Q18- We want to diagnose a lesion in which hematoporphyrin derivative (HPD) is g
ID: 101472 • Letter: Q
Question
Q18- We want to diagnose a lesion in which hematoporphyrin derivative (HPD) is greatly concentrated. We also want to generate light to photoactivate the compound concentrated into the lesion. An endoscope must be used during the procedure simultaneously. Which steps below would you recommend to achieve this procedure successfully?
A). Use a CO2laser to diagnose the lesion, a Kr laser to photoactivate HPD and an endoscope made with focused silica fibers.
B). Use a red HeNelaser to diagnose to lesion, a Kr laser to photoactivate HPD and an endoscope made with fused silica fibers.
C). Use a Kr laser to diagnose the lesion, a red HeNe laser to photoactivate endoscope make with fused silica fibers.
D). Use a Kr laser to diagnose the lesion, a red HeNe laser to photoactivate HPD and an endoscope made with chalcogenide glass fibers.
E). Use an excimer laser to diagnose the lesion and photoactivate HPD. Use an endoscope made with sapphire sibers
Q19 which of the following statements is false?
A). The process of fluorescence is used to excite exogenous fluorophores
b). Er:Yag laser radiation is strongly absorbed by tissue.
C). The penetration of Er:Yag laser is very small in tissue.
D). FREDDY Nd:Yag can be used in lithotripsy
E). Ho:Yag cannot be used in lithotripsy
Explanation / Answer
18. The hematoporphyrin derivative is absorbed selectively by some cells, that is cancerous cells .He-Ne laser is a good alternative to the Krypton laser (violet) for HpD fluorescence excitation.However the procedure is first Kr laser light of 420nm is delivered using laser catheter . Then if luminescence is seen, red light (630nm) laser beam i.e, HE-Ne laser is sent to illuminate the malignant tumor. the endoscope would be with fused silica fibers. So option C would suit.
19. Penetration of Er.Yag is small in tissue, due to higher absorption. Ho:Yag is used in corporeal Lithotripsy. They have a wavelength of 2100nm. They are similar to Nd:Yag lasers.So the last statement is false. Option E is the answer.
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