Radiotherapy is one of the many tools used in treatment of cancer. It is one of the most common treatments for cancer. Radiotherapy can also be referred to as Radiation therapy, irradiation or x-ray therapy.
Radiation therapy uses high-energy particles or waves such as x-ray, gamma rays, electron beams, or protons to destroy or damage cancer cells.
MECHANISM OF RADIOTHERAPY
The exact mechanism of cell death due to radiation is still an area of active investigation.
A large body of evidence supports double-stranded breaks of nuclear DNA as the most important cellular effect of radiation. This breakage leads to irreversible loss of the reproductive integrity of the cell and eventual cell death.The death of the cells causes the tumor to shrink.
Radiotherapy is not specific to cancerous cells and may damage healthy cells as well.
The response of tumors and normal tissues to radiation depend on their growth pattern before therapy starts and during treatment. Death is not instantaneous but occurs when the cells try to divide but fail a process termed abortive mitosis.
For this reason, radiation damage is manifest more quickly in tissues containing cells that are dividing rapidly(Emory university 2016).
TYPES OF RADIATION
There are two main types of radiation
PHOTON RADIATION
This is the most common form of radiation used in the treatment of cancer and involves a beam of high-energy photons
PARTICLE RADIATION
Electron, proton and neutron particle beams can also be used to irradiate areas of the body and damage the replication process of cancerous cell.
STANDARD DOSE
Gray (Gy) is the unit used to measure the total about of radiation the patient is exposed to.
Adjuvant therapy doses typically range from 45 to 60 Gy for cancer of the breast, head and neck.
which is divided into multiple smaller doses given over a period of one to two months.
The specific dose for each patient depends on the location and severity of the tumor and is at the discretion of the oncologist responsible for therapeutic decisions(Smith, 2015).
LENGTH OF TREATMENT
Standard treatment with radiation therapy lasts for five to eight weeks, depending on the specific type of cancer being treated .
Accelerated radiation refers to when the total dose is administered over a shorter period than usual.
This involves more frequent doses, usually more often than once daily, to administer the equivalent total dose over a shorter period.
This can be useful in some types of cancer, when a more aggressive treatment regimen is required.
PRINCIPLES OF RADIATION THERAPY
Precisely locate the target:
When locating a target, its location, its size, shape, and closeness to an important organs and structures must be known. Small targets are harder to locate than large ones. Diagnostics scans such as computerized tomography(CT) and magnetic resonance imaging(MRI) are used to locate the tumor earlier and even a smaller tumor . positron emission tomography(PET) and functional MRI (fMRI) scans provide information about the function of critical areas next to the target. Hold the target still using immobilization devices such as molds masks or frames
Accurately aim the radiation: Multiple radiation beams are aimed so that they all meet at a central point within the target, where they add up to a very high dose of radiation.
Patient alignment :different techniques may be used to position the body, including: skin markers, laser lights, field lights, infrared cameras and x-ray positioners. Machine alignment.
Shape the radiation beam: using treatment planning software and hard ware.
Deliver an optimal dose
Hold the target still using immobilization devices such as molds masks or frames
TYPES OF CANCER TREATED BY RADIATION
About 60% of cancer require radiation.
Certain types cancers are considered more responsive to radiation therapy. These cancers can be successfully treated with radiation therapy .
The cancer in this group include: skin and lip, head and neck, breast, cervical and endometrium, prostate, Hodgkin’s disease, and extranodal lymphoma, Retinoblastoma.
Other tumors with limited response to radiation that may be curable with combined therapies include: wilms tumor, colo-rectal cancer, soft tissue
CONCLUSIONS
Advancement in radiation therapy may continue to evolve in future.
It is therefore imperative that the medical-surgical / oncology radiation nurse must be proactive in developing the knowledge and skill needed to meet the challenges of the future and also to provide care in line with the best practice.
Reference
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.cancer.net/nnavigating-cancer-care
https://www.medicalnewstoday.com/articles/types-of-radiation-therapy
