The article considers Bystander effects - the impact on a cell when a neighbouring cell receives a radiation dose - in radiotherapy situations. The authors demonstrate that the type of effect seen depends on the dose distribution, and describe two new types of Bystander effect that increase cell survival when nearby cells are irradiated. This work lays the foundations for improved mathematical radiobiological models that could ultimately be used to tailor treatment plans (see also: Cell survival offers IMRT insight).
"The prize-winning paper reports the results of the first phase of this research and focuses on the effects of spatial modulation," Elizabeth Claridge Mackonis, lead author and medical physics registrar at the Royal Prince Alfred Hospital, told medicalphysicsweb. "We confirm that the Bystander effect is present following therapeutic irradiation. Furthermore, we classify the Bystander effect into three types, with some increasing cell survival and others reducing it."
Claridge Mackonis explained that this work is part of a larger research programme, the overall goal of which is identifying the radiobiological consequences of both the spatial and temporal modulation of radiation beams used for intensity-modulated radiation therapy (IMRT). "We believe that a thorough study of these effects will provide insight into how they can be used to further optimize radiation treatments, resulting in better patient outcomes," she said.
The team recently published the results of the second investigation in this series, which examined the temporal effects associated with IMRT (Phys. Med. Biol. 53 3567). "We confirm with experimental data, that protracted treatment times of up to 17 minutes can significantly increase the survival fraction, potentially compromising treatment outcomes," Claridge Mackonis explained. "Our current challenge is to use the experimental data to develop a theoretical framework that will enable spatial and temporal effects to be incorporated into treatment planning."
Prize winning
The Roberts Prize is jointly awarded by the publishers of PMB and the journal owners, the Institute of Physics and Engineering in Medicine (IPEM). A jury of 45 IPEM Fellows assessed and rated a shortlist of 10 papers (selected according to the referees' quality assessments) and selected a winner. The 2007 winning paper was described by one of its original referees as "the most exciting and potentially important paper I have seen in a long, long time".
"We are pleased the Roberts Prize has been awarded to this work, which was entirely carried out in Australia," said Claridge Mackonis. "It will help to raise awareness in the community of the importance of the effects of spatial and temporal modulation and their potential to further maximize the benefits of radiation therapy."
The following ten articles (listed in alphabetical order) were shortlisted for the 2007 Roberts Prize:
- P E Barbone and A A Oberai 2007 Elastic modulus imaging: some exact solutions of the compressible elastography inverse problem Phys. Med. Biol. 52 1577
- M Bencsik, R Bowtell and R Bowley 2007 Electric fields induced in the human body by time-varying magnetic field gradients in MRI: numerical calculations and correlation analysis Phys. Med. Biol. 52 2337
- E Claridge Mackonis et al. 2007 Cellular response to modulated radiation fields Phys. Med. Biol. 52 5469 (The 2007 winner)
- S J Holden et al. 2007 Electromagnetic modelling of current flow in the heart from TASER devices and the risk of cardiac dysrhythmias Phys. Med. Biol. 52 7193
- S Kamath et al. 2007 Generalized field-splitting algorithms for optimal IMRT delivery efficiency Phys. Med. Biol. 52 5483
- M Lazebnik et al. 2007 A large-scale study of the ultrawideband microwave dielectric properties of normal breast tissue obtained from reduction surgeries Phys. Med. Biol. 52 2637
- C Lee et al. 2007 Hybrid computational phantoms of the male and female newborn patient: NURBS-based whole-body models Phys. Med. Biol. 52 3309
- A Olivo and R Speller 2007 Modelling of a novel x-ray phase contrast imaging technique based on coded apertures Phys. Med. Biol. 52 6555
- J Weizenecker, J Borgert and B Gleich 2007 A simulation study on the resolution and sensitivity of magnetic particle imaging Phys. Med. Biol. 52 6363
- X G Xu et al. 2007 A boundary-representation method for designing whole-body radiation dosimetry models: pregnant females at the ends of three gestational periods—RPI-P3, -P6 and -P9 Phys. Med. Biol. 52 7023
More information on the shortlisted papers can be found here.
• Last year, the 2006 Roberts Prize was awarded to:
M Krämer and M Scholz 2006 Rapid calculation of biological effects in ion radiotherapy Phys. Med. Biol. 51 1959