[en] The sterilization of radium needles (applicators) is possible with the device. The system has the simultaneous function of a shielding container (concrete or lead chamber), of a washing vessel and of a sterilization chamber. The shielding container surrounds the cleaning vessel into which the cleaning liquids can be sprayed and extracted again and into which a bactericide gas (ethylene oxide with CO or freon) can be introduced. Due to the poison gas sterilization of the applicators collected in the wash vessel or sterilization chamber, a temperature of 80⁰C is not exceeded so that the soldered points on the applicators do not become loose. (DG)

[en] Intra-operative dosimetry in prostate brachytherapy requires 3D coordinates of the implanted, radioactive seeds. Since CT is not readily available during the implant operation, projection x-rays are commonly used for intra-operative seed localization. Three x-ray projections are usually used. The requirement of the current seed reconstruction algorithms is that the seeds must be identified on all three projections. However, in practice this is often difficult to accomplish due to the problem of heavily clustered and overlapping seeds. We have developed an algorithm that permits seed reconstruction from an incomplete data set. Instead of all three projections, the new algorithm requires only one of the three projections to be complete. Furthermore, even if all three projections are incomplete, it can reconstruct 100% of the implanted seeds depending on how the undetected seeds are distributed among the projections. The method utilizes the principles of epipolar imaging geometry and pseudo-matching of the undetected seeds. The algorithm was successfully applied to a large number of clinical cases where seeds imperceptibly overlap in some projections

No abstract available

No abstract available

[en] Purpose: To treat children with retinoblastoma, who require whole eye radiotherapy, with a specially designed ¹²⁵I applicator that irradiates the eye while sparing the surrounding tissues. Methods and Materials: Under general anesthesia, a pericorneal ring is attached to the 4 extraocular muscles, and 4 appendages, each loaded with ¹²⁵I seeds, are inserted beneath the conjunctiva in-between each pair of muscles and attached anteriorly to the ring. Twenty-nine eyes were treated. Eighteen received a median dose of 28 Gy during 91 hours and 11 received 40 Gy during 122 hours, when the relative biologic effectiveness was taken as 1 instead of 1.5. Six had received prior chemotherapy. Results: Twenty-four eyes were followed up for 2-157 months (median 29). Although 22 eyes responded, local control was achieved in 13 patients, 3 of whom required additional treatment for new tumors; a further 3 required additional treatment for tumor recurrence as well as new tumors. One of these eyes was enucleated for neovascular glaucoma. All 6 Group I-III eyes and 6 of 18 Group V eyes were retained for 2-157 months (median 39), with good vision in 10 eyes. Three developed cataracts 7, 8, and 12 years later, 1 of which has been removed. Conclusions: This is a new way of irradiating the whole eye with a minimal dose to the surrounding tissues. The treatment time is only 5 days. It is effective in Groups I-III, but only 33% of Group V eyes retained vision. No late cosmetic defects occurred

[en] An investigation was undertaken into possible dose conformity advantages and technical limitations of utilizing radially asymmetric internally applied radiation sources for intensity-modulated brachytherapy (IMBT). A feasible form of a source for IMBT would be a linear source with a high-intensity angular region, with some fractional transmission through the remainder of the source, which inhibits the resolution achievable in intensity modulation. Indexed rotation of the source about its axis would provide radial intensity modulation, which could compensate for variations in the spatial relationship between the source position and location of the target edge. Two treatment situations were simulated - one two-dimensional and one three-dimensional - both utilizing a single source (single catheter). The optimal intensity distribution of the source was determined by simulated annealing optimization using a conformality-based objective. The parameters in the optimization included the angular size of the source high-intensity region, and the fractional transmission through the low-intensity part of the source. Results indicate that limitations in source design suggest an optimal high-intensity resolution of approximately π/4 to π/8. The advantages of IMBT are rapidly reduced when fractional transmission through the low-intensity side of the source is increased. (author)

[en] Three dimensional (3-D) imaging/planning facilitates the definition of the GTV. It allows us to use CT (or other 3-D imaging such as PET) based anatomic information when designing treatment beams. Detailed 3-D dosimetric and anatomic information can be readily displayed and enables the physician to better select ?optimal? beam orientations and beam shapes. Care must be taken to review the RT fields actually on the patient, since some clinically meaningful information is not included in the imaging (drain sites, scars, palpable induration). Overall, 3-D/conformal planning has been one of the most important advances in clinical radiation oncology. The limitation of this approach relates to the occasional inability to visualize target tissues on CT imaging (e.g. some head and neck sites are not easily visualized on CT, and when the target is largely based on areas of possible microscopic disease such as post-operative breast or rectal cancer). However, even in these cases the imaging can help to define critical normal tissues to be spared

[en] A delivery system for interstitial radiation therapy is described, comprising: an integral elongated member made from a material which is absorbable in living tissue the member having a length substantially greater than its width, and a plurality of radioactive sources

[en] Purpose: The feasibility of high dose rate iridium afterloaded molds in the treatment of skin tumors. Methods and Materials: Expanded silicone rubber and bronchial applicator tubes were used in the construction of various molds. The number of tubes used and the separation between them depends on the size and area to be treated. Source dwell position and time are set to follow Paterson--Parker rules. Single plane expanded silicone rubber molds between 15 x 15 mm and 60 x 70 mm were used in 120 different sites, and of the others, seven were perspex double molds, two were cylindrical applicators, and one was a partially shielded intranasal applicator. One hundred and thirty lesions of various site and histology were treated in all. After exclusion of treatments that were combined with either external beam or chemotherapy, 106 lesions (76 patients) were evaluated. Results: Full response was obtained in all but four basal cell carcinomas. The acute reaction ranged from moist desquamation (27 sites) to erythema only. Follow-up at 5 or more months revealed no changes whatever in 47 sites; 53 showed an excellent cosmetic outcome, although slight changes in pigmentation or minimal atrophy was demonstrable and 6 sites became noticeably atrophic with patchy pigmentation. For 9.6 months of average follow-up time, no recurrences have been observed. Conclusion: The high-dose-rate iridium-loaded skin applicators offer the possibility of improved therapeutic ratio in the treatment of superficial skin tumors. With the availability of a high-dose-rate afterloader this technique is simple and straightforward

No abstract available