Computed tomography-based three-dimensional dosimetry of intracavitary brachytherapy for cervical cancer

• Published in: Japanese Journal of Radiology Vol. 28; no. 10; pp. 740 - 745
• Main Authors: Wadasaki, Koichi, Monzen, Yoshio, Kurose, Taichi, Okazaki, Hajime, Mito, Mio
• Format: Journal Article
• Language: English
• Published: Japan Springer Japan 01-12-2010; Springer Nature B.V
• Subjects: Adult; Aged; Aged, 80 and over; Brachytherapy - methods; Cervical cancer; Female; Humans; Imaging; Imaging, Three-Dimensional - methods; Medicine; Medicine & Public Health; Middle Aged; Nuclear Medicine; Original Article; Radiology; Radiometry; Radiotherapy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Tomography, X-Ray Computed - methods; Uterine Cervical Neoplasms - radiotherapy; Computed tomography; Cervical cancer; Three-dimensional dosimetry; Intracavitary brachytherapy
• ISSN: 1867-1071; 1862-5274; 1867-108X
• DOI: 10.1007/s11604-010-0504-3

Purpose
The aim of this study was to show the results of computed tomography (CT)-based dosimetry of intracavitary brachytherapy for cervical cancer.
Materials and methods
A total of 20 patients with cervical cancer underwent intracavitary brachytherapy with external beam radiation therapy. The prescribed dose of brachytherapy was 6 Gy per fraction to point A. In every fraction a CT scan was performed after applicator insertion and three-dimensional (3D) dosimetry was done. The tumor dose was evaluated using D90 (the minimum dose delivered to 90% of the volume), and the doses of risk organs were evaluated using D2cc (the minimum dose in the most irradiated 2 cm
3
of the volume).
Results
The mean D90 for the clinical target volume (CTV) was 7.0 Gy (range 4.8–9.8 Gy). There was a negative correlation between the volume and the D90 for the CTV. The mean D2cc doses for the rectum and bladder were 6.0 Gy (range 3.9–9.0 Gy) and 6.5 Gy 5 Gy 2.9–9.0 Gy), respectively.
Conclusion
CT-based 3D dosimetry of intracavitary brachytherapy for cervical cancer was useful for evaluating the doses of the CTV and the organs at risk. In cases with a large CTV, CTV D90 was often lower than the point A dose, and modulation of the prescribed dose might have to be considered.