Page 20 - EngineerIt February 2021

MEASUREMENT

Hospital radiation monitoring,

incorporation with BMS not

the best option

By Gary Bradshaw, director at remote monitoring specialist Omniflex

Many hospitals combine their radiation monitoring systems with their building management

systems (BMS). While this is an easy choice to make, it’s not necessarily the best one.
So, why should hospitals move away from fragmented setups in favour of independent
radiation and critical alarm monitoring?

nyone who has ever had a positron emission tomography (PET) scan will be familiar officer shall inspect this record at least
with the process of receiving an injection filled with a tracer. This radioactive once a month, noting findings and any
Asubstance allows the scanner to create a detailed 3D scan of the body to help doctors unusual activity”.
detect early signs of cancer, heart disease and brain disorders, amongst other illnesses. To secure their sites, hospital
However, most people are probably unaware that the radioactive material that goes into managers must use monitoring and
those injections is often produced on site. Most major hospitals are home to a secure bunker safety equipment at various stages
in the basement of the facility that houses a cyclotron, a type of particle accelerator used to throughout the facility. This can range
produce the radioactive isotopes that make up the tracer. The short two-hour half-life of the from alpha, beta and gamma radiation
material means that it’s far quicker, safer and more practical than transporting it in. monitors in the cyclotron area, in the hot
cells and in the ventilation stack, to door
The PET scan interlocking safety systems that prevent
After the radioactive isotope has been created, a separate hot cell — effectively a shielded operators being locked inside active
chamber — is used to handle the material, to refine it using further chemical processes and areas during production. Because the
dispense it into syringes as well as into other modes of delivery, such as orally or as a gas. cyclotron is typically housed below
Once inside the patient, the tracer is absorbed by the body and begins to concentrate in ground level, flood-level warning systems
cells with a higher metabolic rate, such as cancer cells. are also important.
Here, the radioactive decay of the tracer releases sub-atomic particles called positrons, This safety equipment also extends to
which interact with electrons in the body to release gamma photons. This radiation is picked the use of alarms placed outside of active
up by the surrounding PET scanner to produce a detailed 3D scan of the affected area. areas which safely alert operators of
The radiation risk to a patient from imaging tests is fairly low, about eight times higher potential problems without them having to
than the normal background radiation a person is normally exposed to in one year — and be physically present in a potentially
something that is quickly flushed from the body in a few hours. However, practitioners hazardous part of the facility. It also
must balance this risk of higher radiation exposure with their ability to use imaging to applies to patient areas, as well as areas
better treat patients. outside the hospital, to monitor air quality.

Secure the facility Fragmented monitoring
The greater risks of radioactive material come instead from the facility itself. The ongoing Monitoring and managing safety-critical
production, handling and waste management of radio-nuclides in hospitals can potentially systems is not an easy task and, in my
put staff and the environment at risk. experience, many hospitals have tried to
In South Africa, this process is policed using various regulations managed combine radiation protection and critical
predominantly by the South African Health Products Regulatory Authority (SAHPRA), an alarm systems in their building
entity of the National Department of Health. These include the Hazardous Substances Act management systems to achieve
1973, as well as the Regulations concerning the control of Electronic Products. compliance. The problem with this
Here, operators are told to assess the likely impact of the permitted activity in terms approach is that it not only adds
of the effective dose to members of the public. In part, the regulations state that “a holder complexity, it’s not always the most
of an authority shall ensure a monitoring record is kept daily and a radiation control optimal solution.

EngineerIT | February 2021 | 18