Journal Article DKFZ-2026-00953

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Influence of Interfractional Variations of Bladder and Rectal Filling on Vaginal Cuff Movement and the Role of Rectal Balloons in Gynecological Pelvic Proton Beam Therapy.

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2026
Sage Publishing Thousand Oaks, CA

Technology in cancer research & treatment 25, 15330338261438327 () [10.1177/15330338261438327]
 GO

Abstract: IntroductionPostoperative active raster-scanning intensity modulated proton beam therapy (IMPT) for gynecological cancers requires precise target coverage, yet interfractional motion of the vaginal cuff and adjacent pelvic organs may compromise dosimetric robustness. This study retrospectively assessed interfractional organ movement and evaluated the clinical need for rectal balloon (RB) use to ensure adequate target coverage.Methods23 patients, 17/6 with/without RB, received postoperative IMPT between 2017 and 2020 at Heidelberg Ion-beam Therapy Center (HIT). Positioning verification computed tomography (pv-CT) and treatment planning CT (tp-CT) images were retrieved and rectum, bladder and the vaginal cuff (VC) were contoured. The clinical target volume (CTV) and planning target volume (PTV) were mapped from tp-CT to the pv-CT images and forward dose calculation was performed. To assess the volume of the VC not covered by the CTV or PTV, the region of interest (ROI), VC outside of CTV (VC-CTV) and outside of PTV (VC-PTV) were created. Volume differences (Δ) to the tp-CT images and dose parameters for each ROI were evaluated.Results139 pv-CTs were analysed. The use of RB significantly reduced VC displacements, resulting in fewer pv-CTs with the VC located outside the CTV (40% vs. 91%, p = 0.0252) and PTV (28% vs. 68%, p = 0.0362). CTV/PTV coverage and ROI doses remained stable across all fractions and there was no significant difference between groups. The applied PTV margins ensured robust dose coverage despite interfractional anatomical variations.ConclusionRB application effectively reduced interfractional VC motion and there was no significant Δ in target coverage or ROI doses. Using tp-CT images with full and empty bladder for definition of the CTV and standardized PTV margins contributed to stable dosimetry outcomes, confirming the robustness of the used IMPT treatment protocol. However, the use of RB may be beneficial, especially in patients with known gastrointestinal comorbidities or trapped air in the rectum.

Keyword(s): Humans (MeSH) ; Female (MeSH) ; Proton Therapy: methods (MeSH) ; Rectum: radiation effects (MeSH) ; Rectum: diagnostic imaging (MeSH) ; Urinary Bladder: diagnostic imaging (MeSH) ; Urinary Bladder: radiation effects (MeSH) ; Radiotherapy Planning, Computer-Assisted: methods (MeSH) ; Vagina: radiation effects (MeSH) ; Vagina: diagnostic imaging (MeSH) ; Genital Neoplasms, Female: radiotherapy (MeSH) ; Genital Neoplasms, Female: pathology (MeSH) ; Retrospective Studies (MeSH) ; Radiotherapy Dosage (MeSH) ; Radiotherapy, Intensity-Modulated: methods (MeSH) ; Tomography, X-Ray Computed (MeSH) ; Middle Aged (MeSH) ; Organs at Risk: radiation effects (MeSH) ; Aged (MeSH) ; cervical cancer ; endometrial cancer ; interfractional organ movement ; proton beam therapy ; rectal balloon ; vaginal cuff

Classification:

Note: #DKTKZFB26# / #NCTZFB26#

Contributing Institute(s):
  1. E210 KKE Translationale Radioonkologie (E210)
  2. E050 KKE Strahlentherapie (E050)
  3. DKTK HD zentral (HD01)
  4. Koordinierungsstelle NCT Heidelberg (HD02)
Research Program(s):
  1. 315 - Bildgebung und Radioonkologie (POF4-315) (POF4-315)

Appears in the scientific report 2026
Database coverage:
Medline ; DOAJ ; Article Processing Charges ; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; DOAJ Seal ; Essential Science Indicators ; Fees ; IF < 5 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection
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 Record created 2026-04-22, last modified 2026-04-27



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