Preliminary dose estimation for the medical staff during emergency treatment of a patient with recurrent papillary thyroid cancer under Radioiodine (131I) radiotherapy

• Published in: The Journal of nuclear medicine (1978) Vol. 60
• Main Authors: Yang, Suyun, Tang, Guohua, Wei, Jinping, Wang, Hongli, Liu, Haiyan, Li, Sijin, Chi, Cuiping
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01-05-2019
• Subjects: Ablation; Cancer; Cancer therapies; Data points; Dosimeters; Drug dosages; Edema; Emergency medical services; Equivalence; Exponential functions; Exposure; Incident radiation; Iodine 131; Iodine radioisotopes; Larynx; Lead; Medical personnel; Medicine; Monitoring; Monitoring systems; Nuclear medicine; Nurses; Occupational exposure; Occupational health; Papillary thyroid cancer; Patients; Physicians; Protective clothing; Radiation; Radiation dosage; Radiation measurement; Radiation protection; Radiation therapy; Real time; Rot; Thyroid; Thyroid cancer
• ISSN: 0161-5505; 1535-5667

Objectives: The aim of the present study was to assess the radiation doses received by medical staff during the emergency treatment of a patient with recurrent papillary thyroid cancer received Radioiodine (131I) radiotherapy using a real-time radiation monitoring system, for the purpose of radiation protection of occupational exposure. Methods: A patient with recurrent papillary thyroid cancer treated with radioiodine (131I ) ablation for the second time, larynx edema occurred after administration of 131I. There were 3 nurses and 7 doctors participating the emergency treatments of the patient and none of them wore a radiation dosimeter. In order to retrospective assessment the doses received by the medical staff, a new patient undergoing the same 131I radiotherapy was selected to simulate the radiation scenario of the original case. Real-time radiation monitoring system contained 3 personal dosimeters loaded with the function of delivering data by wireless to the repeater, where the signals were magnified and sent to the hub, finally to the main unit of the system at the nurse station. One of the dosimeters was worn by the patient at the anatomic position of the sternal angle, the other two were laid at 20 cm away (the bedside cupboard) or 150cm away ( the wooden sill). Dose equivalent rate of the three dosimeters and corresponding accumulated dose equivalent were collected by the monitoring system. Data analyzing and graph making were performed with Microsoft Excel. The dose received by each medical staff was given by the sum of accumulated doses equivalent at different time intervals according to data at 20cm or at 150cm. Results: The monitoring time was 86.4hrs long after the patient was administered with 131I. Time -dose equivalent curves and –accumulated dose equivalent curves were obtained at the sites of the sterna angle, 20cm or 150cm, with average 7200 data points for each curve( as shown in Fig1, Fig2 and Fig3). And the fitted curves present exponential functions for time-dose equivalent curves, and logarithmic functions for time-accumulated dose equivalent curves. As a result, three nurses N1, N2, N3 received accumulated dose equivalent of 4μSv, 7.5μSv, and 4.8μSv; and 7 doctors , D1, D2, D3, D4, D5, D6, D7, 8.2, 0.8, 1.5, 1.5, 1.5, 0.1 and 0.1μSv, respectively. Among them, N1, N2, N3 and D1, staff of Department of Nuclear Medicine, were received relatively larger doses. Conclusions: The definitions and association of dose equivalent and effective dose were reviewed. The dose equivalent value at the 10mm depth could be considered a conservative or appropriate value for effective dose when the incident radiation present AP, ROT and ISO position under ICRU slab phantom, and the scatter radiation could contribute 2% dose equivalent to the 10mm deep site. Taking all together, under this case, we think even the doses received by medical staff were small relative to the dose limit of occupational exposure, however, personal dosimeter should be worn, and lead clothes should be prepared in the department of nuclear medicine, in order to Implementation of the principle of as low as reasonably achievable (ALARA). And this real-time monitoring system is a convenient and effective tool for radiation protection of occupational exposure for medical staff. [Key words] DTC;131I radiotherapy;real-time radiation monitoring system