Basic ablation phenomena during laser thrombolysis

Abstract

This paper presents studies of microsecond ablation phenomena that take place during during laser thrombolysis. The main goals were to optimize laser parameters for efficient ablation, and to investigate the ablation mechanism. Gelatin containing an absorbing dye was used as the clot model. A parametric study was performed to identify the optimal wavelength, spot size, pulse energies, and repetition rate for maximum material removal. The minimum radiant exposures to achieve ablation at any wavelength were measured. The results suggest that most visible wavelengths were equally efficient at removing material at radiant exposures above threshold. Ablation was initiated at surface temperatures just above 100°C. A vapor bubble was formed during ablation. Less than 5% of the total pulse energy is coupled into the bubble energy. A large part of the delivered energy is unaccounted for and is likely released partly as acoustic transients from the vapor expansion and partly wasted as heat. The current laser and delivery systems may not be able to completely remove large clot burden that is sometimes encountered in heart attacks. However, laser thrombolysis may emerge as a favored treatment for strokes where the occlusion is generally smaller and rapid recanalization is of paramount importance. A final hypothesis is that laser thrombolysis should be done at radiant exposures close to threshold to minimize any damaging effects of the bubble dynamics on the vessel wall.

Detection and Treatment Systems based on Optics and Photonics in New Age Healthcare Management

“…Endoscopic examination of GIT involves use of light and camera inserted using a flexible tube and a colour TV monitor is the basic example of use of optics for imaging and visualization of disease manifestations [1]. On the other hand, lasers are part of helpful optical instruments in the medical sector from deep vein thrombosis (DVT) to sutures and vessels sealing from time to time [2,3] In case of DVT by 'Laser Thrombolysis' (Use of laser pulses to remove the clots) using different sets of lasers and intensity, timings are used to disintegrate the clot without making unnecessary incisions [2][3][4]. Lasers are also deployed in sensitive surgical procedures for vision impairment owing to its precision, reach, and less invasive properties.…”

“…Apart from proven aesthetic uses like tattoo and pigmentation removal, optical instruments are also to be utilized in the field of non-invasive patient monitoring systems as optical pulse and oxygen saturation analyser for uninterrupted patient recovery and observation. Various skin diseases are being tested by scope of optical scanning including skin cancer, chronic pain using 'photo-dynamic therapy' [2,3]. The scope of optical techniques in diagnostic and therapeutic usage has been described in the adjoining (Figure 1).…”

“…Telemedicine and remote analysis can provide a huge possibility for screening by non-invasive method and remote execution. Development of analytic tools in movement and body structure related disorders with added benefit of being non-invasive as in GAIT and posture analysis [2][3][4][5][6][7]. Different types of lasers are being combined for the therapies like CO 2 lasers are used to make incisions in tissues with low vascularity (mostly used in neurosurgery for precision), while on the other hand with Nd-YAG (neodymium-doped yttrium aluminium garnet; Nd:Y3Al5O12) lasers are applicable in high vascular areas and tumour shrinkage, or surgical removal without leaving scars owing to energy dependent concentration where tumours can be thermally destroyed by concentrating the laser beam.…”

“…It also allows separation of tumours from vital structures minimizing low risk to surrounding tissues in the removal of tumours with surgeries. Use of monochromatic light absorption property different levels of tissues within internal layers can be operated with success [3,4]. Another example is maintenance of secretory activity of small glands glands can be maintained by using a catheter to remove over-secretory regions by flashing laser pulses.…”

“…Whenever brain is exposed to resource scanty conditions the important physiological responses are hampered as brain doesn't have any kind of storage facility for energy produced. The brain does not have pain receptors or physical warning signs for indicating ongoing damage which ultimately leads to brain tissue death [1,[2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Cerebral hypoxia causes a partial/complete loss of functionality of brain tissues due to degeneration [12][13][14][15][16][17][18].…”