X-rays are one of the most useful and unique tools to examine patients, but how exactly do X-rays work to create images of inside our bodies? A new video by TED-Ed explains the process in detail, and it turns out X-ray imaging is a lot more simple than we thought.

It all starts with the X-rays themselves, which are beams of electromagnetic radiation that have higher energy quantities than visible light. Because X-rays have this high degree of energy, they are able to penetrate many different types of matter, which becomes very useful when examining the inside of the human body. When X-rays pass through matter, they collide and interact with electrons within that substance. Sometimes the electrons will absorb the energy of the X-rays, but often that energy will become scattered.

What’s key in the making of an X-ray image is how frequently X-rays can interact with electrons and transfer energy. In matter that is dense, collisions of X-rays with electrons are more likely. Collisions are also more likely with elements that have higher atomic numbers, because they have more electrons for the X-rays to interact with. Human bone is mostly made of calcium, an element with a high atomic number, allowing a high frequency of collisions with electrons as the X-ray passes through. As the rest of human tissue tends to consist of elements like hydrogen, carbon, and oxygen, which have low atomic numbers, X-rays pass through these components more easily. What results is a 2-dimensional image detailing the bones of the human body.

Traditional X-ray images do have their setbacks; because X-rays must pass through multiple different tissues when going through the body, the film that results reflects all of those interactions. The image is thus not very detailed. For instance, if a tumor is detected, doctors may be able to see where it is in your body, but not its depth, or shape.

For this, doctors will use Spiral CT scans. A CT scan, or a computed tomography scan, is a more advanced technology that utilizes X-rays by sending them through a cone to an array of detectors. Usually, this cone of X-rays will be moved around and up and down the patient, so a full, in-depth image may be taken. CT scans are so detailed, they allow doctors to see intricate images of tumors, blood clots, and infections. CT scans can even detect heart disease in mummies that have been buried over thousands of years ago.

To find out more about this wondrous innovation in medical technology, watch the video above.