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X-ray radiation is a kind of energy, one that Radiation Oncologist Andrew Howard uses to help people recover from cancer.
Have you ever had an X-ray? What did it do for you?
“We’re surrounded by radiation all the time by living on Earth and in this universe,” says Radiation Oncologist Andrew Howard. It comes from stars, from radioactive elements like radium, which was discovered by Marie Curie in the end of the 19th century, and from other sources.
X-rays are one type of electromagnetic radiation. They can be used to see whether you broke a bone or have a cavity in a tooth. They also help Howard and other radiation oncologists kill cancer cells.
Howard explained to Math4Science that there are three ways to cure cancer: you can cut it out with surgery; you can use chemotherapy or other medications to poison it; or you can “zap it with radiation.”
If you shine X-ray radiation onto a petri dish containing cells from someone’s body, the normal (“benign”) cells will “handle it pretty well.” Most cells in your body have ways of checking their genetic material, finding any damage, and fixing that. But cancer (“malignant”) cells “lose those checkpoints and can’t repair DNA damage from radiation very well.” After being “zapped” by radiation, when they try to divide to reproduce themselves, many cancer cells die.
Radiation oncologists take advantage of this situation. In Howard’s words, “you can take tissue with a tumor embedded in it and shine radiation at it. Normal cells won’t handle it perfectly but they will more or less be ok.” The cancer cells in the tumor will die.
This works especially well when you combine radiation with other cancer treatments, like medication, chemotherapy, or surgery. After surgery, Howard can use radiation to kill any cancer cells that were left behind in the area near the tumor. And many anti-cancer medications, including chemotherapy, have been found to be “radiation sensitizers – they make the cancer cells more likely to melt away like butter.”
The way all this happens is that a radiation therapy machine sends electrons towards a tumor that’s not too deep in a person’s body (perhaps on their skin). Or it might first hurl those electrons towards a piece of heavy metal, often tungsten. Tungsten is the metal with the highest melting point (6,170 degrees Fahrenheit / 3,410 degrees Celsius!). “When the electrons slam into the tungsten, X-rays spray out. We use a special aperature [opening] to shape and direct the x-rays towards the patient’s tumor.” The X-rays work better on tumors deeper inside a person’s body.
When Andrew was growing up in Wisconsin, he admired a friend of his parents who was a radiologist. And he noticed that when a person asks a child what they want to be when they grow up and they answer “a doctor,” the child usually gets a very positive reaction from the person who asked.
Still, Andrew wanted to be an actor. He tried out for his high school’s musical as a sophomore. “To my shock, I got in, and I loved it!” He especially enjoyed “the friends I made and the silly adventures we had together.” But when he was in college, it was difficult to get into the acting classes at the University of Wisconsin.
Because he had traveled and read a book called Guns, Germs, and Steel, by Jared Diamond, Howard was curious about what made certain countries wealthier and others less wealthy. So he studied economics. At the same time, perhaps thinking of that family friend, he took his father’s advice and chose the courses necessary for applying to medical school.
After college, Howard ended up going to the Medical College of Wisconsin, in Milwaukee. He made good friends there (like he did acting!) and says that “being a medical student was so much more fun than being a doctor,” because he had less responsibility and got to learn so much. “I just loved it.” When it came time to choose an area of specialization, he chose radiation oncology.
Math helps radiation oncologists zap cancer cells. And if the math gets “at all hairy,” oncologists work with medical physicists to solve problems. Together, they explore which angles will help them target the right cells and avoid hitting normal cells nearby. By beaming the X-rays from different spots, at many different angles, Howard and his colleagues can use smaller doses at each angle, hitting normal cells at those smaller doses and aiming a total higher dose on the cancer cells. This method is called VMAT – Volumetric Modulated Arc Therapy.
They also have a formula that helps them plan how much radiation they will give a patient, for how long, over how many days and weeks.
You’ve learned about fractions – pieces of things or of numbers – in math class. Radiation oncologists practice something called “fractionation.” A patient who will receive radiation treatments gets a total dose of radiation. That dose does not happen all at once. The oncologist works with medical physicists to decide how to kill as many malignant cells as possible while protecting the patient’s normal cells.
Malignant cells are more likely to be affected by the radiation when they’re in certain parts of their life cycles, for instance when they have more oxygen in them. So it’s important to try to catch them at times when this is true. Fractionation, dividing up the total dose of radiation into smaller doses given on different days, helps with this. It also gives the healthy cells time to repair their DNA between doses. The doses, also called “fractions,” are measured in Gy, which stands for “Gray.” One Gy means that one joule of radiation is absorbed per kilogram.
If a patient needs 60 Gray in all, they might receive it in 20 fractions. How many Gray would that mean they would receive in each fraction or dose? And if they’re seeing their radiation oncologist Monday through Friday, how many weeks will they come in for fractions?
For a while, Howard had the opportunity to work at the Jesse Brown VA Medical Center, in Illinois. He particularly enjoyed getting to know the veterans he helped, including a patient with prostate cancer. That man told Howard about skydiving while in the military and also about scuba diving. “He was full of crazy stories” set high in the air and deep in the water, where he sometimes encountered sharks.
Howard also tells stories and once wrote a novel. He didn’t publish that but has shared stories that will help his patients better understand cancer and its treatment. A few years back, he took a drawing class at the Hyde Park Art Center. Inspired by conversations he had with his wife and by the picture books he read to his daughters when they were young, he created a comic series about breast cancer. Cancer Ninja!: A Doctor Fighting Cancer, One Drawing at a Time was a blog he wrote (and drew!) in 2015.
People and their biological systems communicate in many ways. “All we are, in a funny way, is information,” says Howard.
We are a collection of random proteins, fats, and carbohydrates from the food we eat, arranged by the DNA in our bodies. Sometimes that information goes wrong and a cell divides in a crazy way. How weird is it that we can shine these invisible X-rays…. It can affect the information in these cells, their DNA, how they survive. And we can hopefully save patients’ lives.
Study up on your fractions and on angles and other math and add in some story-telling and drawing … and one day you, too, can help people facing diseases like cancer.
