Magnitude and Implications of Interfraction Variations in Organ Doses during High Dose Rate Brachytherapy of Cervix Cancer: A CT Based Planning Study

Table 2

Table showing variation in dose to rectum and bladder in various studies.

Author	Imaging	𝑁	Applicator type	Prescribed dose	Mean variation rectal 𝐷2cc	Mean variation bladder 𝐷2cc
Patel et al. [12]	CT	69	TR	4.2 Gy	1.08 Gy (25.76%)*	1.22 Gy (29.00%)*
Davidson et al. [13]	CT	108	TR/TO	7 Gy	1.70 Gy (24.30%)	4.40 Gy (61.00%)
Kirisits et al. [14]	MRI	62	TR	7 Gy	3.50 Gy3^† (29.10%)	4.20 Gy3^† (24.70%)
Present series	CT	88	TO	9 Gy	1.16 Gy (12.90%)	1.46 Gy (16.20%)

All % variations are with respect to the prescribed dose to point A for the study. Mean variations in minimum dose to 2 cc volume in the most irradiated tissue adjacent to the applicator (𝐷_2cc) for rectum and bladder are shown. Prescribed dose is prescribed dose per fraction. 𝑁: number of insertions studied; CT: computed tomography; MRI: magnetic resonance imaging; TR: tandem ring applicator; TO: tandem ovoid applicator; *dose to 95% volumes of the respective organs; ^†dose in EQD2 assuming 𝛼/𝛽 ratio of 3.