Ocular Brachytherapy (Interventional Radiotherapy): Preserving the Vision.

Uveal melanoma represents the most common intraocular neoplasia among adults. Brachytherapy (interventional radiotherapy; IRT) has a great advantage, when compared with enucleation, both in terms of organ and function sparing. The Collaborative Ocular Melanoma Study introduced into clinical practice a standardised procedure that allowed the equivalence of IRT with enucleation in terms of overall survival to be demonstrated. IRT is carried out by placing a plaque in direct contact with the sclera under the uveal melanoma. Several radioactive sources may be used, including 106-ruthenium, 125-iodine, 103-palladium and 90-strontium. It is a multidisciplinary procedure requiring the collaboration of interventional radiation oncologists and ophthalmologists in the operating theatre and medical physicists for an accurate treatment time calculation. It also relies on ultrasound imaging to identify the lesion and verifiy the correct plaque placement. An emerging tool of paramount importance could be the use of artificial intelligence and predictive models to identify those patients at higher risk of developing late side-effects and therefore who may deserve preventive and supportive therapies.

Treatment of keloids by high-dose-rate brachytherapy: A seven-year study.

PURPOSE: To analyze the results obtained in a prospective group of patients with keloid scars treated by high-dose-rate (HDR) brachytherapy with or without surgery. METHODS AND MATERIALS: One hundred and sixty-nine patients with keloid scars were treated with HDR brachytherapy between December 1991 and December 1998. One hundred and thirty-four patients were females, and 35 were males. The distribution of keloid scars was as follows: face, 77; trunk, 73; and extremities, 19. The mean length was 4.2 cm (range 2-22 cm), and the mean width 1.8 cm (range 1.0-2.8 cm). In 147 patients keloid tissues were removed before HDR brachytherapy treatment, and in 22 HDR brachytherapy was used as definitive treatment. In patients who underwent prior surgery, a flexible plastic tube was put in place during the surgical procedure. Bottoms were used to fix the plastic tubes, and the surgical wound was repaired by absorbable suture. HDR brachytherapy was administered within 30-60 min of surgery. A total dose of 12 Gy (at 1 cm from the center of the catheter) was given in four fractions of 300 cGy in 24 h (at 09.00 am, 15.00 pm, 21.00 pm, and 09.00 am next day). Treatment was optimized using standard geometric optimization. In patients who did not undergo surgery, standard brachytherapy was performed, and plastic tubes were placed through the skin to cover the whole scar. Local anesthesia was used in all procedures. In these patients a total dose of 18 Gy was given in 6 fractions of 300 cGy in one and a half days (at 9.00 am, 3.00 pm, and 9.00 pm; and at 9.00 am, 3.00 pm, and 9.00 pm next day). No further treatment was given to any patient. Patients were seen in follow-up visits every 3 months during the first year, every 6 months in the second year, and yearly thereafter. No patient was lost to follow-up. Particular attention was paid to keloid recurrence, late skin effects, and cosmetic results. RESULTS: All patients completed the treatment. After a follow-up of seven years, 8 patients (4.7%) had keloid recurrences. Five of these had undergone prior surgery (local failure rate 3.4%), and 3 had received only HDR brachytherapy (local persistence rate 13.6%). Cosmetic results were considered to be good or excellent in 130/147 patients treated with prior surgery and in 17/22 patients without surgery. Skin pigmentation changes were observed in 10 patients, and telangiectasias in 12 patients. No late effects such as skin atrophy or skin fibrosis were observed during the 7 years of follow-up. CONCLUSIONS: HDR brachytherapy is an effective treatment for keloid scars. It is well tolerated and does not present significant side effects. The brachytherapy results were more successful in patients who underwent previous surgical excision of keloid scar than in patients without surgery. We favor HDR brachytherapy rather than superficial X-rays or low energy electron beams in keloid scars, because HDR provides a better selective deposit of radiation in tissues and a lower degree of normal tissue irradiation. Other advantages of high-dose-rate brachytherapy over low-dose-rate brachytherapy are its low cost, the fact that it can be performed on an outpatient basis, its excellent radiation protection, and the better dose distribution obtained. From the clinical perspective, the technique provides a high local control rate without significant sequelae or complications.

Treatment of skin carcinomas of the face by high-dose-rate brachytherapy and custom-made surface molds.

PURPOSE: To analyze the results obtained in a prospective group of patients with basal or squamous cell skin carcinomas of the face treated by high-dose-rate (HDR) brachytherapy via custom-made surface molds. METHODS AND MATERIALS: A total of 136 patients with basal or squamous cell carcinomas of the face were treated between March 1992 and March 1997 by surface molds and HDR brachytherapy with iridium-192. Nineteen patients were treated with standard Brock applicators and 117 patients with custom-made polymethyl methacrylate applicators, built over a plaster mold obtained of the patient's face. Minimum dose administered to the tumor was 6000 to 6500 cGy in 33 to 36 fractions at 180 cGy/fraction in lesions of up to 4 cm. Lesions greater than 4 cm were boosted up to 7500-8000 cGy after a 3-week pause. RESULTS: With the custom-made surface molds, the dose distribution was uniform in the surface of the skin and at 5 mm depth in the whole area of the applicator. Differences between the areas of maximum and minimum dose at this depth never reached values higher than 5% of the prescribed dose. At the edges of the custom-made molds dose gradient was sharp, with the detected dose at 5 mm from the applicator being negligible. All the patients were complete responders. There were 3 local recurrences, 1/73 patients treated for primary tumor and 2/63 patients treated for recurrent tumor. Actuarial local control at 5 years for all patients was 98%, for those patients with primary tumors 99%, and for recurrent patients 87%. The treatment tolerance was excellent in all cases. No severe, early, or late, complications were detected. CONCLUSIONS: Radiotherapy is a highly effective treatment of skin carcinomas of the face. Custom-made molds, to be used in conjunction with HDR brachytherapy equipment, make possible a uniform dose distribution, with a sharp dose gradient in the limits of applicators. Custom-made surface molds are easy and safe to use, and they fit very accurately for daily treatment. Local control is excellent with minimal sequelae or complications. Probably they will become the standard way of treatment of face skin carcinomas in the near future.

Monte Carlo calculation of the dose distributions of two 106Ru eye applicators.

BACKGROUND AND PURPOSE: Beta emitting 106Ru applicators are widely used to treat choroidal melanoma. In view of the importance of clinical applications of this radioisotope and the relative lack of knowledge of the dose distributions, three-dimensional dose maps of two concave applicators were calculated by means of Monte Carlo simulation. MATERIALS AND METHODS: Simulations of small CCA and CCB concave applicators manufactured by Bebig were performed using the Monte Carlo code PENELOPE, which allows the description of the structure (geometry and materials) of the applicator in detail. Electrons are emitted from the 106Ru nuclei isotropically, with initial energy randomly sampled from the corresponding Fermi spectra and with initial positions uniformly distributed on the radioactive layer. Primary electrons, as well as the produced delta-rays, are assumed to be absorbed in the medium when they slow down to an energy of 70 keV. Bremsstrahlung photons with energies larger than 7 keV are also simulated. The simulation code has been run on a 166 MHz PENTIUM PC. RESULTS: Three-dimensional dose distributions produced by the CCA and CCB applicators in a water sphere, concentric with the applicator, were evaluated. To minimize the magnitude of statistical uncertainties, advantage has been taken of the cylindrical symmetry of the problem. The relative depth-dose (along the symmetry axis of the applicator) was also evaluated from the applicator surface up to distances larger than I cm, with statistical uncertainties of a few percent. Results compare well with data supplied by the manufacturer. CONCLUSIONS: We have performed accurate Monte Carlo calculations of three-dimensional dose distributions from CCA and CCB 106Ru applicators. The results, presented in the form of two-dimensional maps, depth-dose distributions along the symmetry axis and lateral dose profiles, provide a detailed description of the dose delivered in treatments of choroidal melanoma.

Intraarterial infusion chemotherapy as a primary treatment in cancer of uterine cervix limited to the pelvis.

Percutaneous intraarterial infusion chemotherapy via the internal iliac arteries was performed as a primary treatment in 14 patients with invasive cancer of the uterine cervix. The drugs used were Mitomycin-C, Bleomycin and Cis-Platinum in cycles of 52 hours which were repeated, in some cases, 21 days apart. Complete responses were observed in two patients. Partial responses were seen in 10 patients and no response in two patients. 5 patients were treated surgically and 8 patients received radiotherapy after the infusion. The effect of chemotherapy was more evident in exophytic tumors with less effect on the parametria. Tumor masses can be reduced and patients can then be treated by surgery or radiotherapy. 6 patients died from sepsis.