Dosimetric comparison of ACE algorithm and TG-43 formalism in HDR brachytherapy of carcinoma cervix
Shraddha Srivastava,
India
MO-0304
Abstract
Dosimetric comparison of ACE algorithm and TG-43 formalism in HDR brachytherapy of carcinoma cervix
Authors: Shraddha Srivastava1, Ajay K V1, Mohammad Jabir A1, Nara Moirangthem Singh2
1King George's Medical University, Radiotherapy, Lucknow, India; 2Dr. B. Borooah Cancer Institute, Radiotherapy, Lucknow, India
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Purpose or Objective
TG-43 formalism has been widely used in brachytherapy for dose calculation. However, this method does not consider the tissue and applicator heterogeneities. In the present study, we have compared the effect of model-based dose calculation algorithms like Advanced Collapsed cone Engine (ACE) on dose calculation with the TG-43 dose calculation formalism in patients with cervical carcinoma.
Material and Methods
8 patients with 24 CT data sets of HDR intracavitary brachytherapy plans in cervical cancer were retrospectively studied. HR-CTV and organs at risk (OAR) were contoured in the Oncentra treatment planning system using GYN GEC-ESTRO guidelines. Patients were planned for 7 Gy per fraction for 3 fractions. Plans were initially calculated using TG 43 formalism and then recalculated using the ACE (Elekta, Stockholm, Sweden) algorithm with applicator models selected from the applicator library. The dosimetric parameters of TG-43 and ACE-based plans were compared in terms of target coverage (V100, D90, D100), OAR doses (D2cc, D1cc, and D0.1cc), homogeneity index (HI), and conformity index (CI).
Results
The mean percentage difference between right point A values of TG-43 and ACE was -0.08±0.27%. For HR-CTV, the average D90 values for TG-43 and ACE calculated plans were 5.27±1.17 Gy and 5.27±1.16 Gy respectively. The mean percentage difference for doses D90 and D100 was found to be -0.02±0.59 % and 0.60±1.18% respectively. The average V100 values for TG-43 and ACE calculated plans were 74.80±13.90% and 74.83±13.31% respectively. For bladder, the mean percentage differences for D2cc, D1cc, and D0.1cc values between TG-43 and ACE were -0.39±0.61%, -0.40±0.59%, and -0.28±0.54 % respectively. In the case of the rectum, the mean percentage differences for D2cc, D1cc, and D0.1cc values between TG-43 and ACE were -0.21±0.59%, -0.20±0.55%, and -0.15±0.47% respectively. Similarly, for sigmoid these values were 0.27±1.19%, 0.20±0.98% and 0.14±0.67% respectively.
Conclusion
The ACE improved the dose accuracy compared to the TG-43 formalism. However, we did not find any significant difference between the dose-volume parameters of TG-43 and ACE calculated plans.