Whole blood hafnium concentrations for each patient following NBTXR3 injection. Quantification of NBTXR3 in the blood was performed to evaluate passage into the systemic circulation. The hafnium component of NBTXR3 was quantified through inductively coupled plasma mass spectrometry (ICP-MS). Whole blood samples were collected on Day 1: before injection, immediately after the injection start, at the end of the injection, 5, 10, 15, 60, 120 and 240 minutes after completion of the injection; and on Day 2. Three additional blood samples were collected during radiotherapy, between the 11th and 20th radiotherapy sessions. One blood sample was also collected prior to surgery.