Medical imaging equipment is the set of machines that make pictures of the inside of the body: X-ray machines, CT scanners, MRI scanners and ultrasound machines. Each machine measures a physical signal that passes through the body or bounces back from it. Software inside the machine turns that signal into a picture. For the world's largest scanner makers, much of that software is written in Bengaluru.
The four main kinds differ in what they measure. An X-ray machine sends X-rays through the body and measures how much reaches a detector on the other side. Bone blocks more X-rays than soft tissue, so bone shows up white. A CT scanner, or computed tomography scanner, spins an X-ray tube around the patient and builds thin slices of the body from hundreds of angles. An MRI scanner, or magnetic resonance imaging scanner, uses a strong magnet and radio waves, with no X-rays, to picture soft tissue such as the brain and the knee. An ultrasound machine sends sound waves into the body and measures the echoes.
Each machine holds several layers of software. Firmware, the software built into the hardware, controls the X-ray tube, the magnet or the probe. The console software is what the technician uses: it chooses the scan, sets the radiation dose and shows the patient's details. Image reconstruction software turns the raw measurements into pictures. The parts that make and catch the beam are the X-ray detectors and tubes. Finally, the machine sends each finished image to the hospital's PACS and imaging AI platform, in DICOM, the standard file format for medical images.
Take, for example, a diagnostic centre in Surat. A young man arrives after a motorcycle accident with a head injury. The doctor's order for a head CT reaches the scanner from the hospital EHR, so the technician does not retype his details. The technician chooses the head scan on the console. The scanner takes about 300 thin slices in under 10 seconds. Within a minute, the slices reach the platform, and an AI radiology model checks them for bleeding inside the skull.
In India, scanners are regulated twice. As medical devices, they need approval from the Central Drugs Standard Control Organisation (CDSCO). Because X-ray and CT machines give off radiation, they also need a licence from the Atomic Energy Regulatory Board (AERB). Hospital engineers test each machine's radiation output regularly with biomedical test equipment.
Software that only runs the machine is approved as part of the device. Software that gives a diagnosis on its own, such as AI that reads the scan, is regulated as software as a medical device (SaMD). The CT method is also used in factories, to look for cracks inside metal parts, in industrial CT scanning.