Brachytherapy Protocols for Oncology: Clinical Standards

Eye Tumors

For tumors >15 mm or thickness >10 mm, enucleation is indicated. Otherwise, episcleral plaque brachytherapy is used.

• Isotopes: I-125 (<6 mm).
• Required Data: Tumor drawing, eye diameter, basal diameter, and maximum/minimum tumor thickness. Data is transferred to specific planning software (seeds, activity, position, duration).
• Treatment: Surgical application of episcleral plaques under anesthesia, covering the tumor base with a 2-3 mm margin.
• I-125: Dose 85 Gy (melanoma) and 40 Gy (retinoblastoma); dose rate 0.6-1.05 Gy/h.
• RU-106: Dose 100-130 Gy; dose rate 7.2-12 Gy/h. Inpatient care required.

Breast Tumors

Indications include tumor bed boost, accelerated partial breast irradiation, and HDR for local recurrence.

• Boost Requirements: Needles of different lengths, methacrylate templates with perforated holes, fixing screws, and plastic caps for needle protection.
• EBRT + Brachytherapy: 60 Gy (recurrence risk) or 70 Gy (high risk). 7 Gy at 85% isodose. Technique: 2/3 planes, 5-9 needles with 10-20 mm separation.
• Recurrence: 30 Gy total dose, 2.5 Gy fractions at 85% isodose, 12 fractions in 5 days, >6h interval.
• HDR Irradiation: Total dose 32 Gy, 4 Gy twice daily, >6h interval.

Lip Tumors (LDR)

Typically presents as a crusty squamous cell carcinoma. Local anesthesia is used with 9-12 mm needle separation.

• Sources: 2-3.
• Margins: 5 mm for tumors <1 cm; 10 mm for tumors >1 cm.
• Procedure: Intraoral mold custom-made for the patient.
• Dose: T1 (60-65 Gy), T2 (65-70 Gy), advanced tumors (20-25 Gy + 40-45 Gy EBRT); maximum 70-75 Gy.
• Dose Rate: 45-80 cGy/h. Mucositis is a common reaction; inpatient treatment is required.

Tongue and Floor of Mouth Tumors (LDR)

• Implant Guidelines: Local anesthesia, guide implementation, and substitution of the guide with iridium hairpins, verified by X-ray.
• Prescription Dose: Dose rate 40-50 cGy/h, combined with EBRT (25-30 Gy), GTV margin (5-10 mm), or exclusive brachytherapy (60-70 Gy).
• Vector Forks: For mobile tongue <3 cm, use 2 parallel segments (12 mm separation) and a bridge.

Skin Cancer

Indications include basal cell (local growth) and squamous cell (metastatic) carcinomas. Melanomas are contraindicated.

• Treatment Volume: GTV + margin.
• Techniques: Interstitial (hypodermic needles, Ir-192, 5-10 mm margin), plastic tubes on molds (Paris system), or surface applicators (3-4 cm deep).
• Valencia Applicator: 42 Gy in 6 Gy fractions.