PDT: AFTER 2X24 HOURS

Interstitial technique of PDT is used to debulk huge tumours.
The debulking process started hours after illumination by direct cytotoxic effect of PDT into tumour cells and by vascular shutdown
resulting in tumor apoptosis and necrosis.
In order to treat tumours thicker than 1 cm(limit of light penetration depth into the human tissue),the interstitial illumination technique was invented.
By this technique laser fibres with a light diffuser at the tip are implanted into the tumour tissue.
Laser fibres are feed-through needles,which can be placed under image guidance in the tumour(CT,MRI or US).
In large tumours,several fibres can be placed close to each other(12 cm apart) in order to illuminate the entire tumour volume.
Interstitial light delivery allows PDT to be used in the treatment of large,buried tumours and is particularly suitable for those whose surgery would involve extensive resection or for those who are unsuitable for surgery.
Due to the difficult and non precise light dosimetry in the tumout,interstitial PDT is mainly used with palliativeintention,as stated by Xu et al.
The pictures shown are PDT in large tumour of the neck,before (upper picture)and 2x24 hours (lower picture)after laser interstitial illumination.