10.1378/ chest.11-2863
Lee K, Lee W, Lee J, Lee B, Oh G. Dose reduction and image quality assessment in MDCT using AEC (D-DOM & Z-DOME) and in-plane bismuth shielding. Radiat Prot Dosimetry. 2010; 141(2): 162-167. doi: 10.1093/rpd/ncq159
Gunn ML, Kohr JR. State of the art: Technologies for com-puted tomography dose reduction. Emerg Radiol. 2010; 17(3): 209-218.
Radiological Society of North America. Radiation dose in x-ray and CT exams. 2015. Web site. http://www.radiologyinfo. org/en/pdf/safety-xray.pdf. Accessed October 23, 2016.
Colletti PM, Micheli OA, Lee OA. To shield or not to shield: Application of bismuth shields. AJR. 2013; 200(3): 502-507 doi: 10.2214/AJR.12.9997
Hoang JK, Yoshizumi TT, Ngyuen GG, et al. Organ-based dose current modulation and thyroid shields: Techniques of radi-ation dose reduction for neck CT. AJR. 2012; 198(5): 1132-1138. doi: 10.2214/AJR.11.7445
Lincoln L, Bernland M. To shield or not to shield? Society of computed tomography and magnetic resonance. 2012. Web site. http://www.scbtmr.org/Portals/9/Meetings/2012/Symposium/ To%20Shield%20or%20Not%20to%20Shield-Berland.pdf. Ac-cessed October 23, 2016.
Chatterson LC, Leswick DA, Fladeland DA, Hunt MM, Web-ster ST. Lead versus bismuth-antimony shield for fetal dose reduction at different gestational ages at CT pulmonary angi-ography. Radiology. 2011; 260(2): 560-570. doi: 10.1148/ra-diol.11101575
American Association of Physicists in Medicine. Posi-tion statement on the use of bismuth shielding for the pur-pose of dose reduction in CT scanning. AAPM Board of Directors. Web site. http://citeseerx.ist.psu.edu/viewdoc/ summary?doi=10.1.1.231.4997. Updated Feb 2012, Cited Feb 16, 2016. Accessed October 23, 2016.
Chang KH, Lee W, Choo DM, Lee CS, Kim Y. Dose reduc-tion in CT using bismuth shielding: Measurements and monte Carlo simulations. Radiat Prot Dosimetry. 2009; 138(4): 382- 388. doi: 10.1093/rpd/ncp278
Ngaile JE, Uiso C, Msaki P, Kazema, R. Use of lead shields for radiation protection of superficial organs in patients under-going head CT examinations. Radiol Prot Dosimetry. 2008; 130(4): 490-498. doi: 10.1093/rpd/ncn095
Higgins J, Green S. Cochrane handbook for systematic re-views of interventions. 2016. Web site. http://www.cochrane-handbook.org. Accessed October 23, 2016.
Fleming PS, Koletsi D, Pandis N. Blinded by PRISMA: Are systemic reviewers focusing on PRISMA and ignoring other guidelines? PLoS ONE. 2014; 9(5): e96407. doi: 10.1371/jour-nal.pone.0096407
Stroup DF, Berlin JA, Morton SC, et al. Meta-analysis of observational studies in epidemiology: A proposal for re-porting. JAMA. 2000; 283(15): 2008-2012. doi: 10.1001/ jama.283.15.2008
Khan KS, Kunz R, Kleijnen J, Antes, G. Five steps to con-ducting a systematic review. J R Soc Med. 2003; 96(3): 118-121.
Samei E. Pros and cons of organ shielding for CT imaging. Pediatr Radiol. 2014; 44(3): 495-500. doi: 10.1007/s00247-014- 3084-z
Wang J, Duan X, Christner JA, Leng S, Grant KL, McCol-lough CH. Bismuth shielding, organ-based tube current modu-lation and global reduction of tube current for dose reduction to the eye at head CT. Radiology. 2012; 262(1): 191-198. doi: 10.1148/radiol.11110470
Nikupaavo U, Kaasalainen T, Reijonen V, Ahonen SM, Kortesniemi M. Lens dose in routine head CT: Comparison of different optimization methods with anthropomorphic phan-toms. AJR. 2015; 204(1): 117-123. doi: 10.2214/AJR.14.12763
Huggett J, Mukonoweshuro W, Loader R. A phantom-based evaluation of three commercially available patient organ shields for computed tomography x-ray examinations in diagnostic ra-diology. Radiat Prot Dosimetry. 2013; 155(2): 161-168. doi: 10.1093/rpd/ncs327
Catuzzo, P, Aimonetto, S, Fanelli, G, et al. Dose reduction in multi-slice CT by means of bismuth shields: Results of in vivo measurements and computed evaluation. Radiol Med. 2010; 115(1): 152-169. doi: 10.1007/s11547-009-0469-4
Gbelcona L, Nikodemova D, Horathova M. Dose reduction using bismuth shielding during pediatric CT examinations in Slovakia. Radiol Prot Dosimetry. 2011; 147(1-2): 160-163. doi: 10.1093/rpd/ncr336
Morford K, Watts LK. Bismuth shielding during CT exams: A literature review. Radiol Manage. 2012; 34(3): 45-47.
Mendes M, Costa F, Figueira C, Madeira P, Teles P, Vaz, P. Assessment of patient dose reduction by bismuth shielding in CT using measurements, GEANT4 and MCNPZ simulations. Radiol Prot Dosimetry. 2015; 165(1-4): 175-181. doi: 10.1093/ rpd/ncv059
Raissaki M, Perisinakis K, Damilakis J, Gourtsoyiannis N. Eye-lens bismuth shielding in pediatric head CT: Artifact evaluation and reduction. Pediatr Radiol. 2010; 40(11): 1748- 1754. doi: 10.1007/s00247-010-1715-6
Seoung YH. Evaluation of radiation dose reduction dur-ing CT scans using oxide bismuth and nano-barium sulfate shields. JKPS. 2015; 67(1): 1-6. Web site. https://arxiv.org/ abs/1503.03702. Accessed October 23, 2016.
Lai CW, Cheung HY, Chan TP, Wong TH. Reducing the radi-ation dose to the eyes lens region during CT brain examination: The potential beneficial effect of the combined use of bolus and a bismuth shield. Radioprotection. 2015; 50(3): 195-201. doi: 10.1051/radiopro/2015003
Liebmann M, Lullau T, Kluge A, Poppe B, Von Boetticher H. Patient radiation protection covers for head CT scans: A clini-cal evaluation of their effectiveness. Rofo. 2014; 186(11): 1022- 1027. doi: 10.1055/s-0034-1366279
Kim S, Frush DP, Yoshizumi TT. Bismuth shielding in CT: Support for use in children. Pediatr Radiol. 2010; 40(11): 1739- 1743. doi: 10.1007/s00247-010-1807-3
DeMaio DN, Turk J, Palmer E. Shielding in computed tomog-raphy: An update. Radiol Technol. 2014; 85(5): 563-569. Web site. http://www.radiologictechnology.org/content/85/5/563.ex-tract. Accessed October 23, 2016.
Antypas EJ, Sokhandon F, Farah M, et al. A comprehensive approach to CT radiation dose reduction: One institution’s expe-rience. AJR. 2011; 197(4): 935-940. doi: 10.2214/AJR.11.6460
Lee Y, Park ET, Cho P, et al. Comparative analysis of ra-diation dose and image quality between thyroid shielding and unshielding during CT examination of the neck. AJR. 2011; 196(3): 611-615. doi: 10.2214/AJR.10.4955
Inkoom S, Papadakis A, Raissaki M, et al. Pediatric neck multi-detector computed tomography: The effect of bismuth shielding on thyroid dose and image quality. Radiat Prot Dosimetry. 2016; pii: ncw007. doi: 10.1093/rpd/ncw007
Geleijns J, Wang J, McCollough CH. The use of breast shielding for dose reduction in pediatric CT: Arguments against the proposition. Pediatr Radiol. 2010; 40(11): 1744-1747. doi: 10.1007/s00247-010-1808-2
Kim YK, Sung YM, Choi JH, Kim EY, Kim HS. Reduced radiation exposure of the female breast during low-dose chest CT using organ-based tube current modulation and a bismuth shield: Comparison of image quality and radiation dose. AJR. 2013; 200(3): 537-544. doi: 10.2214/AJR.12.9237
Mathieu KD, Cody DD. Partial arc beam filtration: A nov-el approach to reducing CT breast radiation dose. AJR. 2013; 200(3): 601-607. doi: 10.2214/AJR.12.8771
Rupcich F, Badal A, Popescu LM, Kyprianou I, Schmidt TG. Reducing radiation dose to the female breast during CT coronary angiography: A simulation study comparing breast shielding, angular tube current modulation, reduced kV, and partial angle protocols using unknown location signal detectability metric. Med Phys. 2013; 40(8): 081921. doi: 10.1118/1.4816302
Coakley FV, Gould R, Yeh BM, Arenson RL. CT radiation dose: What can you do right now in your practice? AJR. 2011; 196(3): 619-625. doi: 10.2214/AJR.10.5043
Hulten E, Devine P, Welch T, et al. Comparison of coronary CT angiography image quality with and without breast shields. AJR. 2013; 200(3): 529-536. doi: 10.2214/AJR.11.8302
Wang J, Duan X, Christner JA, Leng S, Yu L, McCollough CH. Radiation dose reduction to the breast in thoracic CT: Comparison of bismuth shielding, organ-based tube current modulation and use of a globally decreased tube current. Med Phys. 2011; 38(11): 6084-6092. doi: 10.1118/1.3651489
Zhang J, Oates EM. CT bismuth breast shielding: Is it time to make your own decision. AJR. 2012; 9(12): 856-858. doi: 10.1016/j.jacr.2012.05.008
Revel MP, Audureau E, Benzakoun J, Lederlin M, Chabi ML, Rousset P. Breast dose reduction options during thoracic CT: Influence of breast thickness. AJR. 2015; 204(4): 421-428. doi: 10.2214/AJR.14.13255
Abadi S, Mehrez H, Ursani A, Parker M, Paul N. Direct quantification of breast dose during coronary CT angiography and evaluation of dose reduction strategies. AJR. 2011; 196(2): W152-W158. doi: 10.2214/AJR.10.4626
Small G, Kazmi M, DeKemp R, Chow B. Established and emerging dose reduction methods in cardiac computed tomography. J Nucl Cardiol. 2011; 18(4): 570-579. doi: 10.1007/ s12350-011-9400-1
Einstein AJ, Elliston CD, Groves DW, et al. Effect of bismuth breast shielding on radiation dose and image quality in coronary CT angiography. J Nucl Cardiol. 2011; 19(1): 100-108. doi: 10.1007/s12350-011-9473-x
Rupcich F, Kyrianou I, Badal A, Schmidt TG. Energy depo-sition in the breast during CT scanning: Quantification and im-plications for dose reduction. SPIE Medical Imaging (796128). 2011. doi: 10.1117/12.878861
Servaes S, Zhu X. The effects of bismuth breast shields in conjunction with automatic tube current modulation in CT imaging. Pediatr Radiol. 2013; 43(10): 1287-1294. doi: 10.1007/ s00247-013-2687-0
Lai NK, Liao YL, Chen TR, Tyan YS. Real-time estimation of dose reduction for pediatric CT using bismuth shielding. 2011; 46(12): 2039-2043.
Akhlaghi P, Miri-Hakimabad H, Rafat-Motavalli L. Effects of shielding the radiosensitive superficial organs of ORNL pediatric phantoms on dose reduction in computed tomography. J Med Phys. 2014; 39(4): 238-246. doi: 10.4103/0971-6203.144490
Sancaktutar AA, Bozkurt Y, Onder H, et al. A new practical model of testes shield. The effectiveness during abdomniopelvic computed tomography. J Androl. 2012; 35(5): 984-989. doi: 10.2164/jandrol.111.015560
Hopper AD, King SH, Lobell ME, TenHave TR, Weaver JS. The breast: In-plane x-ray protection during diagnostic thoracic CT – Shielding with bismuth radioprotective garments. Radiology. 1997; 205(3): 853-858. doi: 10.1148/ radiology.205.3.9393547
Iball GR, Brettle DS. Organ and effective dose reduction in adult chest CT using abdominal lead shielding. Br J Radiol. 2011; 84(1007): 1020-1026. doi: 10.1259/bjr/53865832
McCollough CH, Wang J, Gould RG, Orton CG. Point/ Counterpoint: The use of bismuth shields for CT should be discouraged. Med Phys. 2012; 39(5): 2321-2323. doi: 10.1118/1.3681014
Curtis JR. Computed tomography shielding methods: A literature review. Radiol Technol. 2010; 81(5): 428-436. Web site. http://www.radiologictechnology.org/content/81/5/428. short. Accessed October 23, 2016.
Dobbs M, Ahmed R, Patrick LE. Bismuth breast and thyroid shield implementation for pediatric CT. Radiol Manage. 2011; 33(1): 18-22. Web site. http://citeseerx.ist.psu.edu/viewdoc/dow nload?doi=10.1.1.675.7766&rep=rep1&type=pdf. Accessed
Costello JE, Cecava ND, Tucker JE, Bau JL. CT radiation dose: Current controversies and dose reduction strategies. AJR. 2013; 201(6): 1283-1290. doi: 10.2214/AJR.12.9720
Goldin D, Emerson S, Farah MC, et al. Shielding artificially increases the attenuation of water: Study of CT gradient attenu-ation induced by shielding (CT GAINS). Acad Radiol. 2013; 20(2): 231-237. doi: 10.2214/AJR.12.9720
Correia PD, Granzotti CR, Santos Y, da S, Brochi MA, de Azevedo-Marques PM. Characterization of a lead breast shield-ing for dose reduction in computed tomography. Radiol Bras. 2014; 47(4): 223-227. doi: 10.1590/0100-3984.2013.1861
Matsubara K, Sugai M, Toyodoa A, et al. Assessment of an organobased tube current modulation in thoracic computed to-mography. J Appl Clin Med Phys. 2012; 13(2): 148-157. doi: 10.1002/acm2.12024
Lai NK, Chen TR, Tyan, YS, Tsai HY. Off-center effect on dose reduction to anterior surfaces with organ-based tube-current modulation. Rad Meas. 2013; 59: 155-159.
Kim MS, Choi J, Kim SY, Kweon DC. Adaptive statisti-cal iterative reconstruction and bismuth shielding for evalua-tion of dose reduction to the eye and image quality during head CT. J Korean Phys Soc. 2014; 64(6): 923-928. doi: 10.3938/ jkps.64.923
Published
How to Cite
Issue
Section
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
All content published in Radiology (ROJ) is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). This license allows anyone to copy, distribute, transmit, and adapt the work — including for commercial purposes — provided appropriate credit is given to the original author(s) and source.