Table 1.

Types of radiotherapy used in clinical practice for the treatment of different types of cancer.

Teletherapy (applied externally)
Protocol type	Characteristics	Cancer treated	Example of protocol	Advantage	Disadvantages	References
Three-dimensional conformal radiotherapy (3D-CRT)	Radiation administered geometrically from the volume to be treated	Prostate, spine, esophagus, lung, bladder, pancreas, head and neck cancer	Adjuvant (additional to chemotherapy) for locally advanced non-small-cell lung cancer; 55 to 65 Gy administered in three sessions over approximately 4 weeks	Uses three-dimensional images for the geographic location of the tumor Radiation beam is tailored to target tumor Limits radiation dose to adjacent tissues	Requires very precise dosing and planning to minimize exposure of surrounding normal tissues to radiation dose Requires specialized equipment Long treatment	(17, 21–23)
Intensity-modulated radiation therapy (IMRT)	Controls the shape (similar to 3D-CRT) and also the intensity of each beam emitted Reduces the exposure of healthy tissue to radiation	Prostate, spine, lung, breast, kidney, pancreas, liver, tongue, and larynx cancer	In prostate cancer (PCa), 62 Gy in 20 fractions, over 4 weeks	Dose limitations of the target tumor and adjacent tissues Vary dose intensities in the treatment field	Requires very precise doses Long treatment Requires specialized equipment	(17, 21, 24, 25)
Stereotactic Body Radiation Therapy (SBRT) or Stereotactic Ablative Radiation Therapy (SABR)	Uses multiple beams of radiation, from many different directions, that converge into a very small volume Allows high doses of radiation to be delivered with little damage to surrounding healthy tissue	Used in the treatment of small tumors in the head and brain, also in lung, spine, and liver cancer	In PCa, 25 Gy in five fractions over the course of 1–2 weeks	Precise geographic location of the tumor Use high doses The treatment can be completed in a few fractions (1 to 5) and in a short time (1 to 5 days) Improves response to treatment Can be used in combination with chemotherapy A treatment for inoperable tumors	Difficult to manage Requires a lot of pressure Requires specialized equipment	(21, 24, 25)
Volumetric modulated arc therapy (VMAT)	Supplies the radiation beams by means of a 360° arc integrated into a linear accelerator Treatment cycles are very fast (less than 2 min) Provides very high doses of radiation with precision and speed.	In head and neck tumors, PCa, or central nervous system tumors.	Twenty Gy in a single dose for the treatment of brain metastasis	Radiation adapts to the shape of the tumor to minimize exposure to healthy structures Rapid treatment administration	Longer doses	(21, 26–28)
Brachytherapy (Applied internally)
Protocol type	Characteristics	Cancer treated	Example of protocol	Advantage	Disadvantages	References
Interstitial	Administration within the tumor	Uterus and recurrence of vaginal cuff cancer	In uterus cancer, three or four 6 Gy fractions, one fraction per week	High doses in tumor and low in healthy tissue Allows the treatment of larger tumors	Invasive Formation of necrotic cavities	(29, 30)
Intracavitary	Administration inside a natural (as vagina or larynx) or surgically created cavity	Larynx, uterine, cervical, and endometrial cancer	In cervical cancer, 15 or 20 Gy in three or four fractions.	Uses anatomical pathways to place radioactive sources Can be used without anesthesia You can use low dose, pulsed dose, or high dose	Higher risk of error	(31, 32)
Intraluminal	Application into the lumen of organs	Extrahepatic biliary duct cancer and esophagus cancer	For biliary duct cancer, 30 Gy for definitive dose	High doses of radiation to the tumor and minimize the dose to healthy adjacent organs Allows biliary drainage through the tumor Improve survival	May cause bleeding	(33, 34)
Intravenous	Venous administration of radioactive molecules	Hepatocellular carcinoma	For hepatic cancer, 100 Gy in a single dose	Little invasive Quick and easy administration Therapy targeting specific proteins on the surface of tumor cells	Long treatment May cause side effects	(35)