[Radiation exposure in the environment of patients after application of radiopharmaceuticals. Part 2: Therapeutic procedures]. / Strahlenexposition in der Umgebung von Patienten nach Radiopharmaka-Applikation. Teil 2: Nuklearmedizinische Therapien.

AIM: After therapeutical application of radionuclides the patient has to be regarded as a radioactive source. The radiation exposure differs from diagnostic nuclear medicine due to the amount of radioactivity and due to beta-radiation. Measurements of photon dose rates were carried out and estimates of beta-radiation outside the patient using Monte-Carlo methods. Calculations of maximum beta-ranges in tissue were also performed. Detailed knowledge of the radiation exposure close to the patient is of major importance with respect to radiation protection of the staff. METHOD: Photon dose rates for 32 patients were determined after treatment with [131I]NaI and [131I]meta-iodobenzylguanidin, [32P]Na2HPO4, [90Y]Zevalin and [153Sm]EDTMP. Readings were taken immediately after application at eight distances. RESULTS: For therapies with 131I photon dose rates amount to 2 mSv.h(-1).GBq(-1) close to the patient. Taking the typical activities of 3.7 GBq for thyroid carcinoma and up to 11 GBq for mIBG therapies into account this leads to a considerable radiation exposure of approximately 7.5 mSv/h and 20 mSv/h, respectively. At a distance of 2 m the dose rates fall to 1/100 compared to the vicinity. For 153Sm the maximum of 100 microSv.h(-1).GBq(-1) is significantly lower compared to therapies using radioiodine. After application of 32P or 90Y all photon dose rates are lower (<10 microSv.h(-1).GBq(-1)) but in both cases high energy beta-particles associated with high maximum ranges exceeding 1 cm in tissue have to be considered. CONCLUSION: The remarkable difference of the dose rates in the vicinity of the radioactive patient compared to readings at 2 m distance underlines the major importance of the distance for radiation protection. After application of nuclides emitting high energy beta-particles their contribution outside the patient should be considered. For typical procedures in the patient's vicinity the radiation exposure of the personnel remains below the annual limit of 20 mSv.

[Radiation exposure in the environment of patients after application of radiopharmaceuticals. Part 1: Diagnostic procedures]. / Strahlenexposition in der Umgebung von Patienten nach Radiopharmaka-Applikation. Teil 1: Nuklearmedizinische Diagnostik.

AIM: After application of radiopharmaceuticals the patient becomes a radioactive source which leads to radiation exposure in the proximity. The photon dose rates after administration of different radiopharmaceuticals used in diagnostic nuclear medicine were measured at several distances and different time intervals. These data are of importance for estimating the exposure of technologists and members of the public. PATIENTS, METHOD: In this study dose rates were measured for 67 patients after application of the following radiopharmaceuticals: 99mTc-HDP as well as 99mTc-pertechnetate, 18F-fluorodeoxyglucose, 111In-Octreotid and Zevalin and 123I-mIBG in addition to 123I-NaI. The dose rates were measured immediately following application at six different distances to the patient. After two hours the measurements were repeated and--whenever possible--after 24 hours and seven days. RESULTS: Immediately following application the highest dose rates were below 1 mSv/h: with a maximum at 780 microSv/h for 18F (370 MBq), 250 microSv/h for 99mTc (700 MBq), 150 microSv/h for 111In (185 MBq) and 132 microSv/h for 123I (370 MBq). At a distance of 0.5 m the values decrease significantly by an order of magnitude. Two hours after application the values are diminished to 1/3 (99mTc, 18F), to nearly (1/2) (123I) but remain in the same order of magnitude for the longer-lived 111In radiopharmaceuticals. CONCLUSION: For greater distances the doses remain below the limits outlined in the national legislation.

Graves' disease and radioiodine therapy. Is success of ablation dependent on the achieved dose above 200 Gy?

AIM: This study was performed to determine the results of ablative radioiodine therapy (RIT) when the achieved dose in the thyroid was above 200 Gy and to characterize predictive factors for treatment outcome. PATIENTS, METHODS: A total of 571 consecutive patients were observed for 12 months between July 2001 and June 2004. Inclusion criteria were a confirmed diagnosis Graves' disease, compensation of hyperthyroidism and withdrawal of antithyroid drugs two days before preliminary radioiodine-testing and RIT. The intended dose was 250 Gy and the therapeutically achieved dose was calculated from serial uptake measurements. The end-point measure was thyroid function 12 months after RIT; success was defined as elimination of hyperthyroidism. The relation between success rate and the achieved dose, thyroid volume, age and sex of patients, TSH- and TRAb-values and presence of ophthalmopathy was analysed. RESULTS: Relief from hyperthyroidism was achieved in 96% of patients who received more than 200 Gy, even for thyroid volumes >40 ml. The success of ablative RIT was not influenced by age or sex of patients, or by TSH- or TRAb values or concomitant ophthalmopathy. The mean achieved dose in the thyroid was 298 Gy with a standard deviation of 74.6 Gy. CONCLUSION: To achieve a dose of over 200 Gy with the above standard deviation, we recommend calculating an intended dose of 250 Gy and using a dosimetric approach with early and late uptake values in the radioiodine test, to allow early therapeutic intervention should the posttherapeutic thyroid dose fall unexpectedly below 200 Gy.

Graves' disease and radioiodine therapy. Is success of ablation dependent on the choice of thyreostatic medication?

AIM: This study was performed to analyse the impact of the choice of antithyroid drugs (ATD) on the outcome of ablative radioiodine therapy (RIT) in patients with Graves' disease. PATIENTS, MATERIAL, METHODS: A total of 571 consecutive patients were observed for 12 months after RIT between July 2001 and June 2004. Inclusion criteria were the confirmed diagnosis of Graves' disease, compensation of hyperthyroidism and withdrawal of ATD two days before preliminary radioiodine-testing and RIT. The intended dose of 250 Gy was calculated from the results of the radioiodine test and the therapeutically achieved dose was measured by serial uptake measurements. The end-point measure was thyroid function 12 months after RIT; success was defined as elimination of hyperthyroidism. The pretreatment ATD was retrospectively correlated with the results achieved. RESULTS: Relief from hyperthyroidism was achieved in 96% of patients. 472 patients were treated with carbimazole or methimazole (CMI) and 61 with propylthiouracil (PTU). 38 patients had no thyrostatic drugs (ND) prior to RIT. The success rate was equal in all groups (CMI 451/472; PTU 61/61; ND 37/38; p = 0.22). CONCLUSION: Thyrostatic treatment with PTU achieves excellent results in ablative RIT, using an accurate dosimetric approach with an achieved post-therapeutic dose of more than 200 Gy.

99mTc-MIBI SPECT in primary hyperparathyroidism. Influence of concomitant vitamin D deficiency for visualization of parathyroid adenomas.

UNLABELLED: AIM of the study was to analyse the influence of a concomitant vitamin D deficiency on the results of (99m)Tc-MIBI studies in patients (pts) with primary hyperparathyroidism (pHPT). PATIENTS, METHODS: Between January 1998 and May 2004, 71 pts with pHPT had undergone operation after a (99m)Tc-MIBI study of whom 54 pts (76%) had normal values of 25-OH-vitamin D3 and 17 pts (24%) had vitamin D deficiency. Results of a dual-phase (99m)Tc-MIBI protocol with SPECT were compared with histopathology. RESULTS: In 54 pts with normal vitamin D values late SPECT images identified more lesions (n=51, sensitivity 91%) than early planar (n=45, sensitivity 82%) or late planar images (n=50, sensitivity 88%). In 17 pts with vitamin D deficiency late SPECT images identified more lesions (n=13, sensitivity 72%) than early planar (n=10, sensitivity 56%) or late planar images (n=10, sensitivity 56%) too. In pts with vitamin D deficiency the sensitivity of a (99m)Tc-MIBI SPECT study was lower than in those with normal vitamin D status (72% vs. 91%) and dependent on the value for PTH. However, the results did not reach statistical significance: early planar: p=0.1625; late planar: p=0.0039; (99m)Tc-MIBI SPECT: p=0.1180. CONCLUSION: The likelihood of a pathological (99m)Tc-MIBI study being obtained in pts with pHPT is dependent on the parathyroid hormone level. However, a negative influence of a low vitamin D level on the scintigraphic detection rate of a parathyroid adenoma could not be proven which may be due to the low number of pts with vitamin D deficiency.

[Procedure guideline for thyroid scintigraphy (version 3)]. / Verfahrensanweisung für die Schilddrüsenszintigraphie (Version 3).

The version 3 of the procedure guideline for thyroid scintigraphy is an update of the procedure guideline previously published in 2003. The interpretation of the scintigraphy requires the knowledge of the patients' history, the palpation of the neck, the laboratory parameters and of the sonography. The interpretation of the technetium-99m uptake requires the knowledge of the TSH-level. As a consequence of the improved alimentary iodine supply the (99m)Tc-uptake has decreased; 100,000 counts per scintigraphy should be acquired. For this, an imaging time of 10 minutes is generally needed using a high resolution collimator for thyroid imaging.

[Procedure guideline for radioiodine test (Version 3)]. / Verfahrensanweisung zum Radioiodtest (Version 3).

The version 3 of the procedure guideline for radioiodine test is an update of the guideline previously published in 2003. The procedure guideline discusses the pros and cons of a single measurement or of repeated measurements of the iodine-131 uptake and their optimal timing. Different formulas are described when one, two or three values of the radioiodine kinetic are available. The probe with a sodium-iodine crystal, alternatively or additionally the gamma-camera using the ROI-technique are instrumentations for the measurement of iodine-131 uptake. A possible source of error is an inappropriate measurement (sonography) of the target volume. The patients' preparation includes the withdrawal of antithyroid drugs 2-3 days before radioiodine administration. The patient has to avoid iodine-containing medication and the possibility of additives of iodine in vitamin- and electrolyte-supplementation has to be considered.

[Procedure guideline for iodine-131 whole-body scintigraphy for differentiated thyroid cancer (version 3)]. / Verfahrensanweisung für die Iod-131-Ganzkörperszintigraphie beim differenzierten Schilddrüsenkarzinom (Version 3).

Version 3 of the procedure guideline for (131)I whole-body scintigraphy (WBS) is the counterpart to the procedure guideline for radioiodine therapy (version 3) and specify the interdisciplinary guideline for thyroid cancer of the Deutsche Krebsgesellschaft concerning the nuclear medicine part. (131)I WBS 3-6 months after (131)I ablation remains a standard procedure in an endemic area for thyroid nodules and the high frequency of subtotal surgical procedures. Follow-up without (131)I WBS is only justified if the following preconditions are fulfilled: low-risk group pT1-2, pN0 M0 with histopathologically confirmed pN0, (131)I uptake <2%, (131)I WBS during ablation without any suspicious lesion, stimulated thyroglobulin (Tg)-level 3-6 months after ablation <2 ng/mL, and absence of anti-thyroglobulin-antibodies with normal recovery-testing. If patients from the low-risk group show normal (131)I WBS 3-6 months after ablation and stimulated Tg is of <2 ng/mL, there will be no need for additional routine (131)I WBS. If patients from the high-risk group show normal (131)I WBS and stimulated Tg-level of <2 ng/mL 3-6 months after ablation, the follow-up care should include repeated stimulated Tg-measurements. If the Tg-level remains below 2 ng/mL, an additional (131)I WBS will be not necessary. The recommended intervals for stimulated Tg-testing are adapted to the prior intervals for (131)I WBS-testing in the high-risk group. Increased anti-thyroglobulin-antibodies or incomplete recovery-testing make an individual strategy of follow-up care necessary, which include (131)I WBS.

[Procedure guidelines for radioiodine therapy of differentiated thyroid cancer (version 3)]. / Verfahrensanweisung zur Radioiodtherapie (RIT) beim differenzierten Schilddrüsenkarzinom (Version 3).

The procedure guideline for radioiodine therapy (RIT) of differentiated thyroid cancer (version 3) is the counterpart to the procedure guideline for (131)I whole-body scintigraphy (version 3) and specify the interdisciplinary guideline for thyroid cancer of the Deutsche Krebsgesellschaft concerning the nuclear medicine part. Recommendation for ablative (131)I therapy is given for all differentiated thyroid carcinoma (DTC) >1 cm. Regarding DTC < or =1 cm (131)I ablation may be helpful in an individual constellation. Preparation for (131)I ablation requires low iodine diet for two weeks and TSH-stimulation by withdrawal of thyroid hormone medication or by use of recombinant human TSH (rhTSH). The advantages of rhTSH (no symptoms of hypothyroidism, lower blood activity) and the advantages of endogenous TSH-stimulation (necessary for (131)I-therapy in patients with metastases, higher sensitivity of (131)I whole-body scan) are discussed. In most centers standard activities are used for (131)I ablation. If pretherapeutic dosimetry is planned, the diagnostic administration of (131)I should not exceed 1-10 MBq, alternative tracers are (123)I or (124)I. The recommendations for contraception and family planning are harmonized with the recommendation of ATA and ETA. Regarding the best possible protection of salivary glands the evidence is insufficient to recommend a specific setting. To minimize the risk of dental caries due to xerostomia patients should use preventive strategies for dental hygiene.

[Dosimetry for therapeutic treatment of neuroblastoma by 131I-mIBG]. / Dosimetrie bei der Therapie von Neuroblastomen mit 131I-mIBG.

AIM: Targeted radiotherapies using iodine-131 meta-iodobenzylguanidin have long been in use for treatment of stage IV neuroblastoma but reliable dosimetric data are scarce. METHOD: This work presents an approach to determine the whole body exposure and tumour doses delivered during therapy. Dosimetric data are reported and discussed for six treatments carried out according to the trial protocol NB2004 as it is in use in our study in the last two years. RESULTS: Whole body exposures are found to be in the range of 1.75 to 2.5 Gy whereas tumour doses vary between 15 and 55 Gy. CONCLUSION: The course of action prescribed by the trial protocol allows whole body exposure as well as tumour doses to be determined routinely.

Is there a benefit of 131 I-MIBG therapy in the treatment of children with stage 4 neuroblastoma? A retrospective evaluation of The German Neuroblastoma Trial NB97 and implications for The German Neuroblastoma Trial NB2004.

AIM: (131)I-meta-iodobenzylguanidine ((131)I-MIBG) therapy has been used in neuroblastoma treatment for many years but its value in high intensive first line treatment protocols is not exactly known. PATIENTS, METHODS: Stage 4 neuroblastoma patients >1 year with (123)I-MIBG positive residual disease (primary tumour and/or metastasis) after complete induction chemotherapy according to the German neuroblastoma trial NB97 were retrospectively analyzed. RESULTS: One-hundred-eleven patients had (123)I-MIBG positive residual disease after complete induction chemotherapy. Forty patients received (131)I-MIBG therapy using a median activity of 0.44 GBq/kg body weight. By univariate analysis, patients who underwent (131)I-MIBG therapy had a better 3-year event free survival (3-y-EFS 46 +/- 8%) and 3-year overall survival (3-y-OS 58 +/- 9%) than 71 patients without (131)I-MIBG therapy (3-y-EFS 19 +/- 5%, p = 0.003; 3-y-OS 43 +/- 6%, p = 0.037). However, subgroup analysis of 66 patients who underwent high dose chemotherapy with autologous stem cell transplantation (ASCT) during treatment found a very similar outcome with (131)I-MIBG therapy (3-y-EFS 49 +/- 9%, 3-y-OS 59 +/- 10%) and without (131)I-MIBG therapy (3-y-EFS 33 +/- 9%, p = 0.171; 3-y-OS 59 +/- 9%, p = 0.285) due to the dominating effect of ASCT. By multivariate analysis, (131)I-MIBG therapy had no impact on EFS (p = 0.494) and OS (p = 0.891). Only ASCT, external beam radiation therapy and MYCN amplification were important for EFS and OS. CONCLUSIONS: An independent advantage of I-131-MIBG therapy could not be proven in this retrospective analysis. The ongoing German Neuroblastoma Trial NB2004 will address the influence of (131)I-MIBG therapy with emphasis on tumour dosimetry.

[Established nuclear medicine techniques for tumour diagnosis (tumour SPECT): can they still compete with (18)F-FDG-PET?]. / Konventionelle nuklearmedizinische Tumordiagnostik (Tumor-SPECT): Was ist angesichts von (18)F-FDG-PET noch aktuell?

This overview presents the indications of tumour SPECT in contrast to tumour PET using (18)F-FDG. A number of diagnostic SPECT radiopharmaceuticals have been used for years in oncology and are widely available in nuclear medicine departments. Today, tumour SPECT has to compete with tumour PET using (18)F-FDG. Other PET radiopharmaceuticals are common only in specialised centers. In comparison to SPECT, PET images with their higher resolution are technically superior. Therefore, PET is better than SPECT in localising a tumour, if the special tumour entity accumulates (18)F-FDG. Thus, (18)F-FDG-PET has largely replaced SPECT examinations using (201)Tl chloride, (67)Ga citrate or (99m)Tc anti-CEA. It is questionable whether mammascintigraphy using (99m)Tc-MIBI or (99m)Tctetrofosmine will be broadly accepted in clinical routine. SPECT radiopharmaceuticals are still up to date for examination of tumour entities which do not accumulate (18)F-FDG (e. g. neuroendocrine tumours) and in clinical problem solving if (18)F-FDG-PET is not regarded as superior (e. g. search for recurrent medullary thyroid carcinoma) or in the management of tumours with overlapping diagnosis and therapy as it is the case for differentiated thyroid carcinomas ((123)I/(131)I-NaI), phaeochromozytomas, and neuroblastomas ((123)I/(131)I-MIBG), carcinoids, gastroenteropancreatic tumours, paragangliomas, and Merkel-cell tumours (somatostatin receptor scintigraphy). Future developments concerning new SPECT radiopharmaceuticals and image fusion such as SPECT/CT are expected.

[Radioimmunotherapy with yttrium-90 ibritumomab tiuxetan. Clinical considerations, radiopharmacy, radiation protection, perspectives]. / Radioimmuntherapie mit 90Y-markiertem Ibritumomab-Tiuxetan: Klinik, Radiopharmazie, Strahlenschutz, Perspektiven.

90Y-ibritumomab tiuxetan (Zevalin) is currently approved for radioimmunotherapy of patients with relapsed or refractory follicular non-Hodgkin's lymphoma pretreated with rituximab. Future directions are the combined use of 90Y-ibritumomab tiuxetan as part of the initial treatment and as first-line multi-agent therapy of relapsed disease. Current studies investigate patients with other than follicular indolent histologies, e. g. diffuse large cell lymphoma. Labelling of 90Y ibritumomab tiuxetan is a safe procedure, the radiochemical purity is not disturbed by a higher room temperature or by metallic impurity. Quality control is recommended by thin layer chromatography (TLC), strips >15 cm are favourable. TLC cannot distinguish between the correctly radiolabelled antibodies and radiocolloid impurity. If necessary, additional HPLC should be performed. Radiocolloid impurities are absorbed to the solid phase and do not reach the eluate. If the radiochemical purity test is insufficient (<95%), the additional cleaning using EconoPac 10 DG columns (Biorad, Hercules, CA, USA) is a reliable procedure to reduce the percentage of free radionuclide. However, this procedure is not part of the approval.

Assessment of intracellular water by whole body bioelectrical impedance and total body potassium in HIV-positive patients.

OBJECTIVE: Bioelectrical impedance analysis (BIA) is widely used as bedside assessment of body composition. Body cell mass (BCM) and intracellular water (ICW) are clinically important body compartments. Estimates of ICW obtained from BIA by different calculation approaches were compared to a reference method in male HIV-infected patients. PATIENTS: Representative subsample of clinically stable HIV-infected outpatients, consisting of 42 men with a body mass index of 22.4 +/- 3.8 kg/m(2)(range, 13-l31 kg/m(2)). METHODS: Total body potassium was assessed in a whole body counter, and compared to 50 kHz monofrequency BIA and multifrequency bioelectrical impedance spectroscopy. Six different prediction equations for ICW from BIA data were applied. Methods were compared by the Bland-Altman method. RESULTS: BIA-derived ICW estimates explained 58% to 73% of the observed variance in ICW (TBK), but limits of confidence were wide (-16.6 to +18.2% for the best method). BIA overestimated low ICW (TBK) and underestimated high ICW (TBK) when normalized for weight or height. Mono- and multifrequency BIA were not different in precision but population-specific equations tended to narrower confidence limits. CONCLUSION: BIA is an unreliable method to estimate ICW in this population, in contrast to the better established estimation of total body water and extracellular water. Potassium depletion in severe malnutrition may contribute to this finding but a major part of the residual between methods remains unexplained.

[Influence of disease prognosis and age on the radiation risk from diagnostic nuclear medicine (bone scintigraphy as an example)]. / Einfluss von Krankheitsprognose und Alter auf das Strahlenrisiko durch nuklearmedizinische Diagnostik (am Beispiel der Skelettszintigraphie).

AIM: Of the study was to assess the influence of the patient age and the survival of patients undergoing bone scintigraphy on the calculations of the theoretical lifetime loss. PATIENTS AND METHODS: The evaluated data set included 216 patients undergoing a bone scan for the first time in 1980. From 182 patients a study end point (either the date of death, or existing registration in the German resident office on the 31.12.1995) was obtained. The theoretical life time loss was based on the formalism previously presented by Schicha und Wellner (13). RESULTS: In 74% of the examined patients a malignant disease was present. 28% of the patients had died within one year of the examination. At the end of the follow-up period, of at least 15 years, 58% of the patients were deceased. The theoretical lifetime loss due to radiation exposure within this specified patient group was estimated to be 0.152 d/mSv. Assuming an age distribution of the general population and statistically derived life expectancy, this value should be 0.437 d/mSv. CONCLUSION: The estimates regarding the risk of diagnostic procedures using ionizing radiation should take into account the limited life expectancy of patients in hospitals.

[Exhalation of I-131 after radioiodine therapy (RIT): time dependence and chemical form]. / Exhalation von I-131 nach Radioiodtherapie (RIT): Zeitabhängigkeit und chemische Form.

AIM: The change of both amount and chemical forms of radioiodine exhaled in the air of rooms with patients on the therapy ward should be investigated depending on radioactivity applied, time after application, and kind of thyroid disease. METHODS: The air of ward-rooms of 62 patients with thyroid carcinoma, Graves' Disease, and autonomy which received different therapy doses, was investigated with an portable constant air flow sampler. Different chemical iodine species (organic, elemental, aerosol bound) were collected during 8 hr in various filters until 3 days after application of the radioiodine capsule, according to their chemical form. The radioactivity in the filters was measured with a well counter on defined time points after application. RESULTS: The radioactivity exhaled was between 0.008 and 0.03% related to activity of radioiodine applied. The percentage of radioiodine exhaled related to the activity applied, differed significantly depending on disease and changed as follows: Grave's Disease > autonomy > carcinoma. The exhalation of radioiodine became stronger with increasing applied activities and showed an exponential decrease with time. The most part of radioiodine was present in organic bound form. This organic portion decreased with time in favour of the other iodine species. CONCLUSION: The degree of accumulation of radioiodine orally applied within thyroid seems to be in direct proportion to the extend of its exhalation. Further measurements directly in the breathing air of RIT-patients are necessary, in order to clarify the relationship between degree of thyroid uptake and quantity as well as chemical form of radioiodine exhaled.

[Comparison of the clinical value of an iterative reconstruction procedure with that of a filtered back projection in SPECT of the liver]. / Vergleich der klinischen Wertigkeit eines iterativen Rekonstruktionsverfahrens mit der gefilterten Rück-projektion bei der SPECT der Leber.

We have tested an iterative reconstruction procedure against the usual filtered back-projection in 14 patients with SPECT-examinations of various liver diseases. The aim of the examinations was to assess the presence of liver tumors in most cases. Further indications were Budd-Chiari syndromes and a liver malconfiguration in one case. Three of six haemangiomas and both liver metastases were better delineated with the iterative method, in one patient the haemangioma was visible only with this method. An irregular pattern after filtered back-projection led to misinterpretation as multiple metastases in another patient in whom there was no irregularity after iteration. Diagnostic improvement was not reached in the Budd-Chiari syndromes or in an atypical liver configuration, with a more homogeneous pattern after iteration however. The iterative reconstruction procedure was superior to the filtered back-projection method in the detection of small focal liver diseases.

[An iterative strategy for determining the source distribution in single photon tomography using a rotating gamma camera (SPECT)]. / Eine iterative Strategie zur Bestimmung der Quellverteilung bei der Einzelphotonen-Tomographie mit einer rotierenden Gammakamera (SPECT).

A new iterative strategy for determination of the source distribution in single-photon emission tomography (SPECT) simulates mathematically the scintigraphic imaging process during direction sum computation. Limited spatial resolution and gamma-ray attenuation are taken into account using simplifying approximations. Highly resolved low-noise tomograms without obvious artifacts are obtained. Results of phantom measurements as well as cases of thyroid and brain perfusion imaging are presented to demonstrate the capabilities of the method.

[Exposure of relatives of patients after stationary radioiodine therapy by inhalation of 131I in their homes]. / Strahlenexposition Angehöriger von Patienten nach stationärer Radioiodtherapie durch Inhalation von 131I in der Wohnung.

AIM: From a model of iodine metabolism exhalation coefficients shall become derived to calculate 131I exhalation by patients after a radioiodine treatment. The validity of these exhalation coefficients shall be reviewed by whole body activity measurements of relatives of patients, who inhaled the radioiodine exhaled by the patients in their homes. The exposure of relatives to patients of a nuclear medical ward after release by exhalation of iodine-131 is investigated. METHODS: Iodine 131I-activity of 17 relatives to patients who had to undergo a radioiodine therapy became measured in a whole body counter only a few days after release of the patient from the nuclear medical ward. The results of the measurements have been compared with the results of calculations according to the model of iodine metabolism. RESULTS: The calculated values of incorporated radioiodine in the relatives of the patient at time of measurement (Amodel) correlate with the measured whole body activity (AGK) according to the regression: Amodel = AGK -47.3 (r2 = 0.959). This relation holds if 2.1 micrograms of iodine become exhaled per day of the 60 micrograms of iodine which are the daily intake of iodine by food. The exposure of all relatives did never exceed 100 microSveff. Using the same model parameters the effective dose equivalent of the relatives to our patients rises up to 6.5 mSv under ambulant radio therapy condition. CONCLUSION: The daily exhalation of 131I is able to be calculated by a mathematical model of iodine metabolism. After staying of patients at least 3 days in a nuclearmedical ward the exposure of relatives of patients in their home does not exceed the value of 100 microSveff by inhalation of iodine-131. This are 10% of the limit of 1 mSveff according to the Recommendations of the Commission on Radiological Protection (ICRP 60). Radioiodine therapy outside of a hospital and "iodine therapy tourisme" of German patients to other countries cannot be accepted.

[Procedure guideline for radioiodine test (version 2)]. / Verfahrensanweisung zum Radioiodtest (Version 2).

The version 2 of the procedure guideline for radioiodine test is an update of the guideline published in 1999. The following statements were added or modified: The procedure guideline discusses the pros and cons of a single measurement or of repeated measurements of the iodine-131 uptake and their optimal timing. Different formulas are described when one, two or three values of the radioiodine kinetic are available. The probe with a sodium iodide crystal, alternative or additionally the gamma-camera using the ROI-technique are instrumentations for the measurement of iodine-131 uptake. A possible source of error is an inappropriate measurement (sonography) of the target volume. The patients' preparation includes the withdrawal of antithyroid drugs 2-3 days before radioiodine administration. The patient has to avoid iodine-containing medication and the possibility of additives of iodide in vitamin- or electrolyte-supplementation has to be considered.