131I Therapy For Thyroid Cancer Research Articles

Measurements of 131I activity in thyroid of workers at the place of radioiodine therapy in 38 hospitals in China.

To investigate the levels of 131I activity in thyroid of workers at the place of radioiodine therapy and their main influential factors in China, 341 workers at 38 hospitals performing radioiodine therapy procedure in five provinces were recruited to be measured in 2021. A hand-held gamma spectrometer with NaI(Tl) probe was plastered to the thyroids and thighs of the subjects during the measurement, and each measurement time was 120s. The internal exposure dose was calculated, and the committed effective dose was estimated. In 86 (25.22%) of the 341 examined workers, 131I thyroid activity was above minimum detectable activity (MDA, 26.6Bq). The maximum activity was 4.9 × 103Bq. The detection results above MDA were at 22 (57.89%) different hospitals. The detectable rate for private hospitals (4.8%) was significantly lower than that for public hospitals (26.6%), P < 0.05. The detectable rate for hospitals in provincial capital cities (15.4%) was significantly lower than in nonprovincial capital cities (41.7%), P < 0.001. The detectable rate for hospitals engaged in 131I therapy for thyroid cancer (31.2%) was significantly higher than only for hyperthyroidism (10.3%), P < 0.001. A total of 32 subjects' committed effective dose might exceed 1mSv. Results indicated the 131I activity in the thyroid of workers at the place of radioiodine varied considerably in China, and mainly related to ownership, location and therapy program of the hospitals.

The lacrimal apparatus as an organ at risk during radionuclide therapy

Within the framework of the article, the authors analyzed the available information about the damage to the lacrimal apparatus during radionuclide therapy. In focus of article lesions of the lacrimal production system, the main and accessory lacrimal glands, as well as lacrimal drainage are considered. It was found that damage to the lacrimal apparatus is characteristic of 131I therapy for thyroid cancer, as well as for radioligand therapy using anti-PSMA antibodies labeled with 177Lu and 225Ac. 177Lu-PSMA and 225Ac-PSMA may damage the lacrimal gland with the formation of a clinically pronounced "dry eye syndrome". The pathogenesis of such lesions is associated with the accumulation of a radioisotope in the tissues of the lacrimal apparatus, while during therapy with 131I, accumulation is realized due to the expression of the sodium-iodine symporter in the nasolacrimal duct, and during therapy with 177Lu-PSMA and 225Ac-PSMA, the radiobiological effect is realized in connection with the expression PSMA by lacrimal tissue. An analysis of the available sources showed that to date there are no results of systematic studies on the problem, there is a lack of knowledge regarding the individual risks of developing these complications, methods for their prevention that have proven effectiveness have not been developed, and the treatment methods used, having relatively low efficiency, are not specialized. The authors concluded that the strengthening of interdisciplinary interaction, as well as the organization verification methodology and correct studies, can contribute to solving problems related to the study of the complications under consideration.

Simultaneous measurements of single gamma ray of 131I and annihilation radiation of 18F with Compton PET hybrid camera

In internal 131I therapy for thyroid cancer, a decision to continue treatment is made by comparing 131I scintigraphy and [18F]FDG-PET. However, with current SPECT and PET systems, simultaneous imaging of diagnostic PET nuclides and therapeutic 131I nuclides has not been achieved so far. Therefore, we demonstrated that the recently developed Compton PET hybrid camera with Ce:Gd3(Al,Ga)5O12 (GAGG)- Silicon Photomultiplier(SiPM) scintillation detectors can be used to simultaneously image 131I Compton image and 18F PET image.

Nuclear medicine practice in Japan: a report of the seventh nationwide survey in 2012.

The Subcommittee on the Survey of Nuclear Medical Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. The subcommittee sent questionnaires, including the number and category of examinations as well as the kind and dose of the radiopharmaceuticals during the 30days of June 2012, to all the nuclear medicine institutes. The total numbers for the year 2012 were then estimated. A total of 1,167 institutes responded to the survey, including the 14 in vitro assay institutes and 266 PET centers. The recovery rate was 92%. The number of gamma cameras installed was 1,425 in total, with 9% decrease in 5years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 84 and 10.5%, respectively. The number of single-photon tracer studies in 2012 was 1.15 million which means decrease in 19% in 5years and 29% in 10years. All but cerebral perfusion study and sentinel lymphoscintigraphy have decreased. Bone scintigraphy was a leading examination (38.7%), followed by cardiac studies (29.4%) and cerebral perfusion study (18.5%) in order. SPECT studies showed an increase from 42.3 to 47.2%. PET centers have also increased from 212 to 295, as compared to the last survey. The 135 PET centers have installed one or two in-house cyclotrons. PET studies showed 25.5% increase in 5years, with oncology accounting for 96.3%. (18)F-FDG accounted for 98.2% (505,990 examinations). PET examinations using (11)C-methionine have been increasing, with 3,352 examinations in 2012. The number of new PET studies using (11)C-PIB PET was 695. (131)I-radioiodine targeted therapies showed an increase, including 3,644 patients (53.6%) for thyroid cancer and 4,889 patients (17.9%) for hyperthyroidism. Out-patient thyroid bed ablation therapy with 30mCi of (131)I accounted for 21.0% of cancer patients. The number of admission rooms decreased from 158 to 135 in 5years. In vitro radioassays have been declining continuously since 1992, with the number of studies of 9.0 million in 2012. Single-photon examinations showed a continuous tendency toward a decline in the survey. In contrast, the number of hybrid SPECT/CT scanner examinations has increased. PET/CT study in the oncology field and radionuclide targeted therapy have steadily increased.

Three-dimensional radiobiological dosimetry (3D-RD) with 124I PET for 131I therapy of thyroid cancer

Radioiodine therapy of thyroid cancer was the first and remains among the most successful radiopharmaceutical (RPT) treatments of cancer although its clinical use is based on imprecise dosimetry. The positron emitting radioiodine, (124)I, in combination with positron emission tomography (PET)/CT has made it possible to measure the spatial distribution of radioiodine in tumors and normal organs at high resolution and sensitivity. The CT component of PET/CT has made it simpler to match the activity distribution to the corresponding anatomy. These developments have facilitated patient-specific dosimetry (PSD), utilizing software packages such as three-dimensional radiobiological dosimetry (3D-RD), which can account for individual patient differences in pharmacokinetics and anatomy. We highlight specific examples of such calculations and discuss the potential impact of (124)I PET/CT on thyroid cancer therapy.

A dosimetric algorithm for patient-specific 131I therapy of thyroid cancer based on a prescribed target-mass reduction

131I therapy is used in the treatment of differentiated thyroid cancer both to ablate the post-surgical thyroid remnant and to treat recurrent or metastatic cancer. The optimum administered activity for ablation remains controversial: the most commonly used method is the administration of a fixed radioiodine activity (1110–3700 MBq or more); an alternative is the administration of an activity individually calculated to deliver a prescribed absorbed dose (usually 300 Gy for remnant ablation and 80 Gy for treatment of metastasis). Neither of these two approaches is based on a theoretical model and for this reason the debate on the optimization of 131I therapy of thyroid cancer could have a weak grounding. In this paper, the meaning of the fixed value of target absorbed dose (Gy) is discussed and a mathematical model for remnant/metastasis optimum absorbed dose calculation is presented. This model is based on the desired reduction of the volume of the target (remnant or metastasis) and allows one to calculate individually the value of the optimum target absorbed dose (Gy) and consequently the optimum therapeutic activity to administer to the patient.

Management of 131I therapy for thyroid cancer: cumulative dose from in-patients, discharge planning and personnel requirements

To provide a comprehensive overview with regard to the hospitalization/discharge planning and nursing staff requirements for the management of patients treated with radioiodine for differentiated thyroid carcinoma. A statistical analysis of the fast clearance phase of 131I was performed in 265 hospitalized patients treated after total thyroidectomy with fixed doses ranging from 2590 to 9250 MBq. Two hundred and twenty-five cases were post-surgical ablation treatments and 40 cases were follow-up treatments. The 131I clearance was studied during hospitalization of 2-4 days. No clearance differences were found between the two groups. The median value of the biological half-time (T1/2bio) was 0.65 days, with a variability range of 0.30-2.03 days. A statistical model for the distribution of T(1/2bio) was reported. Some patients on maintenance haemodialysis were also studied, with T(1/2bio) values ranging from 1.6 to 2.6 days. The weekly cumulative dose to personnel from external exposure, corresponding to the 95th percentile, ranged from 0.1 mSv per GBq of administered activity (mSv x GBq(-1)) with a totally ambulant patient to 5.4 mSv . GBq with a totally helpless patient. With patients on maintenance haemodialysis, these values could increase from 1.2 to 1.7 times. The cumulative dose to close relatives was also estimated. The hospitalization times associated with 75% and 95% probabilities of patient discharge were calculated by varying the residual activity limit from 100 to 800 MBq. Finally, using the median T(1/2bio), personnel requirements were evaluated. With totally ambulant and semi-ambulant patients, about 0.5 and 1.0 personnel units per GBq of weekly administered activity were needed so as not to exceed an annual planning dose of 6 mSv per year. The treatment of patients with higher degrees of dependency was impractical. On the basis of statistical analysis, a better organization of in-patient treatment may be obtained, as well as more accurate preliminary evaluations of the cumulative doses to nursing staff and attending personnel, for the management of patients treated with radioiodine for differentiated thyroid carcinoma.

Nuclear medicine practice in Japan: a report of the 5th nationwide survey in 2002.

The Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every five years since 1982 to provide detailed information on its current status. Questionnaires were sent to every institution known to the Japan Radioisotope Association to provide nuclear medicine examinations. The questionnaires address the number and kind of nuclear medicine examinations performed as well as the kind and dose of the radiopharmaceuticals used during the month of June 2002. The annual number of total or specific examinations was then estimated. Of the institutions sent questionnaires, 1,204 were for in vivo study, 124 were for in vitro study, and 36 were for positron emission tomography (PET) study. Out of these, 95.8% answered them. A total of 1,697 gamma cameras were installed in 1,160 facilities, of which 50% were dual-head cameras. The estimated total annual number of examinations expressed by the number of administered radiopharmaceuticals was 1.60 million, similar to that of the previous survey (1997). The frequency of study with single photon emission computed tomography (SPECT) increased to 40%, from 30% in the previous survey. The scintigraphy most frequently performed was bone (35%), followed by myocardium (24%) and brain perfusion (12%). All showed a continuous increase over the past 20 years. Tumor imaging, however, fell from third to fourth place. The most commonly used radiopharmaceutical for each scintigraphy was 99mTc-HMDP for bone, 201Tl-chloride for myocardium, 67Ga-citrate for tumor, and 123I-IMP for brain. A total of 29,376 PET studies were performed yearly. Among them, 18F-FDG rapidly increased 3.7-fold. 131I therapy for thyroid cancer and hyperthyroidism was conducted yearly in 1,647 and 3,347 patients, respectively. A total of 31.35 million in vitro radioassays were carried out yearly, the number of which has been decreasing continuously since 1992. It was proved that the content of nuclear medicine practice in Japan has changed in the past five years. This report might be useful for understanding the current trends of nuclear medicine practice in Japan.

Percent 131I uptake and post-therapy 131I scans: their role in the management of thyroid cancer.

This short review focuses on two questions commonly asked about 131I therapy of thyroid cancer. The first relates to radiation dosimetry. What percentage of 131I uptake is needed for effective therapy? Studies have shown that 131I uptake and therapeutic outcome may not be closely related. A more powerful relationship, however, occurs by using percent uptake per gram. A rearrangement of the basic dosimetry equation shows that for a specific level of radiation, percent uptake per gram and effective half-life are inversely related. Formulas developed from this relationship are useful in determining whether uptake is satisfactory but require estimates of effective half-life and tumor mass. The second question is whether post-therapy 131I scans are useful. Because the sensitivity of 131I scanning is related directly to the amount of radioactivity administered, imaging after therapy may show previously undetected lesions that not infrequently are distant metastases. Thus, information from post-therapy scans may 1) after therapy, 2) direct new diagnostic studies, 3) lead to formal dosimetry studies when maximal 131I doses are needed to treat distant metastases, and 4) be necessary to obtain when 131I therapy is administered to patients with elevated thyroglobulin and negative diagnostic scans. Should post-therapy scans always be performed? They are easy to perform and are clinically useful but may be inconvenient to patients and costly overall. At this time, however, there is not a simple paradigm for selecting patients who may forego these scans.

Micronuclei in lymphocytes of children from the vicinity of Chernobyl before and after 131I therapy for thyroid cancer.

The present study addresses the monitoring of children from the Belorussian and Ukrainian Republics exposed to the fall-out of the Chernobyl accident. Micronucleus analysis has been performed on 56 children from different areas. The micronucleus frequencies in individuals as well as in regional groups were comparable with controls, except for three donors. Such results had to be expected, taking into account that at least 7 years have passed since the accident. Most of the children whose micronucleus frequencies were determined are suffering from thyroid cancer and were treated by radioiodine (131I) therapy. We studied the effect of in vitro exposure with 131I on micronucleus induction and that proliferative ability of lymphocytes. The present investigation indicates that micronuclei can be usefully employed to detect individual exposures to the incorporated radionuclide within several days after the intake of the radionuclide in a dose range of around 65-390 mGy (effective dose).

Predictive estimate of blood dose from external counting data preceding radioiodine therapy for thyroid cancer

Bone marrow depression following 131I therapy for metastatic thyroid cancer can occur in up to one-quarter of all patients so treated. An analysis was made of the 131I whole body (WB) retention and its relationship to activity in blood for 46 patients (45 adult, 1 adolescent in 49 total studies) to define the accuracy of utilizing WB external counting data as a predictor of blood dose in comparison to the more classical method which requires data from sequential blood samples. The mean percentage differences between blood dose estimates based on external WB counting and those calculated by the classical method lie within ±10%. The WB methodology provides a useful first-order approximation for hematopoietic dose estimates in adult patients undergoing 131I therapy for thyroid cancer.