The Therac-25 and Its Accident Investigation - Case Study Example

The Therac-25 falls into a class of machines referred to as Medical linear accelerators (linacs). They use the principal of accelerating electrons so as to create high energy beams that can be used to destroy any cancerous cells without affecting the other surrounding non- cancerous tissues. For shallow tissues, accelerated electrons were enough to treat them but for the deeper ones, the electrons beams have to be converted into X-ray photons. Defects that lead to the accidents The machine consisted of hardware and software that helped the machine run.

The software also monitored the functionality status of the machine and turning on the beam. It was also responsible for turning off the beam and detecting any malfunctions. The software was responsible for running most of the machine functions in conjunction with the hardware. This therefore means that any small bug in the software will lead to malfunctioning of the machine. The software for running the Therac-25 was not extensively tested before it was deployed for use. This was due failure to follow proper system development and implementation practices.

Also the programmer didn’t provide enough documentation about the machine and software errors that could guide operators on when there is malfunction and what to do. The operators therefore were in the dark most of the time despite the machine displaying various error messages as they thought was normal. The hardware that was used to measure the dosage always provided a wrong dosage reading when it as overloaded. Instead of providing a high reading instead it displayed a low reading when it was actually so high.

Another defect was how the machine was made to be operated. The machine was made that the operator and the patient were to be in separate rooms to minimize effect of radiation to the operator. Therefore in case there was any overdose and the patient complaining, the operator could not hear it. Also the operator could not ascertain whether the patient was in the right position every time. This was risky and costly assumptions that lead to the occurrence of the accidents. Therefore, software errors and design defects were major causes of the accidents.

Collective responsibility The accidents happened over a 19-month long period and most certainly someone had to be responsible for allowing such life threatening accidents to occur for that period without doing anything. Many parties were responsible including the manufacturer, the operators and technicians and the federal government. As all the accidents happened from the first to the sixth one, the manufacturer seemed not to care. Only lame excuses were given. For example after the second accident, the manufacturer claimed it was an electrical failure even when an independent electrical firm had ruled out any possibility of the cause of the accident being an electrical fault.

It was only after the sixth accident that there seemed to be any action form the manufacturer. The question one would ask is why did the manufacture remain quiet for that long and let the machines to be in use when they were actually causing accidents. The federal government also had their share of the blame by allowing the AECL Company to continue with its operations despite its machines causing those fatal accidents. It was clear that the manufacturer was not following proper system development and implementation methods but yet was allowed to operate.

Operators and techn