Objective To summarize the experience for diagnosis and treatment of parathyroid carcinoma(PTC).Methods The clinical data of 6 patients with PTC were retrospectively analyzed.Results Five patients complained of primary hyperparathyroidism,3 patients had manifestations of palpable neck mass,4 patients were admitted for hypercalcemia with calcium level of(3.62?0.56)mmol/L,and in 4 patients the parathyroid hormone(PTH) level was higher than two fold of the normal upper limit.Frozen section histopathology established diagnosis in 3 patients,routine histopathology combined with immunohistochemistry established the diagnosis in 2 patients,and routine histopathology combined with immunohistochemistry and clinical data established the diagnosis in 1 patient.Parathyroidectomy and ipsilateral subtotal thyroidectomy was performed in 5 patients,who were followed up for 1-5 years,recurrence in 1 patient 3 years after operation;tumor resection alone was performed in 1 patient with parathyroid cancer complicated with multiple bone metastasis,and the patient died of MOF 16 days postoperation.Conclusions The diagnosis of PTC is difficult before operation.Routine blood examinations,blood PTH,99mTc-MIBI scintigraphy,ultrasonography,CT,observation of specimen,and frozen section histopathology during operation are helpful to diagnosis.The surgical procedure of choice is parathyroidectomy and ipsilateral subtotal thyroidectomy.

Compared with conventional radiotherapy fields, small field has unique dosimetry characteristics such as high dose gradient, charged particle imbalance, and dose effect caused by source occlusion. These characteristics increase the difficulty of dose measurement and thus the uncertainty of clinical dose measurement, far exceeding the requirement of < 5% measurement error in ICRU 24 report. In recent years, with the development of new radiotherapy technologies, the minimum radiotherapy field can reach the millimeter level, and the single irradiation dose of hypofractionated radiotherapy can exceed 6 Gy. The larger dose gradient at the edge of radiotherapy field requires higher accuracy of dose measurement, and accurate small field dosimetry technologies have gradually become a research hotspot in the field of precision radiotherapy. In order to ensure the high accuracy of measurement, this paper reviews the research on small field dosimetry worldwide, and summarizes the key points of small field dosimetry. In this paper, the characteristics of small field dosimetry are introduced, and the current small field dosimetry technologies and optimization methods are summarized, including the optimization of detector selection and detector sensitive volume. The field output correction factor technologies are analyzed. In view of the difficulty in small field dosimetry, this paper provides suggestions on dosimetry based on clinical needs and the characteristics of medical linear accelerators. Our suggestions provide a scientific reference for small field dosimetry in clinical practice in radiotherapy institutions, and facilitate the development of radiotherapy dose verification.