Radiation around your pelvic area can destroy sperm cells and lower sperm counts and testosterone levels, leading to infertility. It may also damage blood vessels or nerves in the area, which can cause erectile dysfunction or a dry orgasm if the prostate was damaged. Radiation therapy to your brain may also damage the pituitary gland, reducing testosterone and sperm production and affecting fertility.
Whether you regain your fertility following radiation therapy depends on the dose of radiation, the area that received it, and how well your reproductive organs were shielded from the radiation. Lower doses may not affect fertility, while higher doses can cause persistent or permanent azoospermia. Sperm production may restart 9 to 18 months after receiving lower doses of radiation, or over 5 years for higher doses.