Asian Pacifc Journal of Cancer Prevention, Vol 15, 2014 4717 DOI:http://dx.doi.org/10.7314/APJCP.2014.15.11.4717 2D- and 3D Image Based Dosing with Brachytherapy for Cervical Cancer Asian Pac J Cancer Prev, 15 (11), 4717-4721 Introduction Cervical cancer is the fourth most common cancer in women, and the seventh overall, with an estimated 528,000 new cases in 2012 (Forman et al., 2013). Radiotherapy is an important modality in treatment of cervical cancer and includes external beam radiotherapy (EBRT) and brachytherapy. Therefore brachytherapy is an integral component in the management of cervical cancer. It is indicated after EBRT in locally advanced disease and also in early stage disease (Logsdon and Eifel, 1999; Nag et al., 2000). Conventional brachytherapy is based on clinical examination and 2D point based planning using 1 Department of Radiation Oncology, 2 Department of Radiodiagnosis, 3 Department of Medical Oncology, Dr. B. R. Ambedkar Institute Rotary Cancer Hospital, 4 Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, New Delhi, India *For correspondence: drspathy@gmail.com Abstract Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Materials and Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned . All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Results: Mean doses received by 100% and 90% of the target volume were 4.24±0.63 and 4.9±0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88±0.72, 2.5±0.65 and 2.2±0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80±0.5, 1.48±0.41 and 1.35±0.37 times higher than ICRU rectal reference point. Conclusions: Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning. Keywords: Cervical cancer - image based brachytherapy - dose-volume parameter RESEARCH ARTICLE Comparative Evaluation of Two-dimensional Radiography and Three Dimensional Computed Tomography Based Dose-volume Parameters for High-dose-rate Intracavitary Brachytherapy of Cervical Cancer: A Prospective Study Renu Madan 1 , Sushmita Pathy 1 *, Vellaiyan Subramani 1 , Seema Sharma 1 , Bidhu Kalyan Mohanti 1 , Subhash Chander 1 , Sanjay Thulkar 2 , Lalit Kumar 3 , Vatsla Dadhwal 4 fxed bony landmarks and orthogonal x-ray images for dose calculations and prescriptions irrespective of size or shape of tumour. This leads to inadequate target coverage and insuffcient dose delivery and treatment failure for larger asymmetrical tumours. Newer advances in imaging including computed tomography, magnetic resonance imaging and F-fuorodeoxyglucose positron emission tomography has signifcant role in cancer staging and management (Petsuksiri et al., 2012). Given the limitation of two dimensional (2D) treatment planning, three- dimensional (3D) image based intracavitary brachytherapy (ICRT) visualizes tumour and adjacent organ and provides improved target coverage, local control and reduced late