Volumetric (3D) bladder dose parameters are more reproducible than point (2D) dose parameters in vaginal vault high-dose-rate brachytherapy.
There is no consensus on the use of computed tomography in vaginal cuff brachytherapy (VCB) planning. The purpose of this study was to prospectively determine the reproducibility of point bladder dose parameters (DICRU and maximum dose), compared with volumetric-based parameters. Twenty-two patients who were treated with high-dose-rate (HDR) VCB underwent simulation by computed tomography (CT-scan) with a Foley catheter at standard tension (position A) and extra tension (position B). CT-scan determined the bladder ICRU dose point in both positions and compared the displacement and recorded dose. Volumetric parameters (D0.1cc, D1.0cc, D2.0cc, D4.0cc and D50%) and point dose parameters were compared. The average spatial shift in ICRU dose point in the vertical, longitudinal and lateral directions was 2.91 mm (range: 0.10-9.00), 12.04 mm (range: 4.50-24.50) and 2.65 mm (range: 0.60-8.80), respectively. The DICRU ratio for positions A and B was 1.64 (p < 0.001). Moreover, a decrease in Dmax was observed (p = 0.016). Tension level of the urinary catheter did not affect the volumetric parameters. Our data suggest that point parameters (DICRU and Dmax) are not reproducible and are not the ideal choice for dose reporting.
Department of Radiation Oncology, A.C. Camargo Cancer Center, São Paulo, 01509-010, Brazil.|Department of Radiation Oncology, Clínicas Oncológicas Integradas (COI-RJ), Rio de Janeiro, 22793-080, Brazil.
Lucas Gomes
LG
Sapienza
Department of Radiation Oncology, A.C. Camargo Cancer Center, São Paulo, 01509-010, Brazil.
Adriana
A
Flosi
Department of Radiation Oncology, A.C. Camargo Cancer Center, São Paulo, 01509-010, Brazil.
Antonio
A
Aiza
Department of Radiation Oncology, A.C. Camargo Cancer Center, São Paulo, 01509-010, Brazil.
Antonio Cassio
AC
de Assis Pellizzon
Department of Radiology, A.C. Camargo Cancer Center, São Paulo, 01509-010, Brazil.
Rubens
R
Chojniak
Department of Gynecologic Oncology, A.C. Camargo Cancer Center, São Paulo, 01509-010, Brazil.
Glauco
G
Baiocchi
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D016889:Endometrial Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014546:Urinary Catheterization; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D055815:Young Adult