- Email: [email protected]
654 poster MRI ASSISTED TREATMENT PLANNING IMPROVES THE DVH PARAMETERS IN CERVIX CANCER BRACHYTHERAPY
S 264
B RACHYTHERAPY: G YNAECOLOGY
vival 5 yr and 10 yr respectively. 5 pts developed relapses. The 4 second primaries (min 1 yr after treatment) have been recorded: 2 for stage II B and 2 for stage III B. Conclusions: The high survival rates have been estimated for cervix uteri carcinoma II B and III B after combined RT including Cf-252 HDR brachytherapy. 652 poster MAGNETIC RESONANCE IMAGING-GUIDED BRACHYTHERAPY FOR CANCER OF CERVIX: CLINICAL RESULTS E. Villafranca Iturre1 , P. Romero1 , V. Chicata1 , S. Pellejero2 , S. Lozares2 , M. Vila1 , A. Sola1 , M. Rico1 , M. Dominguez Dominguez1 , J. C. Muruzabal3 , C. Sanchez4 1 C OMPLEJO H OSPITALARIO DE N AVARRA, Department of Radiation Oncology, Pamplona, Spain 2 C OMPLEJO H OSPITALARIO DE N AVARRA, Medical Physics, Pamplona, Spain 3 C OMPLEJO H OSPITALARIO DE N AVARRA, Gynecology oncology, Pamplona, Spain 4 C OMPLEJO H OSPITALARIO DE N AVARRA, Radiology, Pamplona, Spain
Materials: We have performed a retrospective review of 12 patients with cervical cancer who have been treated with radical external beam radiotherapy (EBRT) followed by intrauterine pulsed dose rate (PDR) brachytherapy between June 2009 and July 2010. All patients received 50.4Gy 28# 1.8Gy/# EBRT. On completion of EBRT a single intrauterine tube is inserted for brachytherapy delivery. Retrospectively we contoured the outer wall of the bladder, rectum and sigmoid on the planning CT scan according to the GECESTRO guidelines and have calculated the D2cc for each organ. The rectum was defined as starting at the anal verge and extended cranially to the inferior extent of the sacro-iliac joints. The sigmoid was outlined from this point to 2cm above uterus. We accepted a D2cc rectum, sigmoid and bladder cumulative dose tolerance of 75Gy, 75Gy, and 90Gy respectively, as recommended by GEC-ESTRO. Results: Of our 12 patients only 3 received 26Gy to the Oxford prescription point. In the remaining 9 patients the dose was modified to between 18-24Gy due to concerns of exceeding previously recommended maximum cumulative rectal or bladder point doses. On reviewing the D2cc for each organ at risk, using the GEC-ESTRO guidelines, the prescribed dose to all of these 9 patients could have been increased without exceeding the GEC-ESTRO recommended D2cc dose limits.
Purpose: To determine the local control and toxicity in patients with cervix cancer using optimized magnetic resonance imaging guided brachytherapy (MR-IBT) Materials: Between May 2008 and September 2010, a total of 26 patients with cervical cancer FIGO Stage IIB-IIIB were treated in our Hospital. All of them were studied with pelvic MRI, abdominal CT and laparoscopic paraorticpelvic lymphadenectomy. They received a total dose of 45 Gy with external beam radiation therapy concomitant to weekly cisplatin 40 mg/m2. Two weekly sessions from a total of 5 fractions of BT insertions with 6 Gy each were delivered the week after pelvic EBRT (RTOG)MRI-compatible intrauterine BT applicator (Nucletron®) was used. MRI scans were acquired after the insertion of the applicator. Gross Tumor Volume at diagnosis and at BT, high-risk (HR- CTV) and intermediate-risk clinical target volume (IR-CTV), and rectal, sigmoid, and bladder were delineated according to GEC-ESTRO guidelines.HDR-BT was planned and delivered based in MRI. Results: Clinical results: 22 patients (p) with histology of squamous cell carcinoma and 4 p with adenocarcinoma. Stage: T1b2 2p, T2b 21p, T3b 2p and T4a 1p; N0 18p, pelvic nodes 5p, paraortic nodes 3p. At a median follow-up of 20 months, all patients are alive with a complete response after MRI and biopsies. The locoregional control is optimal in all patients and only one had a distant metastatic recurrence.Toxicity: rectal-sigmoid G2 in 3p (8%), uretheral stenosis in 1p (4%).Dosimetrical results: The HR-CTV and intermediate-risk CTV were adequately treated in 24 of 26 implants: D90 HR-CTV: median 132.5 % (range: 114-183%). In two patients, the coverage of HR-CTV was suboptimal and the implant was modified to an interstitial implant, the first one with a MUPIT applicator and the second using the Utrecht applicator. With MR-IBT optimization the median mean dose to the 2cm3 of rectal, sigmoid, and bladder wall volume was 68.7%, 72.9% and 86.1% respectively. Conclusions: MRI-based BT for cervical cancer made a low urinary and rectal toxicity and an optimal locoregional control, although a longer following period is needed. 653 poster MOVING TOWARDS GEC-ESTRO GUIDELINES IN CERVICAL CANCER BRACHYTHERAPY. THE OXFORD CANCER CENTRE EXPERIENCE. S. Jonnada1 , M. Costelloe2 , A. Foulsham3 , S. Trent4 1 C HELTENHAM G ENERAL H OSPITAL G LOUCESTERSHIRE H OSPIT, Department of Radiotherapy, Cheltenham, United Kingdom 2 C HURCHILL H OSPITAL, Department of Physics and Radiotherapy, Oxford, United Kingdom 3 C HURCHILL H OSPITAL, Department of Radiotherapy, Oxford, United Kingdom 4 C HURCHILL H OSPITAL, Department of Radiation Oncology, Oxford, United Kingdom Purpose: The GEC-ESTRO working group issued guidelines for 3D based treatment planning in cervical cancer. This included guidelines for outlining the tumour volume and also the organs at risk (OAR). In May 2009 we changed our intrauterine brachytherapy policy at the Oxford Cancer Centre, we moved from LDR to PDR brachytherapy. Initially at the time of the change over we attempted to prescribe a dose of 24Gy to the Oxford prescription point (2cm lateral to the midpoint of the treatment height in the intra-uterine tube); this was then increased to 26Gy in May 2010 following review of radiobiological evidence. For each individual insertion the prescribed dose was modified according to maximum rectal and bladder point dose as defined by clinicians on the CT scan performed with the intrauterine tube in situ. We accept a maximum cumulative rectal point dose of 72Gy and bladder point dose of 75Gy. The ICRU reference points for bladder and rectum are also recorded.
Conclusions: Using the GEC-ESTRO guidelines we hope to optimise the dose to the cervix whilst avoiding excessive toxicity to the organs at risk. We hope that this translates into better local control rate. Prospective toxicity data is being collected. 654 poster MRI ASSISTED TREATMENT PLANNING IMPROVES THE DVH PARAMETERS IN CERVIX CANCER BRACHYTHERAPY P. Petric1 , R. Hudej1 , B. Segedin1 , H. B. Zobec Logar1 1 I NSTITUTE OF O NCOLOGY L JUBLJANA, Department of Radiotherapy, Ljubljana, Slovenia Purpose: Most common method of treatment planning in cervix cancer brachytherapy (BT) is still based on 2D systems of points, defined on pelvic
B RACHYTHERAPY: G YNAECOLOGY
radiographs with the applicator in place. Implementation of 3D imaging into treatment planning enables optimization of dose-volume histogram (DVH) parameters for the target volume and organs at risk (OAR). We report on the intercomparison of DVH parameters, obtained by conventional radiographyand MRI- based treatment planning. Materials: 48 patients with locally advanced cervix cancer, treated at our institution between June 2006 and August 2009 were included. Following 3D conformal external beam radiotherapy (EBRT) of the pelvis (45-50.4 Gy in 25-28 fractions) with or without concurrent chemotherapy and paraaortic field irradiation, 2 weekly applications of MRI guided adaptive BT were performed. GTV, HR CTV, IR CTV, bladder, rectum and sigmoid colon were contoured according to GEC-ESTRO recommendations. The standard nominal prescribed dose was 18.5 Gy per insertion, applied in 25 hourly pulses. Total dose (EBRT+BT), normalized to equivalent dose in 2 Gy fractions (α/β 10 and 3 Gy for tumor and OAR, respectively; repair half-time: 1.5 h) was calculated. Conventional loading (dose prescription at point A) was used as starting point for dose planning. Next, source dwell-times and positions were optimized, when indicated, aiming at a total D90 for the HR CTV of 90 Gy and V100>90%, while respecting our OAR dose constraints (bladder D2cc <75 Gy; rectum and sigmoid D2cc <70 Gy). Mean HR CTV size was 35 cm3 (13-99 cm3 ). DVH parameters of conventional and MRI-based treatment plans were compared separately for the patients with small and large tumors at BT (<35 cm3 and >=35 cm3 ). Results: In small tumors, an exceedingly high mean D90 of 101 Gy (st. dev. 16 Gy) for HR CTV was achieved by conventional plans, while OAR dose constraints were violated in 53% of cases. In large tumors, conventional plans resulted in a mean D90 of 84 Gy (st. dev. 11 Gy), while OAR dose constraints were violated in 30% of cases. MRI-based optimisation equalized the mean D90 value at 90 Gy both for small (st.dev. 4 Gy) and large (st.dev. 5 Gy) tumours, while reducing violation rate for OAR dose constraints to 6% and 8%, respectively. Large standard deviations on DVH parameters, obtained with conventional plans, reflecting high variation between individual values, were reduced by MRI-based optimization (Table).
Conclusions: When compared to conventional radiography-based approach, MRI-assisted treatment planning improves the DVH parameters for target volume and OAR in cervix cancer brachytherapy. The clinical impact of this improvement on our patient series will be reported after a longer follow up. 655 poster MRI-GUIDED INTRACAVITARY BRACHYTHERAPY FOR CERVICAL CANCER – DVH PARAMETERS AND OUTCOMES OF A PROSPECTIVE TRIAL L. Walsh1 , M. Morgia1 , X. (. Xie2 , J. Jezioranski2 , J. YAN2 , Y. B. CHO2 , A. Fyles1 , M. Milosevic1 1 P RINCESS M ARGARET H OSPITAL, Department of Radiation Oncology, Toronto, Canada 2 P RINCESS M ARGARET H OSPITAL, Department of Radiation Oncology and Medical Physics, Toronto, Canada Purpose: To determine initial tumor response rates and analyze dose volume histogram (DVH) parameters, as recommended by GEC ESTRO, utilizing optimized MRI-guided brachytherapy (BT) for locally advanced cervical cancer. Materials: BT plans of 50 patients (pts) (treated with 45-50Gy EBRT and weekly cisplatin from Oct 2008 - Dec 2010), and enrolled on a prospective trial evaluating MRI-guided PDR BT, were evaluated. Patients had a single intrauterine insertion of a custom-made MRI-compatible single-line source applicator. The minimum dose (Gy) delivered to 90% (D90) & 100% (D100) of the high-risk (HR) and intermediate-risk (IR) CTV, and the percentage HR and IR volume encompassed by > 100% target dose (V100) was calculated for each patient. The maximal dose (Gy) delivered to 0.1, 1, and 2cm3 (D0.1cc, D1cc, D2cc) of the organs-at-risk (OARs) was evaluated. Pts achieving complete treatment response (CR) (assessed clinically and by 3-month MRI) was determined. Toxicity was prospectively recorded. Results: FIGO stage was I, II, III, in 15, 12, 23 pts respectively. Median overall treatment time was 42 days (34-85). Median BT and overall total dose was 40Gy (17 - 45) and 85Gy (62.4 - 90.4) respectively. With a median follow-up of 442 days, 45 pts have had 3 month clinical assessment and MRI performed. CR occurred in 40 (90%) pts and 2 (4%) had progressive disease. 3 (6.7%) pts had a partial response: 1 had later local and distal progression, 1 had normal clinical examination but residuum on MRI, and 1 had residuum on clinical and MR assessment. Grade 3 late gastrointestinal and vaginal toxicity occurred in 2 (4%) and (8%) pts respectively. HR CTV D90 was > 87Gy in 46 (92%) pts (Table 1). HR CTV and IR CTV were adequately treated (% volume treated to > 100% of intended dose was > 95%) in 40 (80%) and 49 (98 %) pts
S 265
respectively. Bladder D2cc was <90Gy in 44 (88%) pts. Rectum and sigmoid D2cc was <75Gy in 41 (82%) and 29 (58%) pts respectively.There was no significant correlation between response and DVH parameters, or between OAR dosimetry and toxicity.
Conclusions: Optimized MRI-guided PDR BT using a single line-source applicator, without ovoids or a ring, adhered closely to GEC-ESTRO DVH parameters in this pt group. This method leads to highly satisfactory response rates, with acceptable toxicity. 656 poster MULTI FRACTION HDR BRACHYTHERAPY FOR CERVIX CANCER DURING ONE HOSPITALIZATION: PRELIMINARY RESULT PHASE II S. Guérif1 , A. Berger2 , B. Lavigne3 , O. boissonade3 , C. Chung2 , P. Regnault2 , X. Fritel4 , R. J. Bensadoun5 1 PRC CHU, BRACHYTHERAPY SUITE, POITIERS, France 2 PRC CHU, Department of Radiation Oncology, POITIERS, France 3 PRC CHU, Division of Medical Physics in Radiation Oncology, POITIERS, France 4 P ÔLE M ÈRE ENFANT CHU, Gynecology Department, Toulouse, France 5 CHU DE P OITIERS, Department of Radiation Oncology, Poitiers, France Purpose: The cervix HDR brachytherapy is usually realized in several applications with local or general anesthesia. The access to the anesthesia is limiting the activity of brachytherapy. We propose to evaluate a multifraction HDR brachytherapy with one application under local or general anesthesia for cervix cancer during one hospitalization. Materials: From April 2010 to December 2010, we began the first step ( D90HRCTV= 4,6 gy point A) of a phase II study with inform consent. In patients with bulky disease EBRT was performed with a four-field box technique using a linear accelerator. A total dose of 45 Gy was applied in five fractions of 1.8 Gy weekly. High dose rate (HDR) brachytherapy was performed with five fractions within tree days, with a time interval of at least 6 h between two consecutive fractions (4,6Gy/fraction), starting in two week after EBRT. In case of small tumors, High dose rate (HDR) brachytherapy was performed before surgery with nine fractions within five days, with a time interval of at least 6 h between two consecutive fractions (4,6Gy/fraction). The Bladder were filled with 50cc threw the catheter before each fraction. We use MRI based Brachytherapy with Brachyvision. First step we use Vienna standard Loading with prescribe dose on point A. The D90HRCTV = Dose point A. Then we optimize manual with the local stepper in order to respect constraints on HRCTV and D2cc OAR. For each patient, the cumulative dose was computed, consisting of EBRT and brachytherapy contribution, normalized to 2 Gy per fraction (Diso) with an α/β ratio of 10 Gy. The iso-doses with of D2cc for the rectum, sigmoid and small bowel was low than 75 gy and Bladder <90 gy. Results: From April 2010 to December 201020 brachytherapies (14 ring and tandem, 5 ring and tandem with free needles), 16 brachytherapy + EBRT, 4
B RACHYTHERAPY: G YNAECOLOGY
vival 5 yr and 10 yr respectively. 5 pts developed relapses. The 4 second primaries (min 1 yr after treatment) have been recorded: 2 for stage II B and 2 for stage III B. Conclusions: The high survival rates have been estimated for cervix uteri carcinoma II B and III B after combined RT including Cf-252 HDR brachytherapy. 652 poster MAGNETIC RESONANCE IMAGING-GUIDED BRACHYTHERAPY FOR CANCER OF CERVIX: CLINICAL RESULTS E. Villafranca Iturre1 , P. Romero1 , V. Chicata1 , S. Pellejero2 , S. Lozares2 , M. Vila1 , A. Sola1 , M. Rico1 , M. Dominguez Dominguez1 , J. C. Muruzabal3 , C. Sanchez4 1 C OMPLEJO H OSPITALARIO DE N AVARRA, Department of Radiation Oncology, Pamplona, Spain 2 C OMPLEJO H OSPITALARIO DE N AVARRA, Medical Physics, Pamplona, Spain 3 C OMPLEJO H OSPITALARIO DE N AVARRA, Gynecology oncology, Pamplona, Spain 4 C OMPLEJO H OSPITALARIO DE N AVARRA, Radiology, Pamplona, Spain
Materials: We have performed a retrospective review of 12 patients with cervical cancer who have been treated with radical external beam radiotherapy (EBRT) followed by intrauterine pulsed dose rate (PDR) brachytherapy between June 2009 and July 2010. All patients received 50.4Gy 28# 1.8Gy/# EBRT. On completion of EBRT a single intrauterine tube is inserted for brachytherapy delivery. Retrospectively we contoured the outer wall of the bladder, rectum and sigmoid on the planning CT scan according to the GECESTRO guidelines and have calculated the D2cc for each organ. The rectum was defined as starting at the anal verge and extended cranially to the inferior extent of the sacro-iliac joints. The sigmoid was outlined from this point to 2cm above uterus. We accepted a D2cc rectum, sigmoid and bladder cumulative dose tolerance of 75Gy, 75Gy, and 90Gy respectively, as recommended by GEC-ESTRO. Results: Of our 12 patients only 3 received 26Gy to the Oxford prescription point. In the remaining 9 patients the dose was modified to between 18-24Gy due to concerns of exceeding previously recommended maximum cumulative rectal or bladder point doses. On reviewing the D2cc for each organ at risk, using the GEC-ESTRO guidelines, the prescribed dose to all of these 9 patients could have been increased without exceeding the GEC-ESTRO recommended D2cc dose limits.
Purpose: To determine the local control and toxicity in patients with cervix cancer using optimized magnetic resonance imaging guided brachytherapy (MR-IBT) Materials: Between May 2008 and September 2010, a total of 26 patients with cervical cancer FIGO Stage IIB-IIIB were treated in our Hospital. All of them were studied with pelvic MRI, abdominal CT and laparoscopic paraorticpelvic lymphadenectomy. They received a total dose of 45 Gy with external beam radiation therapy concomitant to weekly cisplatin 40 mg/m2. Two weekly sessions from a total of 5 fractions of BT insertions with 6 Gy each were delivered the week after pelvic EBRT (RTOG)MRI-compatible intrauterine BT applicator (Nucletron®) was used. MRI scans were acquired after the insertion of the applicator. Gross Tumor Volume at diagnosis and at BT, high-risk (HR- CTV) and intermediate-risk clinical target volume (IR-CTV), and rectal, sigmoid, and bladder were delineated according to GEC-ESTRO guidelines.HDR-BT was planned and delivered based in MRI. Results: Clinical results: 22 patients (p) with histology of squamous cell carcinoma and 4 p with adenocarcinoma. Stage: T1b2 2p, T2b 21p, T3b 2p and T4a 1p; N0 18p, pelvic nodes 5p, paraortic nodes 3p. At a median follow-up of 20 months, all patients are alive with a complete response after MRI and biopsies. The locoregional control is optimal in all patients and only one had a distant metastatic recurrence.Toxicity: rectal-sigmoid G2 in 3p (8%), uretheral stenosis in 1p (4%).Dosimetrical results: The HR-CTV and intermediate-risk CTV were adequately treated in 24 of 26 implants: D90 HR-CTV: median 132.5 % (range: 114-183%). In two patients, the coverage of HR-CTV was suboptimal and the implant was modified to an interstitial implant, the first one with a MUPIT applicator and the second using the Utrecht applicator. With MR-IBT optimization the median mean dose to the 2cm3 of rectal, sigmoid, and bladder wall volume was 68.7%, 72.9% and 86.1% respectively. Conclusions: MRI-based BT for cervical cancer made a low urinary and rectal toxicity and an optimal locoregional control, although a longer following period is needed. 653 poster MOVING TOWARDS GEC-ESTRO GUIDELINES IN CERVICAL CANCER BRACHYTHERAPY. THE OXFORD CANCER CENTRE EXPERIENCE. S. Jonnada1 , M. Costelloe2 , A. Foulsham3 , S. Trent4 1 C HELTENHAM G ENERAL H OSPITAL G LOUCESTERSHIRE H OSPIT, Department of Radiotherapy, Cheltenham, United Kingdom 2 C HURCHILL H OSPITAL, Department of Physics and Radiotherapy, Oxford, United Kingdom 3 C HURCHILL H OSPITAL, Department of Radiotherapy, Oxford, United Kingdom 4 C HURCHILL H OSPITAL, Department of Radiation Oncology, Oxford, United Kingdom Purpose: The GEC-ESTRO working group issued guidelines for 3D based treatment planning in cervical cancer. This included guidelines for outlining the tumour volume and also the organs at risk (OAR). In May 2009 we changed our intrauterine brachytherapy policy at the Oxford Cancer Centre, we moved from LDR to PDR brachytherapy. Initially at the time of the change over we attempted to prescribe a dose of 24Gy to the Oxford prescription point (2cm lateral to the midpoint of the treatment height in the intra-uterine tube); this was then increased to 26Gy in May 2010 following review of radiobiological evidence. For each individual insertion the prescribed dose was modified according to maximum rectal and bladder point dose as defined by clinicians on the CT scan performed with the intrauterine tube in situ. We accept a maximum cumulative rectal point dose of 72Gy and bladder point dose of 75Gy. The ICRU reference points for bladder and rectum are also recorded.
Conclusions: Using the GEC-ESTRO guidelines we hope to optimise the dose to the cervix whilst avoiding excessive toxicity to the organs at risk. We hope that this translates into better local control rate. Prospective toxicity data is being collected. 654 poster MRI ASSISTED TREATMENT PLANNING IMPROVES THE DVH PARAMETERS IN CERVIX CANCER BRACHYTHERAPY P. Petric1 , R. Hudej1 , B. Segedin1 , H. B. Zobec Logar1 1 I NSTITUTE OF O NCOLOGY L JUBLJANA, Department of Radiotherapy, Ljubljana, Slovenia Purpose: Most common method of treatment planning in cervix cancer brachytherapy (BT) is still based on 2D systems of points, defined on pelvic
B RACHYTHERAPY: G YNAECOLOGY
radiographs with the applicator in place. Implementation of 3D imaging into treatment planning enables optimization of dose-volume histogram (DVH) parameters for the target volume and organs at risk (OAR). We report on the intercomparison of DVH parameters, obtained by conventional radiographyand MRI- based treatment planning. Materials: 48 patients with locally advanced cervix cancer, treated at our institution between June 2006 and August 2009 were included. Following 3D conformal external beam radiotherapy (EBRT) of the pelvis (45-50.4 Gy in 25-28 fractions) with or without concurrent chemotherapy and paraaortic field irradiation, 2 weekly applications of MRI guided adaptive BT were performed. GTV, HR CTV, IR CTV, bladder, rectum and sigmoid colon were contoured according to GEC-ESTRO recommendations. The standard nominal prescribed dose was 18.5 Gy per insertion, applied in 25 hourly pulses. Total dose (EBRT+BT), normalized to equivalent dose in 2 Gy fractions (α/β 10 and 3 Gy for tumor and OAR, respectively; repair half-time: 1.5 h) was calculated. Conventional loading (dose prescription at point A) was used as starting point for dose planning. Next, source dwell-times and positions were optimized, when indicated, aiming at a total D90 for the HR CTV of 90 Gy and V100>90%, while respecting our OAR dose constraints (bladder D2cc <75 Gy; rectum and sigmoid D2cc <70 Gy). Mean HR CTV size was 35 cm3 (13-99 cm3 ). DVH parameters of conventional and MRI-based treatment plans were compared separately for the patients with small and large tumors at BT (<35 cm3 and >=35 cm3 ). Results: In small tumors, an exceedingly high mean D90 of 101 Gy (st. dev. 16 Gy) for HR CTV was achieved by conventional plans, while OAR dose constraints were violated in 53% of cases. In large tumors, conventional plans resulted in a mean D90 of 84 Gy (st. dev. 11 Gy), while OAR dose constraints were violated in 30% of cases. MRI-based optimisation equalized the mean D90 value at 90 Gy both for small (st.dev. 4 Gy) and large (st.dev. 5 Gy) tumours, while reducing violation rate for OAR dose constraints to 6% and 8%, respectively. Large standard deviations on DVH parameters, obtained with conventional plans, reflecting high variation between individual values, were reduced by MRI-based optimization (Table).
Conclusions: When compared to conventional radiography-based approach, MRI-assisted treatment planning improves the DVH parameters for target volume and OAR in cervix cancer brachytherapy. The clinical impact of this improvement on our patient series will be reported after a longer follow up. 655 poster MRI-GUIDED INTRACAVITARY BRACHYTHERAPY FOR CERVICAL CANCER – DVH PARAMETERS AND OUTCOMES OF A PROSPECTIVE TRIAL L. Walsh1 , M. Morgia1 , X. (. Xie2 , J. Jezioranski2 , J. YAN2 , Y. B. CHO2 , A. Fyles1 , M. Milosevic1 1 P RINCESS M ARGARET H OSPITAL, Department of Radiation Oncology, Toronto, Canada 2 P RINCESS M ARGARET H OSPITAL, Department of Radiation Oncology and Medical Physics, Toronto, Canada Purpose: To determine initial tumor response rates and analyze dose volume histogram (DVH) parameters, as recommended by GEC ESTRO, utilizing optimized MRI-guided brachytherapy (BT) for locally advanced cervical cancer. Materials: BT plans of 50 patients (pts) (treated with 45-50Gy EBRT and weekly cisplatin from Oct 2008 - Dec 2010), and enrolled on a prospective trial evaluating MRI-guided PDR BT, were evaluated. Patients had a single intrauterine insertion of a custom-made MRI-compatible single-line source applicator. The minimum dose (Gy) delivered to 90% (D90) & 100% (D100) of the high-risk (HR) and intermediate-risk (IR) CTV, and the percentage HR and IR volume encompassed by > 100% target dose (V100) was calculated for each patient. The maximal dose (Gy) delivered to 0.1, 1, and 2cm3 (D0.1cc, D1cc, D2cc) of the organs-at-risk (OARs) was evaluated. Pts achieving complete treatment response (CR) (assessed clinically and by 3-month MRI) was determined. Toxicity was prospectively recorded. Results: FIGO stage was I, II, III, in 15, 12, 23 pts respectively. Median overall treatment time was 42 days (34-85). Median BT and overall total dose was 40Gy (17 - 45) and 85Gy (62.4 - 90.4) respectively. With a median follow-up of 442 days, 45 pts have had 3 month clinical assessment and MRI performed. CR occurred in 40 (90%) pts and 2 (4%) had progressive disease. 3 (6.7%) pts had a partial response: 1 had later local and distal progression, 1 had normal clinical examination but residuum on MRI, and 1 had residuum on clinical and MR assessment. Grade 3 late gastrointestinal and vaginal toxicity occurred in 2 (4%) and (8%) pts respectively. HR CTV D90 was > 87Gy in 46 (92%) pts (Table 1). HR CTV and IR CTV were adequately treated (% volume treated to > 100% of intended dose was > 95%) in 40 (80%) and 49 (98 %) pts
S 265
respectively. Bladder D2cc was <90Gy in 44 (88%) pts. Rectum and sigmoid D2cc was <75Gy in 41 (82%) and 29 (58%) pts respectively.There was no significant correlation between response and DVH parameters, or between OAR dosimetry and toxicity.
Conclusions: Optimized MRI-guided PDR BT using a single line-source applicator, without ovoids or a ring, adhered closely to GEC-ESTRO DVH parameters in this pt group. This method leads to highly satisfactory response rates, with acceptable toxicity. 656 poster MULTI FRACTION HDR BRACHYTHERAPY FOR CERVIX CANCER DURING ONE HOSPITALIZATION: PRELIMINARY RESULT PHASE II S. Guérif1 , A. Berger2 , B. Lavigne3 , O. boissonade3 , C. Chung2 , P. Regnault2 , X. Fritel4 , R. J. Bensadoun5 1 PRC CHU, BRACHYTHERAPY SUITE, POITIERS, France 2 PRC CHU, Department of Radiation Oncology, POITIERS, France 3 PRC CHU, Division of Medical Physics in Radiation Oncology, POITIERS, France 4 P ÔLE M ÈRE ENFANT CHU, Gynecology Department, Toulouse, France 5 CHU DE P OITIERS, Department of Radiation Oncology, Poitiers, France Purpose: The cervix HDR brachytherapy is usually realized in several applications with local or general anesthesia. The access to the anesthesia is limiting the activity of brachytherapy. We propose to evaluate a multifraction HDR brachytherapy with one application under local or general anesthesia for cervix cancer during one hospitalization. Materials: From April 2010 to December 2010, we began the first step ( D90HRCTV= 4,6 gy point A) of a phase II study with inform consent. In patients with bulky disease EBRT was performed with a four-field box technique using a linear accelerator. A total dose of 45 Gy was applied in five fractions of 1.8 Gy weekly. High dose rate (HDR) brachytherapy was performed with five fractions within tree days, with a time interval of at least 6 h between two consecutive fractions (4,6Gy/fraction), starting in two week after EBRT. In case of small tumors, High dose rate (HDR) brachytherapy was performed before surgery with nine fractions within five days, with a time interval of at least 6 h between two consecutive fractions (4,6Gy/fraction). The Bladder were filled with 50cc threw the catheter before each fraction. We use MRI based Brachytherapy with Brachyvision. First step we use Vienna standard Loading with prescribe dose on point A. The D90HRCTV = Dose point A. Then we optimize manual with the local stepper in order to respect constraints on HRCTV and D2cc OAR. For each patient, the cumulative dose was computed, consisting of EBRT and brachytherapy contribution, normalized to 2 Gy per fraction (Diso) with an α/β ratio of 10 Gy. The iso-doses with of D2cc for the rectum, sigmoid and small bowel was low than 75 gy and Bladder <90 gy. Results: From April 2010 to December 201020 brachytherapies (14 ring and tandem, 5 ring and tandem with free needles), 16 brachytherapy + EBRT, 4