The Radiation Dose Chart you posted contains information that often provides a distorted comparison of the kind of issues surrounding Chernobyl and Fukushima.
For example, dental xrays are external exposure of limited (seconds) duration after a patient approves the treatment.
Fukushima and Chernobyl do not limit dose, often result in ingestion/inhalation which irradiates bones and flesh continuously for years.
“eating a banana” is displayed on the chart, as if the harmless radiation from potassium in bananas has any comparison to radioactive Strontium, Cesium, Uranium or Plutonium released by Chernobyl and by Fukushima.
Involuntary ingestion and inhalation of radioactive wastes from Chernobyl/Fukushima incurring continuous exposure for years is displayed alongside voluntary exposure to medical xrays or naturally occurring background radiation - unfortunately, it’s an apples to oranges comparison.