Radiation Oncology


The linear accelerator was developed by Henry Kaplan at Stanford University.  The treatment of malignant and non-malignant conditions was limited by skin toxicities.  Linear accelerators generate high energy treatment regimens.  The physician must examine the patient and determine if the cancer patient should be treated with radiation therapy.  He must work up a good case history for the patient and seek for any underlying conditions that may exist that might affect their treatment regimens.  Everything that is needed to be accomplished by radiation therapy can be done by utilizing a linear accelerator.  Neutrons and heavy ions are also used to treat patients.  The isocenter is the center the patient gets rotated around.  The patient must sign a consent form to the procedure.  The radiation oncologist contours the treatments according to the GTV(gross tumor volume or what is seen by the eye), the CTV(clinical target volume or what is perceived by the physician of the span of the cancer), the PTV(the planning target volume or how the patient is adjusted for the radiation treatment); and the ITV(internal target volume or how the internal tumor cells are moving).

The dose of radiation utilized and how many treatments are administered is written by the physician.  Sometimes, the chest wall can’t be irradiated directly because the heart would be in the field of radiation when it is not intended to be.  The doses are characterized by low dosages around the tumor; with higher doses of radiation directed towards the tumor.  Areas of the central nervous system have lower maximum dosage levels of radiation.  Areas housing the prostate and rectum have higher maximum dosage levels of radiation.  Medical physicists check that the prescribed radiation can be delivered to every field within three percent accuracy.  The patients may become fatigued due to the radiation treatments.