Study of Irradiation Parameters in HpD Phototherapy of MS-2 Tumor Model
In phototherapy treatment with hematoporphyrin derivatives (HpD) and laser1, the “beam intensity distribution is usually not uniform on the target, area. Thus an average irradiance is defined as ratio “between the laser output power (emitted directly or by optical fiber) and the brightened area. Moreover, it is well known that in the case of ionizing radiation treatment, tumor response is related to the absorbed dose, and to avoid local relapses, the irradiated area, which has a homogeneous dose distribution, must include the tumor peripheral border. The same principles can be applied to photoradiationtherapy (PRT). Nevertheless, as the irradiance distribution in phototherapy is non-homogeneous and bell-shaped, recurrencies near the field border may occur. In contrast, a hyperthermic effect due to overdose may occur in the center of the exposed area. In these cases evaluation of the mechanism of phototherapy effectiveness is questionable.
KeywordsLaser Output Power Hematoporphyrin Derivative Average Irradiance Italian National Research Council Intensity Diameter
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