Understanding and implementing Image guided Intensity Modulated Radiotherapy (IG-IMRT) for the radical treatment of cervical cancer.

Medical Institution visited: AKH, Vienna, Austria, March 2015.

Supervisors during placement: Professor Richard Potter and Dr Alina Studza

Techniques learned: 

  1. External beam radiotherapy contouring of target concepts (CTV, ITV, and PTV) using MRI and CT as per proposed EMBRACE2 protocol
  2. Clinical application (concept, creation, practical implementation and image review) of Internal Target Volume (ITV) for external beam radiotherapy
  3. Process of treatment floor application of image guided pelvic intensity modulated radiotherapy (IG-IMRT) 
  4. Use of interstitial needles to optimise image guided brachytherapy (IGBT) in complex tumours including selection of patients and pre-planning

Importance of project for advancement of clinical practice in the UK:

Within the UK, many centres have adopted Intensity Modulated Radiotherapy (IMRT) with urgency due to governmental targets that have been set. Experience within the INTERLACE trial has demonstrated a variable approach to the application of IMRT with minimal monitoring or imaging in some centres and a range of margins applied from clinical target volume (CTV) to planning target volume (PTV). The reason for these uncertainties is due to the lack of consensus guidance and reproducible evidence. 

My placement in Vienna, as well as my participation within the EMBRACE2 meetings facilitated by this placament, has provided insight into safe IG-IMRT approaches and, most importantly, how these can be applied on the busy treatment floor. Due to my role within the INTERLACE trial RTQA this experience can facilitate improved safe implementation of IG-IMRT across the UK within INTERLACE participating centres. Centres who wish to treat patients using IMRT for cervical cancer must have their protocols discussed and approved by us. My experience from this placement will assist in this process greatly and I can make recommendations based on this experience as well as give advice on the practical day-to-day application of IG-IMRT.

Within my institution this placement will assist discussion regarding updating our radiotherapy protocols to include an ITV and thereby reduce ITV to PTV margins and facilitate IMRT implementation. The brachytherapy experience will also allow us to move forward with IGBT and start using interstitial needles by autumn 2015. 

How the project has enhanced my skills:

During my placement I was able to view the entire patient pathway from patient selection to brachytherapy completion. This allowed me to learn the techniques as mentioned above. These have built on my current skill base and are very relevant for our patient population, in my institution as well as across the UK. 

I observed the tumour board meeting which occurs weekly. This is a very similar to the UK MDT meetings where cases are discussed and preliminary treatment plans are created; radiologists, surgeons, pathologists and oncologists all attend this meeting and contribute to the case discussions.

The differences observed in this process include the use of vaginal gel in diagnostic imaging and the routine use of PET-CT. The additional information gained from PET-CT is not sufficient in all cases to justify the cost and additional radiation but the use of vaginal gel at MRI does aid tumour delineation and detection of vaginal involvement. 

For the radiotherapy planning process it was interesting to see that fusion of planning CT and diagnostic MRI did not cause problems due to different scanning positions. It was also of interest to see that the pre-brachytherapy MRI was performed with vaginal applicator in situ if applicable or vaginal gel. This certainly aids the brachytherapy planning process.   

Within INTERLACE I have written outlining guidelines. To facilitate this I reviewed the literature regarding guidelines for cervical cancer radiotherapy delineation and therefore have a good basic understanding of delineation for cervix cancer radiotherapy. During my placement I was able to use the more complex contouring instructions from the proposed EMBRACE2 protocol. This is much more detailed than previously used guidelines and involved using multiple imaging modalities. I was also able to attend a meeting at which they were discussing some of the reasoning and details behind this protocol to improve my understanding of new target concepts.

This placement was the first time I directly applied the concept of Internal Target Volume (ITV) for gynaecological radiotherapy. I had an understanding of the concept and had applied it for lung cancer but never for gynaecological cancers. This was very interesting as I learnt how to define ‘movers’ and ‘non-movers’ regarding uterine movement and how to deal with ‘movers’ in the creation of an ITV. 

Reviewing the daily imaging to facilitate application of IG-IMRT built on my previous experience of reviewing cone beam computed tomography (CBCT) within my centre. Observing the clinical application of IGRT on the treatment floor has taught me the importance of educating the treatment radiographers to interpret CBCTs during treatment with a clearly documented pathway to follow for this process. Without regular CBCT review IGRT cannot be implemented safely. This is the key to IG-IMRT implementation and must be learnt in a structured manner with adequate support. This would need to be the priority in centres where this approach is being adopted. 

The Vienna experience so far is that the majority of patients do not fall outside PTV on CBCT imaging which they perform daily for first 5 days. Treatment radiographers can learn to review online CBCT but need physics and clinician input heavily to start with including clear guidance regarding the steps to follow to systematically review the online CBCT. However, when CBCTs are being performed daily the radiographers do learn to interpret them quickly due to the constant exposure to them.

Of interest, other differences in the approach to clinical practice include a daily clinical team meeting where all patients are discussed including progress through patient pathway: whether planning scan done, contours complete, plan created and started treatment. 

In addition to the clinical experience I gained I was able establish collaboration between the INTERLACE and EMBRACE study groups. I met with many of the EMBRACE study team members to discuss the EMBRACE2 protocol and share our radiotherapy quality assurance experience. I was also able to contribute to the protocol of the EMBRACE2 study for external beam radiotherapy.

Participating within the EMBRACE meeting and seeing the processes which they apply to verify data was also instructive. For the EMBRACE study all centres input their own patient data at diagnosis, completion of treatment and follow up. The EMBRACE team including clinical fellows and physicists then review all cases and check for completeness and feasibility for data. They are regularly discovering incomplete data or data that does not appear plausible e.g. grade 3 toxicity at 3 and 9 months but grade 0 at 6 months. This is then fed back to each centre to query the validity of the data. This is a very laborious task but because they have found inconsistent or missing data so frequently they fell this is a valuable resource. This highlights the lack of accuracy of clinical data even in a trial setting.

How the knowledge gained on this placement will translate into direct patient benefit: 

Following this placement I have the knowledge to discuss the in-depth contouring guidance that I have learnt including the concept of ITV which is invaluable for the safe application of IMRT. I am now in a position to discuss how this is applied within my department at University College Hospital London (UCLH) as well as within the INTERLACE trial TMG. I then aim to implement a new radiotherapy protocol to include the ITV concept into our local practice to then move to IG-IMRT. Using INTERLACE I will be able to distribute this knowledge nationally, and will specifically discuss this further with centres treating INTERLACE patients with IMRT to facilitate safer radiotherapy delivery to all of our patients. My IGBT skills will allow us to select patients appropriately within my institution to use interstitial needles in and we will therefore implement IGBT. 

Summary report

My fellowship at Allgemeines Kranhenhaus (AKH), Vienna, Austria under the supervision of Professor Richard Potter and Dr Alina Studza allowed me to observe the entire treatment pathway from initial diagnosis and discussion with the multidisciplinary team to the end of treatment and brachytherapy. Key learning points were in relation to external beam radiotherapy outlining with internal target volume (ITV) creation, application of image-guided intensity modulated radiotherapy (IG-IMRT), image guided brachytherapy (IGBT) planning and interstitial needle use. 

I can now outline according to the detailed EMBRACE2 protocol including creation of an ITV to account for internal organ motion. This process was using multiple imaging modalities and was a more complex outlining protocol compared to current standard UK practice. This experience will aid the development of IMRT at my institution as well as across the UK within the INTERLACE trial. 

I have observed the application of IG-IMRT with the use of the ITV on the treatment floor and now understand key processes and pitfalls with this technique. Key points highlighted by my experience include the training needed for applying IG-IMRT clinically. This is for clinicians and treatment radiographers in particular. There is a need for robust pathways and protocols for treatment radiographers to be able to confidently interpret CBCTs and treat patients using IG-IMRT. The need for regular physics and clinician input to facilitate this was also highlighted. 

For IGBT I have learnt the decision making process behind using interstitial needles in addition to the ring and intrauterine tandem and the steps necessary for this process. The additional benefit of using vaginal gel or a vaginal applicator at MRI for brachytherapy planning has been demonstrated. These skills will be used in my institution to continue with the process of implementing IGBT. Within this I spent time with the clinical brachytherapy physicist who taught me practical tips to allow optimisation of IGBT delivery. 

The other key benefit of this placement is the collaboration which has now developed between the INTERLACE trial group and EMBRACE study group. The INTERLACE trial is a UK based cervical cancer trial in which the quality of radiotherapy has been standardised. EMBRACE is a European based study of radiotherapy for cervical cancer in which they are aiming to standardise radiotherapy practice across Europe. This collaboration can therefore develop to standardise and improve radiotherapy delivery for cervical cancer internationally.