Agripada police said Dr Siddhant Shah was arrested yesterday after the family of the 32-year-old victim, Rajesh Maru, told them that the radiologist was also present when the accident occurred.
Shah was charged with dereliction of duty, police said, adding he was released on bail.
Shah's was the fourth arrest in the case.
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Earlier, police had arrested three hospital staffers- Dr Saurabh Lanjekar, ward boy Vitthal Chavan and attendant Sunita Surve- for negligence causing death.
Maru had accompanied a relative to the hospital for an MRI examination. When he entered the room carrying a liquid oxygen cylinder, the strong magnetic field got activated, pulling him violently towards the machine.
The oxygen cylinder burst on impact and he died after inhaling copious quantities of the gas.
Metal objects are not allowed inside rooms having MRI machines.