X-rays do affect muscle tissue, but the impact depends largely on the dose and duration of exposure. Muscle tissue itself is not the primary target of X-rays in medical imaging because muscles are less dense and absorb fewer X-rays compared to bones. However, when muscle tissue is exposed to radiation, especially at higher doses like those used in radiation therapy or accidental exposure, it can suffer cellular damage that impairs its function and ability to regenerate.
Muscle tissue contains muscle precursor cells (MPCs), which are essential for muscle repair and growth. Research shows that radiation can damage these precursor cells, reducing their ability to proliferate and regenerate muscle fibers effectively. This damage can lead to weakened muscle tissue and impaired healing after injury. The radiation alters key cellular pathways involved in muscle repair, blood vessel formation (angiogenesis), and oxidative stress response, which are critical for maintaining healthy muscle function.
At the molecular level, radiation exposure changes the expression of microRNAs—small molecules that regulate gene activity—in muscle cells. These changes disrupt signaling pathways such as VEGF (vascular endothelial growth factor), PI3K-Akt, and FoxO, which are involved in cell survival, growth, and stress resistance. As a result, the muscle’s ability to recover from damage and maintain its structure is compromised.
In typical diagnostic X-ray procedures, the radiation dose is very low and brief, so the effect on muscle tissue is minimal and generally not harmful. The X-rays pass through muscles with little absorption, which is why muscles appear less distinct on X-ray images compared to bones. However, repeated or high-dose exposures, such as those in radiation therapy for cancer or accidental radiation exposure, can cause significant muscle tissue damage.
Muscle damage from radiation can manifest as reduced muscle mass, weakness, and impaired function. This is particularly important in clinical contexts where radiation is used therapeutically, as it necessitates strategies to protect or restore muscle tissue. Experimental therapies involving extracellular vesicles enriched with microRNAs show promise in mitigating radiation-induced muscle injury by promoting muscle precursor cell function and angiogenesis.
In summary, while routine diagnostic X-rays have negligible effects on muscle tissue, higher doses of radiation can impair muscle precursor cells, disrupt muscle repair mechanisms, and lead to muscle weakness and reduced regenerative capacity. Understanding these effects is crucial for managing radiation exposure in medical treatments and emergencies.