Radiotherapy Technique in Endometrial Cancer

Whole Pelvis

  • Pelvis: 4-field box to 4500cGy in 25 fractions @ 180cGy per daily fractions (go to 50.4 Gy if no vag cuff boost).
  • Whole abdomen: 30.4 Gy @ 80cGy in 38fx\’s BID then 120 BID to pelvis (AP:PA or 4FP) to 45.6 Gy.
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Vaginal Cuff

  • Completely controversial.
  • Decreases vaginal cuff recurrence from 15% to 1%.
  • Treats upper half to upper 1/3rds of vagina/vaginal cuff.

LDR

  • Cs-137 5mm point source of 20-30 mgRaEq. Typically 15, 10, 10 loading
  • Surface dose 100-120cGy/hour
  • Dose calculated at tip and mid surface of the cylinder
  • Vaginal cuff alone: 55-65 Gy at vaginal surface over 72 hours.
  • EBRT pelvis plus vaginal cuff: 20-30 Gy at vaginal surface over 48 hours. (Total of 65-75 Gy at vaginal surface)
  • It is preferable to treat the vaginal cuff only (treatment of the entire length of the vagina is discouraged

and may increase morbidity). Not more than 2/3 of the vagina should be included in the treatment
volume.

Radiation Dose Total Dose Rate Dose calc point Length of vagina
VB alone 55-65 .8-1.2 Gy/hr vaginal mucosa Vaginal cuff, not more than 2/3 of vagina
EBRT + VB 20 .8-1.2 Gy/hr vaginal mucosa Vaginal cuff, not more than 2/3 of vagina

HDR vaginal cylinder.

  • 192 Ir will be used. Active length 3cm.
  • Dose recommendation is as follows:
  • Vaginal cuff alone:
Dose per fraction Fractions Total Dose Dose calc point
7 3 21 0.5 cm from surface at apex betweeen the ovoids
5.5 4 22 0.5 cm from surface at apex betweeen the ovoids
4.7 5 23.5 0.5 cm from surface at apex betweeen the ovoids
10.5 3 31.5 at vaginal surface
8.8 4 35.2 at vaginal surface
7.5 5 37.5 at vaginal surface
  • EBRT pelvis plus vaginal cuff:
Dose per fraction Fractions Total Dose Dose calc point
5.5 2 11 0.5 cm from surface at apex betweeen the ovoids
4 3 12 0.5 cm from surface at apex betweeen the ovoids
8 2 16 at vaginal surface
6 3 18 at vaginal surface

LDR to HDR Conversion

LDR HDR
Dose Dose per Fraction # of Fractions total Dose Use
25 Gy 6 Gy 3 18 Gy VB boost after WPRT for Endometrial CA
40 Gy 6 Gy 5 30 Gy T & O during WPRT for Cervical CA
60 Gy 7.5 Gy 5 37.5 Gy VB alone for Endometrial CA

LDR Dose vs HDR Dose per fraction for a given # of HDR implants
conversion

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