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Objectives: We aimed to evaluate the histopathological alterations in human salivary glands after radioactive iodine (RAI) treatment for thyroid diseases., Study Design: We retrospectively selected patients with a history of RAI treatment for thyroid diseases from a database of patients who underwent surgery for oral and maxillofacial diseases and had specimens of salivary glands at Peking University School of Stomatology between December 2012 and July 2023. The patients' clinical records and histopathological slides of the salivary glands were carefully reviewed., Results: Sixteen patients were included. Three symptomatic patients showed duct cell cytoplasmic vacuolization and increased numbers of disordered duct cell layers (3/3), severe duct stenosis and dilation (2/3), and exfoliated epithelial cells in the duct lumen (1/3). The glandular parenchyma showed severe acinar atrophy (2/2), fat content enhancement (2/2), and severe periductal fibrosis (3/3). Thirteen asymptomatic patients showed duct cell cytoplasmic vacuolization (5/13), acinar atrophy and increased fat content in the parenchyma (5/13), and periductal fibrosis (5/13)., Conclusion: Main histopathologic changes in the salivary glands after RAI treatment for thyroid diseases are cytoplasmic vacuolization of duct cells, acinar atrophy, fat content enhancement, and periductal fibrosis. These changes were evident in symptomatic cases, and were also seen in some asymptomatic patients., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The leading cause of gastritis and its complications is Helicobacter pylori Radioactive iodine ( 131 I) accumulates significantly in the stomach after consumption. On this basis, we decided to determine whether different doses of 131 I in the stomach would be effective in eradicating the infection. Methods: All patients with hyperthyroidism or differentiated thyroid carcinoma who were referred for 131 I treatment were invited to the study. A stool antigen test was conducted before consumption of 131 I (0.15-5.5 GBq) and was repeated 2 mo later to detect H. pylori infection. Results: H. pylori positivity was found in 51.8% (14/27) of the patients. At 2 mo after treatment, 13 of the 14 patients with differentiated thyroid carcinoma or hyperthyroidism who had been identified as positive for H. pylori stool antigen before 131 I administration were still positive, representing a nonsignificant eradication rate of 7.1%. Conclusion: Administration of 131 I to patients with H. pylori did not show potential to eliminate the infection., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Purpose: Radioiodine therapy (RIT) of benign thyroid diseases is an established therapy. This study aimed to identify factors predictive for outcome in patients with non-toxic goiter (NTG), unifocal (UFA), multifocal (MUFA) or diffuse autonomy (DISA) and Graves' disease (GD)., Methods: Retrospective analysis of 205 patients with benign thyroid disease (54 NTG, 46 MUFA, 24 DISA, 26 UFA, 55 GD) who underwent RIT. Follow up time was 12 months for determining treatment outcome., Results: The type of disease was predictive for volume reduction after 12 months (NTS 66%, DISA 67%, MUFA 58%, UFA 51%, GD 71%, p<0.001) and post-treatment hypothyroidism (NTS 48%, DISA 33%, MUFA 15%, UFA 15%, p=0.006). Initial volume, intra-therapeutic uptake and intra-therapeutic half-life were independent prognostic factors for volume reduction 12 months after RIT. In patients with NTG, UFA, MUFA, DISA post-treatment hypothyroidism was significantly correlated with extent of volume reduction 12 months after RIT, achieved dose, higher pre-therapeutic TSH values and younger age. Two different strategies for pre-therapeutic dosimetry used in MUFA showed no differences regarding the therapeutic outcome. In GD, effective half-life, initial volume and Graves' ophthalmopathy were predictive for treatment failure., Conclusion: Reduction of thyroid volume and the percentage of hypothyroid patients one year after RIT was primarily dependent on the type of disease. In MUFA and DISA we could identify volume reduction after 3 months as a reliable predictor for hypothyroidism while in patients with GD a short intra-therapeutic half-life, a large pre-therapeutic volume and active Graves' ophtalmopathy were relevant predictors for treatment failure suggesting an intensified follow-up scheme in these patients., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

This version of the guideline for radioiodine therapy of benign thyroid disorders is an update of the version, which was published by the German Society of Nuclear Medicine (Deutsche Gesellschaft für Nuklearmedizin, DGN) in co-ordination with the German Society of Endocrinology (Deutsche Gesellschaft für Endokrinologie, DGE, Sektion Schilddrüse) and the German Society of General- and Visceral-Surgery (Deutsche Gesellschaft für Allgemein- und Viszeralchirurgie, DGAV) in 2015. This guideline was harmonized with the recommendations of the European Association of Nuclear Medicine (EANM). According to the German "Directive on Radiation Protection in Medicine" the physician specialised in nuclear medicine ("Fachkunde in der Therapie mit offenen radioaktiven Stoffen") is responsible for the justification to treat with radioiodine. Therefore, relevant medical indications for radioiodine therapy and alternative therapeutic options are discussed within the guideline. This procedure guideline is developed in the consensus of an expert group. This fulfils the level S1 (first step) within the German classification of Clinical Practice Guidelines., Competing Interests: Erklärung zu finanziellen InteressenForschungsförderung erhalten: nein; Honorar/geldwerten Vorteil für Referententätigkeit erhalten: nein; Bezahlter Berater/interner Schulungsreferent/Gehaltsempfänger: nein; Patent/Geschäftsanteile/Aktien (Autor/Partner, Ehepartner, Kinder) an Firma (Sponsor der Veranstaltung): nein; Patent/Geschäftsanteile/Aktien (Autor/Partner, Ehepartner, Kinder) an Firma (Nicht-Sponsor der Veranstaltung): nein.Erklärung zu nichtfinanziellen InteressenDie Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht.

This document provides the new EANM guideline on radioiodine therapy of benign thyroid disease. Its aim is to guide nuclear medicine physicians, endocrinologists, and practitioners in the selection of patients for radioiodine therapy. Its recommendations on patients' preparation, empiric and dosimetric therapeutic approaches, applied radioiodine activity, radiation protection requirements, and patients follow-up after administration of radioiodine therapy are extensively discussed., (© 2023. The Author(s).)

Introduction and Aim: According to the German guideline on Radiation Protection in Medicine, the activity to be applied for radioiodine therapy of benign thyroid diseases is determined for each patient by means of the radioiodine test (RJT). The aim of this study is to record the different parameters of the RJT., Material and Methods: A web-based questionnaire was sent to all nuclear medicine departments in Germany via the DGN office. Parameters regarding tracer and activity, type of probe measurement, number and timing of measurements, use of fixed effective half-lives (eHWZ), calculation model and organ doses were requested. An assessment of continuous measurement of the thyroid iodine uptake over seven days by a wearable probe system was also requested., Results: 38 of 94 facilities responded to the questionnaire. Major differences in RJT implementation were found concerning the parameters number and timing of measurements, probe-patient distance, use of fixed disease-specific eHWZ, and intended organ dose. Despite the DGN Guideline and DIN 6861-1, 74% of the facilities still use the simplified Marinelli formula from the DGN Recommendation of 1998. Only 8% have switched to the two-compartment model. 84% of the institutions expect that a wearable probe system could improve the calculation of the radioiodine activity necessary for treatment, but only 57% expect an improvement in the therapeutic outcome., Conclusions: The methodology of RJT in Germany is heterogeneous and still based on the "Marinelli method" in most institutions despite new guidelines and recommendations. A continuous measurement of the iodine kinetics using a wearable probe system could result in further improving the radioiodine test in addition to the newer calculation algorithms., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Purpose: The study aimed to explore the relationship of different exposure measures with 131 I therapy response in patients with benign thyroid disease, estimate the variability in the response, investigate possible covariates, and discuss dosing implications of the results., Methods: A population exposure-response analysis was performed using nonlinear mixed-effects modelling. Data from 95 adult patients with benign thyroid disease were analysed. Evaluated exposure parameters were: administered radioactivity dose (Aa) [MBq], total absorbed dose (ABD) [Gy], maximum of absorbed dose-rate (MXR) [Gy/h] and biologically effective dose (BED) [Gy]. The response was modelled as ordered categorical data: hyper-, eu- and hypothyroidism. The final model performance was evaluated by a visual predictive check., Results: The probability of the outcome following 131 I therapy was best described by a proportional-odds model, including the log-linear model of 131 I effect and the exponential model of the response-time relationship. All exposure measures were statistically significant with p<0.001, with BED and ABD being statistically better than the other two. Nevertheless, as BED resulted in the lowest AIC value, it was included in the final model. Accordingly, BED value of 289.7 Gy is associated with 80% probability of successful treatment outcome 12 months after 131 I application in patients with median thyroid volume (32.28 mL). The target thyroid volume was a statistically significant covariate. The visual predictive check of the final model showed good model performance., Conclusion: Our results imply that BED formalism could aid in therapy individualisation. The larger thyroid volume is associated with a lower probability of a successful outcome., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objectives/hypothesis: To apply a novel sialography classification system to identify parotid and submandibular ductal findings following I-131 therapy and to assess correlates to dose and duration of symptoms., Study Design: Retrospective single-center case series., Methods: Patients who underwent sialography between February 2008 and February 2019 after previously receiving I-131 treatment were identified via a retrospective chart review. Their sialograms were systematically evaluated and scored by applying the Iowa parotid sialogram scale to also include submandibular gland analysis., Results: From 337 sialograms, 30 (five submandibular, 25 parotid) underwent analysis. Ductal stenosis was identified in all sialograms and was graded as moderate (>50%-75%) in 7/30 cases and severe (>75%) in 15/30 cases. The distal (main) duct was narrowed in 23/30 cases. No association was identified between degree of ductal stenosis and I-131 dose (P = .39), age (P = .81), or time from I-131 therapy to sialogram (P = .97)., Conclusions: The Iowa parotid sialogram scale was successfully applied to report abnormalities of the parotid and submandibular ductal system. The most common manifestation of I-131-associated sialadenitis was a severe stenosis within the distal salivary duct. No statistically significant association was found between degree of ductal stenosis and dose of I-131, age, or duration of symptoms., Level of Evidence: 4 Laryngoscope, 131:E1450-E1456, 2021., (© 2020 American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)

Radioactive iodine is commonly used for the treatment of different thyroid conditions since the 1940s. The EANM has developed a standard pre-therapeutic procedure to estimate patient specific thyroid uptake at treatment of benign thyroid diseases. The procedure which models the time dependent fractional thyroid uptake is based on a two-compartment fitting system, one representing the thyroid and the other the blood. The absorbed dose is however only estimated for the thyroid and not for any other organ in the body. A more detailed biokinetic model for iodine is given by the ICRP and includes an iodide transport in the whole body. The ICRP model has 30 different compartments and 48 transfer coefficients to model the biokinetics of iodide and to model different transfer for inorganic iodide and organic iodine. The ICRP model is a recirculation iodine model, and the optimization is performed on the whole model and not exclusively on the thyroid as in the EANM procedure. Combining the EANM method and the ICRP model gives both patient specific estimations of thyroid uptake and retention and include most organs in the body. The new software gives both an improved patient specific dosimetry for the thyroid and an estimation of the absorbed dose to non-target organs and tissues like kidneys, urinary bladder, stomach wall, and uterus. Using the method described in this paper, the repercussions on the daily routines will be minimal., Competing Interests: MA has created a webpage and a distribution channel IDAC-Dose AB to be able to distribute the software generated in this article. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Andersson and Mattsson.)

Objective: For radioactive Iodine-131 ( 131 I) treatments of thyroid diseases, increased efficacy has been reported for personalized dosimetry treatments. The measurement of Iodine-131 thyroid uptake ( 131 IU) is required in these cases. This study aims to investigate whether 99m Tc thyroid uptake ( 99m TcU) may be used in place of 131 IU for implementing personalised treatments., Methods: A retrospective study of 152 benign thyroid disease 131 I treatments was carried out during 2012-2020; 117 treatments were for female patients while 35 were for male patients diagnosed with either Graves' disease, multinodular goitre or toxic nodules., Results: A statistically significant correlation was found between 131 IU and 99m TcU data, with the data more correlated for male than female patients ( r = 0.71 vs 0.38, p -value < 0.001). Patient age and time difference between the two respective uptake measurements significantly influenced the uptake correlation in females but not for the male cohort, although there was no significant difference between the parameters across gender. Thyroid diagnosis and hormone levels showed a significant correlation with uptakes in both genders. Estimating 131 IU based on 99m TcU was shown to be predictive for male but not in female patients (R 2 = 91% vs 16%)., Conclusion: Estimating 131 IU based on 99m TcU is not recommended for females at our centre. Males reported good correlation, but a larger sample would be needed for validation., Advances in Knowledge: The initial findings showed a significant gender difference in benign thyroid uptake parameters at our centre, highlighting the potential need for gender consideration when planning 131 IU patient management and when reporting studies results.

Background: Radioactive iodine ( 131 I) is one of the treatments of hyperthyroidism and differentiated thyroid carcinoma (DTC). Swelling of salivary glands are one of the possible side effects of this treatment, known as radioactive iodine-induced sialadenitis (RAIS). The prevalence of RAIS varies widely and no specific risk ratio has been established., Objectives: To determine the incidence of RAIS, analysing the epidemiological data and tumour- and treatment-related factors that may influence the development of the disease., Material and Methods: 197 patients who received radioiodine treatment between 2015 and 2017 were studied (76.6% women). The variables studied were age, gender, weight, height, and body mass index; presence of high blood pressure, dyslipidemia, diabetes, and thyroid diseases; cumulative radioiodine dose, presence of sialadenitis, affected salivary gland, and the time of onset., Results: 14 patients developed sialadenitis (78.6% women), all with DTC. The incidence of sialadenitis was 3.4% overall and 6.3% among DTC patients. Furthermore, we found that higher cumulative radioiodine doses confer a greater risk of developing sialadenitis, with a hazard ratio of 1.009 ( p  = .001). No association was found between the epidemiologic data studied and sialadenitis., Conclusions: In this series, a dose-dependent relationship was found between radioiodine treatment and sialadenitis.

Since its outbreak in Wuhan, China the SARS-CoV-2 has become a public health emergency of international concern, impacting all areas of daily life, including medical care. Although not in the front line nuclear medicine practice should adjust their standard operating procedures. The adaptations and the flexibility that nuclear thyroidology, among other fields of nuclear medicine, should show during the pandemic, must focus not only in minimizing the risk of infection to staff, patients, and family members, but also in controlling the transmission of the virus while continuing to provide health care services which do not jeopardize patients' prognosis and quality of life. Favorable prognosis and indolent symptoms of most cases of thyroid diseases, allows postponements and rescheduling as well as alternative procedures, provided that they are cautiously considered for each case individually. The objective of the current paper is to provide guidance on how diagnostic and therapeutic management of patients with thyroid diseases can be safely and effectively adjusted during pandemic, in nuclear medicine settings.

Purpose: Radioiodine (I 131 ) therapy is the treatment mainstay for several benign and malignant thyroid disorders, however I 131 is known to cause DNA damage and liberation of thyroidal self-antigens inducing secondary immunoreactivity. The exact mechanisms underpinning cellular death and subsequent induction of autoimmune thyroid disease following I 131 treatment have not yet been fully elucidated. This manuscript aims to review the literature concerning the effects of I 131 on the thyroid gland. Conclusion: The effects of I 131 on malignant thyroid cells appears to depend on absorbed dose with the literature demonstrating a clear initial delay in the triggering of apoptosis in response to I 131 -mediated cellular damage. Some studies also observed necrotic cellular death following high-dose I 131 treatment. Liberation of thyroidal self-antigen following I 131 treatment helps to explain phenomena such as the subsequent induction of autoimmune thyroid disease. The clinical utility of cytokines and autoantibodies for prognostication of hypothyroidism and treatment failure following I 131 remains uncertain and further appropriately-powered studies are required to clarify their role. The potential role of other cell death mechanisms activated after treatment with I 131 should also be explored in order to fully delineate the thyroidal response.

Purpose: Existence and cause of thyroid stunning was controversially discussed for decades but the underlying mechanism remains unclear. Numerous studies describe thyroid stunning in radioiodine-131 therapy (RIT) of differentiated thyroid carcinoma. However, there are no studies evaluating thyroid stunning in benign thyroid diseases caused by the radioiodine uptake test (RIUT). Therefore, the influence of pre-therapeutic tracer radiation dose on therapeutic iodine-131 uptake was evaluated retrospectively., Methods: A total of 914 RIT patients were included. Exclusion criteria were anti-thyroid drugs, pre- and/or intra-therapeutic effective half-lives (EHL) beyond 8.04 days and externally performed RIUT or 24 h RIUT. All patients received RIUT 1 week before RIT. Thyroid volume was estimated via ultrasound. Tracer radiation dose to the thyroid was calculated retrospectively. The dependence of changes in the pre-therapeutic to the therapeutic extrapolated-maximum- 131 I-uptake (EMU) from the dose in RIUT was evaluated statistically., Results: EMU in RIUT ranged from 0.10 to 0.82 (median: 0.35) and EMU in RIT ranged from 0.10 to 0.74 (median: 0.33). Averaged over the whole cohort the therapeutic EMU decreased significantly (2.3% per Gray intra-thyroidal tracer radiation dose). A disease-specific evaluation showed dose-dependent thyroid stunning from 1.2% per Gray in solitary toxic nodules (n = 327) to 21% per Gray in goiters (n = 135) which was significant for the subgroups of disseminated autonomies (n = 114), multifocal autonomies (n = 178) and goiters (p < 0.05) but not for Graves' diseases (n = 160) and solitary toxic nodules (p > 0.05)., Conclusions: The presented data indicate for the first time a significant dependence of pre-therapeutic radiation dose on thyroid stunning in goiter and disseminated and multifocal autonomy. To achieve the desired intra-thyroidal radiation dose, RIT activity should be adapted depending on the dose in RIUT.

Due to the ease with which the radiation field strength is determined for a point source, the field strength emanating from radiopharmaceutical therapy patients is sometimes estimated by using the point source approximation with a correction factor. It is inevitable that the correction factor will occasionally be used under conditions that do not precisely match those for which the factor was originally derived. The difficulty is that the boundary of the correction factor's domain of acceptability is usually unclear. The purpose of this paper is to address this issue. The patient is modeled as a cylinder containing the radionuclide administered to the patient. From first principles, the expression for converting the radiation field strength of an unshielded point source to that of the extended cylindrical volume source is derived. This expression is analytically separated into the component depicting geometric dispersion of the source material into the volume and the component depicting self-absorption (absorption characteristics of I in water are used). These components, along with their composite, are presented showing their dependence on patient size, distance from the patient, and various dispersion patterns of the source material within the patient. Correlation of theory and measurement is demonstrated, and a conceptual grasp is conveyed regarding field strength variations around volume sources with changes in shape, size, distance, and other parameters. Using data presented, the radiation field strength emanating from a radiopharmaceutical therapy patient can be estimated from the point source approximation and customized for patient size and presumed internal radionuclide distribution.

Although use of the term "theranostic" is relatively recent, the concept goes back to the earliest days of nuclear medicine, with the use of radioiodine for diagnosis and therapy of benign and malignant thyroid disease being arguably the most successful molecular radiotherapy in history. A diagnostic scan with 123 I-, 124 I-, or a low activity of 131 I-iodide is followed by therapy with high activity 131 I-iodide. Similarly, adrenergic tumours such as phaeochromocytoma and neuroblastoma can be imaged with 123 I-metaiodobenzylguanidine and treated with 131 I-metaiodobenzylguanidine. Bone scintigraphy can be used to select patients with painful bone metastases from prostate cancer who may benefit from treatment with beta- or alpha-particle emitting bone seeking agents, the most recent and successful of which is 223 Ra radium chloride. Anti-CD20 monoclonal antibodies can be used to image and treat non-Hodgkins lymphoma, though this has not been as commercially successful as initially predicted. More recently established theranostics include somatostatin receptor targeting peptides for diagnosis and treatment of neuroendocrine tumours with agents such as 68 Ga-DOTATATE and 177 Lu-DOTATATE, respectively. Finally, agents which target prostate-specific membrane antigen are becoming increasingly widely available, despite the current lack of a commercial product. With the recent licensing of the somatostatin peptides and the rapid adoption of 68 Ga- and 177 Lu-labelled prostate-specific membrane antigen targeting agents, we have built upon the experience of radioiodine and are already seeing a great expansion in the availability of widely accepted theranostic radiopharmaceuticals.

Purpose: Radioiodine ( 131 I) therapy is the common treatment option for benign thyroid diseases. The objective of this study was to characterize 131 I biokinetics in patients with benign thyroid disease and to investigate and quantify the influence of patients' demographic and clinical characteristics on intra-thyroidal 131 I kinetics by developing a population model., Methods: Population pharmacokinetic analysis was performed using a nonlinear mixed effects approach. Data sets of 345 adult patients with benign thyroid disease, retrospectively collected from patients' medical records, were evaluated in the analysis. The two-compartment model of 131 I biokinetics representing the blood compartment and thyroid gland was used as the structural model., Results: Results of the study indicate that the rate constant of the uptake of 131 I into the thyroid (k tu ) is significantly influenced by clinical diagnosis, age, functional thyroid volume, free thyroxine in plasma (fT 4 ), use of anti-thyroid drugs, and time of discontinuation of therapy before administration of the radioiodine (THDT), while the effective half-life of 131 I is affected by the age of the patients. Inclusion of the covariates in the base model resulted in a decrease of the between subject variability for k tu from 91 (3.9) to 53.9 (4.5)%., Conclusions: This is the first population model that accounts for the influence of fT 4 and THDT on radioiodine kinetics. The model could be used for further investigations into the correlation between thyroidal exposure to 131 I and the outcome of radioiodine therapy of benign thyroid disease as well as the development of dosing recommendations.

Purpose: To characterize the efficacy and safety of radiation therapy in a contemporary Langerhans cell histiocytosis (LCH) cohort and to explore whether there are sites at higher risk for local recurrence., Patients and Methods: Between 1995 and 2015 we identified 39 consecutive LCH patients who were treated primarily with radiation therapy. Patients were staged by single/multisystem involvement and established risk organ criteria. In 46 irradiated lesions, clinical and radiologic responses were evaluated at multiple time points after radiation therapy. Patient demographics, treatment, and local failure were compared by site of lesion., Results: Median age at radiation therapy was 35 years (range, 1.5-67 years). Twelve patients had multisystem involvement, and of those, 5 patients had disease in organs considered to be high risk. The following sites were irradiated: bone (31), brain (6), skin (3), lymph node (3), thyroid (2), and nasopharynx (1). Median dose was 11.4 Gy (range, 7.5-50.4 Gy). At a median follow-up of 45 months (range, 6-199 months), local recurrence or progression was noted in 5 of 46 lesions (11%). There were no local failures of the 31 bone lesions evaluated, whereas the 3-year freedom from local failure in the 15 non-bone lesions was 63% (95% confidence interval 32-83%; P=.0008). Local failures occurred in 2 of 3 skin lesions, in 2 of 6 brain lesions, and 1 of 3 lymph node lesions. Deaths were recorded in 5 of 39 patients (13%), all of whom were adults with multisystem disease., Conclusion: Radiation therapy is a safe and effective measure for providing local control of LCH involving the bone. Whereas bone lesions are well controlled with low doses of radiation, disease in other tissues, such as the skin and brain, may require higher doses of radiation or additional treatment modalities., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The design and implementation of a mobile gamma spectrometry system to in vivo measure the accumulated activity of 131 I in whole body and thyroid of patients with thyroid diseases are presented in this work. This system may be used for both pre-therapeutic and post-therapeutic dosimetry calculations. It consists of a detector and a movable support that allows its movement from one place to another., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Molecular radiotheragnostics directly links nuclear medicine diagnostic imaging to therapy. The imaging study is used to detect a specific molecular target associated with a disease process. A radiotherapeutic molecule with a similar biodistribution to the diagnostic agent can then be used to deliver targeted therapy.Molecular radiotheragnostics have been applied to manage both benign and malignant thyroid disease since the 1940s. The specific molecular pathway targeted is the sodium/iodide symporter (NIS) located on the basolateral membrane of the thyroid follicular cell. Radiolabelling of iodide or a similar ion allows targeting of the NIS system with radiopharmaceuticals for imaging ( 123 I-radioiodine and 99m Tc-pertechnetate) and treatment ( 131 I-radioiodine) by virtue of their gamma ray and beta-particle emissions, respectively.Scintigraphic imaging directly guides 131 I-radioiodine treatment planning to maximise therapeutic benefit while minimising adverse reactions, in a personalised medicine approach., (© Royal College of Physicians 2017. All rights reserved.)

A 62-year-old Caucasian woman presented with hypothyroid symptoms and biochemical thyrotoxic picture. Previously, she underwent right-sided subtotal thyroidectomy and left partial thyroid lobectomy for thyroid lumps, and treated with thyroxine replacement for hypothyroidism. Although there were no significant findings on clinical examination, investigations confirmed thyrotoxicosis with positive autoimmunity against thyroid glandâ€"all in line with a diagnosis of Graves’ hyperthyroidism. We would like to highlight atypical presentations of thyroid dysfunction and conversion of underactive to overactive thyroid status with this case. Early recognition, diagnosis and intervention are essential to prevent and/or reduce associated morbidity and mortality. When encountered with such clinical conundrums, we recommend seeking opinion from an experienced endocrinologist while interpreting such situation., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Purpose: 124 I-PET/CT can be used for pre-therapeutic assessment of radioactive iodine uptake in benign thyroid disorders, however systematic comparisons with intra-therapeutic uptake are still lacking for these disorders. The goals of this study were to compare 124 I RAIU and conventional 131 I RAIU tests with each other; to compare both tests with intra-therapeutic uptake (reference); and to verify the time course of radioactive iodine uptake at three time points (30, 102, and 336 h [14 days] post administration; p.a.)., Methods: Thirteen patients with benign thyroid diseases underwent 131 I RAIU test and 124 I RAIU test one after another before the intra-therapeutic 131 I uptake (reference) was measured via short-range and long-range measurements. After correction for decay, relative uptake differences were calculated and subjected to the Bland-Altman method for the evaluation of levels of agreement., Results: Radioactive iodine uptake tests with 124 I-PET/CT and 131 I probe did not show systematic deviations at any time point. Likewise, at 30 and 102 h p.a. there was no systematic discrepancy between pre-therapeutic and intra-therapeutic uptake levels. At 14 days p.a., however, both pre-therapeutic tests tended to overestimate the uptake compared to reference. Findings showed, for the first time with 124 I, that radioiodine therapy has some early radiobiological effects possibly limiting the accuracy of pre-therapeutic dosimetry., Conclusions: 124 I RAIU tests represent a feasible alternative to standard 131 I RAIU tests. The additional benefits of 124 I-PET/CT (e.g., functional topography, inclusion of retrosternal areas, possibility to enable fusion imaging) may thus increase the scope of this technology in benign thyroid disorders.

Aim: In radioiodine therapy (RIT) of benign thyroid-disorders empirical half-lives (HL emp ) may be used to calculate therapeutic dose. In this study the effective half-life (HLf as well as potential influence factors were retrospectively determined in order to better estimate HL emp ., Methods: Data from patients undergoing RIT from 01/09 to 04/14 were analysed (empirically estimated HL eff stratified by metabolic state and diagnosis). Inclusion criteria were: Benign thyroid-disorders, singular capsule administration and ≥ 6 dosimetry time-points (i. e. > 72 h inpatient stay). The effects of metabolic state, previous thy- reostatic medication and sex on HL eff were assessed by non-parametric ANOVA. The effects of target-volume and patient-age were assessed by regression analysis and nonparametric correlation (Spearman)., Results: Data of 1,498 patients were analyzed: Graves' Disease (GD), n = 286; multinodular goiter/disseminated autonomy (AMG/DA), n = 751; autonomous thyroid nodules (ATN), n = 421; euthyroid goiter (EG), n = 40. Mean HL eff (days ± SD) was 5.4 ± 1.5 in GD, 6.6 ± 1.2 in AMG/DA, 5.5 ± 1.6 in ATN and 6.9 ± 0.7 in EG. HL eff differed by metabolic state in GD, AMG/DA, and ATN, whereas neither thyreos- tatic medication nor sex were relevant. Moreover, target-volume (all diagnoses) and age (ATN and GD only) were associated with HL eft although the effect was small (R 2 < 3.8%)., Conclusion: When using standard HL eff for RIT, diagnosis and metabolic state should be considered for dose-calculations in RIT. Despite partial significance, the effects of target-volume and patient-age are small and a correction of HL eff , for these factors doesn't appear to be necessary in a routine setting., Competing Interests: The authors declare that there is no conflict of interest., (Schattauer GmbH.)

It is well known that a considerable amount of radioiodine is exhaled after radioiodine therapy (RIT) leading to unwanted radiation exposure through inhalation for non-involved persons. This study focuses on the amount of exhalation in the breath-out air of RIT-patients and the dosimetric consequences. Furthermore, the correlation between radioiodine uptake and exhalation was investigated. The radioiodine species were collected in a filter system and quantified over time by measurements with a scintillation counter. The dosimetric implications were then studied for different exposure scenarios. Of the activity administered to the patient, approximately 10 -3 % (50-110 ppm) is exhaled. The radioiodine inhalation taking place following exhalation in the vicinity yields doses of up to 500 μSv (children, staying with the patient immediately after application and for the next 8 h). Three days after administration the doses are significantly reduced. This study lays emphasis on previous assumptions that exhalation depends on thyroid storage. Regardless of the type of thyroid disease, the predominant form exhaled is organic radioiodine. The amount of exhaled radioiodine is small but from the point of view of radiation protection, by no means negligible immediately after administration. Radiation doses received by incorporation of exhaled radioiodine can easily exceed 100 μSv soon after administration of radioiodine. Three days after RIT the radioactivity can still be measured in the exhaled air but even at maximum, the annual doses lie far below 10 μSv and are thus comparatively low., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The aim of this work was the development of a software tool for treatment planning prior to molecular radiotherapy, which comprises all functionality to objectively determine the activity to administer and the pertaining absorbed doses (including the corresponding error) based on a series of gamma camera images and one SPECT/CT or probe data. NUKDOS was developed in MATLAB. The workflow is based on the MIRD formalism For determination of the tissue or organ pharmacokinetics, gamma camera images as well as probe, urine, serum and blood activity data can be processed. To estimate the time-integrated activity coefficients (TIAC), sums of exponentials are fitted to the time activity data and integrated analytically. To obtain the TIAC on the voxel level, the voxel activity distribution from the quantitative 3D SPECT/CT (or PET/CT) is used for scaling and weighting the TIAC derived from the 2D organ data. The voxel S-values are automatically calculated based on the voxel-size of the image and the therapeutic nuclide ((90)Y, (131)I or (177)Lu). The absorbed dose coefficients are computed by convolution of the voxel TIAC and the voxel S-values. The activity to administer and the pertaining absorbed doses are determined by entering the absorbed dose for the organ at risk. The overall error of the calculated absorbed doses is determined by Gaussian error propagation. NUKDOS was tested for the operation systems Windows(®) 7 (64 Bit) and 8 (64 Bit). The results of each working step were compared to commercially available (SAAMII, OLINDA/EXM) and in-house (UlmDOS) software. The application of the software is demonstrated using examples form peptide receptor radionuclide therapy (PRRT) and from radioiodine therapy of benign thyroid diseases. For the example from PRRT, the calculated activity to administer differed by 4% comparing NUKDOS and the final result using UlmDos, SAAMII and OLINDA/EXM sequentially. The absorbed dose for the spleen and tumour differed by 7% and 8%, respectively. The results from the example from radioiodine therapy of benign thyroid diseases and the example given in the latest corresponding SOP were identical. The implemented, objective methods facilitate accurate and reproducible results. The software is freely available., (Copyright © 2015. Published by Elsevier GmbH.)

The calculated dose rate from the radioiodine therapy patient should normally include a factor accounting for the attenuation and scatter of patient body tissues. The attenuation factor is currently neglected, and not applied in operational radiation protection. Realistic estimation of radiation dose rate levels from radioiodine therapy patients when properly performed will reduce operational cost and optimise institutional radiation protection practice. In this work, the existence of a patient body tissue attenuation factor is verified by comparing the dose rates measured from the radioiodine capsules immediately before administration with those measured from the patient immediately after administration. The correlation between the factors suspected to influence the patient body tissue attenuation and the measured dose rates from the patient normalised per unit activity is statistically analysed. The calculated attenuation correction factor based on authors' measurements was (0.55 ± 0.17). The measured dose rate per unit of radioactivity from the patient showed a negative correlation with their body mass index., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Aim: To compare uptake measurements and different methods for the pretherapeutic determination of the effective thyroidal ¹³¹I half life (Teff) to the results of posttherapeutic dosimetric measurements., Patients, Methods: Retrospective study of 1538 patients who received their first RIT in our department for autonomous thyroid nodules (ATN), autonomous multinodular goiter (AMG) or Graves' disease (GD) between November 1999 and January 2011. Pretherapeutic measurements were performed at any combination of 24 h, 48 h and 6 days after 131I administration. Post-therapy dosimetric measurements were performed in 12 h intervals until discharge. Teff was determined through monoexponential curve fitting., Results: Pretherapeutic Teff values based on measurements at 24 h and 48 h, 24 h and 6 d, 48 h and 6 d as well as on day 24 h, 48 h and 6 d yielded implausible (< 2 d or > 8 d) values for Teff, in 60.4%, 25.7%, 29.1 and 21.4% of available calculations, respectively. The plausible results showed significant, clinically relevant and sometimes considerable overestimations of Teff. Using empirically determined fixed disease specific Teff values resulted in a better congruence between the pre- and posttherapeutic dosimetry results. 24 h measurements were marginally more accurate than 48 h ones in AMG and GD whereas 48 h measurements were marginally more accurate in ATN; these differences are however not clinically relevant. 6 d measurements are clearly less accurate than those after 24 h or 48 h., Conclusion: In ATN, AMG and GD, pretherapeutic dosimetry can be performed by a single uptake measurement at 24 h or 48 h using a fixed, disease specific value for Teff. Additional later measurements do not yield a further clinically relevant contribution to accuracy of pretherapeutic dosimetry.

Objectives: Radioiodine is currently used routinely in the treatment of hyperthyroidism including Graves' disease (GD), toxic multinodular goitre (TMNG) and toxic solitary nodule (TSN) but no consensus exists on the most appropriate way to prescribe iodine--fixed dose or calculated doses based on the gland size or turnover of (131)I. We carried out the first nationwide French survey assessing the current practices in radioiodine treatment of hyperthyroidism., Material and Methods: A questionnaire was sent to French nuclear medicine hospital units and cancer treatment centres (n=69) about their practices in 2012., Results: Euthyroidism was considered the successful outcome for 33% of respondents, whereas hypothyroidism was the aim in 26% of cases. Fixed activities were the commonest therapeutic approach (60.0% of GD prescribed doses and 72.5% for TMNG and TSN), followed by calculated activities from Marinelli's formula (based on a single uptake value and thyroid volume). The fixed administered dose was chosen from between 1 to 3 levels of standard doses, depending on the patient characteristics. Factors influencing this choice were disease, with a median of 370 MBq for GD and 555 MBq for TSN and TMNG, thyroid volume (59%) and uptake (52%) with (131)I or (99m)Tc. Even physicians using fixed doses performed pretherapeutic thyroid scan (98%)., Conclusion: This study shows that practices concerning the prescription of (131)I therapeutic doses are heterogeneous. But the current trend in France, as in Europe, is the administration of fixed doses. The study provides the baseline data for exploring the evolution of French clinical practices., (Copyright © 2014. Published by Elsevier Masson SAS.)

Background: Prior to undergoing radioiodine therapy (RIT), patients regularly have concerns about isolation on the ward (mandatory for RIT for at least 48 hours in Germany due to radiation protection legislation) as well as fear of the presence of radioactive substances. In this study, these fears were investigated before and after RIT., Methods: A questionnaire was developed for completion both before and after radioiodine therapy. Questions included: (i) "Are you afraid of a therapy with radioactive substances?" (ii) "Do you have reservations about contact with radioactive substances?" and (iii) "Are you anxious about isolation?" Possible answers were made in a qualitative representation using a scale of 1-4 (4=full agreement, 3=mostly agreement, 2=partial agreement, and 1=no agreement). Further questions included, for example, sources of information used prior to therapy. A total of 209 patients treated by single or preplanned multiple RIT were surveyed over a period of 8 months (return 109). Analysis was done in subgroups according to age, education, disease, and number of RITs., Results: Question 1, "Are you afraid of a therapy with radioactive substances?" showed a similar statistically relevant decline in each subgroup (p<0.05), except for patients with multiple RIT (p=0.81). Asked about the handling of radioactive substances and their perception about the safety in this regard, the entire collective showed a highly statistically significant (p<0.01) decrease with little variability between the groups. The question concerning fear of isolation resulted in a significant decrease (p<0.05) in all subgroups, except for patients with multiple RIT (p=0.13). Analysis of sources of information before RIT showed that older patients preferred printed material and rarely used online resources, while younger patients used the internet more frequently, in addition to printed materials. Finally, most patients would undergo radioiodine therapy again (medical indication provided), with 54% fully agreeing and only 4% not agreeing., Conclusions: The survey demonstrates a reduction in concerns about nuclear radiation, use of unsealed radioactive materials, and isolation on the ward after RIT. Surprisingly, concerns rise again before a subsequent therapy.

Purpose: An easy-to-implement scintigraphic method that enables the assay of thyroid iodine uptake with improved accuracy and without the use of a reference source was developed with an aim to avoid unnecessary high radiation burden to patients undergoing (131)I treatment for benign thyroid disease., Materials and Methods: Dual-energy (123)I planar imaging involving simultaneous recording of both the primary (159 keV) and scatter (130 keV) frames was followed by generation of subtraction 'scatter-free' images. A uniform cutoff level of 15% was chosen to delineate the functional thyroid tissue with the help of isocontour regions of interest, which in turn enabled quantitation of the scatter-free thyroid counts. The ratio of the total counts being recorded in each of the above frames, the 'primary-to-Compton' ratio, was determined and compared with the uniform absorption-free ratio ascribed to all of the thyroid images. This enabled determination of the upscaling factor needed to restore the scatter-free counts to their unmoderated level. The corrected count content was subsequently converted to the iodine dose accumulated by the thyroid with the help of the camera-specific net detection efficiency. As a result, the true uptake value could be determined without the need to image a reference source or phantom., Results: Clinical evaluation of the proposed reference-free method was carried out by reviewing the 24-h uptake values obtained for the 32 patients suffering from Graves' disease, multinodular struma, or autonomous nodule. A comparison with concurrently assayed thyroid uptake values derived from the counts of the 24-h urine samples measured by the well-type scintillation counter (direct assay method) revealed very good linear correlation (r > 0.96). Furthermore, a comparison with uptake values determined using the 159 keV images of the patient as well as those of the reference sample in a commonly used so-called 'classic' manner was also carried out. The outcomes of the classic assay were found on average to underestimate the thyroid uptake in absolute terms by ∼ 25% because of unattended scatter and absorption-induced count losses. In contrast, the results of the reference-free method exhibited slight overestimation only, which on average amounted to less than 2%. However, because of the time-related fluctuations of the gamma camera and the dose calibrator as well as uncertainties induced by the scatter and absorption corrections, the average relative error associated with thyroid uptake values as determined by the proposed reference-free method was found to amount to nearly 10%., Conclusion: Strong evidence in support of the validity of the reference-free method designed to measure thyroid uptake with improved accuracy and without relating to a reference phantom image was produced in a clinical setting. As a result, the unnecessary high radiation burden to patients undergoing (131)I therapy because of systematic uptake underestimation could be avoided.

Radioiodine therapy is a highly recognizable method of treatment of benign thyroid diseases. The therapy gains a widespread interest of research groups, which find it as a promising weapon against endocrine disorders caused by benign thyroid diseases. According to the latest scientific research, factors, previously thought to be impossible to modify (intra-individual variation in radiosensitivity), has become modifiable. This will allow to establish a dose, which will affect functioning of other organs in the smallest possible way and will minimize the risk of side effects. The word, radioiodine" may raise some concern among those who are not highly familiar with endocrinology, but in fact it is a safe method. It is worth to mention that, according to recent research, consumption of common food products can reduce or even prevent potential side effects of radioiodine treatment.

Introduction: External fractionated radiotherapy of cancer increases the risk of cardio- and cerebrovascular events, but less attention has been paid to the potential side effects on the arteries following internal radiotherapy with radioactive iodine (RAI), i.e. 131-iodine. About 279 per million citizens in the western countries are treated each year with RAI for benign thyroid disorders (about 140,000 a year in the EU), stressing that it is of clinical importance to be aware of even rare radiation-induced side effects. In order to induce or accelerate atherosclerosis, the dose to the carotid arteries has to exceed 2 Gy which is the known lower limit of ionizing radiation to affect the endothelial cells and thereby to induce atherosclerosis., Objective: To estimate the radiation dose to the carotid arteries following RAI therapy of benign thyroid disorders., Methods: Assuming that the lobes of the thyroid gland are ellipsoid, that the carotid artery runs through a part of the lobes, that there is a homogeneous distribution of RAI in the lobes, and that the 24 h RAI uptake in the thyroid is 35 % of the (131)I orally administrated, we used integrated modules for bioassay analysis and Monte Carlo simulations to calculate the dose in Gy/GBq of administrated RAI., Results: The average radiation dose along the arteries is 4-55 Gy/GBq of the (131)I orally administrated with a maximum dose of approximately 25-85 Gy/GBq. The maximum absorbed dose rate to the artery is 4.2 Gy/day per GBq (131)I orally administrated., Conclusion: The calculated radiation dose to the carotid arteries after RAI therapy of benign thyroid disorder clearly exceeds the 2 Gy known to affect the endothelial cells and properly induce atherosclerosis. This simulation indicates a relation between the deposited dose in the arteries following RAI treatment and an increased risk of atherosclerosis and subsequent cerebrovascular events such as stroke.

The EANM Dosimetry Committee Series "Standard Operational Procedures for Pre-Therapeutic Dosimetry" (SOP) provides advice to scientists and clinicians on how to perform patient-specific absorbed dose assessments. This particular SOP describes how to tailor the therapeutic activity to be administered for radioiodine therapy of benign thyroid diseases such as Graves' disease or hyperthyroidism. Pretherapeutic dosimetry is based on the assessment of the individual (131)I kinetics in the target tissue after the administration of a tracer activity. The present SOP makes proposals on the equipment to be used and guides the user through the measurements. Time schedules for the measurement of the fractional (131)I uptake in the diseased tissue are recommended and it is shown how to calculate from these datasets the therapeutic activity necessary to administer a predefined target dose in the subsequent therapy. Potential sources of error are pointed out and the inherent uncertainties of the procedures depending on the number of measurements are discussed. The theoretical background and the derivation of the listed equations from compartment models of the iodine kinetics are explained in a supplementary file published online only.

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Radioiodine-131 ((131)I) is widely used for diagnosis and treatment of benign thyroid diseases. Observational studies have not been conclusive about the carcinogenic potential of (131)I and we therefore conducted a meta-analysis. We performed a literature search till September 2011 which included (131)I as a diagnostic or treatment modality ((131)I for treatment of thyroid cancer was excluded). Data on 64 different organ or organ group subsets comprising 22 029 exposed subjects in the therapeutic cohorts and 24 799 in the diagnostic cohorts in seven studies were included. Outcome was pooled as the relative risk (RR) using both standard and bias adjusted methods. Quality assessment was performed using a study-specific instrument. No increase in overall (RR 1.06, 95% CI: 0.94-1.19), main organ group or combined organ group (four groups known to concentrate (131)I; RR 1.11, 95% CI: 0.94-1.31) risks was demonstrable. Individual organs demonstrated a higher risk for kidney (RR 1.70, 95% CI: 1.15-2.51) and thyroid (RR 1.99, 95% CI: 1.22-3.26) cancers with a strong trend for stomach cancer (RR 1.11, 95% CI: 0.92-1.33). A thyroid dose effect was seen for diagnostic doses. While there is no increase in the overall burden of cancer, an increase in risk to a few organs is seen which requires substantiation. The possible increase in thyroid cancer risk following diagnostic (131)I use should no longer be of concern given that it has effectively been replaced by the use of 99mTc-pertechnetate.

Iodine-131 is successfully used in the treatment of hyperthyroidism and differentiated thyroid cancer. Thyroid is the critical organ for iodine. Iodine is taken up by the thyroid follicular cells. Radioactive isotope iodine-131 simultaneously emits two types of radiation: radiation beta minus (β-) used for the treatment and gamma (γ) used for diagnosis. Due to the penetration of beta particles in tissue, damaging effect of β-radiation is restricted to thyroid cells. In this article, characteristic of iodine-131, mechanism of action and mechanism of tissue damage is presented. HIGH energy γ-ray emission, contributes to the dose of both: patient's body and the personnel. In accordance with the principles of radiation protection, reducing exposure to ionizing radiation should be achieved by: use of proper shieldings, organization of work, appropriate distance from the radiation source and reducing the time of exposure. Treatment with I-131, depending on medical indications, may be carried out on stationary or outpatient basis. All activities conducted in the exposure to radiation must comply with the principles of radiation protection, in accordance with the applicable regulations, that are also presented in this article.

Objective: To describe our experience with therapeutic sialendoscopy for radioiodine (iodine 131 [(131)I]) sialadenitis., Design: Retrospective medical chart review., Setting: Academic tertiary referral center., Patients: The study included 11 patients who underwent therapeutic sialendoscopy for the treatment of (131)I sialadenitis after failing medical management., Interventions: Therapeutic sialendoscopy with dilation and irrigation of the ductal system was performed in all patients., Main Outcome Measures: Patient-reported frequency and severity of symptoms., Results: Our series included 9 women and 2 men (mean age, 51 years; age range, 35-65 years). A total of 23 parotid glands and 5 submandibular glands were treated. Sialendoscopy was possible in all patients, except one in whom the Stensen duct could not be cannulated. Typical endoscopic findings included pale ductal mucosa, thick mucous plugs, ductal debris, and stenosis of the duct. Most patients (91%) reported improvement of symptoms after a single procedure. Complete resolution of symptoms, with sustained benefit, was reported by 6 patients (54%) at a mean follow-up of 18 months. Partial improvement of symptoms, with some persistent intermittent episodes of pain or swelling, was reported by 4 patients (36%). One patient reported no subjective symptomatic improvement after 2 procedures and subsequently underwent a parotidectomy., Conclusions: Sialendoscopy is useful for the improvement of symptoms due to radioiodine-induced sialadenitis in patients who are refractory to conservative medical therapy. Therapeutic sialendoscopy appears to provide effective and sustained symptom improvement in most patients in our experience.

The activity to be administered in I-131 therapy of benign thyroid disease is determined by the radiation absorbed dose necessary to cure the disease, the target mass, and the residence time of the I-131 in the target volume. Data from 73 patients with complete sets of uptake measurements 2, 6, 24, 48, and 96 (n=53) or 120 (n=20) hours after oral administration of 1 MBq I-131 were used to deduce residence times from subsets of 3, 2, or only 1 measurement for each individual. The values were compared to those obtained with the reference method, i.e. a fit of an uptake function based on a 2-compartment model to all 5 measurements, to quantify the errors introduced by the less demanding assessments. Deviations are less than 10% if the 2- compartment uptake function is fitted to only 3 values measured after 6, 24, and 96-120h. Use of 2, 24, and 96-120h data results in errors >20% in individual patients. The effective half-lives as determined from 2 measurements after 24 and 96-120h correlate well with those deduced from the reference method with larger deviations in individuals with slow iodine kinetics and late maximal uptake. Residence times determined from the 24h uptake, assuming linear increase during the first day, and the effective half-life limited to maximum 8days underestimate the actual values systematically in patients with long and short half-lives. These errors can be eliminated by a modification of the calculation method resulting in deviations less than 14% in all but one individual for this procedure. The accuracy of methods based on only one retention value increases with the time of measurement after the administration of I-131. While systematic errors up to a factor of two occur if the 24h uptake is used for the estimate, deviations are less than 18% for measurements after 120h. The results suggest that only one late uptake assessment warrants residence time estimates with an acceptable error. Given the high inherent uncertainties in the complete dosimetry procedure, additional measurements must be considered only if a high precision of the absorbed dose assessment is required e.g. for clinical trials., (Copyright © 2011. Published by Elsevier GmbH.)

Purpose: A considerable amount of radioiodine is exhaled after radioiodine therapy leading to unwanted radiation exposure through inhalation. This study focused on the concentration of radioactivity exhaled and its chemical nature., Methods: Air exhaled by 47 patients receiving (131)I-iodine for different thyroid diseases (toxic goitre n = 26, Graves' disease n = 13, thyroid cancer n = 8) was investigated with a portable constant air-flow sampler. Different chemical iodine species were collected separately (organic, elemental and aerosolic) up to 26 h after administration of the radioiodine capsule. The data approximated to a monoexponential time-activity curve when integrated over 100 h. The radioactivity in the filters was measured with a well counter at defined time points after administration., Results: The radioactivity of (131)I in the exhaled air 1 h after administration ranged from 1 to 100 kBq/m(3). Two parameters (half-life of radioiodine exhalation and time-integrated activity over 100 h) were substantially higher in patients with cancer after near-total thyroidectomy (11.8 ± 2.1 h and 535 ± 140 kBq / m(3), respectively) than in patients with hyperfunctioning thyroid tissue due to toxic adenoma (7.6 ± 2.5 h and 115 ± 27 kBq / m(3), respectively) or Graves' disease (6.4 ± 3.6 h and 113 ± 38 kBq / m(3), respectively). The percentage of radioiodine in the exhaled air in relation to radioiodine administered to the patient was between 80 ppm and 150 ppm. The fraction of organically bound radioiodine (mean value) for all time points after administration was 94-99.9%. This percentage did not depend on the type of thyroid disease., Conclusion: The amount of exhaled radioiodine is small but by no means negligible on the first day after administration. This is the first study to provide experimental evidence on a systematic basis that radioiodine becomes exhalable in vivo, i.e. in the patient. The mechanism of organification of orally administered radioiodine remains to be investigated.

Radioiodine therapy (RIT) for benign thyroid diseases in Germany requires the patient to stay in a nuclear medicine therapy ward for at least 48 hours and the dose to the thyroid to be computed from activity measurements performed during that stay. A major part of the total dose will be delivered after the patient's discharge from the hospital and thus has to be predicted through extrapolation with the effective half-life measured peri-therapeutically. We performed repeated thyroid uptake measurements on patients up to five months post therapy to investigate post-therapeutic changes in their effective half-lives and examine the dosimetric consequences. 12 patients (4 m, 8 f; age 36 - 76 y; 4 Graves' disease, 4 toxic adenoma, 3 toxic goitre, 1 non-toxic goitre) underwent late uptake measurements (1 - 7 meas., 13 - 154 d post administration, median 54 d, performed with thyroid probe resp. whole body counter at lower activities). Doses calculated from late measurements were compared to those predicted at discharge; half-lives calculated from the late measurement closest to the median delay (54 d) were compared to those determined at time of discharge. A cross-calibration between activity calibrator, thyroid probe, and whole body counter over an activity range from 52 MBq down to 45 Bq revealed linearity to within 6%, which was considered sufficient. In 9 out of 12 patients the achieved dose was within the range predicted at discharge. Averaged deviation between achieved and predicted dose was 3.1±2.2% (median 2.5%, range 0.7% - 7.2%). Averaged deviation between post- and peri-therapeutic half-lives was 5.1±3.9% (median 3.5%, range 1.3% - 12.5%). For n=5 patients discharged after 3 days, averaged deviations were greater (dose 4.0%, half-life 5.6%) than for those patients (n=7) who stayed in the hospital for a minimum of 4 days (dose 2.5%, half-life 4.8%). Excretion of iodine from the thyroid remains practically unchanged for at least two months after RIT. The dosimetric procedure implemented in our institution warrants a robust prediction of the post-therapeutic half-life and thus the actual achieved dose., (Copyright © 2011. Published by Elsevier GmbH.)

Introduction: Nodular toxic and non-toxic goitres are seen in approximately 15% of Danish women, and the pros and cons of thyroidectomy versus radioiodine (RI) therapy are often discussed. The purpose of this study was to evaluate the type and number of patients treated on the indication of hyperthyroidism or benign goitre who did not achieve a sufficient effect of RI therapy and therefore needed thyroidectomy., Material and Methods: Between 1 January 2003 and 1 January 2008, a total of 873 patients were treated with RI on the indication of benign thyroid disease at Herlev Hospital (Denmark). Data concerning these patients were listed consecutively in a database. The data were subsequently cross-checked with the Danish Thyroid Surgery Quality Register (THYKIR) which contains data on all patients treated with thyroid surgery at Danish departments of ear, nose and throat and head and neck surgery since 1 January 2001. Patient data were also cross-checked with the National Patient Register data. The unique Danish social security numbers were used to compare data., Results: Among the 873 patients treated with RI, 36 were listed in the THYKIR database. Eleven of these had primary thyroid surgery and subsequently underwent RI treatment due to goitre recurrence. Twenty-five patients first received RI therapy and subsequently thyroidectomy due to persisting symptoms (17 had non-toxic goitre and compression symptoms (among these eight had a large goitre with a thyroid volume of > 100 ml (range 100-389 ml)), five had nodular toxic goitre and three had diffuse toxic goitre and continuing hyperthyroidism despite RI treatment. Thyroid surgery revealed a small (2-3 mm) cancer in two patients, both from the group of patients with nodular toxic goitre., Conclusion: The effect of RI therapy sufficiently solved the problem (hyperthyroidism or goitre) and surgery was hence avoided in 848 of 873 (97%) patients. However, within the group of patients with nontoxic goitre, a subgroup of patients with large goitres seems to be resistant to RI treatment and does not achieve sufficient effect under the current RI therapy regime., Funding: not relevant., Trial Registration: Danish Data Protection Agency (Datatilsynet) HEH.afd.O.750.86-7 and 2010-231-0068.

By means of a conservative dosimetry model, the values of operational radiological criteria for patients released from hospital--residual activity in a body and dose rate near the patient's body--are substantiated based on the effective dose limit of 5 mSv for persons helping the patient or living with him and 1 mSv for other adults and children. Two sets of operative criteria for radionuclides (125)I, (131)I, (153)Sm and (188)Re used in Russia for radionuclide therapy were derived. Release criteria for (125)I well differ from such values in other countries because in this work absorption of (125)I low-energy photon radiation in the patient was taken into account. When a patient having undergone radionuclide therapy crosses the frontier of Russia, high-sensitivity devices for radiation control at the custom can detect the patient. A simplified radiological assessment of the patient was suggested aimed at provision of radiation safety for patient companions in transport.