The history of radiation and the treatment of cancer goes back to the 1890’s. The initial machines used radium or low energy X-rays and by the 1930’s million volt machines were being used. After World War II, Cobalt machines became available and by the 1960’s and 1970’s higher energy linear accelerators were being used. Once CT scans and computers were used to identify targets for radiation treatment in the 1990’s, the beam could be conformed (or modified) to better hit the tumor and avoid normal structures in three dimensions (called 3D conformal therapy.) Often 5 or 6 separate beams were used.

Later in 1990’s and early 2000’s the beams could be further modified to even more accurately hit the target using a technique called Intensity Modulated Radiation Therapy (IMRT). Then imaging devices were attached to the linear acceleratory to better ensure that that target was set up accurately every day using a technique called Image Guided Radiation Therapy (IGRT). Often as many as 7 or 9 beams were used to provide even more sophisticated targeting

Finally the ultimate machine was designed and built using technology similar to a CT scanner. Just as a CT scan provides extremely precise and detailed information about normal and abnormal anatomy, the TomoTherapy treatment device is able to deliver radiation extremely accurately to the target area while delivering very little radiation to normal tissues. It is able to do this because instead of delivering the radiation at only a few different directions, it delivers the radiation during a complete 360 degree arc while continuously modifying the shape and intensity of the radiation beam.

Since the device is designed around a CT scanner, it is able to do a CT scan each day before treatment delivery to verify that the target area is where it is expected to be. If it isn’t, the radiation treatment can be modified to adapt to changes in the position of the tumor and changes in the patient’s anatomy (like weight loss) which is a technique called adaptive radiotherapy (ART).

The other transformation occurring in modern cancer treatment is the use of highly targeted radiation to eradicate tumors with surgical precision without the use of surgery (’bloodless’ surgery or more precisely radiosurgery.) Radiosurgery devices (e.g. Gamma Knife) have been remarkably effective for treating benign and malignant tumors but are restricted to tumors of the brain and require that a frame be attached to the patient’s head for accuracy. The most revolutionary device for radiosurgery (The Cyberknife) does not require a frame and can be used to treat tumors anywhere in the body (referred to as frameless, extracranial radiosurgery).

The other approach is to take the radiation directly to the tumor (called brachytherapy or ‘close’ therapy). This commonly done now with high dose rate (HDR machines) for gynecologic or breast cancers (go here) or with seed implants for prostate cancer (go here).