Fig. 5:

Printout of representative subpulses from the system used in the present study (left) with time-resolved spectral distribution and a typical system without this technology (right). For both systems the macropulse width was 70 ms, made up of 3 20 ms micropulses (subpulses) separated by a 20 ms interpulse interval, and the pulse energy was 28 J/cm². Different cut-off filters were used, 510 nm for the study system and 650 nm for the other system. The trial system had an integral cut-on filter at 950 nm, with no cut-on filter for the other system. The absolute regularity of the spectral energy distribution in the subpulses is apparent in the trial system, also giving a very precise cut-off value. On the contrary, the energy distribution across the spectrum in the subpulses for the other system is irregular, potentially leading to unwanted hotspots in the treatment beam with possible side effects such as the ‘tiger skin’ effect.