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Is two-dimensional field definition sufficient for pelvic node coverage in rectal cancer compared to technical
Maria Antonietta Gambacorta1, Danilo Pasini, Bruce Daniel Minsky
1Department of Radiotherapy, Università Cattolica Sacro Cuore, Rome, Italy. magambacorta@rm.unicatt.it
Tumori
|June 11, 2013
Summary
Three-dimensional (3D) treatment planning significantly improves coverage of at-risk pelvic areas for rectal cancer patients compared to 2D planning. This enhanced coverage in rectal cancer radiotherapy is crucial for reducing recurrence risk.
Area of Science:
- Radiation Oncology
- Medical Physics
- Oncology
Background:
- Rectal cancer treatment planning requires precise targeting of pelvic areas at risk for recurrence.
- Traditional 2D planning may offer suboptimal coverage of these critical regions.
- 3D treatment planning offers a potential improvement in dose distribution and target coverage.
Purpose of the Study:
- To compare the effectiveness of 3D-based treatment planning against 2D pelvic bone-based planning in rectal cancer patients.
- To evaluate coverage of mesorectum and pelvic lymph nodes (internal, external, obturator, presacral) in both planning modalities.
- To assess the impact of planning technique on dose coverage and identify potential areas of suboptimal treatment.
Main Methods:
- Computed tomography (CT) scans of 30 rectal cancer patients were used to delineate areas at risk.
- Two planning target volumes (PTV_T3 and PTV_T4) were created, encompassing mesorectum and various lymph node regions.
- Two-dimensional (2D) and 3D treatment plans were calculated and compared for dose coverage and volume irradiated.
Main Results:
- 3D planning achieved optimal coverage for PTV_T3 in 96.7% of patients, compared to 76.7% with 2D planning.
- For PTV_T4, optimal coverage was achieved in 86.7% with 3D planning versus 33.3% with 2D planning.
- Significant differences in coverage were observed between 7%-97% of the total dose, with suboptimal coverage starting at much higher dose levels for 3D plans.
Conclusions:
- Three-dimensional treatment planning demonstrates superiority over 2D planning for covering at-risk pelvic areas in rectal cancer.
- The improved coverage with 3D planning may reduce the risk of local recurrence.
- Further correlation of suboptimal coverage areas with recurrence patterns is warranted.
