• Radiation oncology is that discipline of human
medicine concerned with the generation,
conservation, and dissemination of knowledge
concerning the causes, prevention, and
treatment of cancer and other diseases
involving special expertise in the therapeutic
application of ionizing radiation.
• Medical Oncology is that discipline of human
medicine specializes in diagnosing and treating
cancer using chemotherapy, hormonal therapy,
biological therapy, and targeted therapy.
• Surgical Oncology branch of surgery applied
to oncology; it focuses on surgical
management of tumours mainly cancerous
• Radiation therapy is the clinical modality dealing
with the use of ionizing radiations in the treatment of
patients’ with malignant neoplasias (and occasionally
• The aim of radiation therapy is to deliver precisely
measured dose of radiation to a defined tumour
volume with as minimal damage as possible to the
healthy surrounding tissue, resulting in eradication of
the tumour, high quality of survival and prolongation
of survival at competitive cost.
• G0 – Cell rests and does normal work in the
• G1 – RNA and proteins are made for dividing
• S – Synthesis ( DNA is made for new cell )
• G2 – Apparatus for mitosis is built
• M – Mitosis ( The cell divides into 2 cells )
• Radiation kills cells that are actively dividing.
• It also causes damage to the surrounding
• Radiation doesn’t kill cells instantly, it may
take day to weeks depending on the cell
• Skin, bone marrow, lining of intestines affects
• Nerve, breast, brain, and bone tissue show
TYPE OF RADIATION
– PHOTON THERAPY ( X- RAYS AND GAMMA
– PARTICLE THERAPY ( ELECTRONS,
PROTONS, NEUTRONS, CARBON IONS,
ALPHA PARTICLES AND BETA PARTICLES )
• NON – IONIZING
– RADIO WAVES, MICROWAVES, VISIBLE
• RADIOCURABILITY – It refers to the
eradication of tumour at the primary or
regional site and reflects a direct effect of the
irradiation ; but this does not equate with
patients cure from cancer.
• RADIOSENSITIVITY – is the measure of
tumour radiation response, thus describing the
degree and speed of regression during and
immediately after radiotherapy
Factors affecting Radiosensitivity
• Histologic type
– High sensitivity: Malignant lymphoma, Seminoma, etc.
– Moderate sensitivity: Epithelial tumour (Carcinoma)
– Low sensitivity: Osteosarcoma, Malignant melanoma, etc.
• Oxygen concentration in tumour tissue:
Radiosensitivity is low in the hypoxic state.
• Cell cycle: Radiosensitivity is high in M phase and
low in S phase.
• Cancer-related genes: p53, Bel-2, Fas, VEGF, etc.
• Radiation Oncologist - Plans treatment.
• Radiation Physicist – Working of radiation
equipment & delivering the radiation dose.
• Dosimetrist – Helps the doctor plan and calculate
the needed number of treatment.
• Radiation therapist – operates the equipment.
• Radiation therapy nurse – cares the patient and
advice them on radiation treatment & dealing with
radiation side efftects.