Room: AAPM ePoster Library
Lateral and anterio-posterior dose coverage in intracavitary brachytherapy can provide adequate dosimetric coverage of tumor volumes for the cancer cervix patients. We have developed a 3cm diameter intra–vaginal template for patients with narrow vagina who requires interstitial+intracavitary technique. Commissioning and dosimetric analysis done for the above applicator.
3cm diameter cylinder with 20 needles insertion and central tandem probe was made. Lateral oblique needles have the distance from point A is 3.2cm and anterior oblique needle angulation from central tandem is 12.5°. In the second plane (Left and Right), three needles were angulated laterally to cover the parametrial extension and two straight needles were used to reduce the cold/hot spot. 20 HRCTVs were made in scanned DICOM images of the applicator in TPS. Point A based plan was generated by using central tandem and first lateral plane for both the sides with six needles. These six anterior oblique needles were used for ovoid type loading. As per GEC-ESTRO guidelines, dose coverage was extended to HRCTV by using manual optimization. Autoradiograph was taken with Gafchromic films to correct the offset.
Mean HRCTV volume is 57.7cc. The mean V98% and V95% of all HRCTV is 96.9%(SD = 2.64) and 97.4%(SD = 2.28) respectively. V150% and V200% is 78.6%(SD=11.8%) and 57.2%(SD=12.86%) respectively. Maximum lateral coverage from point A is extending up to 4.2cm. The mean TRAK value is 0.631 and ranging from 0.496 to 0.658 for 7Gy dose prescription. Offset of the needle is 6mm.
The 3cm diameter intracavitary plus interstitial applicator is able to provide adequate coverage for planned HRCTVs without compromising the pear shape distribution. This 3cm template may helpful to treat cancer cervix patients with narrow vagina.