Primary radiation damage in bone evolves via collagen destruction by photoelectrons and secondary emission self-absorption

Abstract

X-rays are invaluable for imaging and sterilization of bones, yet the resulting ionization and primary radiation damage mechanisms are poorly understood. Here we monitor in-situ collagen backbone degradation in dry bones using second-harmonic-generation and X-ray diffraction. Collagen breaks down by cascades of photon-electron excitations, enhanced by the presence of mineral nanoparticles. We observe protein disintegration with increasing exposure, detected as residual strain relaxation in pre-stressed apatite nanocrystals. Damage rapidly grows from the onset of irradiation, suggesting that there is no minimal ‘safe’ dose that bone collagen can sustain. Ionization of calcium and phosphorous in the nanocrystals yields fluorescence and high energy electrons giving rise to structural damage that spreads beyond regions directly illuminated by the incident radiation. Our findings highlight photoelectrons as major agents of damage to bone collagen with implications to all situations where bones are irradiated by hard X-rays and in particular for small-beam mineralized collagen fiber investigations.

C-C Motif Chemokine Ligand 5 (CCL5) Promotes Irradiation-Evoked Osteoclastogenesis

“…Of these, IR, one of the three major means of tumor treatment at present, achieves good tumor therapeutic efficacy; however, it can also lead to imbalances in skeletal reconstruction in the targeted radiation area and even in distant unirradiated areas [6]. In addition, IR would also induce a disruption of the bone microenvironment through the disintegration of the bone matrix and the release of active factors, ultimately increasing the risk of bone metastasis [7][8][9][10][11][12][13].…”