Radiation and cancer biology are dynamic fields with new results appearing daily in the scientific literature. The goal for radiation oncology residents during training is to acquire a solid base of knowledge in cancer and radiation biology, which will be built upon during their careers through regular reading of the scientific literature as well as attendance at seminars and scientific conferences. In addition, it is anticipated that many residents will pursue careers that will permit them to be involved in research for which a detailed understanding of radiation and cancer biology is essential. Of greatest importance, it is hoped that by providing residents with a firm foundation in the biologic principles underlying the treatment of cancer with radiation, they will be able to provide more effective radiotherapy and achieve improved clinical outcomes for their patients.

We would like to thank the Associate and Senior Associate Editors who contributed to the questions which made Rabex 2011 possible and also special thanks to all the past contributors for their continuing support which is maintaining the Radiation and Cancer Biology Practice Examination (RABEX ) alive since its inception in 1995 to present as a preactice examaniation and self-study guide exploring and understanding the effects of radiation interaction and its mechanicism at the celluar level.