Eugene L. Saenger

Relation between Effective Radiation Dose and Outcome of Radioiodine Therapy for Thyroid Cancer

We used a combination of radioiodine scanning and quantitative radiation dosimetry to evaluate responses to therapeutic irradiation with 131I in 76 patients with thyroid adenocarcinoma. Fifty patients received 131I treatment for ablation of residual thyroid tissue after surgical thyroidectomy, and 26 had 131I treatment for metastatic thyroid cancer. Successful ablation was observed in patients receiving higher radiation doses to the thyroid--about 4.4 times those in patients whose lesions were not ablated--largely because of a longer effective half-life of 131I in residual thyroid tissue in the patients with ablated lesions. Patients with metastases that persisted after 131I therapy tended to have more advanced disease and received significantly lower radiation doses per millicurie of administered 131I than did persons whose lesions responded to treatment. Initial 131I treatment resulting in radiation doses of at least 30,000 rad to thyroid remnants and 8000 rad to metastases was associated with a significant increase in the rate of response to therapy.

Neoplasia Following Therapeutic Irradiation for Benign Conditions In Childhood

The question of whether or not radiation can be indicted as the principal causative factor in the induction of neoplasia following radiation exposure for either diagnostic or therapeutic purposes has been of increasing interest over the past several years (4, 12, 18, 19, 20). The present investigation was initiated in 1956, in the Cincinnati area, which appeared to offer abundant material for evaluation. The first case of x-irradiation for treatment of “enlarged thymus” was reported from Cincinnati by Friedlander in 1907 (8), and both roentgen diagnosis and therapy of thymic enlargement enjoyed considerable local popularity until recently. Observations from this city were published by Lange in 1914 (11). Since the majority of patients in the series to be reported here were from a group of private and municipal hospitals, none of which is particularly noted as a cancer center, the possibility of bias being introduced by selection of a neoplasia-prone population was thought to be minimal. Historical Review ...

Ionizing irradiation and the induction of clinically significant disease in the human thyroid gland

Because of increasing concern over continuing medical and potential nonmedical exposure of the thyroid to radiation, risk estimates have been developed for acute thyroiditis, hypothyroidism, and both benign and malignant thyroid nodules following exposure of the human thyroid to external and internal sources of ionizing radiation. These estimates are unique in that they are based entirely on data in human subjects are included corrections for the spontaneous occurrence of thyroid disease in human populations not subjected to radiation whenever possible.

Imaging of Bone Metastases with 99mTc-Sn-EHDP (Diphosphonate), 18F, and Skeletal Radiography

Skeletal scintigraphy employing a new technetium-labeled diphosphonate compound (99mTc-Sn-EHDP) was compared with fluorine-18 bone scanning and radiographic skeletal survey to determine its ability to detect metastatic lesions. Fluorine-18 scanning revealed only 56% of the lesions seen with 99mTc-Sn-EHDP while the latter detected all lesions seen with fluorine-18 scanning. In the 10 patients studied, only 1 of 60 metastases was missed with 99mTc-Sn-EHDP, while skeletal radiography failed to visualize 43 of the 60 lesions.

Quantitative External Counting Techniques Enabling Improved Diagnostic and Therapeutic Decisions in Patients with Well-Differentiated Thyroid Cancer

A quantitative technique is described which allows the physician to predict more accurately whether a recurrent or metastatic well-differentiated thyroid carcinoma is amenable to radioiodine-131 therapy or is better treated by other means. A calibrated uptake probe and scaler system is used to obtain conjugate view (i.e., diametrically opposed) counting rates for both the whole body and for any areas of abnormal uptake (lesion) at 24,48 annd 72 hours following the administration of 2 mCi 131l. Quantitative calculations accounting for patient attenuation, lesion size and geometrical factors then provide a determination of the lesion uptake as well as the effective half-life of 131l in the lesion. The radiation dose which would be delivered to the lesion by a given therapeutic amount of 131l may then be calculated to help determine the desirability of 131l treatment. The results of patient studies indicate the potential benefit of such quantitative evaluation.

Myocardial perfusion imaging with 99mTc-DMPE in man

Technetium-99m DMPE (99mTc-DMPE) is a newly synthesized myocardial perfusion imaging agent that shows intense myocardial accumulation in the dog. In the present study, dosimetry and potential clinical usefulness of this agent were assessed in four human subjects. Absorbed radiation doses were low, with the highest doses consisting of 200 mrad/mCi (54 μGy/MBq) to the gallbladder and 160 mrad/mCi (43 μGy/MBq) to the liver. No evidence of clinical toxicity was found. Technetium-99m DMPE did image the myocardium, but the ratio of target to nontarget activity was less favorable than that observed in the dog. Intense hepatic 99mTc-DMPE activity interfered with clinical imaging of the cardiac apex in two of the four subjects. We conclude that the prototype radiopharmaceutical, 99mTc-DMPE, is capable of myocardial perfusion imaging in man but the planar myocardial images produced are of inferior quality compared with 201Tl myocardial images. Further work is justified to develop related compounds to overcome the clinical limitations described.

Myocardial scintigraphy with 99mTc-tris-DMPE in man

Cardiac scintigraphy was performed in six patients with a documented previous myocardial infarction, in one patient with mitral regurgitation, and in four healthy volunteers following administration of 99mTc-tris-DMPE. An intense early blood pool phase permitted gated blood pool scintigraphy and left ventricular ejection fraction calculation. A myocardial phase 12–14 h later permitted myocardial perfusion imaging. The rest myocardial perfusion image quality with 99mTc-tris-DMPE appeared to be superior to the resting image quality obtained with 99mTc-dichloro-DMPE but was inferior to the resting image quality obtained with 201Tl.

67Ga as a Diagnostic Agent for the Detection of Head and Neck Tumors and Lymphoma

The ability of 67Ga to detect clinically suspected head and neck tumors and lymphoma was evaluated. The radionuclide findings correlated with the pathological findings 65% of the time in tumors of the head and neck and were 87% accurate in lymphoma. Although the sensitivity of 67Ga testing was less in squamous-cell carcinoma of the head and neck than in lymphoma, specificity was comparable. Areas of normal 67Ga uptake in the salivary glands and upper mediastinum may obscure neoplasms in these areas. 67Ga added nothing to the staging of carcinoma of the head and neck but was of value in detecting intraabdominal lymphoma in patients in whom lymphangiography was contraindicated.

Radiation-Associated Carcinoma of the Salivary Glands a Controlled Study

Five hundred fifty-four persons were evaluated who had received external radiation therapy for benign diseases of the head and neck in childhood and whose salivary glands were presumably included in the radiation field. A significant excess of salivary gland cancers were noted when they were compared to 958 nonirradiated control subjects.

RADIATION EXPOSURE FROM RADIOIODINE COMPOUNDS IN PEDIATRICS.

The increasing use of radionuclides in diagnostic procedures and the importance of minimizing radiation exposure to infants and children necessitate accurate and detailed information concerning the doses sustained during these procedures. Although abundant data are available for dosages to adults (1.1, 35, 36) only an occasional reference is found to those received by children of various ages (12). Furthermore, much of the available information deals with exposure to the in-organic form of the radionuclide, while today many of the administered radionuclides are “tagged” to various organic molecules. Since these tagged substances are not handled by the body in the same manner as the inorganic compound, greater or less radiation exposure may result. This situation is particularly pertinent in the case of radioiodine which, because of its abundance, ease of detection, and chemical properties, has been incorporated as a tag for many organic compounds. Table III records the average whole-body radiation doses r...