Radiation exposure of the families of outpatients treated with radioiodine (iodine-131) for hyperthyroidism.

Patients who receive radioiodine (iodine-131) treatment for hyperthyroidism (195-800 MBq) emit radiation and represent a potential hazard to other individuals. Critical groups amongst the public are fellow travellers on the patient's journey home from hospital and members of the patient's family, particularly young children. The dose which members of the public are allowed to receive as a result of a patient's treatment has been reduced in Europe following recently revised recommendations from ICRP. The annual public dose limit is 1 mSv, though adult members of the patient's family are allowed to receive higher doses, with the proviso that a limit of 5 mSv should not be exceeded over 5 years. Unless the doses received during out-patient administration of radioiodine can be demonstrated to comply with these new limits, hospitalisation of patients will be necessary. The radiation doses received by family members (35 adults and 87 children) of patients treated with radioiodine at five UK hospitals were measured using thermoluminescent dosimeters mounted in wrist bands. Families were given advice (according to current practice) from their treatment centre about limiting close contact with the patient for a period of time after treatment. Doses measured over 3-6 weeks were adjusted to give an estimate of values which might have been expected if the dosimeters had been worn indefinitely. Thirty-five passengers accompanying patients home after treatment also recorded the dose received during the journey using electronic (digital) personal dosimeters. For the "adjusted" doses to infinity, 97% of adults complied with a 5-mSv dose limit (range:0.2-5.8 mSv) and 89% of children with a 1-mSv limit (range: 0.2-7.2 mSv). However 6 of 17 children aged 3 years or less had an adjusted dose which exceeded this 1 mSv limit. The dose received by adults during travel was small in comparison with the total dose received. The median travel dose was 0.03 mSv for 1 h travel (range: 2 microSv-0.52 mSv for 1 h of travel time). These data suggest that hyperthyroid patients can continue to be treated with radioiodine on an out-patient basis, if given appropriate radiation protection advice. However, particular consideration needs to be given to children aged 3 years or younger. Admission to hospital is not warranted on radiation protection grounds.     

Radiation exposure to family members of patients with thyrotoxicosis treated with iodine-131

Purpose The purpose of this study was twofold: (1) to measure the radiation exposure to family members of out-patients with thyrotoxicosis treated with radioiodine, ¹³¹I, using the recommendations from the European Commission (EC) guidance and age-specific periods for behaviour restrictions; (2) to use the results to identify necessary restrictions to ensure recommended dose constraints.Methods The study population comprised 76 family members (46 adults and 30 children below the age of 18) of 42 patients. The patients were treated with an average activity of 417 MBq (range 260–600 MBq). They received oral and written EC recommendations about behaviour restrictions (translated into Norwegian). On the day of treatment we repeated the oral instructions to the patient and an adult family member. The time periods for restrictions were 14 days for children aged 0–10 years, 7 days for persons aged 11–59 years and 3 days for persons aged 60 years and older. Family members wore a thermoluminescent dosimeter (TLD) on each wrist day and night for 2 weeks. The doses received were adjusted to give an estimate of the expected values if the TLDs had been worn indefinitely.Results Radiation doses well below the recommended dose constraints were measured for all adult family members and children, except one 2-year-old child; in the latter case the mother probably did not comply with the instructions given.Conclusion The radiation dose to family members of thyrotoxic patients treated with up to 600 MBq of radioiodine is well below recommended dose constraints if EC instructions are given and compliance is adequate. The duration of restrictions for various age groups used in this study may be considered when establishing guidelines in Norway.     

Measurement of the internal dose to families of outpatients treated with <Superscript>131</Superscript>I for hyperthyroidism

Objective  The aim of this study was to measure the internal dose received by family members from ingestion of radioactive contamination after outpatient therapy. Materials and methods  Advice was given to minimise transfer of radioiodine. Home visits were made approximately 2, 7 and 21 days after treatment to measure radioactivity in the thyroids of family members. A decay correction was applied to radioactivity detected assuming ingestion had occurred at the earlier contact time, either the day of treatment or the previous home visit. An effective half-life of 6 or 7 days was used depending on age. Thyroid activity was summed if activity was found at more than one visit in excess of the amount attributable to radioactive decay. Effective dose (ED) was calculated using ICRP72. Results and discussion  Fifty-three adults and 92 children, median age 12 (range 4–17) years participated. Median administered activity was 576 (range 329–690) MBq ¹³¹I. Thyroid activity ranged from 0 to 5.4 kBq in the adults with activity detected in 17. Maximum adult ED was 0.4 mSv. Thyroid activity ranged from 0 to 11.8 kBq in the children with activity detected in 26. The two highest values of 5.0 and 11.8 kBq occurred in children aged 5 and 14 years from different families. Eighty-five children had no activity or <1 kBq detected. ED was <0.2 mSv in 86 out of 92 children (93%). Previous published data showed 93% of children received an ED ≤0.8 mSv from external irradiation. Conclusion  With advice, families of outpatients receiving radioiodine should be able to comply with statutory dose limits and constraints.     

Management of fear of radiation exposure in carers of outpatients treated with iodine-131

Objective

To characterise potential fear of radiation exposure in a normal population of individuals who have volunteered to care for a radioactive family member or friend after outpatient radioimmunotherapy (RIT) treatment for cancer, and obtain their knowing and willing acceptance of the risk.

Methods

Over 750 carers of 300 patients confined to their homes for 1?week following outpatient iodine-131 rituximab RIT of lymphoma were interviewed by a nuclear medicine physicist according to a multi-visit integrated protocol designed to minimise radiation exposure, define risk and gain informed consent.

Results

Median radiation exposure of carers was 0.49?mSv (range 0.01?C3.7?mSv) which is below the Western Australian regulatory limit of 5?mSv for consenting adult carers of radioactive patients. After signing a declaration of consent, only 2 carers of 750 abrogated their responsibility and none of those who carried out their duties expressed residual concerns at the end of the exit interview with respect to their radiation exposure.

Conclusion

Fear of radiation exposure in a normal population may be characterised as a normal emotional response. In the special case of carers of radioactive patients, this fear may be successfully managed by rational, authoritative and empathic explanation to define the risk and gain willing acceptance within the context of domiciliary patient care.     

Unexpected dose to the daughter of a patient treated with iodine-131 for hyperthyroidism

Patients treated with radioiodine for thyrotoxicosis and hyperthyroidism are a source of radiation exposure and represent a potential radiation hazard for the people in their environment. Doses to the relatives can be estimated from dose rates of the patient or measured with a proper dosimeter. Sensitive thermoluminescent dosimeters have been used to measure the doses absorbed by the family members of patients treated with iodine-131 ((131)I) for thyrotoxicosis. In the present case, a 12 year old daughter of a female patient, aged 41 years, treated with 592 MBq of (131)I, received a dose of 7.79 mSv during the first seven days. This value is well above the dose constraints proposed by the International Commission on Radiological Protection, i.e 1 mSv for children and fetuses and 3 mSv for carers. Obviously, the patient and her daughter didn't follow the given restrictions. That was unexpected for a 12 year old child who didn't need special care and was able to understand and follow certain instructions. It is the opinion of the authors that if there are children in the family of a hyperthyroid patient treated with (131)I, they should stay in another house for at least a week. If this is impossible for social reasons, hospitalization of the patient should be considered, although treatment of thyrotoxicosis is held in an out-patient basis.     

The treatment of hyperthyroidism with iodine-131

Radioiodine (131I) treatment of well-differentiated thyroid carcinoma is a well-evaluated therapeutic model for nuclear medicine which has never been equaled by subsequent developments. It is still a unique method of treating cancer. The treatment of thyroid cancer begins with a systematic approach to the most common first symptom or sign; a neck mass. Data have accumulated to show that well-differentiated thyroid cancer does kill commonly enough to warrant aggressive treatment, even in young individuals. There is also evidence that the more complete the thyroidectomy, the lower the death and recurrence rate of the thyroid cancer, and the more effective the use of 131I in both detecting and treating metastases. There are now considerable data demonstrating that 131I after surgery decreases both the recurrence rate and death rate from well-differentiated thyroid cancer. After uptake is "ablated", there is a 1%--2% recurrence rate in patients with the most extensive disease at the time of the initial treatment. This recurrence is effectively retreated with another dose of 131I. Surgery and 131I should be used as long as they are effective before resorting to teletherapy. There are now considerable data to show that the morbidity of surgical and 131I treatment is reasonable in contrast to the recurrence and death rate from nonaggressively treated well-differentiated thyroid carcinoma. Serious consideration should be given to using a low iodine diet before treatment with radioiodine.     

Radiation dosimetry for the adult female and fetus from iodine-131 administration in hyperthyroidism

Through a study of the iodine kinetics of 127 patients, we have developed radiation dose estimates to major organs and the fetus for patients with varying degrees of hyperthyroidism. We observed a negative correlation between maximum thyroid uptake and biologic half-time of iodine in the thyroid and used this correlation to predict the biologic half-time at fixed values of maximum thyroid uptake. Dose estimates to the bladder, gonads, marrow, thyroid, uterus, and whole body were estimated for maximum thyroid uptakes from 20% to 100%. Bladder dose varied from 0.6 to 1.0 mGy/MBq and dose to the uterus varied from 0.036 to 0.063 mGy/MBq under different model assumptions. Dose estimates to the fetus and fetal thyroid were approximated at all stages of pregnancy. Average fetal dose was a maximum between 0 and 2 mo of pregnancy, with the maximum ranging from 0.048 mGy/MBq to 0.083 mGy/MBq, depending on model assumptions. Some radiation risks for irradiation of the fetus and the fetal thyroid are discussed.     

Results of radioiodine (131/125I) therapy of hyperthyroidism.

One individually calculated dose of 131I was sufficient to control the hyperfunction in 75% of the patients with Graves' disease and 85% of the patients with autonomous adenoma. The cumulative myxedema risk 10 years after therapy was: 15% in the patients with Graves' disease and nearly zero in patients with autonomous adenoma. Early results of 125I therapy of Graves' disease are presented. Peculiar aspects of thyroid function after destructive therapy of Graves' disease are discussed.     

分化型甲状腺癌术后患者131I治疗的辐射剂量与防护

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.     

~(131)I治疗非毒性多发结节性甲状腺肿

~(131)I可以有效地减小非毒性多发结节性甲状腺肿 (NTMNG)病人的甲状腺体积 ,减轻局部压迫症状 ,尤其适用于有高手术危险、术后复发及拒绝手术的患者。目前尚需更多病例及更长随访时间的研究     

Influence of therapy with iodine-131 on thyroid tissue pattern in colour and power Doppler sonography

AIM: The aim of this study was to evaluate the influence of radioiodine therapy on sonographic thyroid patterns using power Doppler (PD) and colour Doppler (CD) sonography in hyperthyroid patients with autonomous nodules (AN) and Graves' disease (GD). METHOD: B-mode, colour, and power Doppler sonography, (99m)Tc scintigraphy, and laboratory analyses (free thyronine fT(3), free thyroxine fT(4), thyroid stimulating hormone TSH) were performed in 55 patients (AN = 27, GD = 28) before and 6 months following therapy with (131)I radioiodine therapy (RIT). RESULTS: In patients with an AN (but not in GD), a significant reduction in thyroid vascularization was subjectively noted following radioiodine therapy on both CD and PD ultrasound (Wilcoxon matched pairs, P < 0.05). The pre-therapeutic grade of hypervascularization in the periphery of autonomous nodules correlated closely with the laboratory parameters of hyperthyroidism. As expected, PD indicated a higher grade of vascularization when compared with CD due to its greater sensitivity to flow. CONCLUSIONS: Radioiodine therapy led to a significant reduction in hypervascularization in patients with AN (but not in GD) corresponding to the normalization of serological values. Comparing CD and PD, PD detected a greater number of vessels. CD and PD are not able to replace scintigraphy and/or laboratory analyses in the management of patients with hyperthyroidism.     

Radiation exposure of personnel during digital subtraction angiography

Radiation exposure to the lens of physicians performing intravenous and hand-injected intraarterial digital subtraction angiography (DSA) were monitored with and without a combined face and body shield. Shielding provided nearly a three-fold reduction in dose for both intravenous and intraarterial exams, with the highest doses recorded for intraarterial exams due to longer fluoroscopy and exposure during imaging. When compared with the NCRP guidelines of maximum exposure to the lens, an angiographer could theoretically perform up to two intraarterial and 14 intravenous studies per day with protection or one intraarterial and two intravenous studies per day without protection. The exposure values in this study reflect our equipment and personal technique in carotid DSA and may not apply to other departments, but sould encourage other angiographers to monitor exposure in their own angiography suites.     

Radiation exposure and radiation protection of the physician in iodine-131 Lipiodol therapy of liver tumours

Intra-arterial iodine-131 labelled Lipiodol therapy for liver cancer has been investigated for safety and efficacy over a number of years, but data on radiation exposure of personnel have remained unavailable to date. The aim of this study was to assess the radiation exposure of the physician during intra-arterial 131I-Lipiodol therapy for liver malignancies and to develop appropriate radiation protection measures and equipment. During 20 intra-arterial administrations of 131I-Lipiodol (1110-1924 MBq), radiation dose equivalents (RDE) to the whole body, fingers and eyes of the physician were determined for (a) conventional manual administration through a shielded syringe, (b) administration with an automatic injector and (c) administration with a lead container developed in-house. Administration by syringe resulted in a finger RDE of 19.5 mSv, an eye RDE of 130-140 microSv, and a whole-body RDE of 108-119 microSv. The injector reduced the finger RDE to 5 mSv. With both technique (a) and technique (b), contamination of angiography materials was observed. The container allowed safe transport and administration of the radiopharmaceutical from 4 m distance and reduced the finger RDE to <3 microSv and the eye RDE to <1 microSv during injection. During femoral artery compression, radiation exposure to the fingers reached 170 microSv, but the whole-body dose could be reduced from a mean RDE of 114 microSv to 14 microSv. No more contamination occurred. In conclusion, radiation exposure was high when 131I-Lipiodol was administered by syringe or injector, but was significantly reduced with the lead container.     

Real-life radiation burden to relatives of patients treated with iodine-131: a study in eight centres in Flanders (Belgium)

In view of the EURATOM 96/29 [1] regulations, a prospective multicentre study was performed to evaluate the present guidelines given to relatives of patients treated with iodine-131 for both thyroid carcinoma and thyrotoxicosis, based on the real-life radiation burden. This study comprised 166 measurements carried out on a group of 94 relatives of 65 patients. All relatives wore a thermoluminescent dosemeter (TLD) on the wrist for 7 days. Sixty-one relatives agreed to wear another TLD for an additional 7 days. TLD were placed on nine patients’ bedside tables. The eight participating centres were arbitrarily divided into three groups according to the period of time they advised their patients to sleep separately. Groups I, II and III respectively advised their patients to sleep separately for 0, 7–10 and 14–21 days. The median dose received by in-living relatives of thyroid carcinoma patients during the 14 days following hospital discharge was 281 μSv (doses to infinity not calculated); the median dose to infinity received by in-living relatives of ambulatory treated thyrotoxicosis patients was 596 μSv, as compared with 802 μSv for in-living relatives of hospitalised thyrotoxicosis patients. In general the children of patients received a significantly (P<0.1) lower mean dose than their partners. For thyroid carcinoma patients, only two relatives out of 19 (10%) exceeded the EURATOM 96/29 limit of 1 mSv/year. For thyrotoxic patients, 28% of relatives exceeded the EURATOM 96/29 limit, but none of them were relatives of patients who followed guidelines for 21 days. The results of this study indicate that sleeping separately for 7 days, after a period of hospitalisation of 2–3 days, will usually be sufficient for thyroid carcinoma patients. For thyrotoxicosis patients, up to 21 days of sleeping separately could be necessary in order to strictly abide by EURATOM 96/29. Therefore, the authors propose the implementation of a non-rigid dose constraint for people who ”knowingly and willingly” help patients treated with ¹³¹I, while still following the ALARA principle. Received 16 January and in revised form 21 May 1998     

Brain metastasis from differentiated thyroid cancer in patients treated with radioiodine for bone and lung lesions

Brain metastasis of differentiated thyroid cancer (DTC) often is detected during treatment of other remote lesions. We examined the prevalence, risk factors and treatment outcome of this disease encountered during nuclear medicine practice. Of the 167 patients with metastasis to lung or bone treated 1-14 times with radioactive iodine (RAI), 9 (5.4%) also had lesions in the brain. Five were males and 4 females, aged 49-84, out of the original population of 49 males and 118 females aged 10-84 (mean 54.7) years. Three of them underwent removal of their brain tumors, 5 received conventional external beam irradiation, and 2 had stereotactic radiosurgery with supervoltage X-ray. None of the brain lesions showed significant uptake of RAI despite demonstrable accumulation in most extracerebral lesions. Seven patients died 4-23 (mean 9.4) months after the discovery of cerebral metastasis, brain damage being the primary or at least a contributing cause. The 8th and 9th patients remained relatively well for more than 42 and 3 months, respectively, without any evidence of intracranial recurrence. Our results confirmed that the brain is a major site of secondary metastasis from DTC. No statistically significant demographic risk factor was detected. Any suspicious neurological symptoms in the course of RAI treatment warrant cerebral computed tomography. As for therapy, from our initial experience, radiosurgery seemed promising as an effective and less invasive alternative to surgical removal.     

Prostaglandins as biochemical markers of radiation injury to the salivary glands after iodine-131 therapy?

Because salivary glands, as well as thyroid tissue, are able to concentrate radioiodine, the treatment of thyroid diseases with iodine-131 may have secondary effects on salivary gland function which seriously impair the quality of life. Such effects include sialoadenitis and xerostomia. Salivary secretion is stimulated by prosta- glandins (PGs). In this study we evaluate whether ¹³¹I therapy influences the levels of PGs in saliva. Patients who had previously received ¹³¹I for treatment of hyperthyroidism or differentiated thyroid cancer and healthy volunteers were studied. Levels of PGs [6-oxo-PGF_1α, bicyclo-PGEm, thromboxane B₂ (TXB₂), PGF_2α] in unstimulated saliva were measured using enzyme immunoassay. Significantly lower levels of 6-oxo-PGF_1α, bicyclo-PGEm and PGF_2α and higher levels of TXB₂ were found in the group of patients in comparison with the controls. Differences between patients and controls were more pronounced in smokers. This study demonstrates that salivary gland uptake of ¹³¹I significantly affects PG levels in saliva. Received 25 September and in revised form 24 November 1997     

Decreased uptake of therapeutic doses of iodine-131 after 185-MBq iodine-131 diagnostic imaging for thyroid remnants in differentiated thyroid carcinoma

We performed a prospective random study to assess possible thyroid stunning by a 185-MBq iodine-131 dose used to diagnose thyroid remnants. Patients with differentiated thyroid carcinoma were included after total or near-total thyroidectomy. They were randomly assigned to two groups. In group 0 (G0, 32 patients), iodine-123 administration only was used to diagnose thyroid remnants and/or metastasis, so that no thyroid stunning by ¹³¹I would occur. In group 1 (G1, 19 patients), diagnostic imaging was performed with ¹²³I and 185 MBq ¹³¹I. ¹²³I imaging was less sensitive than ¹³¹I imaging in identifying thyroid remnants in both groups (94%). Thyroid uptake of ¹²³I was measured in both groups (at 2 h) and was not significantly different between the groups. Patients with thyroid remnants who remained in the study (28/32 in G0, 17/19 in G1) were treated with 370 MBq ¹³¹I, 5 weeks after treatment (mean time, range 12–84 days). In 12/17 G1 patients thyroid uptake measurement was repeated immediately before treatment. Uptake was equal to 1.97%±0.71% and significantly lower (P<0.05) than the previous measurement (3.76%±1.50%). Patients were imaged 7 days after administration of the therapeutic dose and the images were compared with the diagnostic images. In 28/28 G0 patients thyroid remnants were unchanged and clearly seen. In 5/17 G1 patients, however, the remnants were hardly identified, although they had been clearly seen at the time of diagnosis. We conclude the following: (1) a diagnostic dose of 185 MBq ¹³¹I decreases thyroid uptake for several weeks after administration and can impair immediate subsequent ¹³¹I therapy; (2) ¹²³I is slightly less sensitive than ¹³¹I in identifying thyroid remnants; and (3) the need to scan for thyroid remnants remains to be confirmed, since only 2/51 patients enrolled in this study were not treated with ¹³¹I. Received 6 August and in revised form 24 October 1997     

Radiation dose rates from patients receiving iodine-131 therapy for carcinoma of the thyroid

Patients treated with radioiodine present a radiation hazard and precautions are necessary to limit the radiation dose to family members, nursing staff and members of the public. The precautions advised are usually based on instantaneous dose rates or iodine retention and do not take into account the time spent in close proximity with a patient. We have combined whole-body dose rate measurements taken from 86 thyroid cancer patients after radioiodine administration with published data on nursing and social contact times to calculate the cumulative dose that may be received by an individual in contact with a patient. These dose estimates have been used to calculate restrictions to patients' behaviour to limit received doses to less than 1 mSv. We have also measured urinary iodide excretion in 19 patients to estimate the potential risk from the discharge of radioiodide into the domestic drainage system. The dose rate decay was biexponential for patients receiving radioiodine to ablate the thyroid after surgery (the ablation group, A) and monoexponential for these receiving subsequent treatments for residual or recurrent disease (the follow-up group, FU). The faster clearance in the follow-up patients generally resulted in less stringent restrictions than those advised for ablation patients. For typical activities of 1850 MBq for the ablation patients and 3700 MBq or 7400 MBq for the follow-up patients, the following restrictions were advised. Patients could travel in a private car for up to 8 h on the day of treatment (for an administered activity of 1850 MBq in group A) or 4 and 2 h (for activities of 3700 or 7400 MBq in group FU) respectively. Patients should remain off work for 3 days (1850 MBq/group A) or 2 days (up to 7400 MBq/group FU). Partners should avoid close contact and sleep apart for 16 days (1850 MBq/group A) or 4–5 days (3700 or 7400 MBq/group FU). Contact with children should be restricted according to their age, ranging from 16 days (1850 MBq/group A) or 4–5 days (3700 or 7400 MBq in group FU) for younger children, down to 10 days (1850 MBq/group A) or 4 days (up to 7400 MBq/group FU) for older children. The cumulative dose to nursing staff for the week after treatment was dependent on patient mobility and was estimated at 0.08 mSv for a self-caring patient to 6.3 mSv for a totally helpless patient (1840 MBq/group A). Corresponding doses to nurses looking after patients in group FU were 0.18–12.3 mSv (3700 MBq) or 0.36–24.6 mSv (7400 MBq). Sensible guidelines can be derived to limit the dose received by members of the public and staff who may come into contact with cancer patient treated with radioiodine to less than 1 mSv. The rapid clearance of radioiodine in patients treated on one or more than one occasion means that therapy could be administered at home to selected patients with suitable domestic circumstances. In most cases the restriction times, despite the high administered activities, are less than those for patients treated for thyrotoxicosis. The concentration of radioiodide in domestic drainage systems should not pose a significant risk.