This dataset comprises raw tree-ring series (ring widths) measured with CooRecorder (Cybis Elektronik & Data AB) from 15 X-ray computed tomography (CT) images obtained at the FleXray Laboratory of the Centrum Wiskunde & Informatica in Amsterdam from the oak ( Quercus sp.) back panel of the Cadmus sawing dragon's teeth painting (Rijksmuseum http://hdl.handle.net/10934/RM0001.COLLECT.5320). The CT images have been uploaded into Zenodo as three separate datasets: Dataset1: 10.5281/zenodo.4334010 Dataset2: 10.5281/zenodo.4336495 Dataset3: 10.5281/zenodo.4338421 Besides the individual tree-ring series obtained from each image, the average curve resulting from merging them has also been included in this dataset (keycode Cadmus). It covers the span 1380-1548. For more information refer to the published article DOI 10.1371/journal.pone.0255792 . ... : This dataset was produced within the Wood for Goods project funded by the Dutch Research Council (Nederlandse organisatie voor wetenschappelijk onderzoek), project number 016.Veni.195.502. ...