Abstract:
Sapphire needle capillary irradiators have been developed for interstitial laser therapy and surgery on a base of thin crystalline tubes with a monolithic needle at the working end. The sapphire capillary protects located inside quartz fiber which deliver laser radiation (including high-power) from chemical and/or mechanical damage, and also transform the axial beam coming out of the fiber into a diffuse distribution for irradiating of tumors of varying sizes and locations. In addition to the geometry of the external surfaces of the irradiator, the shape of the transition from the tubular part of the capillary to the monolithic one (through which the radiation from the quartz fiber enters the monolithic needle end) has an influence on the angular distribution of radiation in the beam. This paper explores how different factors of growth process affect the ability to control the geometry of the transition area – the shape of the channel's bottom. The parameters of the radiation beam emitted from the needle-tipped irradiator were assessed based on the geometry of the transition region. The analysis demonstrates that with a conical monolithic tip, for typical sphericity values of the canal bottom, a partially collimated or focused beam is generated, spreading from the needle tip into the tissue volume. It has been demonstrated that to enhance the resolution of devices utilizing sapphire components with enclosed capillary channels, precise micro-scale control of the geometry and surface quality of the irradiator is essential.
Fulltext:
PDF file (505 kB)