What is Radiation Oncology?
Radiation oncology is the medical specialty that uses ionizing radiation to treat cancer and some non-malignant conditions.
Its aims are curative (eradicate localized cancer), adjuvant (after surgery), neoadjuvant (before surgery to shrink tumours), or
palliative (relieve symptoms). Radiation oncologists design and oversee treatment, working with physicists, dosimetrists, therapists,
nurses and other specialists. (Oncolink+1)
Main types of radiotherapy (short descriptions)
External beam radiotherapy (EBRT) — photons or electrons delivered from a linear accelerator. Common forms: 3D-CRT, IMRT (intensity-modulated), VMAT (arc therapy), and SBRT/SRS (stereotactic body/cranial radiosurgery). IMRT/VMAT allow highly conformal dose while sparing nearby organs.
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Proton (and heavy ion) therapy — charged-particle therapy with different depth-dose properties; useful where normal-tissue sparing is critical (pediatrics, skull base, some re-irradiations).
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Brachytherapy — radioactive sources placed inside/next to tumor (common in cervix, prostate, some breast cancers).
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Emerging/experimental: FLASH ultra-high dose rate RT (preclinical/early trials), spatially fractionated approaches, and advanced adaptive/proton pencil-beam techniques. These are active research areas.
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Who gets radiotherapy — common indications
Radiation is used across most cancer types. Examples:
Curative: localized head & neck, lung, cervix, prostate, some brain tumours.
Adjuvant: post-lumpectomy breast RT, post-prostatectomy where indicated.
Palliative: painful bone mets, bleeding tumors, spinal cord compression (rapid single- or short-fraction courses often used).
Guideline bodies (ASTRO, NCCN) provide tumour-specific recommendations and fractionation options.
Typical clinical workflow (patient pathway)
Referral & initial consult: oncologist assesses history, imaging, and goal (curative vs palliative).
1.Simulation: CT simulation (sometimes fused with MRI/PET), immobilization devices, planning scans.
2.Contouring/Target delineation: radiation oncologist defines target volumes and organs at risk.
3.Treatment planning: dosimetrist/physicist creates a plan (IMRT/VMAT/SBRT) and calculates doses.
4.Quality assurance (QA): physics checks and machine QA before treating patient.
5.Treatment delivery: daily (or hypofractionated) fractions with image guidance (IGRT).
6.On-treatment reviews: monitor acute toxicities.
7.Follow-up & survivorship: assess late effects, recurrence surveillance and rehabilitation.
Key technologies and why they matter
* IMRT / VMAT: dose sculpting; lower acute/late toxicity for many sites.
ASTRO
* SBRT / SRS: very high biologic dose to small targets (oligometastases, early lung tumors, brain mets).
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* Protons: reduce integral dose to normal tissues — valuable in pediatrics, selected head/neck and skull base tumors.
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* Image guidance & adaptive RT: daily imaging (CBCT/MR-guided) enables tighter margins and adaptive replanning when anatomy changes. AI is
accelerating auto-contouring and QA.
