Korean J Androl.  2011 Aug;29(2):101-110. 10.5534/kja.2011.29.2.101.

Basic Principles of Laser for Prostate Surgery

• Kim JW
• Moon DG

• KMID: 2226463
• DOI: http://doi.org/10.5534/kja.2011.29.2.101

Abstract

Recent advances in laser technology have provided a varied arsenal for endoscopic treatment of benign prostatic hyperplasia. Laser is a collimated coherent radiation of photons generated by stimulated emission of gain media, allowing transfer of selective, controlled and focused energy to the targeted tissue. The application of laser to prostate surgery developed hand-in-hand with refinements to the equipment. Earlier lasers were low powered modalities with no significant tissue selectivity, aimed at thermal coagulation and resulted in significant side effects and recurrence. Since then, prostate lasers have developed towards a more high-powered and selective modality that allowed complete ablation of the tissue with fewer complications. Fiber technology has also developed to allow efficient and safe transfer of a continuously increasing energy output. It is important for the surgeon to understand these fundamental principles of laser and prostate surgery, not only to select the proper tools, but also to properly implement the technique as well.

Keyword

Prostatic hyperplasia; Laser therapy; Solid-state lasers

MeSH Terms

Imidazoles
Laser Therapy
Lasers, Solid-State
Niacin
Photons
Prostate
Prostatic Hyperplasia
Recurrence
Imidazoles
Niacin

Figure

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  Fig. 1. Lasers are generated by stimulated emission, brought about by pumping the gain medium to an excited state. Released photons oscillate within the optical resonator to emit a collimated, coherent monochromatic electromagnetic radiation.

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  Fig. 2. Tissue effect can also vary with the depth of penetration, due to different levels of temperature achieved within the affected zone.42

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  Fig. 3. Laser wavelength and mode of emission can affect the depth of penetration, leading to a varied profile of energy density (HPS: high performance system, CW: continuous wave).42

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  Fig. 4. Chromophores allow selective absorption of specific wavelengths, vastly improving the tissue effect of certain lasers. Early Nd:YAG lasers are generally nonspecific to either water or hemoglobin. Modern green light lasers are highly absorbed by hemoglobin, while modern infrared lasers are highly absorbed by water.5

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  Fig. 5. Increased power allows the beam to be more collimated. The tissue laser interaction not only benefits from more power, but also from a more focused high intensity transfer of energy (HPS: high performance system, PV: photo vaporization).44

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  Fig. 6. Laser fibers also develop to accommodate the increased laser energy. Newer fibers are designed to allow more flexibility, less loss of energy and greater safety.41

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