Iodine-123-vascular endothelial growth factor-165 (123I-VEGF165). Biodistribution, safety and radiation dosimetry in patients with pancreatic carcinoma.

AIM: Imaging with radiolabelled vascular endothelial growth factor (VEGF) has been developed for the localisation and diagnosis of a variety of human solid tumors including gastrointestinal tumors. METHODS: In this study we investigated the biodistribution, safety and absorbed dose of iodine-123 radiolabelled VEGF(165) ((123)I-VEGF(165)) in 9 patients with pancreatic carcinoma. Following intravenous administration of (123)I-VEGF(165) (189+/-17 MBq; <130 pmole (<5 microg) VEGF(165) per patient), sequential images were recorded during the initial 30 min PI. Serial whole-body images were acquired in anterior and posterior views at various time points. All patients underwent single-photon emission tomography (SPET) imaging. Dosimetry calculations were performed on the basis of gamma camera data. Estimates of radiation absorbed dose were calculated using the MIRDOSE 3 program. RESULTS: The highest absorbed organ doses were found to be thyroid (0.058+/-0.004 mGy/MBq), spleen (0.046+/- 0.017 mGy/MBq), urinary bladder (0.04+/-0.02 mGy/MBq), lungs (0.034+/-0.009 mGy/MBq) and kidneys (0.033+/-0.005 mGy/MBq). The effective dose was estimated to be 0.017+/-0.002 mSv/MBq. A majority of primary pancreatic tumors and their metastases were visualized by (123)I-VEGF(165) scan. CONCLUSION: In vitro binding results confirmed specific binding of (123)I-VEGF(165) to pancreatic tumor cells and tissues. (123)I-VEGF(165) shows favorable dosimetry and is a safe radiopharmaceutical that may be of potential value for the imaging of VEGF receptor status in vivo.

[Radiation doses deriving from patients treated with (166)Ho-ferric hydroxide]. / Strahlenexposition in der Umgebung von Patienten bei Radiosynoviorthese mit (166)Ho-Eisenhydroxid.

AIM: To estimate radiation doses deriving from patients treated with (166)Ho ferric hydroxide. METHODS: For radiation synoviorthesis about 900 +/- 100 MBq (166)Ho ferric hydroxide was injected into the knee joint of 16 patients. To estimate the radiation exposure of persons in the neighbourhood of the patients measurements of the dose rates were performed at 0.5 m, 1 m and 2 m distance of the treated joint 10 min after tracer injection. Measurements were carried out with and without radiation protection devices of the syringe. RESULTS: The initial values of the dose rate were 11.9 micro Sv/h at 0.5 m, 3.5 micro Sv/h at 1 m and 1 micro Sv/h at 2 m distance, respectively. The whole body doses were 2.9 micro Sv for the physician and 4.6 micro Sv for the technologist. The finger doses for the technologist and the physician were ranging from 65 to 111 micro Sv. After discharge at home other persons might receive 118 micro Sv. CONCLUSION: Our results, under very strict assumptions, clearly demonstrate that the calculated radiation exposure to medical and non medical personnel is well below the maximum annual dose limit. The use of any additional radiation protection device as syringe shielding does not significantly lower radiation exposure.

[Radiation exposure around patients after administration of 123-MIBG]. / Strahlenexposition im Umfeld von Patienten nach 123I-MIBG-Applikation.

AIM: Estimation of the radiation exposure to neighbouring patients, personnel and relatives deriving from patients undergoing 123I-MIBG scintigraphy. METHODS: For scintigraphic studies, 16 patients with suspected pheocromocytoma were injected with 340 +/- 30 MBq 123I-MIBG. Dose rates were measured at a distance of 0.5 m, 1 m, and 2 m after 10 min, 3 h, 21 h, 45 h, and 68 h using three calibrated portable radiation detectors. The emasured values were background corrected. RESULTS: Ten minutes after injection the dose rate was 10.5 microS/h at a distance of 0.5 m, 3.78 microS/h at 1 m, and 0.95 microS/h at 2 m. The effective half-life was estimated to 8.68 +/- 0.15 h. The maximum dose in a distance of 1 m for neighbouring patients was 46 microS/h, for personnel in a ward 27 microS/h, and to relatives in a distance of 2 m 12 microS/h. CONCLUSION: This study demonstrates that the calculated exposure to people around patients after 123I-MIBG injection is well below the maximum permissible annual dose limit of 1 mSv for not professionally exposed persons.

Radiation exposure from patients treated with 165Dy-ferric hydroxide.

In radiation synovectomy about 10 GBq 165Dy-ferric hydroxide is injected into major joints. Measurements of the dose rates were performed at distances of 5 cm, 0.5 m, 1 m and 2 m from the surface of the treated joints (knees) until 200 min after the application in 16 patients in order to estimate the radiation exposure of persons in the neighbourhood of the patients. The highest doses were estimated for the fingers of the technologist (320 microSv) and for the physician (700 microSv). Special shields for the syringes were constructed for dose reduction. The whole-body doses were 103 microSv for the technologist and 40 microSv for the physician. After the discharge of the patient to a ward or home, other persons at 1 m distance from the patient might receive 88 microSv, which is less than 9% of the annual permissible dose. Our results clearly demonstrate that the calculated radiation exposure to personnel and family members is well below the maximum annual dose limit for non-professionally exposed persons.

Radioactive contamination of contact lenses during radioiodine therapy.

Although the secretion of radioiodine in tears is not unexpected, there are only few investigations in that field. We report the measurement of 131I in disposable contact lenses for daily use during radioiodine treatment. After administration of 740 MBq 131I, all contact lenses of a 59-year-old female used the day before and 5 days after radioiodine therapy were collected and measured in a gamma counter. Activities of 124 Bq (right) and 139 Bq (left) were measured in the contact lenses used during the first day after administration of radioiodine. The activity in the contact lenses of the following days was significantly lower. An initial dose rate of approximately 0.31 microSv x h(-1) was caused by the radioactivity resulting in a total dose of 13 microSv to the patient's eye lens. That dose is negligible compared to the dose caused by the incorporated radioactivity.

New radiopharmaceuticals for receptor scintigraphy and radionuclide therapy.

In vitro data have demonstrated a high amount of receptors for various hormones and peptides on malignant cells of neuroendocrine origin. Among these, binding sites for members of the SST-family (hSSTR1-5) are frequently found, and their expression has led to therapeutic and diagnostic attempts to specifically target these receptors. Receptor scintigraphy using radiolabeled peptide ligands has proven its effectiveness in clinical practice. In addition, initial results have indicated a clinical potential for receptor-targeted radiotherapy. Based on somatostatin (SST) receptor (R) recognition, the novel radiopharmaceuticals 111In/90Y-DOTA-lanreotide developed at the University of Vienna as well as 111In/90Y-DOTA-DPhe1-Tyr3-octreotide (NOVARTIS) both have provided promising data for diagnosis and treatment of hSSTR-positive tumors. SSTR scintigraphy using 111In-DTPA-DPhe1-octreotide has a high positive predictive value for the vast majority of neuroendocrine tumors and has gained its place in the diagnostic work-up as well as follow-up of patients. We have used 111In-DOTA-lanreotide scintigraphy in 166 patients since 1997 and have seen positive results in 93% of patients. In 42 patients with neuroendocrine tumors comparative data were obtained. As opposed to 111In-DTPA-DPhe1-octreotide and 111In-DOTA-DPhe1-Tyr3-octreotide, discrepancies in the scintigraphic results were seen in about one third of patients concerning both the tumor uptake as well as tumor lesion detection. Initial results both with 90Y-DOTA-lanreotide as well as 90Y-DOTA-DPhe1-Tyr3-octreotide has pointed out the clinical potential of radionuclide receptor-targeted radiotherapy. This new therapy could offer palliation and disease control at a reduced cost. The final peptide therapy strategy is most probably cheaper than conventional radiotherapies or prolonged chemotherapies. Overall, receptor-mediated radiotherapy with 90Y-DOTA-lanreotide/90Y-DOTA-DPhe1-Tyr3-octre otide might also be effective in patients refractory to conventional strategies.

Radiation synovectomy using 165Dy ferric-hydroxide and oxidative DNA damage in patients with different types of arthritis.

UNLABELLED: Radiation synovectomy is an effective treatment for chronic synovitis refractory to pharmacological treatment in patients with rheumatoid or seronegative arthritis. Concerns persist about possible radiation-induced cytogenetic damage after radiation synovectomy leading to recommendations to use this technique only in the elderly. Micronucleus (MN) frequency in lymphocytes and urinary excretion of 8-hydroxy-2'-deoxyguanosine (8OHdG) as an indicator of cellular oxidative DNA base damage are biomarkers of radiation-induced cytogenetic damage. The course of both biomarkers was studied in patients with different types of chronic synovitis undergoing radiation synovectomy with very short-lived 165Dy-ferric-hydroxide (DFH). METHODS: Radiation synovectomy of the knee was performed in 13 men and 12 women (mean age, 44+/-15 y) using a mean activity of 9.48+/-1.65 GBq 165Dy-DFH in 27 consecutive treatments. MN frequency in lymphocytes and urinary excretion of 8OHdG, measured by high-performance liquid chromatography, were assessed before and 4 (MN only) and 20 h after radiation synovectomy. RESULTS: Urinary excretion of 8OHdG in patients (in micromol/mol creatinine; pretreatment mean, 3.1+/-3.4; median, 2.27) was not significantly different from that in healthy volunteers (mean, 2.0+/-1.2; median, 1.87) and not altered by radiation synovectomy (post-treatment mean, 2.5+/-1.5; median, 2.04, NS). An increase in 8OHdG levels after radiation synovectomy of more than 1 SD was found in only 1 patient, who experienced leakage to the lymph nodes but who already had elevated urinary 8OHdG levels before treatment. The frequency of MN/500 binucleated cells (BNCs) was slightly lower in patients (pretreatment mean, 4.3+/-2.6; median, 4.25) than in healthy volunteers (mean, 5.4+/-2.3; median, 5.3) and did not significantly change after therapy, either (4-h post-treatment mean, 3.9+/-2.1, median, 3.8; 20-h post-treatment mean, 4.1+/-2, median 3.8 MN/500 BNC). In 22 of 27 treatments, no leakage to nontarget organs could be monitored, whereas leakage to the local lymph nodes and the liver was detected after 5 treatments. CONCLUSION: Radiation synovectomy using 165Dy-DFH causes no significant radiation burden to most patients as indicated by the absence of adverse changes in levels of biomarkers of cytogenetic damage and a low incidence of leakage. These data suggest that the risk of malignancy may not be elevated.

"MAURITIUS": tumour dose in patients with advanced carcinoma.

Radioimaging of various human tumours by means of somatostatin analogues and vasoactive intestinal peptide has been introduced into clinical practice in recent years. The finding that human tumours express various subtypes of somatostatin receptors has led to the development and characterization of a novel peptide tracer, termed MAURITIUS. MAURITIUS identifies a broad range of somatostatin receptors with high binding affinity, and somatostatin receptor 1 with low binding affinity. In order to evaluate patients for tumour radiotherapy with 90Y-MAURITIUS, tumour dose calculation is performed with 111In-MAURITIUS [111In-DOTA-lanreotide]. Treatment is initiated in patients presenting a tumour uptake of > or = 10 Gy/GBq (i.e., standard dose for 1 treatment cycle with 90Y-MAURITIUS). In 25 patients with advanced cancer refractory to conventional antineoplastic treatment 111In-MAURITIUS (approximately 150 MBq; 10 nmol/patient), scintigraphy and dosimetry was performed. Dosimetry data were calculated based on scintigraphic results as well as urine, faeces and blood data. In all patients, at least one tumour site was visualized during the initial few minutes of application. Additional tumour sites not seen on conventional imaging (computerized tomography, magnetic resonance imaging bone scan) could be detected in 6 patients with carcinoids, one patient with prostate cancer and one patient with lymphoma. Liver metastases were visualized in all patients with gastrointestinal cancers, while the primary tumour was not detected in 2 patients with pancreatic, and in 1 patient with rectal, cancer. The calculated radiation dose for tumours and/or metastases ranged between 3-60 Gy/GBq for 90Y-MAURITIUS. MAURITIUS is a universal receptor ligand for a large variety of different human tumours, and is suitable for treatment when labelled with 90Y.

Response to treatment with yttrium 90-DOTA-lanreotide of a patient with metastatic gastrinoma.

1,4,7,10-tetraazacyclododecane-N,N',N",N'''-tetraacetic acid (DOTA)-lanreotide is a universal somatostatin (SST) receptor subtype ligand that binds to a large variety of human tumors. We report the case of a patient with metastatic gastrinoma who was treated with 90Y-DOTA-lanreotide. Before treatment, dosimetry with 111In-DOTA-lanreotide (150 MBq, 10 nmol) indicated a dose of 5.8 mGy/MBq for the recurrent abdominal gastrinoma, and a mean dose of approximately 1.0 mGy/MBq for liver metastases (i.e., 56 and approximately 10 mGy/MBq for 90Y-DOTA-lanreotide, respectively). After four infusions of 90Y-DOTA-lanreotide (each 1 GBq, approximately 30 nmol) over a 6-mo period, the 111In-DOTA-lanreotide scintigraphy of the liver had returned to a nearly normal condition and a remarkably decreased uptake by the recurrent gastrinoma was calculated (approximately 5 mGy/MBq for 90Y-DOTA-lanreotide). The imaging results were well-correlated with a 25% regression of the liver metastases as indicated by CT. Blood, urine and whole-body clearances of 111In-DOTA-lanreotide and 90Y-DOTA-lanreotide were very similar. The DOTA-lanreotide promises to be useful for functional tumor diagnosis (111In-DOTA-lanreotide) and receptor-mediated tumor radiotherapy (90Y-DOTA-lanreotide).

Indium-111-DOTA-lanreotide: biodistribution, safety and radiation absorbed dose in tumor patients.

UNLABELLED: Imaging with radiolabeled somatostatin/vasoactive intestinal peptide analogs has recently been established for the localization diagnosis of a variety of human tumors including neuroendocrine tumors, intestinal adenocarcinomas and lymphomas. This study reports on the biodistribution, safety and radiation absorbed dose of 111In-1,4,7,10-tetraazacyclododecane-N,N',N",N'''-tetraacetic acid (DOTA)-lanreotide, a novel peptide tracer, which identifies hSST receptor (R) subtypes 2 through 5 with high affinity, and hSSTR1 with low affinity. METHODS: The tumor localizing capacity of 111In-DOTA-lanreotide was initially investigated in 10 patients (3 lymphomas, 5 carcinoids and 2 intestinal adenocarcinomas). Indium-111 -DOTA-lanreotide was then administered to 14 cancer patients evaluated for possible radiotherapy with 90Y-DOTA-lanreotide (8 neuroendocrine tumors, 4 intestinal adenocarcinomas, 1 Hodgkin lymphoma and 1 prostate cancer). After intravenous administration of 111In-DOTA-lanreotide (approximately = 150 MBq; 10 nmol/patient), sequential images over one-known tumor site were recorded during the initial 30 min after peptide application. Thereafter, whole-body images were acquired in anterior and posterior views up to 72 hr postinjection. Dosimetry calculations were performed on the basis of scintigraphic data, urine, feces and blood activities. A comparison with 111In-DTPA-D-Phe1-octreotide (111In-OCT) scintigraphy was performed in 8 of the patients. RESULTS: After an initial rapid blood clearance [results of biexponential fits: T(eff1) 0.4 min (fraction a1 80%) and T(eff2) 13 min (fraction a2 14%)], the radioactivity was excreted into the urine and amounted to 42% +/- 3% of the injected dose (%ID) within 24 hr and 62% +/- 6%ID within 72 hr after injection of 111In-DOTA-lanreotide. In all patients, tumor sites were visualized during the initial minutes after injection of 111In-DOTA-lanreotide. The mean radiation absorbed dose amounted to 1.2 (range 0.21-5.8) mGy/MBq for primary tumors and/or metastases. The effective half-lives of 111In-DOTA-lanreotide in the tumors were T(eff1) 4.9 +/- 2.2 and T(eff2) 37.6 +/- 6.6 hr, and the mean residence time tau was 1.8 hr. The highest radiation absorbed doses were calculated for the spleen (0.39 +/- 0.13 mGy/MBq), kidneys (0.34 +/- 0.08 mGy/MBq), urinary bladder (0.21 +/- 0.03 mGy/MBq) and liver (0.16 +/- 0.04 mGy/MBq). The effective dose was 0.11 +/- 0.01 (range 0.09-0.12) mSv/MBq. During the observation period of 72 hr, no side effects were noted after 111In-DOTA-lanreotide application. The 111In-DOTA-lanreotide radiation absorbed tumor dose was significantly higher (ratio 2.25 +/- 0.60, p < 0.01) when directly compared with 111In-OCT. CONCLUSION: Indium-111 -DOTA-lanreotide shows a high tumor uptake for a variety of different human tumor types, has a favorable dosimetry over 111In-OCT and is clinically safe.

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

Because salivary glands, as well as thyroid tissue, are able to concentrate radioiodine, the treatment of thyroid diseases with iodine-131 may have secondary effects on salivary gland function which seriously impair the quality of life. Such effects include sialoadenitis and xerostomia. Salivary secretion is stimulated by prostaglandins (PGs). In this study we evaluate whether 131I therapy influences the levels of PGs in saliva. Patients who had previously received 131I for treatment of hyperthyroidism or differentiated thyroid cancer and healthy volunteers were studied. Levels of PGs [6-oxo-PGF1 alpha, bicyclo-PGEm, thromboxane B2 (TXB2), PGF2 alpha] in unstimulated saliva were measured using enzyme immunoassay. Significantly lower levels of 6-oxo-PGF1 alpha, bicyclo-PGEm and PGF2 alpha and higher levels of TXB2 were found in the group of patients in comparison with the controls. Differences between patients and controls were more pronounced in smokers. This study demonstrates that salivary gland uptake of 131I significantly affects PG levels in saliva.

Radiation doses deriving from patients undergoing 111In-DTPA-D-phe-1-octreotide scintigraphy.

The purpose of this study was to estimate the radiation doses to nursing staff, other patients, accompanying persons and family members deriving from patients undergoing 111In-DTPA-d-Phe-1-octreotide (111In-OCT) scintigraphy. Dose rates were measured from 16 patients who had received an intravenous injection of 140+/-40 MBq 111In-OCT. The measurements were performed at three different distances (0.5, 1 and 2 m) at 10-20 min, 5-7 h and 24 h (and in some cases, up to 48 h) after administration of 111In-OCT. The effective half-lives of the biexponential decrease of the dose rates were estimated to be 2.94+/-0.27 h (T1) and 65.17+/-0. 58 h (T2). The calculated maximum dose to other persons in the waiting area was 27.2 microSv, to family members 61.5 microSv, to nursing staff in a ward 24.1 microSv and to neighbouring patients in the ward 69.5 microSv. Our results clearly demonstrate that the calculated maximum radiation exposure to accompanying persons, personnel, family members and other patients is well below the maximum annual dose limit for non-professionally exposed persons.

Monitoring of the biodistribution and biokinetics of dysprosium-165 ferric hydroxide with a shadow-shield whole-body counter.

Radiation synovectomy is indicated when conventional pharmacological treatment of chronic synovitis has proved insufficient. In these cases dysprosium-165 ferric hydroxide (DFH) has been demonstrated to be clinically effective. After application of the agent, blood activity measurements and monitoring of activity distribution by gamma camera imaging over the local lymph nodes and the liver are commonly performed for control of possible leakage. In addition, we have used a shadow-shield whole-body counter with a profile facility to evaluate the biokinetics and biodistribution of 165Dy-DFH. Fifteen intra-articular injections were performed in 13 patients who received a median activity of 6.8 GBq (range 0.5-9.9 GBq) 165Dy-DFH. Activity profiles were obtained with the whole-body counter 2, 4 and 6 h after injection of 165Dy-DFH. The doses to non-target organs were calculated using the software MIRDOSE 3. In 10 of 15 treatments, absence of any leakage could be demonstrated. The effect of scattered rays could be observed in 14 measurements. In three patients small amounts of activity could be detected in the urinary bladder and in three patients activity was detected in the local inguinal lymph nodes, while no leakage could be detected by camera imaging. In these cases the individual doses to the bladder were 15 Gy, 65 mGy and 50 mGy, and those to the lymph nodes, 0.54 Gy, 0.89 Gy and 2.41 Gy. The whole-body counter also enabled the monitoring of activity profiles related to more complex pathological structures. In conclusion, using a whole-body counter activity leakage could be detected with much higher sensitivity than by using a gamma camera. The biodistribution of 165Dy-DFH could be determined, and leakage could be localised and related to organs. These results encourage the use of a whole-body counter to identify the site and extent of activity leakage.

[Radiation exposure in the surrounding of patients after 201Tl myocardial scintigraphy]. / Strahlenexposition in der Umgebung von Patienten nach 201TI-Myokardszintigraphie.

AIM: It was the aim of the study to assess the additional radiation exposure to patients, attendants and nurses by patients who are undergoing nuclear medicine investigations (myocardial scintigraphy) with 201TL-chloride (201TL-CL). METHOD: In 16 cases the dose rates at 0.5 1 and 2 m distance from patients were measured at 0.5, 1.5, 3-4 and 24, in some cases until 370 h after administration of 100 +/- 10 MBq 201TL-CL. From the time courses of the dose rates around the patients the possible radiation exposure of other persons were estimated. RESULTS: The initial values of the dose rate were 3.82 microSv/h at 0.5 m, 1.18 microSv/h at 1 m and 0.30 microSv/h at 2 m distance from the patients respectively. The dose rates were decreasing following a monoexponential course with an effective half-life of 60 h. The maximum doses to other persons at 1 m distance from the patients were determined by considering three scenarios. The values were 13 microSv in the waiting room, 26 microSv for nurses, working in the ward and 105 microSv for persons living in the same house hold CONCLUSION: Even at very restrictive assumptions the closes were far below the maximum permissible dose to non-radiation workers see by radiation protection regulations (1.5 mSv per year).

[How great is radiation exposure in the area surrounding patients after administration ov 99mTc-sestamibi?]. / Wie hoch ist die Strahlenexposition in der Umgebung der Patienten nach Applikation von 99mTc-Sestamibi?

AIM: The aim of the present study was to estimate the additional radiation exposure to personnel, other patients and members of the family caused by patients who had been injected with 99mTc-Sestamibi (Cardiolite DuPONT PHARMA) for preoperative localization of parathyroid adenoma. METHODS: Dose rates were measured from 16 patients who had received an intravenous injection of 600 +/- 50 MBq 99mTc-Sestamibi. All measurements were performed with a portable dosimeter (Berthold LB 133) at 3 different distances (0.5, 1 and 2 m) at 10 min, 180-200 min and 24 h after administration of the tracer. RESULTS: The dose rates amounted to 20.5 microSv/h at 0.5 m, 5.25 microSv/h at 1 m and 1.55 microSv/h at 2 m distance from patients respectively. The biological half-life was 54 h. The calculated maximal dose to other persons in the waiting area was 31.2 microSv, to family members 27.6 microSv and to nurses in a ward 31.2 microSv. CONCLUSION: Our results indicate that the calculated maximal radiation exposure for personnel, family members and other patients even under very unfavourable conditions was below the maximal allowed dose for non-professionally exposed persons.

Vasoactive intestinal peptide receptor scintigraphy.

UNLABELLED: This study presents the biodistribution, safety and absorbed dose of 123I-VIP administered to 18 patients with intestinal adenocarcinomas or endocrine tumors. METHODS: To achieve high-specific activity, 123I-VIP was purified by HPLC. Following intravenous administration of 123I-VIP (172 +/- 17 MBq (4.65 +/- 0.5 mCi); < 300 pmole ( < 1 microgram)/patient), sequential images were recorded during the initial 30 min. Thereafter, whole-body images were acquired in anterior and posterior views at various time points. Dosimetry calculations were performed on the basis of gamma camera data, urine, feces and blood activities. RESULTS: After injection of labeled peptide, the lung was the primary site of 123I-VIP uptake. Peak lung activity represented 40% +/- 7% of the injected dose at 0.7 hr and declined to 21% +/- 7% at 3.5, to 14% +/- 3% at 7 and to 8% +/- 4% 22 hr postinjection. Radioactivity was excreted into the urine and amounted to 37% +/- 16% of the injected dose within 4, 68% +/- 12% within 8, 82% +/- 16% within 16 and 93% +/- 8% within 24 hr postinjection. The mean effective half-life of 123I-VIP in the lungs was 2.2 and 6 hr in the urinary bladder. The highest radiation absorbed doses were calculated for the lungs [67 muGy/MBq (248 mrad/mCi)], urinary bladder [77 muGy/MBq (284 mrad/mCi)] and thyroid gland [104 muGy/MBq (386 mrad/mCi)]. The effective dose was 28 muSv/MBq (104 mrem/mCi). CONCLUSION: HPLC-purified 123I-VIP shows favorable dosimetry and is a safe and promising peptide tracer for localization of tumors expressing receptors for VIP.

[Radiation exposure in the vicinity of patients after administration of Tc-99m-DPD]. / Strahlenexposition in der Umgebung von Patienten nach Gabe von 99mTc-DPD.

Dose rate measurements were performed in 0.5, 1 and 2 m distance from the surface of the bodies of 16 patients within the first 4 h after they had received 600 +/- 30 MBq of 99mTc-DPD. The various individual time to dose rate courses are discussed. The radiation dose rates around the patients were determined and the possible radiation exposure of other patients, attendants, and nurses in the surroundings of the "radiating" patients were estimated. The doses were far below the limits set by radiation protection regulations.

The use of a high-purity germanium detector for routine measurements of 125I in radiation workers.

A high-purity germanium detector was calibrated for the assessment of 125I uptake in the thyroid gland of radiation workers. A cylindrical water phantom (perspex walls) with high flexibility for position and size of the thyroid was constructed. Within a massive shielding chamber built for a whole-body counter, an activity of 2.2 Bq was detectable (MDA). This is well below the very restrictive limiting value of 20 Bq for inhalation specified by Austrian law. An activity of 128 Bq was measured with a statistical uncertainty of 5% in a counting period of 10 min. Various parameters influencing the result are investigated as well as the performance of two other measurement geometries outside the shielding chamber.

[Radiosynovectomy with dysprosium-165 iron hydroxide]. / Radiosynovektomie mit Dysprosium-165-Eisen-Hydroxid.

Treatment of chronic rheumatoid synovitis (RS) is directed to control the inflammatory process causing pain and disability. Radiation synovectomy is suggested to be an alternative to surgical treatment, but its clinical use has been restricted because of significant leakage (> 10%) associated with the use of the standard radionuclide 90-Yttrium (used as 90-Yttrium silicate colloid) and because of its long physical half-life of 64 hours prolonging the patients' stay in the hospital. 165-Dysprosium possesses promising nuclear properties for the treatment of patients suffering from RS. The maximum soft tissue penetration of its beta-particles is 5.7 mm which is the range being necessary to penetrate the inflamed synovia. Using as carrier ferric hydroxide macroaggregates (DFH) 165-Dy is expected to minimize the cumulative radiation dose to non-target organs by its very low leakage. Animal studies were performed in 13 rats and 6 rabbits to obtain the rationale and safety data for its clinical evaluation. These studies revealed that 98.2 +/- 0.6% of the injected dose remained in the joint with a nontarget organ uptake of less than 0.1%. Clinical results were obtained from 8 patients with rheumatoid arthritis. 24 hours after injection scintigraphy was performed over the treated joint and the liver region revealing no detectable leakage of the injected activity from the joint. Blood pool activity was also assessed revealing a leakage of 0.02% of the dose injected in the knee 24 hours after injection.(ABSTRACT TRUNCATED AT 250 WORDS)