RADIOBIOLOGY
Division of Radiation Therapy
Dr. Laure Marignol Junior Sophister 2010-2011
marignl@tcd.ie
1. OVERVIEW OF MODULE
a. AIM
The module aims to enable you to visualise the radiotherapy treatment field as a series of interconnected biological
entities whose response to radiation exposure is variable. You will be encouraged to explore the differences between
normal and malignant tissues that can be exploited for improved treatment outcomes, while being fully aware of the
limiting biological factors to the tolerance of normal tissues to radiation exposure. Finally the module intends to
sensitize you to the public health aspect of the exposure of populations to medical and/or accidental ionising
radiation.
b. RATIONALE
Radiobiology is a mandatory one-semester course taken by Junior Sophister Radiation Therapy students. The
module is intended to enable students to integrate the scientific background acquired in the Freshman years
(Biology, Chemistry, Physiology) into their clinical experience of radiation therapy. The module leads to a more
comprehensive understanding of treatment planning dose restrictions and calculations, conventional delivery
protocols and purpose of alternative fractionation schedules.
c. LEARNING OUTCOMES
On successful completion of this module, the students will be able to:
• Learning Outcome 1: Compare and contrast the main characteristics of normal and malignant tissue
biology and structure.
• Learning Outcome 2: Explain and apply the 5 basic radiobiological principles to clinical situations.
• Learning Outcome 3: Characterise and predict the effects of altered fractionation schedules on normal
tissue complications and tumour control.
• Learning Outcome 4: Explain and appraise the cancer risk associated with radiation exposure
2. COURSE CONTENT
1: Generalities
• Basic cell biology
• Organization of normal tissues
• Tumour biology and microenvironment
• Introduction to radiation biology
2: Radiation preferentially targets mitotically-active cells
• Interaction of Ionizing radiation with matter: the role of free radicals
• Critical DNA damage
• Critical chromosome aberration
• Mitotic cell death and Measure of radiation damage
• Consequences in tissues and tumours
• Dose response curves and predictive assays
3: Maximizing radiation-induced cell kill
• Role of radiation quality
• Role of repair
• Role of oxygen
• Fractionation
4: Clinical implications of radiobiology
• Dose rate effect
• Fractionation schedules
• Improving radiation sensitivity
• Risk of second cancers
• Clinical radiobiology
SEMINAR: Sources of radiobiological data
TUTORIAL: Revisions and Exam Preparation
3. READING LIST/ INDICATIVE RESOURCES:
“Radiobiology of the radiologist”, Eric J. Hall and Amato J. Giaccia. Philadelphia, Pa. ; London : Lippincott
Williams & Wilkins, 2006.
“ Basic clinical radiobiology”, Gordon Steel Edward Arnold (London) 2006
“Cancer biology” / Raymond W. Ruddon. New York ; Oxford : Oxford University Press, 2007.
4. ASSESSMENT
Assessment of this module is by examination (70%) AND an assignment (30%).
• The examination is two hours long and you will require answering three assay questions from a selection of
four. Each question consists of a statement that you are expected to discuss. To help the direction of the
answer, the question clearly states that based on your understanding of the basic radiobiological principles,
you should address the specific aspects of the course outlined in the question. The examination is assessed
on knowledge (basic understanding) and ability to apply this theoretical knowledge to the statement
provided.
• The assignment is a 2,000 word essay on a radiobiological problem. You will be given the assignment topic
and guidelines during the last class in Michaelmas term. The assignment is due on Monday 8th March
2011, 5pm.
Sample Exam question:
The formation of double-strand-breaks is essential for the induction of cell killing.
From your understanding of the basic principles of radiobiology,
• Describe and explain the chain of event leading to cell killing following the induction of double-strand-
breaks.
• Discuss how this chain of event relates to the shape of the radiation survival curve and associated α/β ratio.
• Describe and discuss the factors that can alter each step of this chain of event and lead to increased
radiation resistance.
