Iodine 125 Source in Interstitial Tumor Therapy

Percutaneous computed tomography/ultrasonography-guided permanent iodine-125 implantation as salvage therapy for recurrent squamous cell cancers of head and neck

“…low-energy radioactive seed implants offer three potential advantages: (1) high-dose gradients are available at tumor/normal tissue interfaces; (2) continuous radiation increases the probability of damaging malignant cells during a vulnerable phase of the cell cycle; (3) continouse low dose rate irradiation from low-energy sources is effective against the hypoxic components found in rapidly dividing cell populations. 15,16 In this study, we determined the efficacy and feasibility of percutaneous 125 iodine seed implantation under ultrasonography or computed tomography (CT) guidance for recurrent squamous cell carcinomas of the head and neck and analyzed the local control rates, survival rates and complications involved.…”

Sensitization to Radiation from an Implanted125I Source by Sustained Intratumoral Release of Chemotherapeutic Drugs

“…There are similar limitations on brachytherapy, and sites that are appropriate for interstitial radiation treatment are similarly accessible to interstitial chemotherapy by radiosensitizers or other drugs, and, in fact, insertion of separate or combined devices could be achieved with a single intervention. 125 I has been used extensively in clinical brachytherapy protocols since its introduction in 1975 (8), and 125 I seeds have been used as permanent implants in the treatment of prostate, lung and pancreatic cancer and as temporary implants in tumors of the breast and eye. 125 I has the advantage of low mean energy, with a half-value layer (HVL) in lead of less than 0.003 cm.…”

Choice of Radioisotope in Stereotactic Interstitial Radiotherapy of Small Brain Tumors

“…Kim and Hilaris [5] observed a greater percentage of local control and a lower percentage of complications with l2?I compared to l92Ir and 222Rn in treating cancer of the lung and metastatic epidermoid carcinoma of the neck lymph nodes. The !25I RBE value relative to l27Cs was determined to be in the range of 1.2-2 for the CHO cells between the dose-rate of 7.5-53 cGy/h [I], The RBE of 1.5 was measured for l25I relative to i92Ir for the roots of Vicia faba [4], Thus, the 125I RBE value of 1.0 remains consistent when compared to other radioisotopes.…”

“…There- fore, radiation exposure to the personnel during source handling and implant procedure depends very much on the isotope. In addition, clinical evidence suggests that one isotope may be more effective than another in treating various malignancies in humans [5]. In other words, the relative biological effectiveness (RBE) of the isotope used may af fect, to some extent, the tumor regression rate.…”