Mr. Costas M. Pitsillides Profile

Costas M. Pitsillides

at Massachusetts General Hospital

SPIE Involvement:

Author

Publications (4)

SPIE Journal Paper | 1 January 2011 Open Access

Optical techniques for tracking multiple myeloma engraftment, growth, and response to therapy

Judith Runnels, Alicia Carlson, Costas Pitsillides, Brian Thompson, Juwell Wu, Joel Spencer, John Kohler, AbdelKareem Azab, Anne-Sophie Moreau, Scott Rodig, Andrew Kung, Kenneth Anderson, Irene Ghobrial, Charles Lin

JBO, Vol. 16, Issue 1, 011006, (January 2011) https://doi.org/10.1117/12.10.1117/1.3520571

KEYWORDS: Tumors, Bone, In vivo imaging, Cancer, Flow cytometry, Confocal microscopy, Green fluorescent protein, Skull, Optical tracking, Biomedical optics

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SPIE Journal Paper | 1 November 2007 Open Access

Optical detection of intracellular cavitation during selective laser targeting of the retinal pigment epithelium: dependence of cell death mechanism on pulse duration

Ho Lee, Clemens Alt, Costas Pitsillides, Charles Lin

JBO, Vol. 12, Issue 06, 064034, (November 2007) https://doi.org/10.1117/12.10.1117/1.2804078

KEYWORDS: Cavitation, Cell death, Backscatter, Particles, Pulsed laser operation, Sensors, Scattering, Luminescence, Biomedical optics, Laser scattering

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Proceedings Article | 19 February 2007 Paper

In vivo imaging flow cytometer

Clemens Alt, Ho Lee, Costas Pitsillides, Mehron Puoris'haag, Charles Lin

Proceedings Volume 6441, 64410I (2007) https://doi.org/10.1117/12.702180

KEYWORDS: In vivo imaging, Luminescence, Velocity measurements, Confocal microscopy, Microscopes, Blood, Ear, Beam splitters, Imaging systems, Blood vessels

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Proceedings Article | 14 July 2003 Paper

Monitoring intracellular cavitation during selective targeting of the retinal pigment epithelium

Clemens Alt, Costas Pitsillides, Jan Roegener, Charles Lin

Proceedings Volume 4951, (2003) https://doi.org/10.1117/12.477956

KEYWORDS: Cavitation, Signal detection, Cell death, Retina, Lamps, Laser damage threshold, In vitro testing, In vivo imaging, Laser coagulation, Pulsed laser operation

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Selective targeting of the Retinal Pigment Epithelium (RPE), by either applying trains of microsecond laser pulses or, in our approach, by repetitively scanning a tightly focused spot across the retina, achieves destruction of RPE cells while avoiding damage to the overlying photoreceptors. Both techniques have been demonstrated as attractive methods for the treatment of retinal diseases that are caused by a dysfunction of the RPE. Because the lesions are ophthalmoscopically invisible, an online control system that monitors cell death during irradiation is essential to ensure efficient and selective treatment in a clinical application. Bubble formation inside the RPE cells has been shown to be the cell damage mechanism for nano- and picosecond pulses. We built an optical system to investigate whether the same mechanism extends into the microsecond regime. The system detects changes in backscattered light of the irradiating beam during exposure. Samples of young bovine eyes were exposed in vitro using single pulses ranging from 3 μs to 50 μs. Using the viability assay calcein-AM the ED50 threshold for cell death was determined and compared to the threshold for bubble formation. We also set up a detection system on our slit lamp adapted scanning system in order to determine the feasibility of monitoring threshold RPE damage during selective laser treatment in vivo. Intracellular cavitation was detected as a transient increase in backscattering signal, either of an external probe beam or of the irradiation beam itself. Monitoring with the irradiation beam is both simpler and more sensitive. We found the threshold for bubble formation to coincide with the threshold for cell damage for pulse durations up to 20 μs, suggesting that cavitation is the main mechanism of cell damage. For pulse widths longer than 20 μs, the cell damage mechanism appears to be increasingly thermal as the two thresholds diverge. We conclude that bubble detection can be used to monitor therapeutic endpoint for pulse durations up to 20 μs (or equivalent dwell time in a scanning approach). We have integrated a detection module into our slit lamp adapted laser scanner in order to determine threshold RPE damage during selective laser treatment in vivo.

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