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甲状腺癌约占全身恶性肿瘤的1%,且其发病率在全世界呈上升趋势。分化型甲状腺癌(differentiated thyroid carcinoma,DTC)包括乳头状癌和滤泡状癌,占甲状腺恶性肿瘤的80%以上,目前国内外公认的最佳治疗方法是“手术+131I治疗+TSH抑制”。131I是最早用于临床的核素之一,其物理半衰期是8.04 d,主要γ射线的能量是365 keV,同时发出β射线。DTC患者术后经131I治疗后对患者自身、工作人员、患者家属的及周围的公众都可能造成一定的辐射危害。本文就DTC患者术后131I治疗有关的辐射防护规定和建议,以及辐射剂量与防护作一综述,以更好地规范131I治疗DTC患者的辐射防护。
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2002年,我国以国际辐射防护委员会(International Commission on Radiological Protection,ICRP)历次基本建议书和国际原子能机构有关国际组织基本安全标准作为参照,发布了GB18871-2002《电离辐射防护与辐射源安全基本标准》[1],明确规定了辐射相关工作人员和公众受到来自获准实践的综合照射所致的个人总有效剂量和有关器官或组织的总剂量当量不超过相应的剂量限值。对从事辐射工作的人员,连续5年内年平均有效剂量低于20 mSv,任何单一年份内不超过50 mSv;一年中晶状体所受剂量当量低于150 mSv;四肢(手和足)或皮肤的年剂量当量不超过500 mSv。对于从事各种实践活动导致公众人员的照射不得超过下列剂量限值:一年内有效剂量为1 mSv;特殊情况下,如果5个连续年的年平均剂量不超过1 mSv,则某一单一年份的有效剂量可提高到5 mSv;眼晶状体的年当量剂量15 mSv;四肢、皮肤年当量剂量50 mSv。
对于工作人员体素、内衣、工作服以及工作场所的设备和地面等表面放射性污染的控制应遵循表 1所规定的限值[1]。
表面类型 α放射性物质 β放射性物质 极毒性 其他 工作台、设备、墙壁、地面 控制区a 4 4×10 4×10 监督区 4×10-1 4 4 工作服、手套、工作鞋 控制区、监督区 4×10-1 4×10-1 4 手、皮肤、内衣、工作袜 4×10-2 4×10-2 4×10-1 注:表中,a:该区内的高污染子区除外。 表 1 工作场所的表面放射性污染控制水平(Bq/cm2)
Table 1. Control level of surface radioactive contamination in the workplace(Bq/cm2)
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2004年ICRP发布的放射性核素治疗后患者的辐射防护建议[2]中并未对131I治疗患者出院活度及剂量率水平作任何推荐,而是对患者所致周围人员的照射剂量推荐了剂量限值和剂量约束值。对医务人员或公众的外照射遵循剂量限值,而对于患者的陪护和照料亲属包括儿童则使用剂量约束值的概念。
欧洲放射防护委员会对不同年龄人群131I治疗患者的剂量约束值规定如下:家庭成员中儿童(包括胎儿)为1 mSv,成人为3 mSv(这一剂量不包括照顾重病患者的家人和亲密朋友,比如母亲照顾住院的患儿),老年人(超过60岁)为15 mSv,而普通公众为0.3 mSv[3]。不同欧洲国家对131I治疗患者的出院标准的规定有所不同。大多数国家采用400~600 MBq作为131I治疗患者的出院指导活度。在德国,这一标准尤其严格,接受131I治疗的患者须住院至少48 h,出院的活度限值为250 MBq。
1997年,美国核管理委员会明确规定:对于服用核素治疗的患者,如果其周围个体所接受的有效剂量当量经估算可能小于5 mSv,周围1 m处的当量剂量率小于0.05 mSv/h,或者服用131I的剂量小于1100 MBq,则允许该患者解除隔离[4]。2006年,国家原子能机构推荐采用这一标准作为患者出院的指导剂量水平[5]。
2002年,我国《电离辐射防护与辐射源安全基本标准》[1]规定:接受放射性核素治疗的患者应在其体内的放射性物质的活度降至一定水平后才能出院,以控制其家庭与公众成员可能受到的照射。接受了131I治疗的患者,其体内的放射性活度降低至400 MBq(10.8 mCi)之前不得出院。必要时应向患者提供其与人员接触时辐射防护措施的书面指导。
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近年来核医学对131I的使用活度不断增加,随着防护设备的改善、工作人员防护意识及教育、训练和科室管理的加强,各国报道的核医学科工作人员的辐射剂量存在较大差异,但均有不同程度的减低,且远远低于国内外主流机构所规定的放射工作人员的剂量限值[22-25]。
Kim等[26]估算出DTC患者接受大剂量131I治疗后,距离身体1 m处随时间变化的辐射剂量当量公式为:Hbody=0.236e-0.0501t(mSv·h-1·GBq-1);紧贴患者甲状腺的辐射剂量当量公式为:Hthy=2.676e-0.0443t(mSv·h-1·GBq-1);患者体内131I的有效半衰期为13.86 h。这些公式可用于估算DTC患者131I治疗后对周围人群的辐射剂量当量并可推算合理的住院时间。
一些研究关注了经131I治疗后的瘫痪患者对护理人员的辐射剂量问题。Barrington等[27]研究发现,服131I后的DTC患者对护理人员的辐射剂量很大程度上取决于患者的生活自理能力,其护理人员1周的累积辐射剂量当量估算见表 2。
患者治疗次数 患者服131I剂量(MBq) 患者生活能否自理 护理人员辐射剂量当量(mSv) 首次 1840 完全能 0.08 完全不能 6.3 再次或复发后 3700 完全能 0.18 完全不能 12.3 7400 完全能 0.36 完全不能 24.6 表 2 DTC术后患者服131I后对护理人员1周的累积辐射剂量当量估算
Table 2. Accumulation radiation dose equivalent estimate of DTC postoperative patients of 131I treatment on nursing staff for 1 week
然而Williams和Woodward[28]认为,对于完全瘫痪的服131I患者的护理人员的辐射剂量当量被高估了,对于1例服用131I 1 GBq的瘫痪DTC患者,按照公式估算得到的护理人员7 d(按每8小时轮班护理)的总辐射剂量当量约为3400 μSv,但是实际测量得到的总辐射剂量当量为148 μSv,实际接触时间要小于之前的估算,因此护理1例131I治疗的完全瘫痪患者的辐射剂量当量在标准限值之内。
对于核医学科医务人员来说,铅衣是一个不错的辐射防护的选择,尽管其不被常规使用且防护效果因核素的不同而有差异。一些学者认为铅衣对核医学科医务人员仅仅提供了很少的防护,并不能有效保证核医学科的常规防护要求[29]。而另一些学者则认为,当患者的辐射剂量较高,或者工作人员与之接触时间较长时,铅衣是有必要的,且厚度应大于5 mm铅等值[30]。但有许多因素制约了铅衣在核医学科的广泛应用,例如:铅衣较重致长时间穿戴时引起医务人员背痛;轻型防护服可能对γ射线的防护并不适合;核医学科γ射线透过铅衣可能产生低能量的散射电子,从而加大工作人员的辐射剂量[31]。澳大利亚弗林德斯医学中心核物理的研究人员利用蒙特卡罗仿真研究发现,对于140 keV的γ光子,在铅衣后1 mm以内辐射剂量将增加50%~300%,且越薄的铅衣辐射剂量增加幅度越大;但在铅衣后1 mm以外,辐射剂量减小,140 keV的光子在铅衣后1 mm处辐射剂量减少20%~80%,铅衣后2 cm处减少幅度相似[31]。Young[32]采用新的测量方法研究表明,在短距离内,距离防护中的平方反比定律被大大高估,而使用铅衣能不同程度地减少辐射剂量,其中对99Tcm的防护效果最佳,能够减少64.5%的辐射剂量。131I发射的γ射线的能量介于99Tcm与高能正电子核素之间,医务人员在患者131I辐射剂量较高或者接触时间较长时,使用铅衣是能够起到一定的防护效果的。
分化型甲状腺癌术后患者131I治疗的辐射剂量与防护
Radiation dose and protection of differentiated thyroid carcinoma postoperative patients with 131I treatment
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摘要: 监测分化型甲状腺癌(DTC)患者术后131I治疗的辐射剂量并规范其辐射防护对DTC患者131I治疗后自身及周围人群的健康有重要意义。目前研究表明,131I治疗的DTC患者自身的辐射不良反应大多都能得到较有效地缓解和控制。只要能严格规范地遵守131I治疗DTC的辐射防护相关法规和建议,加强辐射剂量监测,并对患者、工作人员和患者家属进行适当的教育和指导,其对周围人群的辐射剂量都能达到和符合国际上的辐射防护规定。Abstract: It is of great significance to monitor radiation dose and standardize radiation protection of differentiated thyroid carcinoma (DTC) patients after 131I treatment.It can protect patients and the surrounding people from radiation risks.The present study showed that the adverse reactions can be alleviated and controlled effectively in DTC patients after 131I treatment.The radiation dose of the surrounding people can be in line with the international radiation protection regulations, as long as the related laws and regulations of radiation protection in 131I treatment can be strictly obeyed, as well as the radiation dose is monitored and the right guidance and instructions are given to the patients, staff and family members.
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Key words:
- Thyroid neoplasms /
- Iodine radioisotopes /
- Brachytherapy /
- Radiation dosage /
- Radiation protection
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表 1 工作场所的表面放射性污染控制水平(Bq/cm2)
Table 1. Control level of surface radioactive contamination in the workplace(Bq/cm2)
表面类型 α放射性物质 β放射性物质 极毒性 其他 工作台、设备、墙壁、地面 控制区a 4 4×10 4×10 监督区 4×10-1 4 4 工作服、手套、工作鞋 控制区、监督区 4×10-1 4×10-1 4 手、皮肤、内衣、工作袜 4×10-2 4×10-2 4×10-1 注:表中,a:该区内的高污染子区除外。 表 2 DTC术后患者服131I后对护理人员1周的累积辐射剂量当量估算
Table 2. Accumulation radiation dose equivalent estimate of DTC postoperative patients of 131I treatment on nursing staff for 1 week
患者治疗次数 患者服131I剂量(MBq) 患者生活能否自理 护理人员辐射剂量当量(mSv) 首次 1840 完全能 0.08 完全不能 6.3 再次或复发后 3700 完全能 0.18 完全不能 12.3 7400 完全能 0.36 完全不能 24.6 -
[1] 中华人民共和国国家质量监督检验检疫总局. GB18871-2002电离辐射防护与辐射源安全基本标准[S].北京: 中国标准出版社, 2003.
[2] International Commission on Radiological Protection. Release of patients after therapy with unsealed radionuclides[R]. ICRP Publication 94. Ann ICRP, 2004, 34(2): v-vi, 1-79. [3] European Commission. Radiation protection 97: radiation protection following iodine-131 therapy (exposures due to outpatients or discharged inpatients)[R]. Belgium: Office for Official Publications of the European Communities, 1998. [4] Vetter RJ. Regulations for radioiodine therapy in the United States: current status and the process of change[J]. Thyroid, 1997, 7(2): 209-211. doi: 10.1089/thy.1997.7.209 [5] International Atomic Energy Agency. Nuclear medicine resources manual[R]. Vienna: International Atomic Energy Agency, 2006. [6] 中华医学会内分泌学分会, 中华医学会外科学分会, 中国抗癌协会头颈肿瘤专业委员会, 等.甲状腺结节和分化型甲状腺癌诊治指南[J].中国肿瘤临床, 2012, 39(17): 1249-1272.
[7] Kloos RT, Duvuuri V, Jhiang SM, et al. Nasolacrimal drainage system obstruction from radioactive iodine therapy for thyroid carcinoma[J]. J Clin Endocrinol Metab, 2002, 87(12): 5817-5820. doi: 10.1210/jc.2002-020210 [8] Jeong SY, Kim HW, Lee SW, et al. Salivary gland function 5 years after radioactive iodine ablation in patients with differentiated thyroid cancer: direct comparison of pre- and postablation scintigraphies and their relation to xerostomia symptoms[J]. Thyroid, 2013, 23(5): 609-616. doi: 10.1089/thy.2012.0106 [9] Kolbert KS, Pentlow KS, Pearson JR, et al. Prediction of absorbed dose to normal organs in thyroid cancer patients treated with 131I by use of 124I PET and 3-dimensional internal dosimetry software[J]. J Nucl Med, 2007, 48(1): 143-149. [10] Jentzen W, Schneider E, Freudenberg L, et al. Relationship between cumulative radiation dose and salivary gland uptake associated with radioiodine therapy of thyroid cancer[J]. Nucl Med Commun, 2006, 27(8): 669-676. doi: 10.1097/00006231-200608000-00009 [11] de Keizer B, Hoekstra A, Konijnenberg MW, et al. Bone marrow dosimetry and safety of high 131I activities given after recombinant human thyroid-stimulating hormone to treat metastatic differentiated thyroid cancer[J]. J Nucl Med, 2004, 45(9): 1549-1554. [12] Lassmann M, Hänscheid H, Reiners C, et al. Blood and bone marrow dosimetry in radioiodine therapy of differentiated thyroid cancer after stimulation with rhTSH[J]. J Nucl Med, 2005, 46(5): 900-901. [13] 王建涛, 赵卫威, 刘斌, 等. 131I治疗对青少年分化型甲状腺癌患者外周血的影响[J].生物医学工程学杂志, 2011, 28(6): 1185-1188.
[14] Pahlka RB, Sonnad JR. The effects of dialysis on 131I kinetics and dosimetry in thyroid cancer patients-a pharmacokinetic model[J]. Health Phys, 2006, 91(3): 227-237. doi: 10.1097/01.HP.0000214660.13440.64 [15] Courbon F, Caselles O, Zerdoud S, et al. Iodine-131 pharmacokinetics in patients on hemodialysis for end stage renal disease: clinical implications[J]. Q J Nucl Med Mol Imaging, 2006, 50(4): 363-370. [16] Sawka AM, Lakra DC, Lea J, et al. A systematic review examining the effects of therapeutic radioactive iodine on ovarian function and future pregnancy in female thyroid cancer survivors[J]. Clin Endocrinol (Oxf), 2008, 69(3): 479-490. doi: 10.1111/j.1365-2265.2008.03222.x [17] Hyer S, Vini L, O′Connell M, et al. Testicular dose and fertility in men following I131 therapy for thyroid cancer[J]. Clin Endocrinol(Oxf), 2002, 56(6): 755-758. doi: 10.1046/j.1365-2265.2002.t01-1-01545.x [18] Garsi JP, Schlumberger M, Ricard M, et al. Health outcomes of children fathered by patients treated with radioiodine for thyroid cancer[J]. Clin Endocrinol(Oxf), 2009, 71(6): 880-883. doi: 10.1111/j.1365-2265.2009.03561.x [19] Rosário PW, Barroso AL, Rezende LL, et al. Testicular function after radioiodine therapy in patients with thyroid cancer[J]. Thyroid, 2006, 16(7): 667-670. doi: 10.1089/thy.2006.16.667 [20] Popova L, Hadjidekova V, Hadjieva T, et al. Cytokinesis-block micronucleus test in patients undergoing radioiodine therapy for differentiated thyroid carcinoma[J]. Hell J Nucl Med, 2005, 8(1): 54-57. [21] Sawka AM, Thabane L, Parlea L, et al. Second primary malignancy risk after radioactive iodine treatment for thyroid cancer: a systematic review and meta-analysis[J]. Thyroid, 2009, 19(5): 451-457. doi: 10.1089/thy.2008.0392 [22] Samerdokiene V, Atkocius V, Ofomala R. Radiation exposure received by the medical radiation workers in Lithuania at the Institute of Oncology, Vilnius University, 2004-2011[J]. Radiat Prot Dosimetry, 2013, 157(1): 152-157. doi: 10.1093/rpd/nct111 [23] Piwowarska-Bilska H, Supinska A, Listewnik MH, et al. Radiation doses of employees of a Nuclear Medicine Department after implementation of more rigorous radiation protection methods[J]. Radiat Prot Dosimetry, 2013, 157(1): 142-145. doi: 10.1093/rpd/nct107 [24] Piwowarska-Bilska H, Birkenfeld B, Gwardyś A, et al. Occupational exposure at the Department of Nuclear Medicine as a work environment: A 19-year follow-up[J]. Pol J Radiol, 2011, 76(2): 18-21. [25] Masood K, Ahmad M, Zafar J, et al. Assessment of occupational exposure among pakistani medical staff during 2007-2011[J]. Australas Phys Eng Sci Med, 2012, 35(3): 297-300. doi: 10.1007/s13246-012-0156-y [26] Kim CB, Jung JW, Jeong KH, et al. Measurements and prediction of the ambient dose rate from patient receiving radioiodine administration after thyroid ablation[J]. Radiat Prot Dosimetry, 2012, 151(1): 158-161. doi: 10.1093/rpd/ncr456 [27] Barrington SF, Kettle AG, O′Doherty MJ, et al. Radiation dose rates from patients receiving iodine-131 therapy for carcinoma of the thyroid[J]. Eur J Nucl Med, 1996, 23(2): 123-130. doi: 10.1007/BF01731834 [28] Williams CE, Woodward AF. Management of the helpless patient after radioiodine ablation therapy-are we being too strict?[J]. Nucl Med Commun, 2005, 26(10): 925-928. doi: 10.1097/00006231-200510000-00012 [29] Cherry SR, Sorenson JA, Phelps ME. Physics in nuclear medicine[M]. 4th ed. Philadelphia: Saunders, 2012. [30] Muir S, McLeod R, Dove R. Light-weight lead aprons-light on weight, protection or labelling accuracy?[J]. Australas Phys Eng Sci Med, 2005, 28(2): 128-130. doi: 10.1007/BF03178704 [31] Fog LS, Collins P. Monte Carlo simulation of the dose to nuclear medicine staff wearing protective garments[J]. Australas Phys Eng Sci Med, 2008, 31(4): 307-316. doi: 10.1007/BF03178600 [32] Young AM. Dose rates in nuclear medicine and the effectiveness of lead aprons: updating the department′s knowledge on old and new procedures[J]. Nucl Med Commun, 2013, 34(3): 254-264. [33] North DL. Uptake of 131I in households of thyroid cancer patients[J]. Health Phys, 2013, 104(4): 434-436. doi: 10.1097/HP.0b013e31828326ae [34] Rémy H, Coulot J, Borget I, et al. Thyroid cancer patients treated with 131I: radiation dose to relatives after discharge from the hospital[J]. Thyroid, 2012, 22(1): 59-63. [35] Gabriel S, Farman-Ara B, Bourrelly M, et al. Radiation doses to cohabitants of patients undergoing radioiodine ablation for thyroid cancer: poor compliance with radiation protection guidelines but low radiation exposure[J]. Nucl Med Commun, 2011, 32(9): 829-833. doi: 10.1097/MNM.0b013e328347f1c2 [36] de Carvalho JW, Sapienza M, Ono C, et al. Could the treatment of differentiated thyroid carcinoma with 3.7 and 5.55 GBq of (131I)NaI, on an outpatient basis, be safe?[J]. Nucl Med Commun, 2009, 30(7): 533-541. doi: 10.1097/MNM.0b013e32832b79bc [37] Willegaignon J, Sapienza M, Ono C, et al. Outpatient radioiodine therapy for thyroid cancer: a safe nuclear medicine procedure[J]. Clin Nucl Med, 2011, 36(6): 440-445. doi: 10.1097/RLU.0b013e3182184fa0 [38] Sisson JC, Freitas J, McDougall IR, et al. Radiation safety in the treatment of patients with thyroid diseases by radioiodine 131I: practice recommendations of the American Thyroid Association[J]. Thyroid, 2011, 21(4): 335-346. doi: 10.1089/thy.2010.0403 [39] Sapienza MT, Willegaignon J, Ono CR, et al. Radioiodine therapy of differentiated thyroid cancer: radiologic impact of out-patient treatment with 100 to 150 mCi Iodine-131 activities[J]. Arq Bras Endocrinol Metabol, 2009, 53(3): 318-325. doi: 10.1590/S0004-27302009000300004 [40] de Carvalho AB Jr, Hunt J, Silva AX, et al. Use of a voxel phantom as a source and a second voxel phantom as a target to calculate effective doses in individuals exposed to patients treated with 131I[J]. J Nucl Med Technol, 2009, 37(1): 53-56. doi: 10.2967/jnmt.108.058172 [41] Asli IN, Baharfard N, Shafiei B, et al. Relation between clinical and laboratory parameters with radiation dose rates from patients receiving iodine-131 therapy for thyroid carcinoma[J]. Radiat Prot Dosimetry, 2010, 138(4): 376-381. doi: 10.1093/rpd/ncp269 [42] Nakada K, Ishibashi T, Takei T, et al. Does lemon candy decrease salivary gland damage after radioiodine therapy for thyroid cancer?[J]. J Nucl Med, 2005, 46(2): 261-266. [43] Van Nostrand D, Atkins F, Bandaru VV, et al. Salivary gland protection with sialagogues: a case study[J]. Thyroid, 2009, 19(9): 1005-1008. doi: 10.1089/thy.2008.0381 [44] Kulkarni K, Van Nostrand D, Atkins F, et al. Does lemon juice increase radioiodine reaccumulation within the parotid glands more than if lemon juice is not administered?[J]. Nucl Med Commun, 2014, 35(2): 210-216. [45] Fallahi B, Beiki D, Abedi SM, et al. Does vitamin E protect salivary glands from I-131 radiation damage in patients with thyroid cancer?[J]. Nucl Med Commun, 2013, 34(8): 777-786. doi: 10.1097/MNM.0b013e328362b1f2 [46] Bhartiya US, Joseph LJ, Raut YS, et al. Effect of Ocimum sanctum, turmeric extract and vitamin E supplementation on the salivary gland and bone marrow of radioiodine exposed mice[J]. Indian J Exp Biol, 2010, 48(6): 566-571. [47] Liu B, Kuang A, Huang R, et al. Influence of vitamin C on salivary absorbed dose of 131I in thyroid cancer patients: a prospective, randomized, single-blind, controlled trial[J]. J Nucl Med, 2010, 51(4): 618-623. doi: 10.2967/jnumed.109.071449 [48] Mendoza A, Shaffer B, Karakla D, et al. Quality of life with well-differentiated thyroid cancer: treatment toxicities and their reduction[J]. Thyroid, 2004, 14(2): 133-140. doi: 10.1089/105072504322880373 [49] Ma C, Xie J, Jiang Z, et al. Does amifostine have radioprotective effects on salivary glands in high-dose radioactive iodine-treated differentiated thyroid cancer[J]. Eur J Nucl Med Mol Imaging, 2010, 37(9): 1778-1785. doi: 10.1007/s00259-009-1368-6 [50] Valdez IH, Wolff A, Atkinson JC, et al. Use of pilocarpine during head and neck radiation therapy to reduce xerostomia and salivary dysfunction[J]. Cancer, 1993, 71(5): 1848-1851. doi: 10.1002/1097-0142(19930301)71:5<1848::AID-CNCR2820710522>3.0.CO;2-F [51] Almeida JP, Kowalski LP. Pilocarpine used to treat xerostomia in patients submitted to radioactive iodine therapy: a pilot study[J]. Braz J Otorhinolaryngol, 2010, 76(5): 659-662. doi: 10.1590/S1808-86942010000500021 [52] Koca G, Gültekin SS, Han U, et al. The efficacy of montelukast as a protective agent against 131I-induced salivary gland damage in rats: scintigraphic and histopathological findings[J]. Nucl Med Commun, 2013, 34(5): 507-517. doi: 10.1097/MNM.0b013e32835ffecd [53] Hosseinimehr SJ. Potential utility of radioprotective agents in the practice of nuclear medicine[J]. Cancer Biother Radiopharm, 2009, 24(6): 723-731. doi: 10.1089/cbr.2009.0635