Room: ePoster Forums
Purpose: Comparison of plans created using the traditional method of point based Manchester system and the volume based treatment proposed by ICRU 89 in HDR brachytherapy, using tandem and ovoid in the treatment of cervical cancer. The plan quality is based on dose coverage to target volumes while keeping the dose to critical structures within tolerance.
Methods: The first and last fraction of 10 cases treated in our institution using the Manchester system were selected for this study. The HR_CTV was contoured on the planning CT by the physician and re-planned according to the ICRU 89. MRI studies were used when they were available to aim in the volume segmentation. For each patient the plans generated by the two methods were compared. The prescription dose per fraction varied from 5.5Gy to 6Gy. Constrains to the critical structures (rectum and bladder) in both sets of plans were, 2cc of the volume receiving less than prescription dose.
Results: The ICRU based plans had up to 32% greater coverage of HR_CTV than those plans normalized to point A. The range of D90% for both sets of plans ranged from 77% to 130%. There was a general decrease in volume of HR_CTV from first fraction to the last as a result of the partial treatment.
Conclusion: The coverage of the HR_CTV in the plans based on ICRU recommendations was greater because they take in consideration the volume to treat, rather than prescribing to a point. In a quarter of the cases the coverage were comparable. The dose to the Bladder and rectum were comparable.