Dosimetric comparison between conventional and conformal radiotherapy for carcinoma cervix: Are we treating the right volumes?
OBJECTIVE
Conventional portals, based on bony anatomy, for external beam radiotherapy for cervical cancer have been repeatedly demonstrated as inadequate. Conversely, with image-based conformal radiotherapy, better target coverage may be offset by the greater toxicities and poorer compliance associated with treating larger volumes. This study was meant to dosimetrically compare conformal and conventional radiotherapy.


METHODS
Five patients of carcinoma cervix underwent planning CT scan with IV contrast and targets, and organs at risk (OAR) were contoured. Two sets of plans-conventional and conformal were generated for each patient. Field sizes were recorded, and dose volume histograms of both sets of plans were generated and compared on the basis of target coverage and OAR sparing.


RESULTS
Target coverage was significantly improved with conformal plans though field sizes required were significantly larger. On the other hand, dose homogeneity was not significantly improved. Doses to the OARs (rectum, urinary bladder, and small bowel) were not significantly different across the 2 arms.


CONCLUSIONS
Three-dimensional conformal radiotherapy gives significantly better target coverage, which may translate into better local control and survival. On the other hand, it also requires significantly larger field sizes though doses to the OARs are not significantly increased.
Department of Radiotherapy, Westbank Hospital, Howrah, Kolkata, West Bengal, India.
Jyotirup
J
Goswami
Department of Radiotherapy, Medical College, Kolkata, West Bengal, India.
Niladri B
NB
Patra
Department of Radiation Oncology and Medical Physics, Advanced Medicare and Research Institute Cancer Centre, Kolkata, West Bengal, India.
Biplab
B
Sarkar
Department of Radiation Oncology, United Hospital, Dhaka, Bangladesh.
Ayan
A
Basu
Department of Radiotherapy, Medical College, Kolkata, West Bengal, India.
Santanu
S
Pal
Conventional radiotherapy; carcinoma cervix; conformal radiotherapy; dosimetric comparison