External Beam Alternatives to Vaginal Cuff Brachytherapy
Z Carter1, J Fang2, X Li3*, (1) Georgia Institute of Technology, Atlanta, GA, (2) Ascension Saint Thomas Rutherford Hospital, Murfreesboro, TN, (3) University of Utah, Salt Lake City, UT
Presentations
PO-GePV-T-357 (Sunday, 7/10/2022) [Eastern Time (GMT-4)]
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Purpose: To investigate possible alternatives to the traditional Ir-192 HDR vaginal cuff brachytherapy (VCB) technique using a common linear accelerator 6 MV photon beam.
Methods: Both the VMAT, and MLC-defined conformal arc techniques are evaluated to mimic the dose distribution of an HDR VCB cylinder treatment. All plans have a prescription of 2100 cGy to the 0.5 depth of 30 mm Cylinder, 4 cm treatment length. In order to keep the coverage similar, a PTV from the original HDR plan was created and used in dose optimization in these techniques. Transverse profiles with dose fall off information among these techniques are compared to the HDR plan.
Results: All plans demonstrate very similar dose coverage for the defined PTV. After evaluating the dose at a different distances from the cylinder surface along the profiles, the HDR plan shows the fastest dose fall off, followed by the VMAT plan and the conformal arc plan.
Conclusion: This preliminary work indicates the potential for use of a simple arc technique that may allow clinics to treat VCB without the need for an Ir-192 source. Since VCB requires the use of a radioactive Ir-192 source, clinics which do not possess an HDR remote afterloader are unable to perform this technique. Additionally, regulations for use of the HDR source and extra staffing and facility requirements may make it difficult to fit these patients into the treatment schedule of a typical busy radiation oncology center. Although the HDR plan shows a better dose fall off, the two external beam techniques are comparable to the HDR technique with acceptable dose increase to the organ at risk but more uniform target coverage. We conclude that these external beam techniques are feasible as alternative methods for HDR VCB, and further investigation with different energies, machines, immobilization, etc. will be required.
Keywords
HDR, Intensity Modulation, Treatment Techniques
Taxonomy
TH- Brachytherapy: HDR Brachytherapy
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