人体中的镭-226、镭-228、钋-210、铅-210

本文报道了广东阳江高本底地区6名、对照地区8名人尸体的骨²²⁶Ra、²²⁶Ra的浓度以及部分居民内脏器官中。²¹⁰Po、²¹⁰Pb的浓度。结果轰明阳江高本底地区和对照地区居民骨镭-226、镭-228的浓度分别为29.9pCi/kg, 26.9pCi/kgl 8.7pCi/kg, 8.2pCi/kg.由此估算出阳江高本底地区屠民骨中²²⁶Ra、²²⁸Ra的负薄璧及对骨衬、骨髓所产生的剂量当量分别为对照地区民民的3.4倍, 3.3倍。两地区居民内脏器官中^{210Po、210Pb的测定分析铡数较少但仍看出, 高本底地区均明显高于对照地区.}     

Pre-therapeutic dosimetry and biodistribution of 86Y-DOTA-Phe1-Tyr3-octreotide versus 111In-pentetreotide in patients with advanced neuroendocrine tumours

Purpose For the internal radiotherapy of neuroendocrine tumours, the somatostatin analogue DOTATOC labelled with ⁹⁰Y is frequently used [⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide (SMT487-OctreoTher)]. Radiation exposure to the kidneys is critical in this therapy as it may result in renal failure. The aim of this study was to compare cumulative organ and tumour doses based upon dosimetric data acquired with the chemically identical ⁸⁶Y-DOTA-Phe¹-Tyr³-octreotide (considered as the gold standard) and the commercially available ¹¹¹In-pentetreotide.Methods The cumulative organ and tumour doses for the therapeutic administration of 13.32 GBq ⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide (three cycles, each of 4.44 GBq) were estimated based on the MIRD concept (MIRDOSE 3.1 and IMEDOSE). Patients with a cumulative kidney dose exceeding 27 Gy had to be excluded from subsequent therapy with ⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide, in accordance with the directives of the German radiation protection authorities.Results The range of doses (mGy/MBq ⁹⁰Y-DOTA-Phe¹-Tyr³-octreotide) for kidneys, spleen, liver and tumour masses was 0.6–2.8, 1.5–4.2, 0.3–1.3 and 2.1–29.5 (⁸⁶Y-DOTA-Phe¹-Tyr³-octreotide), respectively, versus 1.3–3.0, 1.8–4.4, 0.2–0.8 and 1.4–19.7 (¹¹¹In-pentetreotide), with wide inter-subject variability. Despite renal protection with amino acid infusions, estimated cumulative kidney doses in two patients exceeded 27 Gy.Conclusion Compared with ⁸⁶Y-DOTA-Phe¹-Tyr³-octreotide, dosimetry with ¹¹¹In-pentetreotide overestimated doses to kidneys and spleen, whereas the radiation dose to the tumour-free liver was underestimated. However, both dosimetric approaches detected the two patients with an exceptionally high radiation burden to the kidneys that carried a potential risk of renal failure following radionuclide therapy.     

Technetium-99m mercaptoalbumin as a potential substitute for technetium-99m labelled red blood cells

Technetium-99m labelled red blood cells (^99mTc-RBCs) are far superior to ^99mTc-labelled human serum albumin (^99mTc-HSA) for radionuclide ventriculography, but their labelling is more complex, time consuming and risk bearing (in vitro labelling) or suffers from interference by some medications (in vivo labelling). We have now modified HSA by the introduction of mercapto groups with the purpose of preparing stable and practical ^99mTc-mercaptoalbumin with long retention in the vascular system, that could replace ^99mTc-RBCs. HSA was incubated with N-succinimidyl S-acetylthioacetate (SATA) or N-succinimidyl 2,3-di(S-acetylthio) propionate (SATP) to introduce a chain containing one or two protected sulfhydryl groups on some of the lysine amino groups. After purification by size-exclusion chromatography (SEC), the mercapto groups were deprotected by incubation at alkaline pH or by treatment with hydroxylamine. The reaction products were used with or without SEC purification for direct or exchange labelling experiments with ^99mTc at neutral pH. SEC-HPLC was used to determine labelling yields and to isolate pure ^99mTc-mercaptoalbumin. Stable ^99mTc-mercaptoalbumin complexes could be formed in 90%–95% yield after coupling albumin with SATA or SATP in all molar ratios used followed by deacetylation in one of the mentioned conditions. The most favourable results were obtained after reaction of SATA or SATP with HSA in a 25: 1 ratio and deprotection with NH₂OH. The stability of the resulting ^99mTc-mercaptoacetyl-albumin (^99mTc-MAHSA) and ^99mTc-dimercaptopropionyl-albumin (^99mTcDMP-HSA) and their retention in vivo in plasma of mice and rabbits are clearly higher than that of conventional ^99mTc-HSA preparations. ^99mTc-DMP-HSA approaches the behaviour of ¹²⁵I-HSA quite well in both animal species. A preliminary study with ^99mTc-DMP-HSA in a volunteer showed a retention in the vascular compartment almost identical to that of ^99mTc-RBCs and clearly higher than that of a common ^99mTc-HSA preparation. The results indicate that these ^99mTc-mercaptoalbumins and especially ^99mTc-DMP-HSA are very promising as a practical alternative to ^99mTc-RBCs.K.A. Verbeke is a Research Assistant for the Belgian National Fund for Scientific Research     

A novel aluminum vanadate ion exchanger and its use for separation of Ba, In and Ag from Cs, Cd and Au, respectively

A newly designed inorganic ion exchanger, based on aluminum vanadate, has been synthesized and characterized by elemental analysis, spectroscopic tools and powdered X-ray diffraction. The insoluble poorly polycrystalline material is highly stable towards thermal and radiation doses and in various chemical environments. The data of exchange capacities of the solid material for the different alkali and alkaline metal ions determined by batch technique show that the compound can be employed as an ion exchanger. The successful radiochemical separations of the no carrier added daughter nuclides; ^137mBa and ^115mIn from their respective parents present in equilibrium mixtures have been carried out using this material. Elutions of ^137mBa and ^115mIn were performed using 0.0426 mol L⁻¹ ascorbic acid solution and 4.0 mol L⁻¹ HCl, respectively, after sorption of the equilibrated mixtures ¹³⁷Cs–^137mBa at 0.01 mol L⁻¹ HCl medium and ¹¹⁵Cd–^115mIn at pH 7.0, respectively. In another column operation, it has been observed that the separation of gold and silver is possible with the help of the eluents, 0.01% alcoholic solution of Rhodamine-B for gold and 0.5% thiourea solution in 0.1 mol L⁻¹ HClO₄ for silver, respectively, after the sorption of no carrier added onto this material at pH 2.0, at a no carrier added level.     

Uptake of99mTc-tetrofosmin,99mTc-MIBI and201TI in malignant thymoma

99mTc-tetrofosmin, Thallium-201-chloride (201Tl) and 99mTc-MIBI imagings were performed in a patient with malignant thymoma. Tracer uptake in the primary tumor was demonstrated. The tumor-to-background ratios of planar and SPECT imagings were 1.60 and 1.98 for 99mTc-tetrofosmin, 1.12 and 2.09 for 201Tl, and 1.19 and 1.80 for 99mTc-MIBI, respectively. In another patient 99mTc-tetrofosmin and 201Tl imagings were performed. Not only the primary tumor but also the direct invasions and metastatic lesions (bone metastases) were clearly detected. The tumor-to-background ratios of planar and SPECT imagings were 2.31 and 2.78 for 99mTc-tetrofosmin and 2.45 and 3.58 for 201Tl, respectively. In 99mTc-tetrofosmin scintigraphy we acquired delayed images, and the tumor-to-background ratios of planar and SPECT delayed images were 1.20 and 1.86, the retention ratios were -1.11 and -0.92 and the retention indices were -48.1 and -33.1, respectively. Our preliminary results suggest that 99mTc-tetrofosmin is useful in detecting not only the primary tumor but also metastatic lesions from malignant thymoma.     

226Ra 228Ra 210Pb和210Po在水生生物及食物链中转移规律的探讨

目的 为了解天然放射性核素²²⁶Ra、²²⁸Ra、²¹⁰Pb与²¹⁰Po在水生物及食物链中转移和蓄积情况。方法 定点采集养殖水产品及栖息环境中水与底质沉积物, 按不同的实验需要, 每个鲜样分别剥取肉, 骨(壳),鳞片和胃肠。烹饪样品, 洗净、称重、清炖, 熟后分离出骨(壳),余为食物。样品分别测定²²⁶Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po含量。数据按统计学要求处理, 配对数据, 作了配对显着性检验。结果 ²²⁶Ra、²²⁸Ra和²¹⁰Pb主要沉积于骨(壳)中, 浓集系数为10²～10³,肉中为10⁰～10².²¹⁰Po主要蓄积在水生物胃肠中, 浓集系数在10²～10⁴,鱼类胃肠与贝类肉中可达10⁴.水产食品烹饪加工过程²²⁶Ra、²²⁸Ra和²¹⁰Pb在食物链中转移不明显, 经配对显着性检验, 差异无显着性(P0.05);然而210Po在淡水鱼类和虾类中转移是明显的, 肉配对检验有非常显着性差别(P<0.01).结论水生物对²²⁶Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po有很强浓集能力。     

Rapid determination of Sr impurities in freshly “generator eluted” Y for radiopharmaceutical preparation

⁹⁰Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life (t_1/2=64.14 h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that ⁹⁰Y is available conveniently and inexpensively from a radionuclide “generator” by decay of its parent, ⁹⁰Sr. Nevertheless, current and planned clinical applications with [⁹⁰Y] labelled compounds employ activity levels that cannot be readily obtained from an in-house generator, but from commercial sources. We have evaluated Eichrom's Sr-resin, either as an “in-house” generator or as a fast QC method for analysis of ⁹⁰Y solutions.In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8 M HNO₃ eluate: in this fraction the concentration of ⁹⁰Sr must be smaller than 10⁻⁵% (recommendations of the International Commission on Radiological Protection). For evaluation as a rapid QC method, we analyzed the concentration of ⁹⁰Y in all the fractions containing “only” radio-Sr: ⁹⁰Y should not be present in these eluates. After the collection of β⁻ and γ spectra and analysis of them, we concluded that commercial Sr-resin minicolumn cannot give us the results expected; we developed an in-house system loaded with 4 mL of Sr-resin which gave better results as a generator and a rapid QC method.     

Production of large quantities of 90Y by ion-exchange chromatography using an organic resin and a chelating agent

The performance of a system composed of an organic cation exchanger (Dowex 50Wx8) and a chelating agent (EDTA) previously described for the successful production of (90)Y via a (90)Sr/(90)Y generator is assessed under dynamic conditions. In an attempt to overcome the established limitation of ion-exchange resins for the separation of subcurie quantities of activity, (90)Y is repeatedly isolated from an 11.8-GBq (320 mCi) (90)Sr cow using a three-column tandem arrangement. The high recovery and radionuclidic purity obtained for (90)Y and the parameters of the separation (time, eluant concentration, pH and flow rate range) strongly suggest that Ci quantities of (90)Y can be handled satisfactorily by the ion-exchange method. No replacement or treatment of the cow, low waste generation and (90)Sr losses less than 0.1% after each run were observed during the present study which, in combination with the low cost of this resin, may result in an attractive alternate method for the production of large quantities of (90)Y.     

Radiobiological Issues in the Anomalous Enhanced Effect of Low-dose-rate Fission-spectrum Neutrons: Reply to Letter to the Editor by G. W. Barendsen

Summary

The influence of diet or its ingredients on ¹⁴¹Ce absorption and retention was investigated in six-day-old rats. Animals were fed over 8 h with cow's milk, rat diet or a mixture of rat diet ingredients (fish meal, sunfiower meal, alfalfa, cane molasses and premix) labelled with ¹⁴¹Ce. Whole-body radioactivity was determined in a double crystal scintillation counter every 24 h over a six-day period. Gut, liver, kidney and femur retention and cerium distribution in the gut was determined at the end of the experiment. Compared to milk diet, administration of rat diet or ingredients caused respectively 3 and 7·5 times lower whole body retention. Carcass retention was reduced by rat diet or ingredients 2–3 times and intestinal retention 3 and 8 times respectively. Irrespective of the dietary treatment the main site of cerium intestinal retention was the ileum. Our present results indicate that some compounds of rat diet might be considered as a means of reducing cerium absorption and intestinal retention in the very young.     

<Superscript>99m</Superscript>Tc-HYNIC octreotide in neuroblastoma

Disease status assessment of neuroblastoma patients requires computed tomography (or magnetic resonance imaging), bone scan, metaiodobenzylguanidine (MIBG) scan, bone marrow tests, and urine catecholamine measurements. There is no clinical experience concerning the evaluation of these patients by means of technetium-99m (^99mTc)-somatostatin analog scintigraphy. Furthermore, these radiopharmaceuticals are promising imaging agents owing to their lower cost, availability, dosimetry, and ease of preparation. An 8-year-old boy already diagnosed with stage-IV neuroblastoma received chemotherapy. In the follow-up, after obtaining the parents’ informed consent, iodin 131 (¹³¹I)-MIBG and ^99mTc-6-hydrazinopyridine-3-carboxylic acid (HYNIC)-octreotide scans were done on separate days to evaluate tumor extension. Even as the ¹³¹I-IBG scan showed mild diffuse uptake in the projection of both lung hili, the ^99mTc-HYNIC-octreotide scan showed multiple axial and appendicular bone uptakes and paravertebral, abdominal, mediastinal, and supraclavicular ganglionar uptakes. The ^99mTc-HYNIC-octreotide showed much more lesion extension than the ¹³¹I-MIBG. Therefore, ^99mTc-HYNIC-octreotide may be a promising radiopharmaceutical for the evaluation of neuroblastoma patients. This finding justifies the pre liminary evaluation of this tracer in the context of a clinical trial.     

Cross sections of the Ar(d,α)Cl, Ar(d,α)Cl, and Ar(d,p)Ar nuclear reactions below 8.4 MeV

We have measured the cross section for production of the medically interesting isotope ^34mCl, along with ³⁸Cl and ⁴¹Ar, using deuteron bombardments of ³⁶Ar and ⁴⁰Ar below 8.4 MeV. ALICE/ASH analytical codes were employed to determine the shape of nuclear excitation functions, and experiments were performed using the University of Wisconsin tandem electrostatic accelerator to irradiate thin targets of argon gas.     

99mTc-labelling of leucocytes with 99mTc-DPO: a complex developed for myocardial imaging

The lipophilic ^99mTc-DPO complex, developed as a myocardial imaging radiopharmaceutical, was used to label leucocytes. After an incubation of 0.1 ml ^99mTc-DPO (8 g DMPE*2HCl) with mixed leucocytes in plasma, the labelling efficiency was over 70%. During incubation in 5 ml plasma, a loss of activity was found between 20% (1 h) and 35% (3 h) caused by elution. Disturbances of cell viability could not be found with the help of the chemiluminescence test. The in vivo recovery was determined in three dogs and was 45%–50% (0.5 h), 30%–36% (1 h), and 18%–24% (3 h). Autologous ^99mTc-DPO-leucocytes were used on seven patients with suspected osteomyelitis, there were four true negative and three true positive results. The target/nontarget ratio determined by ROI in the positive cases was 1.8 to 2.5 at 3 h after injection.     

<Superscript>11</Superscript>C-methionine uptake in cerebrovascular disease: A comparison with<Superscript>18</Superscript>F-FDG PET and<Superscript>99m</Superscript>Tc-HMPAO SPECT

OBJECTIVES: Carbon-11-L-methyl-methionine (11C-methionine) has been reported to be useful for evaluating brain tumors, but several other brain disorders have also shown signs of high methionine uptake. We retrospectively evaluated the significance of 11C-methionine uptake in cerebrovascular diseases, and also compared our results with those for 18F-FDG PET and 99mTc-HMPAO SPECT. METHODS: Seven patients, including 3 patients with a cerebral hematoma and 4 patients with a cerebral infarction, were examined. All 7 patients underwent both 11C-methionine PET and 99mTc-HMPAO SPECT, and 6 of them underwent 18F-FDG PET. RESULTS: A high 11C-methionine uptake was observed in all 3 patients with cerebral hematoma. Increased 99mTc-HMPAO uptake was observed in 2 out of 3 patients, and all 3 patients had decreased 18F-FDG uptake. Of 4 patients with a cerebral infarction, high 11C-methionine uptake was observed in 3. Increased 99mTc-HMPAO uptake was also observed in one patient, whereas 3 patients had decreased 18F-FDG uptake. CONCLUSIONS: We should keep in mind that high 11C-methionine uptake is frequently observed in cerebrovascular diseases. CVD should therefore be included in the differential diagnosis when encounting patients with a high 11C-methionine uptake.     

Single-photon agents for tumor imaging:<Superscript>201</Superscript>TI,<Superscript>99m</Superscript>Tc-MIBI,and<Superscript>99m</Superscript>Tc-tetrofosmin

This review aims at fostering comprehension and knowledge not only for expert physicians who can skillfully handle various techniques for tumor imaging but also for young practitioners in the field of nuclear medicine. As image processing software and hardware become smaller, faster and better, SPECT will adapt and incorporate these advances. A principal advantage of SPECT over PET is the more widespread availability of the equipment and lower cost for the introduction of the system in community-based facilities. Moreover, SPECT has become less dependent on a limited number of acknowledged experts for its interpretation owing to a variety of handy computer tools for imaging analyses. The increasing use of PET in tumor imaging is not necessarily proportional to the decline of SPECT. General physicians' attention to SPECT technology would also increase more by evoking their interest in "tracer imaging."     

Scintigraphic findings of MALT lymphoma of the thyroid

Mucosa-associated lymphoid tissue (MALT) lymphoma has been established as a distinct entity among non-Hodgkin's lymphomas, and the most common primary site is the stomach. We describe scintigraphic findings in a patient with MALT lymphoma of the thyroid. A 71-year-old woman with Hashimoto's thyroiditis suffered from rapid cervical swelling, and ultrasonography and CT revealed a thyroid nodule. The nodule showed accumulation of 99mTc pertechnetate comparable to the surrounding thyroid tissue, mimicking a benign nodule. Both 67Ga and 201Tl imaging visualized the lesion as an increased uptake area. After radiotherapy, abnormally increased uptake disappeared on 67Ga images, which predicted a favorable outcome. MALT lymphoma of the thyroid may be visualized as a warm nodule on 99mTc pertechnetate scintigraphy.     

Brown adipose tissue: Evaluation with<Superscript>201</Superscript>Tl and<Superscript>99m</Superscript>Tc-sestamibi dual-tracer SPECT

Brown adipose tissue is one kind of adipose tissue and regulates body temperature and balance of energy via non-shivering thermogenesis. The authors present a case that strongly suggested the presence of activated brown adipose tissue in the neck, shoulders and axillary space by increased 18F-FDG uptake. 99mTc-sestamibi and 201Tl dual-tracer SPECT study showed increased 99mTc-sestamibi uptake and non-increased 201Tl uptake in the corresponding 18F-FDG uptake sites. Brown adipose tissue has dense mitochondria in the cells, which play an important role in thermogenesis. 99mTc-sestamibi uptake and retention depend on the mitochondrial activity but 201Tl uptake does not. Therefore, the activity of mitochondria in activated brown adipose tissue may explain the discrepant uptake between 99mTc-sestamibi and 201Tl.     

Better visualization of a lung tumour with 99mTc-DPD than with 99mTc-glucoheptonate or 67Ga-citrate

A case of a squamous cell lung carcinoma detected with ^99mTc-DPD, ⁶⁷Ga-citrate and ^99mTc-glucoheptonate (GH) is reported. The highest uptake was seen with DPD and the lowest with ⁶⁷Ga. Emission-computed tomography was very useful in DPD imaging but gave less new information in GH and ⁶⁷Ga studies in comparison to traditional planar imaging. The patient had been given both irradiation and chemotherapy, which might be the cause of good accumulation of DPD and rather poor accumulation of GH and ⁶⁷Ga.     

Bone marrow dosimetry in peptide receptor radionuclide therapy with [177Lu-DOTA0,Tyr3]octreotate

Purpose  Adequate dosimetry is mandatory for effective and safe peptide receptor radionuclide therapy (PRRT). Besides the kidneys, the bone marrow is a potentially dose-limiting organ. The radiation dose to the bone marrow is usually calculated according to the MIRD scheme, where the accumulated activity in the bone marrow is calculated from the accumulated radioactivity of the radiopharmaceutical in the blood. This may underestimate the absorbed dose since stem cells express somatostatin receptors. We verified the blood-based method by comparing the activity in the blood with the radioactivity in bone marrow aspirates. Also, we evaluated the absorbed cross-dose from the source organs (liver, spleen, kidneys and blood), tumours and the so-called “remainder of the body” to the bone marrow. Methods  Bone marrow aspirates were drawn in 15 patients after treatment with [¹⁷⁷Lu-DOTA⁰,Tyr³]octreotate. Radioactivity in the bone marrow was compared with radioactivity in the blood drawn simultaneously. The nucleated cell fraction was isolated from the bone marrow aspirate and radioactivity was measured. The absorbed dose to the bone marrow was calculated. The results were correlated to the change in platelet counts 6 weeks after treatment. Results  A strong linear correlation and high agreement between the measured radioactivities in the bone marrow aspirates and in the blood was found (r=0.914, p<0.001). No correlation between the calculated absorbed dose in the bone marrow and the change in platelets was found. There was a considerable contribution from other organs and the remainder of the body to the bone marrow absorbed dose. Conclusion  (1) After PRRT with [¹⁷⁷Lu-DOTA⁰,Tyr³]octreotate, the radioactivity concentration in the bone marrow is identical to that in the blood; (2) There is no significant binding of the radiopharmaceutical to bone marrow precursor stem cells; (3) The contribution of the cross dose from source organs and tumours to the bone marrow dose is significant; and (4) There is considerable variation in bone marrow absorbed dose between patients. These findings imply that for individual dose optimization, individual calculation of the bone marrow absorbed dose is necessary.     

Uptake of 99mTc-phytate in osteosarcoma cases

During routine liver spleen scintigraphic studies using ^99mTc-phytate in patients with proven osteosarcoma, an unusual uptake of this radiopharamaeutical at the primary site was observed. In all, five cases have been investigated and we have observed the uptake of ^99mTc-phytate at the primary tumor site. Early and delayed imaging showed persistant concentration of the radiopharmaceutical. Studies with ^99mTc-sulfur colloid in one of the patients did not show any uptake at the tumor site.     

Comparison of [18F]FDG-PET and L-3[123I]-iodo-alpha-methyl tyrosine (I-123 IMT)-SPECT in primary lung cancer

OBJECTIVE: The aim of this study was to evaluate L-3[123I]-iodo-alpha-methyl tyrosine (IMT)-SPECT and FDG-PET in pulmonary lesions suspected to be lung cancer. METHODS: Whole body PET (measured transmission corrected emission scans) was performed 45 minutes after i.v. injection of 222-370 MBq (6-10 mCi) 18F-FDG on a Siemens PET scanner (ECAT EXACT 47) including 5-6 bed positions. 123I-IMT-SPECT (chest) was performed after injection of 370 MBq (10 mCi) with a dual head camera (Picker Prism 2000) and commercially available reconstruction algorithms. Ten patients (6 male and 4 female) with suspected lung cancer were investigated. The results were compared to histological findings after surgery or bronchoscopic biopsies and CT. RESULTS: 123I-IMT-SPECT and FDG-PET were able to detect all 9 cases of lung cancer (1-8 cm in diameter). One case was true negative. Both imaging methods were true positive with respect to mediastinal lymph node metastases in one patient. The tumor/background ratio was higher with PET (8.20 vs. 2.84). CONCLUSION: Despite the limited number of patients it may be concluded that IMT-SPECT as well as FDG-PET are suited to correctly diagnose lung cancer. Nevertheless, FDG-PET, if available, seems to be better suited because of the higher tumor/background ratio and better resolution.