*Article* **Preservation of Bone Tissue Integrity with Temperature Control for In Situ SR-MicroCT Experiments**

#### **Marta Peña Fernández 1, Enrico Dall'Ara 2, Alexander P. Kao 1, Andrew J. Bodey 3, Aikaterina Karali 1, Gordon W. Blunn 4, Asa H. Barber 1,5 and Gianluca Tozzi 1,\***


Received: 28 September 2018; Accepted: 30 October 2018; Published: 1 November 2018

**Abstract:** Digital volume correlation (DVC), combined with in situ synchrotron microcomputed tomography (SR-microCT) mechanics, allows for 3D full-field strain measurement in bone at the tissue level. However, long exposures to SR radiation are known to induce bone damage, and reliable experimental protocols able to preserve tissue properties are still lacking. This study aims to propose a proof-of-concept methodology to retain bone tissue integrity, based on residual strain determination using DVC, by decreasing the environmental temperature during in situ SR-microCT testing. Compact and trabecular bone specimens underwent five consecutive full tomographic data collections either at room temperature or 0 ◦C. Lowering the temperature seemed to reduce microdamage in trabecular bone but had minimal effect on compact bone. A consistent temperature gradient was measured at each exposure period, and its prolonged effect over time may induce localised collagen denaturation and subsequent damage. DVC provided useful information on irradiation-induced microcrack initiation and propagation. Future work is necessary to apply these findings to in situ SR-microCT mechanical tests, and to establish protocols aiming to minimise the SR irradiation-induced damage of bone.

**Keywords:** bone; X-ray radiation; tissue damage; SR-microCT; digital volume correlation; temperature control
