- Email: [email protected]
The Benefits of MRI-based Optimised Planning verses CT-based Planning in HDR Brachytherapy for Cervix Cancer
Clinical Oncology 23 (2011) S1eS58 Contents lists available at ScienceDirect
Clinical Oncology journal homepage: www.elsevier.com/locate/clon
Invited Speakers IS1 Delivering World Class Radiotherapy Services M. Williams &, T. Cooper on behalf of the National Radiotherapy Implementation Group (NRIG) Cambridge University Hospitals NHS Trust, Cambridge, UK NRIG aims to improve the clinical outcomes of radiotherapy. To achieve this, there must be equitable access to high quality, safe, timely, protocol driven quality controlled radiotherapy based on patients' needs. This presentation will describe NRIG's approach to these aims. By December 2010 waiting times (which are known to be deleterious for patients) should have fallen substantially in response to the 31 day target. The inclusion of subsequent treatment draws in the 85% of radiotherapy patients who are not receiving this modality as their first treatment. This should mark the end of waiting lists for radiotherapy across the country. Access rates are low compared to international benchmarks and vary significantly across England. To understand this, NRIG has commissioned an analysis of local variation in the demand for radiotherapy. This will use local data on cancer incidence and stage in order to advise on the use of radiotherapy appropriate to the local population. This should lead to better informed decision making, stronger commissioning and improved patient choice. NRIG has developed an implementation training programme for IMRT with the aim that this service is available to patients in at least one centre in each cancer network by 2012. This will include quality control of planning processes and quality assurance of delivery. It is our aim that 30% of all radical fractions should be delivered using IMRT to improve patients' experience by minimising the long term side-effects of treatment. The quality of radiotherapy is critical. Outcomes from radiotherapy treatment should be improved by developing a package of measures to assure safety and quality by self-assessment, peer review, clinical trial entry and external assessment of process and outcomes. An analysis of consistency of practice to evidence based protocols across England should be undertaken to reduce departmental variation and support commissioning. Outcome measures specific to the quality of radiotherapy (i.e. toxicity, locoregional recurrence) should be developed, initially focusing on selected tumour sites to pilot the concept. Data from the Radiotherapy Data Set (RTDS) provide the opportunity to assess radiotherapy services across the country to understand local variation in access and treatment. It will also be possible to assess linac throughput and productivity to ensure optimum use of equipment and value for money. A clear link from research and development through to treatment delivery must be maintained. This is vital to ensure we continue the momentum of maximising the benefit from our delivery capability. Awareness of radiotherapy should be raised among the public, patients, future workforce, commissioners, healthcare professionals, politicians to ensure that the real benefits of radiotherapy are well understood.
1 Throughput Modelling for a Proton Therapy Centre A.H. Aitkenhead, C.G. Rowbottom, R.I. MacKay North Western Medical Physics, The Christie NHS Foundation Trust, Manchester, UK Background and purpose: A Matlab-based throughput model has been created to study the behaviour of a single-beam, multi-room proton therapy centre. The aim was to provide a reasonable approximation to the complex case of
a real proton therapy centre, and to provide insight into the sensitivity to various real physical parameters. Method: The model uses a Monte Carlo approach to simulate the behaviour of the centre over a number of independent days, tracking each simulated patient through the treatment process. Distinct groups of patients (such as adults and paediatrics) can be configured independently, defining the mix of fields-per-treatment and the proportions of patients requiring cone-beam CT and anaesthesia. Random variation is introduced via application of Gaussian or Rayleigh statistics. Since the beam can be assigned to only one room at a time, a queuing system allocates it according to which room has been waiting the longest. Results: For the example of a three gantry centre with a caseload of 80% one and two field treatments and 20% more complex three and four field treatments, with a small number of treatments requiring anaesthetic, the predicted throughput is 105 fractions in a 16 hour day, in good agreement with the throughput of typical clinical centres. With current technology (beam switch time w2 min) it is possible to saturate a three gantry system if the patient mix includes a high proportion of complex cases, such that the addition of a fourth gantry provides only a marginal increase in throughput accompanied by a large increase in waiting times. Reducing the beam switch time to <1 min would be necessary to utilise a fourth gantry under such conditions. Conclusions: The model provides the ability to predict patient throughput in a proton therapy centre, identifying the critical parameters that will affect throughput and waiting times in a planned UK centre.
2 The Benefits of MRI-based Optimised Planning verses CT-based Planning in HDR Brachytherapy for Cervix Cancer K.E. Chalmers *, A.L. Cameron *, A.M. Paton *, H. Coomber *, C. Herbert *, J. Hughes y, P. Humphrey *, P. Cornes * * Bristol Haematology and Oncology Centre, University Hospitals Bristol NHS Foundation Trust, Bristol, UK y Department of Radiology, University Hospitals Bristol NHS Foundation Trust, Bristol, UK Introduction: This study investigated the percentage of patients with uterine cervix cancer for whom MRI-optimised brachytherapy (BT) planning provides improvement regarding coverage of tumour or reducing dose to organs at risk (OAR) versus CT-based planning using the recommendations of the Gynaecological GEC-ESTRO Working Group. Methods: Thirty patients with International Federation of Gynaecology and Obstetrics stage IB2-IVA uterine cervix cancer were treated with external beam radiotherapy (45e50.4 Gy) followed by intracavitary BT (9e16.2 Gy). At first BT treatment all patients were scanned with a CT and MRI scan of the pelvis. Catheters and OAR were outlined on both scan sets, and high- and intermediate-risk clinical target volumes (HR-CTV/IR-CTV) were contoured on the MRI scan. Standard Manchester-based plans were applied to both scans. MRI-based plans were then optimised where necessary to achieve prescription dose to HR-CTV and/or to reduce OAR dose to tolerance, and were then compared to standard CT plans. Results: With CT-based planning the whole of the HR-CTV was covered by the prescription dose in 50.0% of patients. MRI-based optimisation improved this to 83.3% (P ¼ 0.0127). Only two patients exceeded OAR tolerance using the standard CT-based plan and all of these were reduced to tolerance with MRIbased planning, but in one patient this could only be achieved with
S14
Abstracts / Clinical Oncology 23 (2011) S1eS58
a reduction in dose to HR-CTV. With a standard CT BT plan, 50% of patients did not achieve 100% dose to HR-CTV and two of these also exceeded tolerance dose to OAR: all attained an improved plan regarding these factors with MRI-based BT plan optimisation (P < 0.0001). Conclusion: A clinically and statistically significant 50% of patients benefit from MRI-based plan optimisation compared to CT-based standard brachytherapy planning in uterine cervix cancer regarding improving coverage of the residual tumour volume and reduced dose to OAR.
3 I-125 LDR Prostate Brachytherapy in a UK Centre: Evolution of a Technique E. Chadwick, S. Langley, R. Laing Royal Surrey County Hospital, Guildford, UK Aim: LDR prostate brachytherapy has been performed in Guildford since 1999. Innovation, and the availability of new technology, has brought about improvements in technique and outcomes. This evolution of technique is described here. Methods: In 1999, the modified Seattle technique was used. At implantation, loose seeds were placed in the central prostate, using pre-loaded needles. Peripherally, stranded seeds were used. CT was initially performed at day 28, but more latterly at days 1 or 0. From 2005, a novel approach was developed in response to concern regarding potency and catheterisation rates. Loose seeds used centrally were implanted individually, extending around the margins of the apex, avoiding the rectum, urethra and penile bulb. Peripheral stranded seeds were used as previously. By 2007, intra-operative planning had become available. This allowed adjustments to the plan, based on dosimetric analysis intra-operatively. In 2008, a one stage technique was developed. Patients undergo TRUS volume estimation in the clinic. A nomogram for seed ordering has been developed based on this measurement. After the peripheral seeds have been implanted, a plan is created to determine the number and placement of the central loose seeds. Results: The 4 year bRFS was 93.78% (91.19e96.36) vs 94.49% (92.37e96.61) for the novel vs previous techniques. There was an improvement in dosimetry (D90 155 Gy vs 147 Gy, P ¼ 0.03; V100 91.7% vs 90.7%, P ¼ 0.29). This was also associated with an improvement in potency from 61.7 to 83.3% at 2 years (P ¼ 0.008). Post-implant catheter use fell from 17% to 2.6%. In 1999, the duration of anaesthesia for implant was 30e45 min, whereas in 2010, the same time is taken for a one-stage procedure. Conclusions: A brachytherapy technique has been developed that is convenient to both the patient and clinician. Improved toxicity has been achieved without detriment to efficacy.
4 Image Guided HDR Brachytherapy Boost for Locally Advanced Prostate Cancer using Oncentra Prostate HDR Planning System A. Challapalli *, A. Robinson *, P. Dunn *, G. Hellawell y, E. Jones *, C. Harvey z, S. Mangar * * Department of Clinical Oncology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK y North West London Hospitals NHS Trust, Northwick Park Hospital, London, UK z Department of Radiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK Introduction: High dose rate (HDR) brachytherapy is an attractive treatment option for carcinoma prostate not only because it allows for safe dose escalation, but also exploits the radiobiological advantage of using a high dose rate/fraction. We evaluate our early experience in using HDR as a boost to pelvic external beam radiotherapy (EBRT) using Oncentra Prostate real-time ultrasound guided planning system. Methods: Thirty patients with high risk localised/locally advanced carcinoma prostate and subject to a satisfactory volume study prior to EBRT were analysed. Under general anaesthesia, the clinical target volume (CTV) was outlined from transrectal ultrasound images (prostate and base of seminal vesicles). HDR treatment was delivered through catheters placed transperineally using a multi channel microselectron unit under ultrasound guidance. The catheters were reconstructed in real time using Oncentra Prostate, allowing for re-optimisation of the plan according to pre-set dose
constraints (DC). A 12.5 Gy single fraction was delivered followed 2 weeks later with pelvic EBRT (46 Gy). Results: A range of volumes were implanted (15.5e83.4 ml, mean 37), using an average of 15 needles (range 8e19). The average time taken (implant + treatment) was 3.5 h. Eighty-five per cent of patients were discharged home within 24 h. Good dose coverage to the CTV was achieved: mean D90 of 100.2% (DC > 90%), V200 of 12.8% (DC < 15%). Urethral and rectal sparing was satisfactory: urethral D10 e 113.9% (DC < 115%), rectal D2 cc- 61.6% (DC < 75%). Five patients (16.6%) developed urinary retention, however no grade 2 acute bowel/bladder toxicity was observed 6 weeks after completion of EBRT. Conclusion: Our experience with HDR brachytherapy confirms this to be a safe and well tolerated method of dose escalation. Using real-time ultrasound planning allows for a greater chance of achieving optimal dose coverage to the prostate while respecting dose tolerance to the rectum and urethra.
5 Optimisation Technique for MRI Based 3D Treatment Planning for HDR Cervix Treatments S.E. Aldridge *, G. Block *, M. Naeem *, R.I. Johnstone *, A.Z. Winship y * Department of Medical Physics, Guy's and St Thomas' NHS Foundation Trust (GSTT), London, UK y Department of Clinical Oncology, Guy's and St Thomas' NHS Foundation Trust (GSTT), London, UK Introduction: Intracavitary brachytherapy (BT) plays a crucial role in the therapeutic management of patients with invasive cervical carcinoma from stage IB2 to IV. MRI has been proven to be the gold standard [1] for target and organ at risk (OAR) delineation for BT cervix treatments enabling the dose distribution to be conformed to the target for individual patients. GSTT implemented MRI based 3D treatment planning for HDR treatments of cervical carcinoma following the GYN GEC-ESTRO recommendations [2,3] in May 2010 and have optimised treatment plans for every patient to date [4]. Method: MR and CT scan scans are acquired for every BT fraction. The 3D image sets are fused, the MR images are used to delineate the target and critical structures (OAR), and the CT images are used to reconstruct the applicators (Rotterdam). A standard plan (set-up during commissioning to mimic dose distributions of Manchester LDR loadings) is viewed. The plan is then optimised as required to keep the OAR below tolerance and achieve required target doses. Results: One hundred per cent of our treatment fractions (seven patients, 21 plans) required individual plan optimisation. For our plans we used a variety of optimisation techniques; including removing the dwell positions from the top of the IUT (15/21), using asymmetric dwell times in the ovoids (13/21) and using asymmetric ovoid sizes (11/21). These optimisation techniques resulted in the dose to point A being reduced in 16 of the cases with the desired D90 coverage of the HR-CTV achieved. Conclusion: Individual optimisation of treatment plans per fraction is required for all patients to account for differences in applicator position, OAR location and tumour response/position. MR imaging and planning has allowed a dose reduction to point A for some patients, which it is hoped will reduce BT associated toxicities while still achieving good tumour control. References [1] Viswanathan AN, et al. Computed tomography versus magnetic resonance imaging-based contouring in cervical cancer brachytherapy: results of a prospective trial and preliminary guidelines for standardized contours. Int J Radiat Oncol Biol Phys 2007;68(2):491e498. [2] Recommendations from gynaecological (GYN) GEC ESTRO working group (I): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy with emphasis on MRI assessment on GTV and CTV. Radiother Oncol 2005;74:235e245. [3] Recommendations from gynaecological (GYN) GEC ESTRO working group (II): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy e 3D dose volume parameters and aspects of 3D image-based anatomy. Radiat Phys Radiobiol Radiother Oncol 2006;78:67e77. [4] Kirisits C., et al. Dose and volume parameters for MRI-based treatment planning in intracavitary brachytherapy for cervical cancer. Int J Radiat Oncol Biol Phys 2005;62(3):901e911.
Clinical Oncology journal homepage: www.elsevier.com/locate/clon
Invited Speakers IS1 Delivering World Class Radiotherapy Services M. Williams &, T. Cooper on behalf of the National Radiotherapy Implementation Group (NRIG) Cambridge University Hospitals NHS Trust, Cambridge, UK NRIG aims to improve the clinical outcomes of radiotherapy. To achieve this, there must be equitable access to high quality, safe, timely, protocol driven quality controlled radiotherapy based on patients' needs. This presentation will describe NRIG's approach to these aims. By December 2010 waiting times (which are known to be deleterious for patients) should have fallen substantially in response to the 31 day target. The inclusion of subsequent treatment draws in the 85% of radiotherapy patients who are not receiving this modality as their first treatment. This should mark the end of waiting lists for radiotherapy across the country. Access rates are low compared to international benchmarks and vary significantly across England. To understand this, NRIG has commissioned an analysis of local variation in the demand for radiotherapy. This will use local data on cancer incidence and stage in order to advise on the use of radiotherapy appropriate to the local population. This should lead to better informed decision making, stronger commissioning and improved patient choice. NRIG has developed an implementation training programme for IMRT with the aim that this service is available to patients in at least one centre in each cancer network by 2012. This will include quality control of planning processes and quality assurance of delivery. It is our aim that 30% of all radical fractions should be delivered using IMRT to improve patients' experience by minimising the long term side-effects of treatment. The quality of radiotherapy is critical. Outcomes from radiotherapy treatment should be improved by developing a package of measures to assure safety and quality by self-assessment, peer review, clinical trial entry and external assessment of process and outcomes. An analysis of consistency of practice to evidence based protocols across England should be undertaken to reduce departmental variation and support commissioning. Outcome measures specific to the quality of radiotherapy (i.e. toxicity, locoregional recurrence) should be developed, initially focusing on selected tumour sites to pilot the concept. Data from the Radiotherapy Data Set (RTDS) provide the opportunity to assess radiotherapy services across the country to understand local variation in access and treatment. It will also be possible to assess linac throughput and productivity to ensure optimum use of equipment and value for money. A clear link from research and development through to treatment delivery must be maintained. This is vital to ensure we continue the momentum of maximising the benefit from our delivery capability. Awareness of radiotherapy should be raised among the public, patients, future workforce, commissioners, healthcare professionals, politicians to ensure that the real benefits of radiotherapy are well understood.
1 Throughput Modelling for a Proton Therapy Centre A.H. Aitkenhead, C.G. Rowbottom, R.I. MacKay North Western Medical Physics, The Christie NHS Foundation Trust, Manchester, UK Background and purpose: A Matlab-based throughput model has been created to study the behaviour of a single-beam, multi-room proton therapy centre. The aim was to provide a reasonable approximation to the complex case of
a real proton therapy centre, and to provide insight into the sensitivity to various real physical parameters. Method: The model uses a Monte Carlo approach to simulate the behaviour of the centre over a number of independent days, tracking each simulated patient through the treatment process. Distinct groups of patients (such as adults and paediatrics) can be configured independently, defining the mix of fields-per-treatment and the proportions of patients requiring cone-beam CT and anaesthesia. Random variation is introduced via application of Gaussian or Rayleigh statistics. Since the beam can be assigned to only one room at a time, a queuing system allocates it according to which room has been waiting the longest. Results: For the example of a three gantry centre with a caseload of 80% one and two field treatments and 20% more complex three and four field treatments, with a small number of treatments requiring anaesthetic, the predicted throughput is 105 fractions in a 16 hour day, in good agreement with the throughput of typical clinical centres. With current technology (beam switch time w2 min) it is possible to saturate a three gantry system if the patient mix includes a high proportion of complex cases, such that the addition of a fourth gantry provides only a marginal increase in throughput accompanied by a large increase in waiting times. Reducing the beam switch time to <1 min would be necessary to utilise a fourth gantry under such conditions. Conclusions: The model provides the ability to predict patient throughput in a proton therapy centre, identifying the critical parameters that will affect throughput and waiting times in a planned UK centre.
2 The Benefits of MRI-based Optimised Planning verses CT-based Planning in HDR Brachytherapy for Cervix Cancer K.E. Chalmers *, A.L. Cameron *, A.M. Paton *, H. Coomber *, C. Herbert *, J. Hughes y, P. Humphrey *, P. Cornes * * Bristol Haematology and Oncology Centre, University Hospitals Bristol NHS Foundation Trust, Bristol, UK y Department of Radiology, University Hospitals Bristol NHS Foundation Trust, Bristol, UK Introduction: This study investigated the percentage of patients with uterine cervix cancer for whom MRI-optimised brachytherapy (BT) planning provides improvement regarding coverage of tumour or reducing dose to organs at risk (OAR) versus CT-based planning using the recommendations of the Gynaecological GEC-ESTRO Working Group. Methods: Thirty patients with International Federation of Gynaecology and Obstetrics stage IB2-IVA uterine cervix cancer were treated with external beam radiotherapy (45e50.4 Gy) followed by intracavitary BT (9e16.2 Gy). At first BT treatment all patients were scanned with a CT and MRI scan of the pelvis. Catheters and OAR were outlined on both scan sets, and high- and intermediate-risk clinical target volumes (HR-CTV/IR-CTV) were contoured on the MRI scan. Standard Manchester-based plans were applied to both scans. MRI-based plans were then optimised where necessary to achieve prescription dose to HR-CTV and/or to reduce OAR dose to tolerance, and were then compared to standard CT plans. Results: With CT-based planning the whole of the HR-CTV was covered by the prescription dose in 50.0% of patients. MRI-based optimisation improved this to 83.3% (P ¼ 0.0127). Only two patients exceeded OAR tolerance using the standard CT-based plan and all of these were reduced to tolerance with MRIbased planning, but in one patient this could only be achieved with
S14
Abstracts / Clinical Oncology 23 (2011) S1eS58
a reduction in dose to HR-CTV. With a standard CT BT plan, 50% of patients did not achieve 100% dose to HR-CTV and two of these also exceeded tolerance dose to OAR: all attained an improved plan regarding these factors with MRI-based BT plan optimisation (P < 0.0001). Conclusion: A clinically and statistically significant 50% of patients benefit from MRI-based plan optimisation compared to CT-based standard brachytherapy planning in uterine cervix cancer regarding improving coverage of the residual tumour volume and reduced dose to OAR.
3 I-125 LDR Prostate Brachytherapy in a UK Centre: Evolution of a Technique E. Chadwick, S. Langley, R. Laing Royal Surrey County Hospital, Guildford, UK Aim: LDR prostate brachytherapy has been performed in Guildford since 1999. Innovation, and the availability of new technology, has brought about improvements in technique and outcomes. This evolution of technique is described here. Methods: In 1999, the modified Seattle technique was used. At implantation, loose seeds were placed in the central prostate, using pre-loaded needles. Peripherally, stranded seeds were used. CT was initially performed at day 28, but more latterly at days 1 or 0. From 2005, a novel approach was developed in response to concern regarding potency and catheterisation rates. Loose seeds used centrally were implanted individually, extending around the margins of the apex, avoiding the rectum, urethra and penile bulb. Peripheral stranded seeds were used as previously. By 2007, intra-operative planning had become available. This allowed adjustments to the plan, based on dosimetric analysis intra-operatively. In 2008, a one stage technique was developed. Patients undergo TRUS volume estimation in the clinic. A nomogram for seed ordering has been developed based on this measurement. After the peripheral seeds have been implanted, a plan is created to determine the number and placement of the central loose seeds. Results: The 4 year bRFS was 93.78% (91.19e96.36) vs 94.49% (92.37e96.61) for the novel vs previous techniques. There was an improvement in dosimetry (D90 155 Gy vs 147 Gy, P ¼ 0.03; V100 91.7% vs 90.7%, P ¼ 0.29). This was also associated with an improvement in potency from 61.7 to 83.3% at 2 years (P ¼ 0.008). Post-implant catheter use fell from 17% to 2.6%. In 1999, the duration of anaesthesia for implant was 30e45 min, whereas in 2010, the same time is taken for a one-stage procedure. Conclusions: A brachytherapy technique has been developed that is convenient to both the patient and clinician. Improved toxicity has been achieved without detriment to efficacy.
4 Image Guided HDR Brachytherapy Boost for Locally Advanced Prostate Cancer using Oncentra Prostate HDR Planning System A. Challapalli *, A. Robinson *, P. Dunn *, G. Hellawell y, E. Jones *, C. Harvey z, S. Mangar * * Department of Clinical Oncology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK y North West London Hospitals NHS Trust, Northwick Park Hospital, London, UK z Department of Radiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK Introduction: High dose rate (HDR) brachytherapy is an attractive treatment option for carcinoma prostate not only because it allows for safe dose escalation, but also exploits the radiobiological advantage of using a high dose rate/fraction. We evaluate our early experience in using HDR as a boost to pelvic external beam radiotherapy (EBRT) using Oncentra Prostate real-time ultrasound guided planning system. Methods: Thirty patients with high risk localised/locally advanced carcinoma prostate and subject to a satisfactory volume study prior to EBRT were analysed. Under general anaesthesia, the clinical target volume (CTV) was outlined from transrectal ultrasound images (prostate and base of seminal vesicles). HDR treatment was delivered through catheters placed transperineally using a multi channel microselectron unit under ultrasound guidance. The catheters were reconstructed in real time using Oncentra Prostate, allowing for re-optimisation of the plan according to pre-set dose
constraints (DC). A 12.5 Gy single fraction was delivered followed 2 weeks later with pelvic EBRT (46 Gy). Results: A range of volumes were implanted (15.5e83.4 ml, mean 37), using an average of 15 needles (range 8e19). The average time taken (implant + treatment) was 3.5 h. Eighty-five per cent of patients were discharged home within 24 h. Good dose coverage to the CTV was achieved: mean D90 of 100.2% (DC > 90%), V200 of 12.8% (DC < 15%). Urethral and rectal sparing was satisfactory: urethral D10 e 113.9% (DC < 115%), rectal D2 cc- 61.6% (DC < 75%). Five patients (16.6%) developed urinary retention, however no grade 2 acute bowel/bladder toxicity was observed 6 weeks after completion of EBRT. Conclusion: Our experience with HDR brachytherapy confirms this to be a safe and well tolerated method of dose escalation. Using real-time ultrasound planning allows for a greater chance of achieving optimal dose coverage to the prostate while respecting dose tolerance to the rectum and urethra.
5 Optimisation Technique for MRI Based 3D Treatment Planning for HDR Cervix Treatments S.E. Aldridge *, G. Block *, M. Naeem *, R.I. Johnstone *, A.Z. Winship y * Department of Medical Physics, Guy's and St Thomas' NHS Foundation Trust (GSTT), London, UK y Department of Clinical Oncology, Guy's and St Thomas' NHS Foundation Trust (GSTT), London, UK Introduction: Intracavitary brachytherapy (BT) plays a crucial role in the therapeutic management of patients with invasive cervical carcinoma from stage IB2 to IV. MRI has been proven to be the gold standard [1] for target and organ at risk (OAR) delineation for BT cervix treatments enabling the dose distribution to be conformed to the target for individual patients. GSTT implemented MRI based 3D treatment planning for HDR treatments of cervical carcinoma following the GYN GEC-ESTRO recommendations [2,3] in May 2010 and have optimised treatment plans for every patient to date [4]. Method: MR and CT scan scans are acquired for every BT fraction. The 3D image sets are fused, the MR images are used to delineate the target and critical structures (OAR), and the CT images are used to reconstruct the applicators (Rotterdam). A standard plan (set-up during commissioning to mimic dose distributions of Manchester LDR loadings) is viewed. The plan is then optimised as required to keep the OAR below tolerance and achieve required target doses. Results: One hundred per cent of our treatment fractions (seven patients, 21 plans) required individual plan optimisation. For our plans we used a variety of optimisation techniques; including removing the dwell positions from the top of the IUT (15/21), using asymmetric dwell times in the ovoids (13/21) and using asymmetric ovoid sizes (11/21). These optimisation techniques resulted in the dose to point A being reduced in 16 of the cases with the desired D90 coverage of the HR-CTV achieved. Conclusion: Individual optimisation of treatment plans per fraction is required for all patients to account for differences in applicator position, OAR location and tumour response/position. MR imaging and planning has allowed a dose reduction to point A for some patients, which it is hoped will reduce BT associated toxicities while still achieving good tumour control. References [1] Viswanathan AN, et al. Computed tomography versus magnetic resonance imaging-based contouring in cervical cancer brachytherapy: results of a prospective trial and preliminary guidelines for standardized contours. Int J Radiat Oncol Biol Phys 2007;68(2):491e498. [2] Recommendations from gynaecological (GYN) GEC ESTRO working group (I): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy with emphasis on MRI assessment on GTV and CTV. Radiother Oncol 2005;74:235e245. [3] Recommendations from gynaecological (GYN) GEC ESTRO working group (II): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy e 3D dose volume parameters and aspects of 3D image-based anatomy. Radiat Phys Radiobiol Radiother Oncol 2006;78:67e77. [4] Kirisits C., et al. Dose and volume parameters for MRI-based treatment planning in intracavitary brachytherapy for cervical cancer. Int J Radiat Oncol Biol Phys 2005;62(3):901e911.