Validation of automated image co-registration integrated into in-house software for voxel-based internal dosimetry on single-photon emission computed tomography images.

Objective: To develop an automated co-registration system and test its performance, with and without a fiducial marker, on single-photon emission computed tomography (SPECT) images.

Materials And Methods: Three SPECT/CT scans were acquired for each rotation of a Jaszczak phantom (to 0°, 5°, and 10° in relation to the bed axis), with and without a fiducial marker. Two rigid co-registration software packages-SPM12 and NMDose-coreg-were employed, and the percent root mean square error (%RMSE) was calculated in order to assess the quality of the co-registrations.

Influence on voxel-based dosimetry: noise effect on absorbed dose dosimetry at single time-point versus sequential single-photon emission computed tomography.

Objective: The purpose of this study was to evaluate how statistical fluctuation in single-photon emission computed tomography (SPECT) images propagate to absorbed dose maps.

Methods: SPECT/computed tomography (CT) images of iodine-131 filled phantoms, using different acquisition and processing protocols, were evaluated using STRATOS software to assess the absorbed dose distribution at the voxel level. Absorbed dose values and coefficient of variation (COV) were analyzed for dosimetry based on single time-point SPECT images and time-integrated activities of SPECT sequences with low and high counts.

Radiation safety measures in diagnostic nuclear medicine, based on the potential radiation dose emitted by radioactive patients.

Objective: To measure the potential radiation dose emitted by patients who have recently undergone diagnostic nuclear medicine procedures, in order to establish optimal radiation safety measures for such procedures.

Materials And Methods: We evaluated the radiation doses emitted by 175 adult patients in whom technetium-99m, iodine-131, and fluorine-18 radionuclides were administered for bone, kidney, heart, brain, and whole-body scans, as measured with a radiation detector. Those values served as the basis for evaluating whole-body radiopharmaceutical clearance, as well as the risk for the exposure of others to radiation, depending on the time elapsed since administration of the radiopharmaceutical.

Ultrasonography Echotexture as a surrogate for Sialadenitis secondary to 131I Radioiodine Therapy for differentiated Thyroid Cancer: a review and metaanalysis.

Unlabelled: To systematically review and analyze the medical literature to assess ultrasonography echotexture changes in thyroid cancer patients for the detection of chronic sialadenitis caused by radioiodine therapy.

Methods: Sources were retrieved from PubMed, Scopus, EMBASE and LILACS through November 2018. All studies that assessed ultrasonographic features before 131I administration and at 12 months after 131I administration were selected.

Evaluation of Parotid Salivary Gland Echo Texture by Ultrasound Examinations and Correlation With Whole-Body Scintigraphy After Radioiodine Therapy in Patients With Differentiated Thyroid Carcinoma.

Objectives: This study aimed to evaluate the echo texture of the parotid salivary glands before and after radioiodine therapy (RIT) using ultrasound (US) images in patients with differentiated thyroid cancer and to evaluate the correlations between post-RIT whole-body scintigraphy (WBS) images and US image patterns in salivary and cervical areas.

Methods: A retrospective study was performed with data on demographic and clinical information, US examinations, and WBS images collected through medical recordings.

Results: Comparing the US features before and after RIT, significant echo texture heterogeneity was found in 31.

Radionuclide therapy: current status and prospects for internal dosimetry in individualized therapeutic planning.

The efficacy and toxicity of radionuclide therapy are believed to be directly related to the radiation doses received by target tissues; however, nuclear medicine therapy continues to be based primarily on the administration of empirical activities to patients and less frequently on the use of internal dosimetry for individual therapeutic planning. This review aimed to critically describe the techniques and clinical evidence of dosimetry as a tool for therapeutic planning and the main limitations to its implementation in clinical practice. The present article is a nonsystematic review of voxel-based dosimetry.

Pediatric 131I-MIBG Therapy for Neuroblastoma: Whole-Body 131I-MIBG Clearance, Radiation Doses to Patients, Family Caregivers, Medical Staff, and Radiation Safety Measures.

Purpose: I-metaiodobenzylguanidine (I-MIBG) has been used in the diagnosis and therapy of neuroblastoma in adult and pediatric patients for many years. In this study, we evaluated whole-body I-MIBG clearance and radiation doses received by patients, family caregivers, and medical staff to establish appropriate radiation safety measures to be used in therapy applications.

Methods: Research was focused on 23 children and adolescents with metastatic neuroblastoma, with ages ranging from 1.

Estimating (131)I biokinetics and radiation doses to the red marrow and whole body in thyroid cancer patients: probe detection versus image quantification.

Objective: To compare the probe detection method with the image quantification method when estimating (131)I biokinetics and radiation doses to the red marrow and whole body in the treatment of thyroid cancer patients.

Materials And Methods: Fourteen patients with metastatic thyroid cancer, without metastatic bone involvement, were submitted to therapy planning in order to tailor the therapeutic amount of (131)I to each individual. Whole-body scans and probe measurements were performed at 4, 24, 48, 72, and 96 h after (131)I administration in order to estimate the effective half-life (Teff) and residence time of (131)I in the body.

Prediction of iodine-131 biokinetics and radiation doses from therapy on the basis of tracer studies: an important question for therapy planning in nuclear medicine.

Objectives: This study aimed to present a comparison of iodine-131 (I) biokinetics and radiation doses to red-marrow (rm) and whole-body (wb), following the administration of tracer and therapeutic activities, as a means of confirming whether I clearance and radiation doses for therapy procedures can be predicted by tracer activities.

Methods: Eleven differentiated thyroid cancer patients were followed after receiving tracer and therapeutic I activity. Whole-body I clearance was estimated using radiation detectors and OLINDA/EXM software was used to calculate radiation doses to rm and wb.

Diagnostic reference level: an important tool for reducing radiation doses in adult and pediatric nuclear medicine procedures in Brazil.

Objectives: This study aimed to establish a concise method for determining a diagnostic reference level (DRL) for adult and pediatric nuclear medicine patients on the basis of diagnostic procedures and administered radioisotope as a means of controlling medical exposure.

Methods: A screening was carried out in all Brazilian Nuclear Medicine Service (NMS) establishments to support this study by collecting the average activities administered during adult diagnostic procedures and the rules applied to adjust these according to the patient's age and body mass. Percentile 75 was used in all the activities administered as a means of establishing DRL for adult patients, with additional correction factors for pediatric patients.

Effects of Thyroid Hormone Withdrawal and Recombinant Human Thyrotropin on Glomerular Filtration Rate During Radioiodine Therapy for Well-Differentiated Thyroid Cancer.

Background: Renal function is related to thyroid hormonal status, and glomerular filtration rate (GFR) seems to be impaired in patients with hypothyroidism. The aim of this work was to evaluate quantitatively the effect of hypothyroidism on GFR using a (51)Cr-EDTA radioisotope assay.

Methods: Twenty-eight patients without known renal disease or dysfunction who had been referred for radioiodine therapy (RIT) after total thyroidectomy were enrolled in this study and divided into two groups.

Dose Calibrator Linearity Testing: Radioisotope (99m)Tc or (18)F? An Alternative for Reducing Costs in Nuclear Medicine Quality Control.

Dose calibrator linearity testing is indispensable for evaluating the capacity of this equipment in measuring radioisotope activities at different magnitudes, a fundamental aspect of the daily routine of a nuclear medicine department, and with an impact on patient exposure. The main aims of this study were to evaluate the feasibility of substituting the radioisotope Fluorine-18 ((18)F) with Technetium-99m ((99m)Tc) in this test, and to indicate it with the lowest operational cost. The test was applied with sources of (99m)Tc (62 GBq) and (18)F (12 GBq), the activities of which were measured at different times, with the equipment preadjusted to measuring sources of (99m)Tc, (18)F, Gallium-67 ((67)Ga), and Iodine-131 ((131)I).

Clinical and Dosimetric Variables Related to Outcome After Treatment of Graves' Disease With 550 and 1110 MBq of 131I: Results of a Prospective Randomized Trial.

Unlabelled: : Therapy of Graves' hyperthyroidism (HTG) with I is still mostly performed on an empirical basis. The present study was carried out to evaluate clinical and dosimetric variables associated with outcome in HTG therapy, which could contribute to planning and defining the most appropriate activity to be administered.

Methods: Patients with HTG were randomly assigned to therapy with 555 MBq (15mci) or 1110 MBq (30 mCi) of I.

Dose calibrator linearity test: (99m)Tc versus (18)F radioisotopes.

Objective: The present study was aimed at evaluating the viability of replacing (18)F with (99m)Tc in dose calibrator linearity testing.

Materials And Methods: The test was performed with sources of (99m)Tc (62 GBq) and (18)F (12 GBq) whose activities were measured up to values lower than 1 MBq. Ratios and deviations between experimental and theoretical (99m)Tc and (18)F sources activities were calculated and subsequently compared.

Graves' disease radioiodine-therapy: choosing target absorbed doses for therapy planning.

Purpose: The precise determination of organ mass (mth) and total number of disintegrations within the thyroid gland (Ã) are essential for thyroid absorbed-dose calculations for radioiodine therapy. Nevertheless, these parameters may vary according to the method employed for their estimation, thus introducing uncertainty in the estimated thyroid absorbed dose and in any dose-response relationship derived using such estimates. In consideration of these points, thyroid absorbed doses for Graves' disease (GD) treatment planning were calculated using different approaches to estimating the mth and the Ã.

Radioiodine therapy for Graves disease: thyroid absorbed dose of 300 Gy-tuning the target for therapy planning.

Purposes: Based on the committed thyroid absorbed dose, the aim was to compare the efficiency of I therapy against Graves disease (GD) within 1 year after treatment and, by exploring the dose-response relationship, indicate an absorbed dose to be targeted into patient therapeutic planning.

Methods: Thyroid-absorbed doses were calculated to 196 patients with GD by applying Medical Internal Radiation Dose formalism and taking into account administered I activity, thyroid radioiodine uptake, effective half-life, and gland tissue mass. Statistical analysis was applied to assess the relationship between absorbed doses and the patient's clinical response.

Determining thyroid (131)I effective half-life for the treatment planning of Graves' disease.

Purpose: Thyroid (131)I effective half-life (T(eff)) is an essential parameter in patient therapy when accurate radiation dose is desirable for producing an intended therapeutic outcome. Multiple (131)I uptake measurements and resources from patients themselves and from nuclear medicine facilities are requisites for determining T(eff), these being limiting factors when implementing the treatment planning of Graves' disease (GD) in radionuclide therapy. With the aim of optimizing this process, this study presents a practical, propitious, and accurate method of determining T(eff) for dosimetric purposes.

[Correlation between thyroid volume determined either by ultrasound or by scintigraphy and its implications in dosimetric radioiodine calculations in Graves disease treatment].

Introduction: Graves disease (GD) is the most common cause of hiperthyroidism, and the most common treatment options are surgery, antithyroid drugs and radioiodine therapy. In radiodosimetric calculations to determine radioiodine dosage it is possible to use thyroid volume estimatives based on ultrasound or scintigraphy.

Objective: The present study aimed to correlate these methodologies emphasizing volume estimatives and dosimetric implications.

Comparison of different dosimetric methods for red marrow absorbed dose calculation in thyroid cancer therapy.

Several dosimetric methods have been proposed for estimating red marrow absorbed dose (RMAD) when radionuclide therapy is planned for differentiated thyroid cancer, although to date, there is no consensus as to whether dose calculation should be based on blood-activity concentration or not. Our purpose was to compare RMADs derived from methods that require collecting patients' blood samples versus those involving OLINDA/EXM software, thereby precluding this invasive procedure. This is a retrospective study that included 34 patients under treatment for metastatic thyroid disease.

Outpatient radioiodine therapy for thyroid cancer: a safe nuclear medicine procedure.

Purposes: To evaluate the dosimetric effect of outpatient radioiodine therapy for thyroid cancer in members of a patient's family and their living environment, when using iodine-131 doses reaching 7.4 GBq. The following parameters were thus defined: (a) whole-body radiation doses to caregivers, (b) the production of contaminated solid waste, and (c) radiation potential and surface contamination within patients' living quarters.

Is it necessary to reduce the radioiodine dose in patients with thyroid cancer and renal failure?

The objective of this study were to obtain dosimetric data from a patient with thyroid cancer simultaneously undergoing peritoneal dialysis therapy, so as to determine the appropriate amount of 131I activity to be applied therapeutically. Percentages of radioiodine in the blood and the whole-body were evaluated, and radiation absorbed doses were calculated according to OLINDA/EXM software. Whole-body 131I effective half-time was 45.

[Radioiodine therapy of differentiated thyroid cancer: radiologic impact of out-patient treatment with 100 to 150 mCi Iodine-131 activities].

Purpose: To evaluate exposure and dosimetry to family members and environment due to outpatient radioiodine therapy of differentiated thyroid carcinoma.

Methods: Twenty patients were treated with 100-150mCi of iodine-131 on an out-patient basis. Family members dosimetry (n = 27) and potential doses inside the house were measured with thermoluminescent dosimeters.

Correction factors for more accurate estimates of exposure rates near radioactive patients: experimental, point, and line source models.

Radioactive patients may expose others after radiopharmaceutical administrations, and evaluation of the absorbed dose or exposure rates close to patients is important in keeping radiation doses as low as reasonably achievable. Two theoretical exposure models, point source and line source models, are frequently used to calculate exposure or dose rates without the support of actual measurements. If measurements of exposure rates were performed near patients, an experimental exposure model could be implemented.

A new proposal for monitoring patients in nuclear medicine.

The measurement of exposure rates is fundamentally important in the release of patients given radioactive materials and for keeping the exposures of others as low as reasonable achievable. Similar measurement methodologies have generally been used for point and extended sources, but this approach may lead to methodological errors in calculating radiation dose estimates. In this study, nuclear medicine patients who received high activities of Na131I for therapy were monitored using different measurement methodologies, and the results showed that the usual measurement performed at 1.

Evaluation of the potential absorbed doses from patients based on whole-body 131I clearance in thyroid cancer therapy.

The evaluation of the absorbed dose from radioactive patients during the treatment of thyroid disease is an important factor in establishing precautions in these procedures, and the I retention/excretion by patients' bodies provides additional information to medical and radioprotection service. In 94 patients, the measurement of exposure rates was performed over 7 d following NaI administration, and the rates permitted the study of the dynamics of excretion and the potential dose evaluation. The administered activities ranged from 3.