Kamerling, C.P.

Nill, S.

Oelfke, U.

Ziegenhein, P.

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S778                                                                                                                                         3rd ESTRO Forum 2015 
 
 
 
Conclusions: The study demonstrates the tissue sparing 
benefits of proton therapy over photon therapy for Ewings 
sarcomas in the pelvis and thoracic spine. 
   
EP-1439   
IMRT and IMPT of cervical cancer and effect of reduced 
margins 
A. Arpit1, M.R. Arnesen1, B.L. Rekstad1, E. Malinen1, T.P. 
Hellebust1 
1Oslo University Hospital, Medical Physics, Oslo, Norway  
 
Purpose/Objective: The objective of the study was to 
compare intensity modulated radiotherapy (IMRT) and 
intensity modulated proton therapy (IMPT) for locally 
advanced cervical cancer in terms of dose-volume 
parameters, dose coverage and conformity. Furthermore, to 
study the effect of reduced margins. 
Materials and Methods: External beam radiotherapy planning 
of the pelvic region was carried out for 5 patients with locally 
advanced cervical cancer. Planning target volume (PTV) was 
defined by primary tumour, pelvic and regional lymph nodes. 
Dose prescription was 50.4 Gy in 28 fractions. PTV dose 
coverage criteria was set to D98% 95%. Two sets of treatment 
plans were prepared based on different CTV-PTV margins: 
clinical margin ( 7 mm L-R, 10 mm S-I, 15 mm A-P) and 
reduced margin (7 mm isotropic). The IMRT and IMPT plans 
were generated using the Eclipse treatment planning system. 
Dose-volume histograms (DVHs) were analyzed for the PTV 
and various organs at risk (OARs; rectum, bladder, bowel, 
sigmoideum and pelvic bone). Student’s t-test was used for 
all statistical comparison. 
Results: All IMRT and IMPT plans covered 98% of PTV with 95% 
isodose, so the dose prescription was well achieved. IMPT 
demonstrated the potential in sparing doses to OARs, where 
significant differences were seen compared to IMRT for many 
dose-volume parameters (table 1). Concerning the reduced 
margins, increased differences between IMPT and IMRT were 
seen for the bladder (data not shown). However, for the high 
dose regions in bowel and sigmoideum the potential sparing 
by IMPT was found to be less with reduced margins.  
 
 
 
Conclusions: IMPT has considerable potential to spare the 
OARs, while maintaining excellent planning target coverage, 
for patients with cervical cancer. Image guidance and 
adaptive strategies could open this therapeutic window 
further. Further studies on patients with paraaortic lymph 
node involvement are in progress. 
    
EP-1440   
Interfacing RayStation in native C++: a novel methodology 
to utilise research software in a clinical setting 
C.P. Kamerling1, P. Ziegenhein1, S. Nill1, U. Oelfke1 
1The Institute of Cancer Research, Physics, London, United 
Kingdom  
 
Purpose/Objective: Modern commercial treatment planning 
systems (TPS) become increasingly more flexible for research 
through the exposure of scripting APIs (Application 
Programming Interfaces). RayStation (RaySearch) even allows 
write access to the internal model in a controlled manner. 
However such APIs are limited to the structure of the TPS in 
terms of e.g. workflow and model assumptions. We have 
developed the in-house research TPS Dynaplan to facilitate 
the development of real-time interactive IMRT treatment 
planning. It is programmed in C++, tapping the power from 
parallel hardware architectures and optimised memory 
management. Often the development of in-house research 
software does not comply with medical device software 
standards like the software life cycle process (IEC 62304). We 
propose a solution that has the potential to mitigate the risks 
involved with in-house developed software by interfacing to 
the script client from RayStation.  
Materials and Methods: RayStation provides a scripting API 
through IronPython, which is part of .NET (Microsoft). As 
IronPython cannot be accessed through native C++ code, we 
have developed an interface called NativeRaystationConnect 
(NRC) as DLL, which converts native C++ into managed 
3rd ESTRO Forum 2015                                                                                                                                         S779 
 
C++/CLI function calls. The interface connects to RayStation 
by identification of its process ID and setting up a pipe to its 
scripting client. The library handles the required memory 
conversions and communicates with a RayStation instance 
through direct IronPython calls. The NRC interface was tested 
by its integration in our in-house research TPS Dynaplan. 
Results: A clinical case for a prostate treatment was 
imported from the RayStation database into Dynaplan 
through the NRC interface. After the generation of a 
treatment plan in Dynaplan, the respective leaf 
configurations were sent to RayStation (through the NRC 
interface) and incorporated into a new plan and beam set. 
Subsequently a dose calculation request was sent to 
RayStation. An automatic window focus change to RayStation 
allowed for clinical approval of the dose distribution, which 
in the meantime was also sent to Dynaplan. 
 
 
 
Conclusions: We successfully developed a library to interface 
the RayStation scripting API through native C++, allowing a 
risk decrease for the use of research software in a clinical 
environment. We could show by example how the NRC 
interface can be used in Dynaplan by exploiting the synergy 
of scripted access to a certified TPS and the power of 
traditional programming models. The legal implication on in-
house developed software used in combination with an API of 
a certified TPS will need to be further evaluated based on 
local and European legislation changes.  
   
EP-1441   
Evaluation of Eclipse Rapidplan for semi-automatic 
treatment planning of prostate radiation treatment 
M. Zamburlini1, J. Krayenbühl1, Y. Najafi1, S. Verlaan1, S. 
Graydon1, T. Streller1, S. Klöck1 
1University Hospital Zürich, Radiation Oncology, Zürich, 
Switzerland  
 
Purpose/Objective: Quality of modulated treatment plans is 
highly dependent on the planner skill and experience. Plan 
optimization is also a time consuming process which involves 
several iteration cycles before an acceptable plan is 
achieved. Rapidplan (Varian Medical System, USA) is a semi-
automated planning solution which promises to increase 
treatment planning efficiency and result in a more consistent 
plan quality as compared with individual manual 
optimization. The treatment planning process with Rapidplan 
relies on the creation of a model, obtained using high quality 
treatment plans previously optimized. A prostate model 
made available by Varian has been implemented in Eclipse 
(Varian Medical System, USA). The aim of this study was to 
compare the quality of plans created with the Eclipse 
prostate model and the model generated with plans from our 
institution with the manually optimized prostate plans. 
Materials and Methods: In total 40 post-operative prostate 
plans were retrospectively used in this study. Patients were 
planned with a dose fractionation 33x2Gy. 30 out of these 40 
plans were used to create an in-house prostate model. 
Varian’s prostate model and our model were used to re-
optimize ten prostate plans. The manual optimization was 
compared to the semi-automatic optimization obtained with 
the Varian and our prostate models. The comparison was 
done based on DVH parameters and MU. The target volume 
receiving 95% of the dose was compared between 
optimizations. The major OAR in postoperative prostate 
treatment is the rectum and at our institution it is paramount 
to achieve a high sparing of this OAR. The rectal volume 
receiving 40Gy (V40), 60 Gy (V60) and 65 Gy (V65) was 
compared between optimizations. Additionally the mean and 
max doses to the femoral heads were compared. 
Results: Rapidplan was easy and fast to use and no re-
optimization was required. The semiautomatic plans using 
the Varian prostate model reached a better PTV coverage 
respect to our plans (average V95 was 99.4% vs 97.2%). For 
the OAR, large dose differences were observed between 
Varian model optimized plans and our plans. Rectal V40, V60 
and V65 were in average 90%, 40% and 14% lower for the plan 
optimized by us than the one optimized using the Varian 
model, but the maximal dose to the femoral heads was in 
average 6 Gy higher. Total MU was in average 20% lower for 
the semi-automated optimized plans.  
Conclusions: Rapidplan is user friendly and requires less user 
input than manual optimization. The plan optimization and 
calculation was done at our station within 1 hour. Varian 
provides a prostate model which was developed by the 
Cancer Care Manitoba (Winnipeg – Canada) and it is based on 
the experience and treatment rationale in this clinic. We 
found that this model provided plans which are dosimetrically 
very different to what is currently expected and accepted in 
our clinic. Therefore our own model needed to be developed. 
 
EP-1442   
Investigating the impact of treatment delivery 
uncertainties for lung SABR: a pilot study 
S. Blake1, S. Arumugam2, L. Holloway3, S. Vinod2, C. Ochoa2, 
P. Phan2, D. Thwaites1 
1University of Sydney, School of Physics, Sydney NSW, 
Australia  
2Liverpool & Macarthur Cancer Therapy Centres, Department 
of Radiation Oncology, Liverpool NSW, Australia  
3South Western Sydney Cancer Services, Department of 
Radiation Oncology & Ingham Institute, Liverpool NSW, 
Australia  
 
Purpose/Objective: Advanced RT techniques require 
conservative approaches to be taken due to a lack of detailed 
knowledge about treatment delivery uncertainties. For 
example, safety margins are added to target volumes and in-


EP-1440: Interfacing RayStation in native C++: a novel methodology to utilise research software in a clinical setting 

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EP-1440: Interfacing RayStation in native C++: a novel methodology to utilise research software in a clinical setting

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