ESTRO 36 Abstract Book

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S176 ESTRO 36 2017
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SP-0337 “From the ground up” – tackling challenges at
the country level
M.L. Yap1
1 Liverpool Cancer Therapy Centre, Ingham Institute for
Applied Medical Research, Liverpool, Australia
The global incidence of cancer is rising rapidly,
particularly in low and middle-income countries (LMICs).
Radiotherapy is a core component of cancer care and has
been demonstrated to be cost effective. Despite this,
there is a significant shortfall of services in LMICs, with
65% of low-income countries having no radiotherapy
services available. Recently, an evidence-based case for
investment in radiotherapy services in LMICs has been
developed. The Collaboration for Cancer Outcomes,
Research and Evaluation (CCORE) group have
demonstrated that if the gap in radiotherapy services in
LMICs were closed by 2035, millions of patients would
derive local control and/or survival benefits as a result of
radiotherapy. In addition, the Global Task Force for
Radiotherapy in Cancer Control (GTFRCC)'s Lancet
Oncology Commission paper demonstrated that although
initial outlays are required to start up a radiotherapy
service, economic net gains can be achieved in LMICs over
a 20-year period. IT has been estimated that >5500
megavoltage machines would be required to meet the gap
in radiotherapy services in LMICs.
However the challenges pertaining to radiotherapy in
LMICs are not just limited to the supply of radiotherapy
machines, but also concern the safe and effective running
of new and established radiotherapy departments. The
breakdown of the solitary radiotherapy machine in Uganda
was publicised in the mainstream media last year, as a
stark image of the challenges facing LMIC radiotherapy
departments. There is a severe shortage of trained
radiotherapy and oncology staff in LMICs, with the GTFRCC
report estimating that over 30 000 radiation oncologists,
22 000 medical physicists and 78 000 radiation therapists
will need to be trained in LMICs by 2035 in order to meet
the projected radiotherapy demand. Regional
organisations such as RANZCR-FRO’s Asia Pacific Radiation
Oncology Special Interest Group (APROSIG) aim to support
LMIC radiotherapy departments in this endeavour,
alongside international initiatives such as the
International Cancer Experts Corp, and Medical Physicists
without Borders.
As well as regional/international support, the key factors
on a local level imperative to success will be discussed,
with examples such as Cambodia and Botswana used to
illustrate these. With regards to technology use in these
countries, the approach has been stratified to the needs
and expertise on a local level. Collaboration between
these local, regional and international initiatives, as well
as the IAEA, PACT, ESTRO, ASTRO and other organisations
is crucial to the safe and effective delivery of radiotherapy
in LMICs.
SP-0338 Access to radiotherapy: cancer-specific
approaches to a global problem
D.Rodin
1Princess Margaret Centre, Department of Radiation
Oncologym Toronto, Canada
Abstract not received
Proffered Papers: Dose measurement and dose
calculation for proton beams
OC-0339 Water calorimetry in a pulsed PBS proton
beam
S. Rossomme1, R. Trimaud 2, V. Floquet2, M. Vidal2, A.
Gerard 2, J. Herault2, H. Palmans3,4, J.M. Denis5, D.
Rodriguez Garcia5, S. Deloule6, S. Vynckier1,5
1Université Catholique de Louvain- Institute of
Experimental & Clinical Research, Molecular Imaging-
Radiotherapy & Oncology, Brussels, Belgium
2Centre Antoine Lacassagne, Medical Physics, Nice,
France
3EBG MedAustron GmbH, Medical Physics, Wiener
Neustadt, Austria
4National Physical Laboratory, Acoustics and Ionising
Radiation Division, Teddington, United Kingdom
5Cliniques Universitaire St-Luc, Radiotherapy and
Oncology Dep., Brussels, Belgium
6IBA Dosimetry GmbH, Schwarzenbruck, Germany
Purpose or Objective
The main application of calorimeters in standards
laboratories is as primary standard of absorbed dose to
water against which ionisation chambers (ICs) are
calibrated. At present, no calorimeter is established as a
primary standard instrument in proton beams.
Based on the absorbed dose-formalism of IAEA TRS-398,
this work describes a direct comparison between a water
calorimeter (WCal) and plane-parallel ICs in clinical pulsed
pencil beam scanning (PBS) proton beams, delivered by a
synchrocyclotron. The temporal beam characteristics and
the absence of a dosimetry protocol for such beams create
significant challenges in absorbed dose determination.
The aim of this work is to demonstrate the feasibility a
water calorimetry in pulsed PBS beams.
Material and Methods
The method consisted in comparing the response of WCal
and ICs (PPC40 and PPC05) in the same reference
conditions. Measurements have been performed at a
depth of 3.1 cm using two mono-layers maps of proton
beams (10 x 10 cm²), with incident beam energies of 96.17
MeV (range in water = 6.8 g/cm²) and 226.08 MeV (range
in water = 31.7 g/cm²), respectively. The response of the
WCal is corrected for heat transfer (calculated using
numerical simulations based on finite element method)
and non-water material inside the WCal (using
experimentally derived factors). Using hydrogen-
saturated high-purity water in the WCal, the chemical
heat defect is assumed to be zero. Classical correction
factors are applied to the response of ICs: temperature
and pressure, polarity and recombination (ks). k s was
studied in detail due to the very high beam dose rate used
with the delivery method.
Results
Table 1 shows preliminary relative differences of Dw
measured with WCal and IC, during two independent
experimental campaigns, for both energies. A small
positioning uncertainty could explain that the ratios
obtained during campaign B are higher for the low energy
beam. For campaign A, however, ratios are higher for the
high energy beam, which cannot be explained by a
positioning uncertainty. A new campaign is planned to
repeat the measurement of correction factors to improve
the statistics of the results.
Conclusion
The preliminary results are very encouraging and
demonstrate that water calorimetry is feasible in a clinical
pulsed PBS proton beam. The absolute relative differences
between Dw derived from WCal and IC are inferior to 2%,
which is within the tolerance of the IAEA TRS-398 protocol.
Due to the depth-dose distribution, a depth inferior to 3.1
cm (e.g. 2 cm where the gradient is lower) would be more
suitable to minimise the uncertainty in positioning.
Further numerical and experimental investigations are