K. Serkies et al., Rectal doses in intracavitary brachytherapy of gynecological malignancies:comparison of two dosimetric methods, RADIOTH ONC, 58(1), 2001, pp. 37-41
Citations number
18
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Onconogenesis & Cancer Research
Purpose: To compare calculated rectal doses obtained by two dosimetric meth
ods in intracavitary brachytherapy of gynecological malignancies
Materials and methods: This analysis included 124 intracavitary application
s performed in 102 patients with cervical or endometrial cancer. The pelvic
dose distribution based on orthogonal intracavitary placement films was ca
lculated with the computer planning system. In each application the rectal
dose was defined in the specific rectal point determined by both the use of
a wire marker inserted into the rectum (R1) and by packing the vagina with
radio-opaque gauze - the method recommended by the ICRU Report 38 (R2). Th
e comparison included R1 and R2 doses as well as the respective radiobiolog
ical equivalent doses determined by the linear-quadratic model (r1 and r2).
Results: In 83% of applications the absolute value of R1 was lower than R2.
The mean difference between R1 and R2 was 3.7 Gy (95% CI 3.03-4.41 Gy) and
between r1 and r2 7.2 Gy (95% CI 5.77-8.56 Gy). These differences were sig
nificant (P < 0.001 for both comparisons). The difference between the doses
was not influenced by the type of applicator and remained significant even
when a systemic +/- 10% error of method was assumed.
Conclusion: The rectal point dose determined with the use of rectal wire ma
rker may be underestimated, therefore this method should be discouraged in
gynecological brachytherapy. (C) 2001 Elsevier Science Ireland Ltd. All rig
hts reserved.