Oxygen Modelling and Tumour Hypoxia
The availability of oxygen in a tumour has a large effect on patient prognosis; Oxygen is a potent radio-sensitizer and greatly magnifies cell-kill. Unlike healthy tissue, chaotic and poorly perfused vasculature is a hallmark of tumours and as a result regions of hypoxia (low oxygen) are common. These regions are less responsive to radiotherapy, but if oxygen distribution can be well estimated, then in theory one could selectively boost dose to regions of low oxygen without over-dosing the surrounding tissue. This concept is known as dose-painting, but it's complicated by the fact that it is very difficult to measure oxygen in situ. Much of my current research focuses on modelling underlying oxygen distribution in both vascular and avascular tumours to better understand oxygen distribution and the factors that influence it. I also do some modelling of tumour growth, and work closely with biologists here at University of Oxford to validate these models.
A DLD-1 tumour spheroid - Oxygen can diffuse only a certain distance through the ball of tumour cells before being entirely consumed by the respiring cells, resulting in an anoxic core. Some of our research indicates information about the rate of oxygen consumption can be estimated with when the radius of the anoxic core and over-all spheroid radius are known. This also yield information about the evolution of these growths in time Here's a short video with Mike, Alex and I explaining some of our work on tumour oxygenation for Royal Society Open Science
Ultraviolet radiation dose modelling
My PhD research focused on Ultraviolet phototherapy, a treatment for common skin conditions such as psoriasis. Whilst the treatment is very effective, over-exposure can be biologically detrimental and unlike highly-ionizing treatments, dose is often not well regulated. My research here focuses the development of accurate and powerful dosimetric models, which can predict the exact amount of irradiance on a patient's skin at any orientation. I also do some modelling of how cabin design impacts dose received at the patient epidermis.
Modelling Ultraviolet Radiation is complicated as dose is deposited at the skin surface, so orientation matters. There is also complex interplay of UVR reflection and source placement which heavily influences the quantity and homogeneity of the dose. This figure shows the dose shape from a bank of ten ultraviolet emitters with surrounding reflectors.
Other InterestsI have a interest in applying a physics approach to a variety of topics, and have published research on things as diverse as the physics of guitar strings to why homeopathy cannot work from a physical sciences perspective. Measuring bend angle on a guitar fretboard and the subsequent effect on pitch. I still feel guilty about hammering nails into a fretboard, but it was for science.. Me on BBC World, explaining guitar physics whilst looking like a disheveled pirate...
Full list of publications are available from my Google Scholar page.. Selected publications below.
- "Ultraviolet radiation therapy and UVR dose models" (Grimes) 2015 Medical Physics
- "Commentary on “Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water”" (Grimes) 2015 British Medical Journal - Epidemilogy and community health
- "Oxygen consumption dynamics in steady-state tumour models" (Grimes, Fletcher and Partridge) 2014 Royal Soceity Open Science
- "String Theory - The Physics of String-Bending and Other Electric Guitar Techniques" (Grimes) 2014 PLOS One
- "A method for estimating the Oxygen Consumption Rate in Multicellular Tumour Spheroids" (Grimes, Kelly, Bloch and Partridge) 2014 Royal Society Interface
- "Can you kill your enemy by giving Homeopathy? Invited Responce " (Grimes) 2013 International Journal of Clincal Practice
- "Computational Simulation of Reflector and Tube Effects in Ultraviolet Phototherapy" (Grimes) 2012 Physics in Medicine and Biology
- "Investigations of Cabin Design in UV Phototherapy" (Grimes, Martin and Phanco) 2012 Medical Physics
- "Proposed Mechanisms for Homeopathy are Physically Impossible" (Grimes) 2012 Focus on Alternative and Complementary Therapies
- "Reflection modelling in Ultraviolet Phototherapy " (Grimes, Robbins, Martin, Phanco and O'Hare) 2011 Medical Physics
- " Development of a Computation Dose Model for use in Ultraviolet Phototherapy " (Grimes) 2011 PhD Thesis, Dublin City University
- "Dose Modeling in Ultraviolet Phototherapy " (Grimes, Robbins and O'Hare) 2010 Medical Physics