An interstitial light assembly for photodynamic therapy in prostatic carcinoma

BJU Int. 1999 Nov;84(7):821-6. doi: 10.1046/j.1464-410x.1999.00314.x.


Objective: To develop an interstitial laser light delivery system using multiple optical fibres for photodynamic therapy (PDT) in the treatment of prostate cancer.

Patients and methods: A laser beam was divided equally with a 1 x 4 fibre splitter to deliver PDT simultaneously through four 2-cm long, flexible cylindrical optical diffusers. Biplanar transrectal ultrasonography (TRUS) and a template were used to position the optical fibres percutaneously. In vivo measurements of light penetration depth (1/micro[eff] ) in prostate tissue were made in seven patients, using a sheathed isoprobe to measure light fluence rates at varying radial distances from the diffuser. The prostate was fixed with stabilization needles to minimize displacement during needle placement.

Results: The mean (sd, range) micro(eff) in the prostates of the seven patients was 0.35 (0.07, 0.22-0.44) mm-1, which produced closely parallel slopes of light attenuation. However, there was up to a 10-fold variation in absolute light levels at the same diffuser-detector separation distances amongst the seven patients, probably caused by blood pooling around the diffuser light source. A similar problem around the isoprobe detector was overcome by sheathing the probe in clear plastic tubing. By stabilizing the prostate, the optical fibre positioning was precise to within 2 mm.

Conclusion: Although this light delivery and TRUS assembly were developed for clinical PDT in the prostate, the same instrumentation can be used reliably for in vivo light-penetration studies. Haemorrhage was unpredictable and highlighted one of the main problems which needs to be overcome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Equipment Design
  • Fiber Optic Technology / instrumentation
  • Humans
  • Laser Therapy*
  • Male
  • Needles
  • Photochemotherapy / instrumentation
  • Photochemotherapy / methods*
  • Prostatic Neoplasms / drug therapy*