A comparison between revised Manchester Point A and ICRU-89–recommended Point A definition absorbed-dose reporting using CT images in intracavitary brachytherapy for patients with cervical carcinoma

Abstract

PurposeThis study is a comparison between revised Manchester Point A and International Commission on Radiation Units and measurements (ICRU) 89 report–recommended Point A absorbed-dose reporting in intracavitary brachytherapy for patients with cervical carcinoma. Methods and MaterialsThe retrospective dosimetric study is based on the data of 32 patients with cervical carcinoma treated with high-dose-rate brachytherapy. Patients received 21 Gy in three fractions (7.0 Gy X three fractions) to Point A (Aflange, revised Manchester definition). All the patients were replanned with a new Point A (Aicru89) defined on CT images as per the American Brachytherapy Society/ICRU-89. The data collected were compared with the data obtained from Point A (Aflange). ResultsWhen using the Aflange plan normalization method, the mean dose of 0.1 cc, 1 cc, and 2 cc bladder volumes was 820.79 ± 207.47 cGy, 654.66 ± 152.69 cGy, and 588.91 ± 136.35 cGy, respectively. Likewise, when using the ICRU-89 Point Aicru89 normalization method, the mean dose of 0.1 cc, 1 cc, and 2 cc bladder volumes was 869.30 ± 224.67 cGy, 693.24 ± 166.20 cGy, and 616.61 ± 150.32 cGy, respectively. For the rectum, Point Aflange normalization plans, the mean dose of 0.1 cc, 1 cc, and 2 cc volumes was 589.37 ± 163.26 cGy, 487.51 ± 126.03 cGy, and 442.70 ± 111.43 cGy, respectively. Likewise, using the Aicru89 plan, the mean 0.1 cc, 1 cc, and 2 cc rectum volume was 625.07 ± 171.31 cGy, 517.50 ± 131.05 cGy, 464.94 ± 121.81 cGy, respectively. The statistical mean difference of Total Reference Air Kerma rate, V100 (cc), bladder, rectum and sigmoid, was found significant. ConclusionsIt has been found that the position of revised Manchester (Aflange) and ICRU-89 Point A does not match on CT images/radiograph, which resulted in variation in doses to the tumor, V100 (cc), organ at risk, and Total Reference Air Kerma.