Indications and methods of Radiotherapy

Indications and methods of Radiotherapy is described below.

Indication of Radiotherapy

1. Radiotherapy Indicated for localized, solid neoplasm that can’t be excised completely.
2. Radiotherapy Indicated when surgery is expected to do or already failed
3. Radiotherapy Indicated when regional or distant metastasis has not occurred.
4. Radiotherapy Indicated when radical surgery is unable to remove whole neoplasm
5. Radiotherapy Indicated when bulk of the neoplasm needs reduction in size so that it can be subsequently removed surgically

Methods of Radiotherapy

A patient can acquire life-threatening complications during radiation therapy due to destruction of healthy cells. The injuries, which normal cells undergo, are compensated for the cells by shortening the cell division time and by increasing their relative number. This is done by four R’s of radio therapy–

1. Reoxygenation
2. Repopulation
3. Redistribution
4. Repair

Radiotherapy is done by multiple treatments given over a period of time termed as Fractioned therapy. In animals, they are giving 10 –12 fractions of radiation dose of 4 –5Gy for 3 times per week. In humans 1.8-2.00 Gy with a total dose of 60 –70 Gy over a period of 6-7 weeks.

Teletherapy

In teletherapy, radiation source is kept at a distance from the lesion which consists of four types-

1. Superficial X-ray therapy: with X- ray machine of 60–100 keV
2. Deep X-ray therapy: 200-300 keV
3. Super Voltage therapy:
   • X-ray machine with linear accelerator (1 meV to 20 meV or cyclotron or betatron (20 meV to 100 meV)
   • Through isotopic X-ray machine with cobalt or cesium in a sealed form.
4. Particulate beam therapy: Beam of Electron, Proton or Neutron used as a mode of teletherapy.

Brachytherapy

Brachytherapy is the therapeutic use of radio isotopes either within the interstitium or on the surface of the neoplasm. Brachytherapy sources are usually in the form of surface applicators, needles, seeds or grains etc., Permanently implanted isotopes in the body are ²²² Rn(Radon), ¹⁹⁸ AU (Aurum), ¹²⁵K. Removable isotopes are ¹⁹²Ir (Iridium), ⁶⁰Co (Coblat) and ¹³⁵Cs (Caesium).

Brachytherapy is done with four types-

1. Interstital brachtheraphy: when the source of branchytherapy are within the interstitum of the neoplasm. For example- ¹⁹⁸ Au, ⁶⁰Co etc.
2. Pliesotherapy or Surface brachytherapy: use of ⁹⁰Sr (strontium) for superficial therapy
3. Systemic brachytherapy:use of ¹³¹I and ³²P administered systemically