Dr Amit Chakraborty, Jan 2023
Are x–rays safe?
X–ray is a part of the electromagnetic spectrum. Visible light, infrared, ultraviolet, gamma rays etc are some of the other components of the electromagnetic spectrum.
X–ray beams are more energetic than light waves or ultraviolet rays. They can penetrate the human skin and flesh and are usually reflected by mineralised material. This is the reason why x–rays are reflected by bones, and thus, bones show up on an x–ray.
That’s all well and good, what’s the worry?
Well, the x–ray forms part of the ionising radiation spectrum. When x–rays enter the human body, they have and ionising effect on the human tissue. Excessive exposure to this ionising effect causes breakdown of the various cellular systems inside the human body. This causes cells to malfunction. In very high doses, radiation can be rapidly fatal. The effects of radiation
are usually irreversible. In prolonged moderate–dose exposure, radiation can lead to abnormal growth of the human tissue which could result in the development of cancer.
Not all radiation come from an x–ray generating machine. There is naturally occurring radiation in our environment. Cosmic rays penetrate the earth’s atmosphere and reach the surface. There is radiation that is absorbed by various minerals in the soil which, in turn, emit that radiation back. As we climb higher in the atmosphere during a high altitude flight, we receive additional radiation dose. This means that by simply living our life, we are
exposed to low levels of radiation almost every day.
Annual dose limits on radiation
The international experts have agreed on an annual dose limit of radiation received by an individual which is thought to be non–harmful. This dose is set at 20 mSv (millisieverts). Up to this dose, our human body is able to cope with the minuscule damage that radiation causes. Our body is able to repair the damaged cells. Usually, no harmful effects are felt below with this radiation dose.
What about radiation exposure during imaging?
CT scanners emit higher radiation dose although the amount received by an individual is below what is considered harmful. However, repeated exposure to CT scans may be harmful.
Not all CT scanners are created equal. The older, earlier generation scanners are less advanced, and therefore, emit more radiation. The new generation scanners are vastly superior. Instead of using higher doses of radiation to produce better quality images, the computers in these scanners use sophisticated software algorithms to produce better quality images whilst keeping the radiation dose minimal. Additionally, several new scanners have employ additional x–ray beam filtering technology which reduces unnecessary dose received by the patient.
The radiation dose received by an individual patient whilst undergoing a CT scan may greatly vary due to the parameters set by the operator of the machine. The scanning protocol used by the operator also has a role to play in the final dose received by the patient.
The above variables mean that the radiation dose received from a newer CT machine at the hands of an experienced operator who follows a protocol determined by a skilled and conscientious radiologist may be significantly lower than an older generation machine. The final radiation dose received by a patient could be further lowered if a radiologist prescribes an imaging modality that does not involve radiation, such as ultrasound or MRI examinations.
This means that from a radiation exposure point of view, one imaging centre can be significantly safer than the other.
Are there any guidelines?
Ultrasound examination performed at the hands of a skilled operator and under the guidance of an experienced radiologist can often detect problems for which CT scans are used by others.
If you require a medical imaging examination that uses x–rays, please rest assured that the Australian Government has specific guidelines in place and imaging centres are required to follow them strictly. These guidelines ensure a safe and ‘as low as possible’ radiation exposure whilst maximising the diagnostic accuracy of the requested examination.
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