Page 19 - APPENDIX B: Trials Investigating the Management of Acute Radiation-Induced Skin Reactions Reading Qualitative Research

19
WOUND CARE

Context of radiotherapy as a treatment modality. Radiation therapy is a local

treatment for cancer with the use of high-energy particles or x-rays, which possess sufficient

energy to create ionizing radiation by ejecting electrons from their orbit. The effects of radiation

occur because of physical, chemical and biochemical factors. Physical factors consist of the

energy of the radiation that is able to eject electrons, creating instability; chemical reactions

occur because ionization creates powerful oxidizing and reducing agents, known as free radicals,

in cellular field. The target of radiation effect is cellular deoxyribonucleic acid (DNA).

Radiation results in biochemical damage of the chemical bonds which loosely hold DNA

together. Double-strand breaks in DNA are the most important effect of radiation on cells

(Newton, Hickey, & Marrs, 2009).

Therapeutic ionizing radiation used to treat malignancies includes electromagnetic

radiation and particulate radiation. Sources of electromagnetic radiation include x-rays (photons)

which are generated from an electrical machine or gamma rays emitted from the nucleus of a

radioactive source such as cobalt. Particulate radiation comprises of alpha particles, neutrons

and protons that are rarely used for clinical treatment and electrons, which are generally used to

treat superficial malignancies (Khan, 2003; Moore-Higgs, 2007).

Radiation treatments are prescribed in units of measurement known as GY (Gray) or cGY

(centiGray) with one GY equaling 100 cGY. Programmed cell death is facilitated by radiation.

Radiation effect most often takes place at the time that the cell tries to divide. Cells are most

susceptible to radiation damage during the G2 and M phase of cell cycle and least sensitive

during the S-phase. Cells with a higher mitotic index are more sensitive to radiation damage.

Normal cells have a better ability to recuperate and restore from radiation damage unlike the

cancer cells therefore, the radiobiological basis for the use of dose fractionation in standard