Target dose conformity in 3-dimensional conformal radiotherapy and intensity modulated radiotherapy.
OBJECTIVE
Dose conformity to the planning target volume is an important criterion in radiotherapy treatment planning, for which the conformity index is a useful assessment tool. The purpose of this study is to compare the differences in CI for the treatment planning of four cancers including the nasopharynx, oesophagus, lung and prostate.


METHODS
Seventy patients with cancers of nasopharynx (30), oesophagus (15), lung (15) and prostate (10) were recruited. Each of these patients was planned with three sets of treatment plans using the FOCUS treatment planning system: the forward and inverse 3DCRT plans and the IMRT plan. The CI was generated for each treatment plan. The mean CI from each cancer patient group was calculated and compared with the other three cancer groups. The mean value of CI was also compared among the three planning methods.


RESULTS
The oesophageal and lung cancers demonstrated relatively higher overall mean CI values (0.64 and 0.62, respectively), whereas that of the nasopharynx and prostate were lower (0.54 and 0.50, respectively). With regards to the planning method groups, the IMRT plans produced the highest overall mean CI (0.62), while those for the forward and inverse 3DCRT were similar (0.57 and 0.55, respectively).


CONCLUSIONS
For the four selected cancers, oesophageal and lung cancers were easier to conform than the nasopharyngeal and prostate cancers. The IMRT plans were more effective in achieving better dose conformity than that of the 3DCRT.
Wu
Vincent W C
VW
Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China.
Kwong
Dora L W
DL
Sham
Jonathan S T
JS
D015331:Cohort Studies; D004307:Dose-Response Relationship, Radiation; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed