Question

Radiobiological principles in radiotherapy

Answer 1

it causes cancer

Explanation:

it produces the radiation effect the tumor

Answer 2

Answer:

Explanation:

Understanding radiobiologic principles and their application to nursing care is integral to assisting optimal outcomes. Radiotherapy aims to treat cancer through delivering sufficient doses of ionising radiation to a specific area of the body to damage target DNA that eventually results in cell death.8 Ionising radiation causes cell death either directly or indirectly.  

Direct damage to the atoms that make up the DNA results in either single or double-strand breaks, faulty cross-linking of chains after breakage, damage or loss of a nitrogenous base, or breakage of the hydrogen bond between the two chains of the DNA molecule causing impaired cellular functioning or cell death.1

Indirect damage is caused by the interaction of ionising radiation with the molecules of the cellular fluid, resulting in toxic changes caused by the creation of unstable free radical ions that impair cellular functioning. While a direct hit causes the most lethal damage, the most common injury occurs as a result of the interaction of radiation and the water molecule.13

 

Radioactive substances emit both gamma rays and radiation particles until all their atoms are stable in a process called radioactive decay. The activity and rate of decay varies from one radioactive source to another. The most important feature of any type of ionising radiation in determining its application in radiotherapy is its penetrating power. The deeper the tumour within a patient, the higher the penetrating power required of the radiation.14  

The basic principles of radiobiology are:1, 13, 15, 16

Reoxygenation: occurs when radiation is delivered in multiple fractions to cells that may be relatively resistant due to hypoxia; cells may become reoxygenated and therefore more radiosensitive.

Redistribution: is defined by cells that survive a dose of radiation due to synchronisation in resistant phases of the division cycle and redistributing into more sensitive phases of the cell cycle during subsequent doses of radiation.

Repopulation: describes cells responding to lethal injury by repopulating or regenerating themselves.

Repair: occurs following sub lethal cellular injury which represents damage to the strands of the DNA and which can be repaired by enzymatic processes.