Search

Purpose: During intracavitary brachytherapy (ICBT) for cervical cancer, the choice of applicator system remains rather arbitrary. However, as the applicator geometry may play an important role in dose distribution, thereby improving the the rapeutic ratio, this study was conducted to compare the Manchester-style and Fletcher-style applicator systems. Material and methods: After completion of EBRT, 22 patients with cervical cancer (stage IIA-IIIB) underwent in tracavitary brachytherapy. Two different types of applicators: Manchester-style and Fletcher-style were used for each patient for alternate insertions. The purpose was to compare the dose distribution obtained when two different appli cators were applied to the same patient. CT based computerized treatment planning was done and dose was prescribed to point A. After optimization, height, width and thickness of the 100% isodose curve, as well as the 100% isodose vol ume were noted. Dose received by the urinary bladder and rectum were noted. Results: The 100% isodose volume and its maximum width were significantly greater ( P value < 0.0001 in both oc casions) when Manchester-style applicator was used. However, the dose received by 0.1 cc, 1.0 cc and 2.0 cc of the uri nary bladder were all significantly greater ( P value < 0.0001) with the Manchester-style applicator. No significant dif ference was found in rectal doses. Conclusions: The larger 100% isodose volume, as well as the greater width achieved with the use of Manchesterstyle applicator can be helpful in circumstances where the tumour is large in size. However, this must be balanced against the increased dose received by the urinary bladder. J Contemp Brachyther 2012; 4, 4: 213‐218 DOI: 10.5114/jcb.2012.32555

Purpose: This study was initiated to prove feasibility of hydrogel application in recto-vaginal space in intracavitary brachytherapy (ICBT) of cervical cancer in order to reduce rectal toxicity. Material and methods: In a case of stage IIB cervical cancer, after external beam radiotherapy (EBRT), we planned ICBT 7 Gy x 3 fractions. In 1st fraction (Plan 1), due to narrow separation between rectum and cervix (0.18 cm), only 5 Gy was delivered at point A (with high-risk clinical target volume [HR-CTV] D 90 5.94 Gy, intermediate risk clinical target volume [IR-CTV] D 90 4.54 Gy, rectum D 2cc 5.72 Gy, bladder D 2cc 5.52 Gy, and sigmoid colon 5.82 Gy). In 2nd fraction (Plan 2), interstitial brachytherapy (ISBT) was attempted. For the prescription of 5 Gy, we get dose levels almost similar to the 1st insertion: HR-CTV D 90 (6.7 Gy), IR-CTV D 90 (3.06 Gy), bladder D 2cc (5.7 Gy), rectum D 2cc (4.8 Gy), sigmoid colon D 2cc (1.3 Gy) (separation = 0.23 cm). During 3rd fraction (Plan 3), prior doing interstitial insertion, we instilled 50 cc of hydroxypropyl methylcellulose (Viscomet®) up to the tip of recto-vaginal septum. A repeat computed tomography (CT) scan was done 4 hours after Plan 3 treatment and it was re-planned (Plan 4) to find out migration of hydrogel if any and its dosimetric impact. Results : 9 Gy was delivered to point A with a separation of 1.1 cm in Plan 3 (with HR-CTV D 90 16.4 Gy, IR-CTV D 90 11.3 Gy, rectum D 2cc 3.6 Gy, bladder D 2cc 6.9 Gy, and sigmoid colon 2.2 Gy). We achieved an optimum cumulative EQD 2 dose (HR-CTV D 90 98.4 Gy, IR-CTV D 90 76.1 Gy, rectum D 2cc 67.7 Gy, bladder D 2cc 73.2 Gy, and sigmoid colon 59.3 Gy). Hydrogel volume was decreased in Plan 4 without a major dosimetric changes. Conclusions : Hydrogel instillation is a useful tool for recto-vaginal separation during cervical cancer brachytherapy. It increases therapeutic ratio without any adverse event.

Purpose During intracavitary brachytherapy (ICBT) for cervical cancer, the choice of applicator system remains rather arbitrary. However, as the applicator geometry may play an important role in dose distribution, thereby improving the therapeutic ratio, this study was conducted to compare the Manchester-style and Fletcher-style applicator systems. Material and methods After completion of EBRT, 22 patients with cervical cancer (stage IIA-IIIB) underwent intracavitary brachytherapy. Two different types of applicators: Manchester-style and Fletcher-style were used for each patient for alternate insertions. The purpose was to compare the dose distribution obtained when two different applicators were applied to the same patient. CT based computerized treatment planning was done and dose was prescribed to point A. After optimization, height, width and thickness of the 100% isodose curve, as well as the 100% isodose volume were noted. Dose received by the urinary bladder and rectum were noted. Results The 100% isodose volume and its maximum width were significantly greater (P value < 0.0001 in both occasions) when Manchester-style applicator was used. However, the dose received by 0.1 cc, 1.0 cc and 2.0 cc of the urinary bladder were all significantly greater (P value < 0.0001) with the Manchester-style applicator. No significant difference was found in rectal doses. Conclusions The larger 100% isodose volume, as well as the greater width achieved with the use of Manchester-style applicator can be helpful in circumstances where the tumour is large in size. However, this must be balanced against the increased dose received by the urinary bladder.