Photoselective vaporization of the prostate (PVP) is considered a minimally invasive procedure to treat benign prostatic
hyperplasia (BPH). During the PVP, the prostate gland is irradiated by the 532-nm laser and the fiber is swept and
dragged along the urethra. In this study the speed of sweeping fiber during the PVP is being investigated. In vitro
porcine kidney model was used (N=100) throughout the experiment. A Q-switched 532-nm laser, equipped with sidefiring
750-Um fiber, was employed and set to power levels of 120 and 180 W. The speed of fiber sweeping was the only
variable in this study and varied at 0 (i.e. no sweeping), 0.5, 1.0, 1.5, and 2.0 sweep/s. Ablation rate, depth, and
coagulation thickness were quantified. Based on the current settings, ablation rate decreased as sweeping speed increased
and was maximized between 0 to 1.0 sweep/s for 120-W power level and between 0 to 0.5 sweep/s for 180-W power
level. Ablation rate at 180 W was higher than that at 120 W, regardless of sweeping speed. Ablation depth at both 120
and 180 W was maximized at 0 sweep/s and decreased 35% at 0.5 sweep/s. The overall coagulation thickness was less
than 1.5 mm and comparable from 0 to 1.5 sweep/s (0.8~0.9 mm) and increased at 2.0 sweep/s (~1.1 mm). This study
demonstrated that tissue ablation performance was contingent upon sweeping speed and maximized at slow sweeping
speed due to longer laser-tissue interaction time and larger area coverage by the 532-nm light.
Photoselective vaporization of the prostate (PVP) has been widely used to treat benign prostatic hyperplasia (BPH). It is
well regarded as a safe and minimally invasive procedure and an alternative to the gold standard transurethral resection
of the prostate (TURP). Despite of its greatness, as well aware of, the operative procedure time during the PVP is still
prolonged. Such attempts have been tried out in order to shorten the operative time and increase its efficacy. However,
scientific study to investigate techniques used during the PVP is still lacking. The objective of this study is to investigate
how sweeping angle might affect the PVP performance. Porcine kidneys acquired from a local grocery store were used
(N=140). A Q-switched 532-nm GreenLight XPSTM (American Medical Systems, Inc., MN, USA), together with 750-
μm core MoXyTM fiber, was set to have power levels of 120 W and 180 W. Treatment speed and sweeping speed were
fixed at 2 mm/s and 0.5 sweep/s, respectively. Sweeping angles were varied from 0 (no sweeping motion) to 120 degree.
Ablation rate, depth, and coagulation zone were measured and quantified. Tissue ablation rate was peaked at 15 and 30
degree for both 120- and 180-W power levels and dramatically decreased beyond 60 degree. At 180 W, ablation rate
increased 20% at 30 degree compared to 0 degree. This study demonstrated that ablation rate could be maximized and
was contingent upon sweeping angle.
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