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Does inadequate Point-A dose warrant treatment plan modifications in CT-image-based cervix high dose-rate brachytherapy planning? A dosimetric perspective

  • R. Yaparpalvi (a1), K. J. Mehta (a1), S. Mutyala (a2), H. C. Kuo (a1), L. Hong (a1) and S. Kalnicki (a1)...

Abstract

Background and purpose

To investigate whether inadequate dose to Point-A necessitates treatment plan changes in a time of computed tomography (CT)-image-guided brachytherapy treatment planning for cervix cancer.

Materials and methods

A total of 125 tandem and ovoid insertions from 25 cervix patients treated were reviewed. CT-image-based treatment planning was carried out for each insertion. Point-A is identified and the dose documented; however, dose optimisation in each plan was based on covering target while limiting critical organ doses (PlanTarget). No attempts were made to equate prescription and Point-A dose. For each insertion, a second hypothetical treatment plan was generated by prescribing dose to Point-A (PlanPoint-A). Plans were inter-compared using dose–volume histogram analyses.

Results

A total of 250 treatment plans were analysed. For the study population, the median cumulative dose at Point-A was 80 Gy (range 70–95) for PlanTarget compared with 84·25 Gy for PlanPoint-A. Bladder and rectal doses were higher for PlanPoint-A compared with PlanTarget (p < 0·0001). Target D90 did not correlate with Point-A dose (p = 0·60).

Conclusions

Depending on applicator geometry, tumour size and patient anatomy, Point-A dose may vary in magnitude compared with prescription dose. Treatment plan modifications purely based on inadequate Point-A dose are unnecessary, as these may result in higher organ-at-risk doses and not necessarily improve target coverage.

Copyright

Corresponding author

Correspondence to: Ravindra Yaparpalvi, Department of Radiation Oncology, Montefiore Medical Center, 111 East 210th Street, Bronx, New York 10467, USA. Tel: +718-920-7750. Fax: +718-882-6914. E-mail: ryaparpa@montefiore.org

References

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Keywords

Does inadequate Point-A dose warrant treatment plan modifications in CT-image-based cervix high dose-rate brachytherapy planning? A dosimetric perspective

  • R. Yaparpalvi (a1), K. J. Mehta (a1), S. Mutyala (a2), H. C. Kuo (a1), L. Hong (a1) and S. Kalnicki (a1)...

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