# MRS360 Radiation Dosimetry Biology & Protection (8)

In this subject the physical concepts of ionising radiation energy deposition in tissue, biological effects of ionising radiation and radiological protection are developed. Broad study areas include; the microscopic description of energy deposition, external and internal radiation dosimetry, concepts and theory of radiobiology, health physics and principles and applications of radiation protection. A mathematical treatment is used throughout.

## Availability

Session 2 (60)
On Campus
Port Macquarie Campus
Wagga Wagga Campus

Continuing students should consult the SAL for current offering details: MRS360. Where differences exist between the Handbook and the SAL, the SAL should be taken as containing the correct subject offering details.

## Subject Information

HD/FL

One session

##### School

School of Dentistry and Health Sciences

## Learning Outcomes

##### Upon successful completion of this subject, students should:
• Be able to analyse and solve problems of symbolic and numerical nature.
• Be able to analyse and derive elementary quantitative models of radiation action and risk/dose minimisation and use these in the explanation of physical dependencies between variables.
• Be able to deduce and relate dependent bio-physical variables, applicable physical laws, and then apply them in the solution of dosimetric, radiobiological, and radiation protection problems.

## Syllabus

##### This subject will cover the following topics:

The Microscopic Description of Energy Deposition in Matter:
Development of ideas of energy deposition in matter by radiation; linear energy transfer (LET - energy and track averages, track structure, macro versus micro dosimetric quantities, specific dose, lineal energy transfer, probabilities and cross sections. Poissonate distributions and radiation events.

External Dosimetric Calculations: energy imparted and mean absorbed dose calculations utilising energy fluence approach for matter particle and photon beams, the 'f factor' and energy fluence approach to calculation of point absorbed dose. Multi and single energy photon beam calculations. Incorporation of scatter factors BSF and TAR in calculations, exposure area product measurement.
Internal Dosimetric Calculations: Source strength Gamma for gamma radiation, specific effective energy, effective half life, total dose and dose commitment, method for gamma emitters. the basis and use of the MIRD method : absorbed fraction and specific absorbed fraction. Neutron absorbed dose.

Influencing chemical and biological variables, relationship to physical character of radiation, targets in tissue, target structure, target repair, relative biological effect (RBE), relationship of RBE and LET for simple versus structured (eg. mammalian ) cells, oxygen effect mechanism and quantification by oxygen enhancement ratio (OER), relation of OER and LET, analysis of cell survival curves and calculation of RBE and OER, classification and explanation of type A B and C curves, simple target theory and simple target models (including SH/ST, SH/MT, MH/ST, MH/MT), a simple explanatory repair model, simple target theory based explanatory model for LET and RBE dependence, theoretical basis of the linear quadratic relationship for biological effects, the two component model of cell survival, and the basis of the linear ?hypothesis? for radiation protection.

Health Physics and Principles of Radiation Protection:
The use of the linear hypothesis as a basis for radiation protection, the stochastic basis of stochastic and deterministic effects, the International Commission for Radiological Protection (ICRP) approach to radiation protection and principles of justification, optimisation (ALARA), and limitation, the International Commission for Radiological Units (ICRU) units for radiological protection dosimetry; equivalent dose, effective dose (including committed and collective variants), genetically significant dose, Allowable Limits on Intake (ALI), risk factors, additive and multiplicative models, calculation of individual and population radiation risk and use of radiological (nuclear medicine and diagnostic radiography), natural, warfare, and accident examples.

Analysis in ALARA context for radiographic and nuclear medicine diagnostic approaches.
Comparative absorbed dose/risk analyses utilizing kVp, mAs, distance, and beam area variables for:
- Alteration of density for given thickness part.
- Fixed and variable kVp approaches to manual exposures, compensating for variable part thickness
Nuclear Medicine:
- An analysis of the influence of dependent variables upon patient dose.
- Different exam procedures and comparison in terms of dose and the ALARA principle.

Analytical Methods introduced (integrated within the study of the above topics): use of the Poisson distribution formula, power series approximation of exp(x).