An image reading device includes plural light sources that irradiate an image reading target with light at different angles; and a switching mechanism that sequentially switches the light incident to the image reading target from the plural light sources during an image reading operation on the image reading target.

A device is disclosed for determining an access flow rate of a patient when connected to a blood treatment machine. The device performs a measurement phase in which the blood treatment machine is caused to operate in first and second operating states, where the second operating state at least differs from the first operating state by a change of flow direction of blood or treatment fluid through a dialyzer of the blood treatment machine. Based on sensor values representing a fluid property of the treatment fluid in the first and second operating states, the device computes a measurement value of comparison parameter (e.g. a ratio or a difference) that compares treatment efficiency in the first operating state to treatment efficiency in the second operating state, and determines, based on the measurement value, an estimated value of the access flow rate.