Three-dimensional dosimetric evaluation of a conventional radiotherapy technique for treatment of nasopharyngeal carcinoma

Plan Dose Evaluation of Three Dimensional Conformal Radiotherapy Planning (3D-CRT) of Nasopharyngeal Carcinoma (NPC): Experience of a Tertiary Care University Hospital in Pakistan

“…The area of under coverage was found to be superior (base of skull) followed by posterior/superior or posterior (brainstem/spinal cord) (Waldron et al, 2003). Chau et al (2001) also did the 3D dosimetric evaluation of the conventional radiotherapy technique found that problem of geographical miss was less significant in early stage diseases and the area with highest potential for missing include edge of shielding, blocks and field border (Chau et al, 2001). One of the interesting and important differences between 2D and 3D techniques is the pattern of failure 2D results in loco regional failure while three dimensional results in failure at distant site due to improved local control (Teo et al, 2004).…”

Pathogenesis of Cognitive Decline Following Therapeutic Irradiation for Head and Neck Tumors

“…The median volume of gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV) covered by the 95% isodose line in the 2-D plan was 60%. When 3-D beam eye views (BEV) customization of the treatment portals was used, there was a signi cant improvement in the median volume of target covered by the 95% isodose (50). M oreover, with the introduction of a hypoth alamico-pituitary shield, 50% of the volume of the optic chiasmata and temporal lobe received 19.3 G y and 4.5 G y, respectively, out of a total possible dose of 66 G y.…”

Preliminary Results of a Phase I/II Study of Simultaneous Boost Irradiation Radiotherapy for Locally Advanced Nasopharyngeal Carcinoma

“…And as for national conditions of develpoing countries like ours, conventional radiotherapy will still play an important role in the treatment of nasopharyngeal carcinoma for a period of time in the future (Yin et al, 2008). Chau et al (2001) believe two-dimensional radiation therapy could not achieve satisfactory coverage dose for pathological changes of invaded areas like base of skull and parapharyngeal space.Therefore, how to increase local control for advanced nasopharyngeal carcinoma without increasing late toxic reactions by conventional radiotherapy is a burning difficult problem. Due to the extensive invasion of advanced nasopharyngeal carcinoma, the relatively large tumor-volume load results in radioresistance because of local hypoxia (Li et al, 2006).…”

“…Researches on 3-d dosiology by some scholars indicate that there is usual attenuation of dose in sclerotin of base of skull treated by irradiation of 60Co or X-ray beams of MV degree linear accelerator, because this region locates at the edge of field, dose in the base of skull is 7%-15% less than that in the center, so it could be controlled in a high dose (Chau et al, 2001). Wolden et al (2006) suggest an increase of irradiation dose in the tumor target volume to improve local control rate after the analysis of reasons for local failure.But there are many adjacent OARs with low-tolerated dose, single beam direction of conventioanal radiotherapy could not increase target volume dose and simultaneously reduce irradiation dose in normal tissues.…”