[Cytological radiotoxicity of radioiodine therapy in patients with differentiated thyroid carcinoma]

Cytological radiation damage to lymphocytes can result in augmentation of cells with micronuclei. In this study we investigated Cytological radiation damage to peripheral blood lymphocytes using the micronuclei assay [MNA] method. Considering the value of Iodine-131 in diagnostic and therapeutic nuclear medicine and high absorbed dose of I131 radioiodine in comparison with gamma emitters and the effect of type of radiation, dose and species on radiosensitivity of patients, this study was conducted. To evaluating the Cytological radiotoxicity of therapeutic radiotracers such as radioiodine I131. We studied 22 patients with differential thyroid carcinoma who were referred for treatment with 100 or 150 mci I131. Before and one weak after treatment the peripheral lymphocytes were harvested and isolated by a Cytological method and assayed for frequency of micronuclei as a marker of Cytological radiotoxicity. The means of micronuclei in one hundred binuclear lymphocytes were 6.3 +/- 2.2 before treatment and 9.6 +/- 3.1 after treatment, differences in the number of micronuclei being statistically significant [p value <0.05]. High doses of radioiodine therapy used after surgery for differentiated thyroid carcinoma can increase micronuclei among peripheral lymphocytes as an indirect marker of chromosomal aberrations and cytotoxic radiation damage

Pediatric radiation exposure from diagnostic nuclear medicine examinations in Tehran

As a part of a nationwide survey to estimate population exposure to radiation from diagnostic nuclear medicine in Iran, this paper presents the pediatric population radiation exposure due to nuclear medicine examinations in Tehran. The effective dose equivalent, HE, was used to calculate the collective effective dose in pediatric patients undergoing nuclear medicine procedures, and the corre-sponding data were obtained from thirty out of thirty seven active nuclear medicine departments in Tehran. Annually about 5.26% of nuclear medicine examinations were performed on patients under 15 years of age in Tehran. The most frequent was renal examinations [38.2%], followed by thyroid [27.4%] and bone [26.7%]. The annual collective HE for patients under 15 was 19.03 human-Sv, which contributed 3.96% to the collective HE for all patients. The contribution of renal, bone and thyroid examinations to the pediatric collective HE were 24.6%, 48.8% and 13.5% respectively. The mean effective dose equivalent per pediatric patient was 3.75 mSv. Among the three most frequent examinations, the bone with a relative frequency of 27.4% constituted 48.8% of the collective HE, which was the highest absorbed dose per examination. The mean effective dose per examination for patients younger than 15 years was 67.9% of the adults

Staff and patient absorbed doses due to diagnostic nuclear medicine procedures

Background: Annual patient effective dose equivalent can be considered as a quantitative physical parameter describing the activities performed in each nuclear medicine department. Annual staff dose equivalent could be also considered as a parameter describing the amount of radiation risk for performing the activities. We calculated the staff to patient dose equivalent ratio to be used as a physical parameter for quantification of ALARA law in nuclear medicine departments

Materials and Methods: As a part of nationwide study, this paper reports the staff and patient absorbed dose equivalents from diagnostic nuclear medicine examinations performed in four nuclear medicine departments during 1999-2002. The type and frequency of examinations in each department were determined directly from hospital medical reports. Staff absorbed dose equivalents were calculated from regular personal dosimeter reports

Results: The total number of examinations increased by 16.7% during these years. Annual patient collective dose equivalent [EDE] increased about 13.0% and the mean effective dose equivalent per exam was 3.61+/-0.07 mSv. Annual total staff absorbed dose equivalent [total of 24 radiation workers] in four departments increased from 40.45 mSv to 47.81 mSv during four years that indicates an increase of about 20.6%. The average of annual ratios of staff to patient effective dose equivalents in four departments were 1.83×10[-3], 1.04×10[-3], 3.28×10[-3] and 3.24×10[-3], respectively, within a range of 0.9×10[-3] - 4.17×10[-3]. The mean value of ratios in four years was about 2.24×10[-3] +/- 1.09×10[-3] that indicates the staff dose of about two 1000[th] of patient dose

Conclusion: The mean value of ratios in four years was about 1.89×10[-3] +/- 0.95×10[-3] indicating the staff dose of about one 1000th of the patient dose. The staff to patient absorbed dose equivalent ratio could be used as a quantitative parameter for describing ALARA law in radiation protection and risk-benefit assessments

Tissue uptakes of 67Ga-bleomycin and carrier free 67Ga in fibrosarcoma - bearing mice

67Gallium-bleomycin complex [67Ga-BLM] was prepared using Thakour method. Radio-thin-layer-chromatography of prepared complex showed A2 and B2 radiopeaks with Rf at 0.7 and 0.4 respectively with a purity of above% 95. Tissue uptake of 67Ga-BLM and 67GaCl3 in twelve tissues including tumor, blood, liver, lung, spleen, muscle, skin, heart, kidney, colon, colon content,bladder and the total body were counted by well counter at 1, 2, 4, 24 and 48 hours post injection of radiopharmaceuticals. Uptakes of tissues are expressed as percent injected dose per gram of tissue. The clearance rate of 67Ga-BLM was 1.75-1.95 times faster than 67GaCl3 at all time intervals. Bladder uptakes of 67Ga-BLM were highest among twelve tissues at 1,2 and 4 hours after injection, then falling rapidly after 24 and 48 hours. Blood uptake of 67Ga-BLM was lower than 67GaCl3 in all time intervals. Colon content uptake of 67Ga-BLM was highest among twelve tissues at 2 and 4 hours post injection. Tumor to tissue activity ratios were also calculated, showing an increase of tumor to blood and muscle ratios. Tumor to blood ratio increased from 0.3 at 1 hour to 5.3 at 48 hours. Activity ratio of muscle increased from 0.5 at 1 hour to 5.5 at 48 hours. Whole body counting of animals showed that effective half lives of 67Ga-BLM and 67GaCl3 were about 1 and 15 hours respectively, which renders faster excretion of 67Ga-BLM complex. Biodistribution data clearly indicates that prepared complex in comparison with carrier free 67Ga [67GaCl3] has two main advantages: 1] high tumor to soft tissue uptake ratio that make it suitable for tumor imaging, 2] faster excretion specially at first three hours post injection. In addition complex is stable in vitro and in vivo

Preparation, distribution, stability and tumor imaging properties of [62 Zn] bleomycin complex in normal and tumor - bearing mice

Bleomycin [BLM] has been labeled with radioisotopes and widely used in therapy and diagnosis. In this study BLM was labeled with [62Zn] zinc chloride for oncologic PET studies. The complex was obtained at the pH=2 in normal saline at 90°C in 60 min. Radio-TLC showed an overall radiochemical yield of 95-97% [radiochemical purity > 97%]. Stability of complex was checked in vitro in mice and human plasma/urine. Preliminary in vivo studies performed to determine complex stability and distribution of [62Zn] BLM in normal and fibrosarcoma-bearing mice. [62Zn] BLM accumulated significantly in induced fibrosarcoma tumors in mice according to bio-distribution/imaging studies. [62Zn] BLM can be used in PET oncology studies due to its suitable physico-chemical properties as a diagnostic complex in vitro and in vivo. Further studies should be performed for evaluation of the complex behavior in higher animals