You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

REMNANT UPTAKE AS A POSTOPERATIVE ONCOLOGIC QUALITY INDICATOR. BACKGROUND: The purpose of this study was to examine the utility of remnant uptake on postoperative radioiodine scans as an oncologic indicator after thyroidectomy for differentiated thyroid cancer (DTC). METHODS: We conducted a retrospective review of patients undergoing total thyroidectomy for DTC and subsequent radioactive iodine (RAI) treatment. Of the eight surgeons included, three were considered high volume, performing at least 20 thyroidectomies per year. Patients with distant metastases at diagnosis or poorly differentiated variants were excluded. To control for the effect of varying RAI doses, the remnant uptake was analyzed as a ratio of the percentage uptake to the dose received (uptake to dose ratio, UDR). Multivariate logistic regression was used to determine the influence of UDR on recurrence. RESULTS: Of the 223 patients who met inclusion criteria, 21 patients (9.42%) experienced a recurrence. Those who recurred had a ten-fold higher UDR compared to those who did not recur (0.030 vs. 0.003, p = 0.001). Similarly, patients with increasing postoperative thyroglobulin measurements (0.339 vs. 0.003, p<0.001) also had significantly greater UDRs compared to those with stable thyroglobulin. The UDRs of high volume surgeons were significantly smaller than low volume surgeons (0.003 vs. 0.025, p = 0.002). When combined with other known predictors for recurrence, UDR (OR 3.71, C.I 1.05 - 13.10, p = 0.041) was significantly associated with recurrence. High volume surgeons maintained a low level of permanent complications across all UDRs whereas low volume surgeons had greater permanent complications associated with higher uptake.
{"Chemical": ["radioiodine", "iodine"]}