Superficial and Deep Therapy: Techniques, Applications, and Advantages/Disadvantages
1. Introduction to Radiation Therapy Depths
Radiation therapy is categorized based on penetration depth into tissue:
- Superficial Therapy – Low-energy X-rays (50–150 kV) for treating skin and shallow tumors.
- Deep Therapy (Megavoltage Therapy) – High-energy X-rays (>1 MeV) for treating deep-seated tumors.
The choice of therapy depends on:
- Tumor location and depth
- Desired dose distribution
- Surrounding healthy tissue sensitivity
2. Superficial Therapy
Superficial therapy, also called orthovoltage therapy, uses low-energy X-rays (50–150 kVp) that are absorbed mostly in the first few millimeters of tissue.
2.1 Techniques
- Kilovoltage X-ray Therapy: Uses 50–150 kV X-rays.
- Contact Therapy: X-rays applied directly to the tumor (e.g., eye or skin lesions).
- Grenz Ray Therapy: Uses 10–20 kV X-rays for treating psoriasis and benign skin conditions.
2.2 Applications
- Skin cancer (Basal Cell & Squamous Cell Carcinoma)
- Superficial vascular malformations
- Psoriasis and inflammatory skin conditions
- Benign tumors (e.g., keloids, warts)
2.3 Advantages & Disadvantages
| Advantages | Disadvantages |
| Non-invasive and painless | Limited penetration depth |
| Minimal damage to deep tissues | High dose to skin (risk of burns) |
| Effective for skin cancers | Less effective for deep tumors |
| Simple setup, no anesthesia needed | Not suitable for thick tumors (>5 mm) |
3. Deep Therapy (Megavoltage Therapy)
Deep therapy delivers high-energy X-rays or gamma rays (1–25 MeV) to treat tumors deep within the body.
Image: Deep Therapy Treatment
(A diagram showing a linear accelerator (LINAC) delivering radiation to a deep tumor in the lung.)
3.1 Techniques
- Cobalt-60 Therapy – Uses gamma rays (~1.25 MeV) for deep tumors.
- Linear Accelerator (LINAC) – Produces megavoltage X-rays (4–25 MV) with precise dose delivery.
- Proton Therapy – Uses protons (rather than X-rays) for precise energy deposition.
- Intensity-Modulated Radiation Therapy (IMRT) – Adjusts radiation intensity for targeted tumor therapy.
- Stereotactic Radiosurgery (SRS) – High-precision radiation for brain tumors and small lesions.
3.2 Applications
- Deep-seated tumors (e.g., lung, prostate, breast, brain)
- Lymphomas and sarcomas
- Palliative treatment (pain relief for bone metastases)
3.3 Advantages & Disadvantages
| Advantages | Disadvantages |
| Deep tissue penetration | More expensive and complex |
| Can spare skin and superficial tissues | Requires specialized machines (e.g., LINAC, Cobalt-60) |
| Precise tumor targeting (e.g., IMRT, SRS) | Potential radiation exposure to surrounding tissues |
| Suitable for large, deep-seated tumors | Treatment duration may be longer |
4. Comparison of Superficial vs. Deep Therapy
| Feature | Superficial Therapy | Deep Therapy |
| Energy | 50–150 kV | 1–25 MeV |
| Penetration Depth | <5 mm | Several cm |
| Best for | Skin cancers, superficial lesions | Deep-seated tumors (e.g., lung, prostate) |
| Machine Type | Orthovoltage X-ray | LINAC, Cobalt-60, Proton Therapy |
| Side Effects | Skin burns, erythema | Organ toxicity, fatigue, nausea |
5. Conclusion
- Superficial therapy is ideal for treating skin cancers and superficial lesions with low-energy X-rays.
- Deep therapy is used for internal tumors requiring high-energy radiation.
- Advanced techniques (IMRT, Proton Therapy) help reduce side effects and improve targeting.
