Tag: radioactive

Posted in Psychology & Medicine

Viscera: Thyroid

Posted on by Jinavie

(Learn more about the organs of the human bodies in other posts in the Viscera series here: https://jineralknowledge.com/tag/viscera/?order=asc)

There lies a small, butterfly-shaped organ called the thyroid gland in your neck, just in front of your windpipe above the clavicles. The thyroid may not seem important given its small size, but it has the important function of controlling the body’s rate of metabolism. Metabolism is a group of chemical reactions your body relies on to function as a lifeform. Chemicals such as glucose are processed by various enzymes – biological catalysts that encourage chemical reactions – and converted in to fuel (such as ATP) that cells can use for numerous bodily functions. The thyroid produces the thyroid hormones, thyroxine and triiodothyronine, to fine-tune the rate at which these reactions occur.

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To see the function of the thyroid gland, we can look at two types of diseases: hyperthyroidism and hypothyroidism.

In hyperthyroidism, the thyroid is overactive and produces too much thyroxine. This causes the body’s metabolic rate to speed up, causing increased heart rate, weight loss, sweating, tremors and sensitivity to heat. Depending on the cause, the eyes may be affected as well, causing them to protrude forwards, giving a rather scary appearance. This disease may happen for various reasons, but the most common cause is Grave’s disease, where antibodies lock on to receptors in the thyroid to stimulate thyroxine production, much like a stuck key on a keyboard.

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Hypothyroidism is the direct opposite syndrome caused by an underactive thyroid. This causes a reduction in metabolic rate, leading to weight gain, tiredness (due to lack of energy), slow heart rate and cold intolerance. It can also be caused by an autoimmune disorder (called Hashimoto’s thyroiditis), or more commonly due to iodine deficiency, as the thyroid uses up iodine to produce thyroid hormones.

Both diseases may cause the thyroid to grow to an abnormal size, which is called goitre (seen as a large neck lump). The treatment is usually adjusting the total level of thyroid hormone produced by removing parts of or all of the thyroid, or replacing thyroid hormone if needed via medication.

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Because the thyroid uses iodine to make hormones, thyroid diseases such as thyroid cancer can be treated using an interesting method. If you inject radioactive iodine into the patient, it will make its way to the thyroid gland, which actively collects the iodine from the blood. Overactive thyroid tissue (such as in Grave’s or thyroid cancer) take up iodine at a faster rate. The iodine then delivers a focussed dose of radiation to the thyroid, leaving the other tissues in the body unharmed. This method is used for both first-line treatment of hyperthyroidism and to clean-up remaining cancer cells after thyroid surgery.

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Posted in Science & Nature

Banana Equivalent Dose

Posted on by Jinavie

No form of energy has been more feared or creatively explored in science fiction (e.g. Godzilla) as radiation, yet the layman tends to know little about the actual properties and effects of radiation. The word “radiation” is commonly associated with things like Chernobyl, mutation and cancer. However, most people only know that radiation is “bad” while not knowing exactly how and why it is dangerous. Radiation is essentially high-frequency light which can deliver a large dose of energy (just like how microwaves cook food and sunlight can burn paper when focussed through a magnifying glass). When this high-dose of energy passes through living organisms, it damages the DNA in cells, potentially causing irreparable damage. This can lead to mutation and disruption of cell division (which can lead to cancer) or cell death (which is why radiation is ironically used to kill cancer cells).

The more technical question is “how much” radiation is harmful. For example, how much more dangerous was the Chernobyl incident compared to an x-ray? Like many other things in science, radiation is measured using an internationally universal unit called the Sievert (Sv). The radiation received from standing next to the Chernobyl reactor core after meltdown was 50Sv, while a chest x-ray is 20μSv (1000μSv = 1mSv, 1000mSv = 1Sv). Therefore, the Chernobyl incident could be considered to be as strong as 2.5 million chest x-rays. Although there is great variation, it is considered that a dose of 400mSv can cause symptoms of radiation poisoning, while 4~8Sv of radiation will lead to certain death.

Fascinatingly, radiation is not an uncommon thing. Radiation is all around us, with an average person receiving about 10μSv of background radiation per day just by living on Earth. Ergo, two days of walking around gives you the same amount of radiation as a single chest x-ray. A CT scan gives out a significantly greater dose of radiation at about 7mSv (approximately 350 x-rays or a year’s worth of background radiation).

However, the Sievert is a unit that is difficult to understand. Thus, some scientists devised a clever, humorous equivalent unit called the banana equivalent dose (BED). Bananas contain a certain amount of radioactive isotopes (radioactive potassium), making them technically radioactive. A banana contains 0.1μSv of radiation. Ergo, a chest x-ray is the equivalent to eating 200 bananas, a CT scan is 70000 bananas, while the Chernobyl incident gave people nearby a dose of roughly 500 million bananas.

The banana equivalent dose is a rather useful (and hilarious) way of comparing the danger of radiation from different sources. The next time you go to hospital for an x-ray, just picture 200 bananas being shot through your chest.