Blackmon Richard L, Irby Pierce B, Fried Nathaniel M
Department of Physics and Optical Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-000, USA.
Lasers Surg Med. 2010 Mar;42(3):232-6. doi: 10.1002/lsm.20893.
The holmium:YAG laser is currently the most common laser lithotripter. However, recent experimental studies have demonstrated that the thulium fiber laser is also capable of vaporizing urinary stones. The high-temperature water absorption coefficient for the thulium wavelength (mu(a) = 160 cm(-1) at lambda = 1,908 nm) is significantly higher than for the holmium wavelength (mu(a) = 28 cm(-1) at lambda = 2,120 nm). We hypothesize that this should translate into more efficient laser lithotripsy using the thulium fiber laser. This study directly compares stone vaporization rates for holmium and thulium fiber lasers.
Holmium laser radiation pulsed at 3 Hz with 70 mJ pulse energy and 220 microseconds pulse duration was delivered through a 100-microm-core silica fiber to human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Thulium fiber laser radiation pulsed at 10 Hz with 70 mJ pulse energy and 1-millisecond pulse duration was also delivered through a 100-microm fiber for the same sets of 10 stones each.
For the same number of pulses and total energy (126 J) delivered to each stone, the mass loss averaged 2.4+/-0.6 mg (UA) and 0.7+/-0.2 mg (COM) for the holmium laser and 12.6+/-2.5 mg (UA) and 6.8+/-1.7 (COM) for the thulium fiber laser.
UA and COM stone vaporization rates for the thulium fiber laser averaged 5-10 times higher than for the holmium laser at 70 mJ pulse energies. With further development, the thulium fiber laser may represent an alternative to the conventional holmium laser for more efficient laser lithotripsy.
钬激光目前是最常用的激光碎石设备。然而，最近的实验研究表明，铥光纤激光也能够汽化尿路结石。铥波长的高温水吸收系数（在λ = 1908 nm时μ(a)=160 cm(-1)）显著高于钬波长（在λ = 2120 nm时μ(a)=28 cm(-1)）。我们推测，这意味着使用铥光纤激光进行激光碎石术效率更高。本研究直接比较了钬激光和铥光纤激光的结石汽化率。
钬激光以3 Hz的频率脉冲发射，脉冲能量为70 mJ，脉冲持续时间为220微秒，通过一根100微米芯径的石英光纤传输至人体尿酸（UA）结石和一水草酸钙（COM）结石，均为体外实验（每种结石各10个）。铥光纤激光以10 Hz的频率脉冲发射，脉冲能量为70 mJ，脉冲持续时间为1毫秒，同样通过一根100微米光纤传输至相同的每组10个结石。
对于传输至每个结石的相同脉冲数和总能量（126 J），钬激光导致的质量损失平均为2.4±0.6 mg（UA结石）和0.7±0.2 mg（COM结石），而铥光纤激光导致的质量损失平均为12.6±2.5 mg（UA结石）和6.8±1.7 mg（COM结石）。
在70 mJ脉冲能量下，铥光纤激光对UA和COM结石的汽化率平均比钬激光高5至10倍。随着进一步发展，铥光纤激光可能成为传统钬激光更高效激光碎石术的替代方案。
