<![CDATA[X-ray technologies are essential to modern diagnosis and treatment, but their biological effects depend on dose, dose rate, exposure duration, irradiated volume, age, and clinical context. This systematic review synthesized evidence on the cellular, organ-specific, reproductive, carcinogenic, and occupational consequences of high-dose and repeated X-ray exposure. PubMed, Scopus, Web of Science, and Google Scholar were searched, together with reference lists and organizational reports. Of 1,690 records identified, 92 studies met the eligibility criteria for synthesis, and 28 provided comparable numerical data. X-rays injured cells through direct DNA ionization and indirect reactive-oxygen-species generation, producing strand breaks, chromosomal instability, senescence, apoptosis, or necrosis, with tissue injury varying by organ and exposure pattern. Bone marrow and gastrointestinal epithelium were most vulnerable to whole-body exposure, while skin and lens damage related more to localized or cumulative doses. Gonadal and fetal irradiation was linked to reproductive and developmental effects, although diagnostic imaging carried far lower risk than therapeutic or accidental exposure. Repeated CT examinations, especially in younger patients, were associated with a small increase in long-term cancer probability, while radiotherapy carried added risks of tissue injury and second primary malignancy. Occupational exposure arose mainly from patient-scattered radiation during fluoroscopically guided procedures. The findings support careful justification, dose optimization, personal monitoring, staff training, and risk communication to preserve the benefits of X-rays while reducing avoidable harm.]]>
