The problem is cancer. Cancer is the second leading cause of death in the world and my interest in the subject is simple. My mother is the most resilient person I have ever met. Any time I need any kind of inspiration, I need only to think of her. When she was eighteen she was diagnosed with Hodgkins disease. The doctors gave her a less than thirty percent chance of living. Since then she has had cancer three other times. Breast cancer twice in 85 and 90, and most recently, colon cancer two summers ago. She has had many different treatments including chemo and radiation therapy as well as surgery to remove lumps in both breasts and her colon.
What is cancer? There are more than 100 different types of cancer. It occurs when cells become abnormal and divide without control or order. Normally, cells divide in an orderly way to produce more cells only when the body needs them. If cells keep dividing when new cells are not needed, a mass of tissue forms. This mass of extra tissue, called a growth or tumor, can be benign or malignant. (National Institute of Health)
Benign tumors are not cancer. They do not invade nearby tissue or spread to other parts of the body. Benign tumors usually can be removed and are seldom a threat to life. Malignant tumors are cancer. They can invade and damage nearby tissues and organs. Cancer can also break away from a malignant tumor and enter the bloodstream and lymphatic system.
Through the lymphatic system is one of cancers best modes of transport for spreading to form new tumors in other parts of the body. The spread of cancer is called metastasis. Malignant tumors must be treated or will be fatal.
There are many treatments for cancer. Among these are radiation, chemotherapy, surgery and the rapidly growing field of genetic therapy. It was discovered that when radioactive waves were directed on human cells, the cells would be destroyed. The idea of using this technology on cancer was a good one but was unsuccessful at first due to the damage caused to surrounding tissues. Then the analogy drawn from a simple story gave insight on how to focus the rays on the cancer and not harm the surrounding tissues and organs. The story goes like this.
A small country was ruled from a strong fortress by a dictator. The fortress was situated in the middle of the country, surrounded by farms and villages. Many roads led to the fortress through the countryside. A rebel general vowed to capture the fortress. The general knew that an attack by his entire army would capture the fortress. He gathered his army at the head of one of the roads, ready to launch a full-scale direct attack. However, the general then learned that the dictator had planted mines on each of the roads. The mines were set so that small bodies of men could pass over them safely, since the dictator needed to move his troops and workers to and from the fortress. However, any large force would detonate the mines. Not only would this blow up the road, but it would also destroy many neighboring villages. It therefore seemed impossible to capture the fortress. However, the general devised a simple plan.
He divided his army into small groups and dispatched each group to the head of a different road. When all were ready he gave the signal and each group marched down a different road. Each group continued down its road to the fortress so that the entire army arrived together at the fortress at the same time. In this way, the general was able to capture the fortress and overthrow the dictator.
This simple story was the basis for intensity modulated radiotherapy (IMRT). This is a technique used to treat cancerous tumors on which a removal operation could not be performed. Interesting dose distributions generated by IMRT allow a better sparing of normal tissues with decreased acute and late toxicity, and offer a window for further dose escalations. (De Neve W; Claus F; Van Houtte P; Derycke S; De Wagter C) In order to get a radiation beam of high enough intensity to hit