C. Lapuz

Dosimetric comparison of optimization methods for multichannel intracavitary brachytherapy for superficial vaginal tumors

PURPOSE Multichannel vaginal applicators allow treatment of a more conformal volume compared with a single, central vaginal channel. There are several optimization methods available for use with multichannel applicators, but no previous comparison of these has been performed in the treatment of superficial vaginal tumors. Accordingly, a feasibility study was completed to compare inverse planning by simulated annealing (IPSA), dose point optimization (DPO), and graphical optimization for high-dose-rate brachytherapy using a multichannel, intracavitary vaginal cylinder. METHODS AND MATERIALS This comparative study used CT data sets from five patients with superficial vaginal recurrences of endometrial cancer treated with multichannel intracavitary high-dose-rate brachytherapy. Treatment plans were generated using DPO, graphical optimization, surface optimization with IPSA (surf IPSA), and two plans using volume optimization with IPSA. The plans were evaluated for target coverage, conformal index, dose homogeneity index, and dose to organs at risk. RESULTS Best target coverage was achieved by volume optimization with IPSA 2 and surf IPSA with mean V100 values of 93.89% and 91.87%, respectively. Doses for the most exposed 2-cm(3) of the bladder (bladder D2cc) was within tolerance for all optimization methods. Rectal D2cc was above tolerance for one DPO plan. All volume optimization with IPSA plans resulted in higher vaginal mucosa doses for all patients. Greatest homogeneity within the target volume was seen with surf IPSA and DPO. Highest conformal indices were seen with surf IPSA and graphical optimization. CONCLUSIONS Optimization with surf IPSA was user friendly for the generation of treatment plans and achieved good target coverage, conformity, and homogeneity with acceptable doses to organs at risk.

Stage IB cervix cancer with nodal involvement treated with primary surgery or primary radiotherapy: Patterns of failure and outcomes in a contemporary population.

The purpose of this study is to evaluate patterns of failure, overall survival (OS), disease‐free survival (DFS), prognostic factors and late toxicities in node positive International Federation of Gynaecology and Obstetrics (FIGO) stage IB cervix cancer treated with curative intent.

Outcomes and relapse patterns following chemotherapy in advanced Hodgkin lymphoma in the positron emission tomography era

Background This study evaluated relapse patterns and survival in advanced Hodgkin lymphoma (HL) patients treated with doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) with positron emission tomography (PET) used for staging and response assessment. Patients and methods Patients aged 18 years or above with newly diagnosed histologically proven Stage III or IV HL treated with ABVD at Calvary Mater Newcastle from January 2005 to December 2012 were included in this study. All patients underwent pre-chemotherapy staging with 18F-fluorodeoxyglucose PET or PET/computed tomography and post-chemotherapy PET or PET/computed tomography for the assessment of response. Results Forty-three patients were included in the study. The 5-year disease-free survival, progression-free survival and overall survival were 88%, 74% and 86%, respectively. PET complete response was seen in 35 patients (81%), and the 5-year overall survival for this group was 94%. Relapse following a PET complete response was low (three patients) and occurred predominantly at the initial sites of disease. Four of five patients with bulky disease received consolidative radiotherapy and no in-field relapses were observed. Conclusion Advanced stage HL with a PET complete response following ABVD is associated with an excellent prognosis.

EP-1262: Four field radiotherapy, IMRT or VMAT in cervix cancer: when do the benefits of advanced planning become redundant?

Purpose/Objective: To analyse 4 field conventional radiotherapy (4FRT), intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in the definitive management of cervix cancer and to assess whether any dosimetric differences persist with the use of larger geometric PTV margins to account for daily variability in uterine position. Materials and Methods: CT datasets were obtained for 20 consecutive patients with intact cervix cancer previously treated with definitive external beam radiotherapy (with or without chemotherapy). The clinical target volume was contoured to encompass gross tumour and potential microscopic disease including the remaining cervix, uterus, upper vagina, parametrium, adnexa and regional lymph nodes. The planning target volume (PTV) was generated with uterine margins of 1.5cm, 2cm, 2.5cm, 3cm and 4cm used to account for internal motion of the uterus, generating five PTVs for each patient: PTV1.5, PTV2, PTV2.5, PTV3 and PTV4. The rectum, bladder, bowel and femoral heads were contoured as organs at risk (OARs). For each patient, a 4FRT plan was generated based on conventional field borders ensuring coverage of PTV1.5. IMRT and VMAT plans were generated for each PTV, except when the PTV extended outside 4FRT fields. Prescription dose was 45Gy in 25 fractions. Plans were evaluated for target coverage, conformity, dose homogeneity and dose to OARs. Planning time, total monitor units and estimated delivery time were also evaluated. Results: The median patient age was 56 years (range: 27-84 years). Stage 1, 2, 3 and 4A disease was seen in 1, 12, 4 and 3 patients respectively with nodal involvement in 13 patients. PTV2.5, PTV3 and PTV4 extended outside the 4FRT fields in 9 (45%), 13 (65%) and 20 (100%) patients respectively. Target coverage was excellent for the 4FRT, IMRT and VMAT plans generated, with no significant difference between techniques, however, IMRT and VMAT plans were associated with a reduction in dose to OARs compared to 4FRT. Mean monitor units was lowest with 4FRT, followed by VMAT then IMRT. Conclusions: IMRT and VMAT are associated with dosimetric advantages over 4FRT when margins less than 3cm are used, with exceptional target coverage and superior OAR sparing. Uterine margins of 3cm or greater commonly resulted in the PTV extending outside conventional radiotherapy fields, demonstrating no benefit for these advanced planning techniques in patients with large variation in uterine position. Furthermore, accurate uterine localisation with image guidance is critical when considering implementation of IMRT or VMAT for cervix cancer treatment. Prospective studies are also needed to verify that these newer techniques reduce the rates of acute and late toxicities without compromising long-term disease control. EP-1263 A new look at the tumor lesion of the vagina through the prism of MRI: diagnosis and monitoring of brachytherapy N.V. Nudnov, J.M. Kreynina, S.P. Aksenova Russian Scientific Center of Roentgenoradiology, Deputy Director of Research, Moskow, Russian Federation Russian Scientific Center of Roentgenoradiology, Brachytherapy, Moskow, Russian Federation Russian Scientific Center of Roentgenoradiology, Radiology, Moskow, Russian Federation