OPTIma: simplifying calorimetry for proton computed tomography in high proton flux environments

Objective.Proton computed tomography (pCT) offers a potential route to reducing range uncertainties for proton therapy treatment planning, however the current trend towards high current spot scanning treatment systems leads to high proton fluxes which are challenging for existing systems. Here we demonstrate a novel approach to energy reconstruction, referred to as 'de-averaging', which allows individual proton energies to be recovered using only a measurement of their integrated energy without the need for spatial information from the calorimeter.Approach.The method is evaluated in the context of the Optimising Proton Therapy through Imaging (OPTIma) system which uses a simple, relatively inexpensive, scintillator-based calorimeter that reports only the integrated energy deposited by all protons within a cyclotron period, alongside a silicon strip based tracking system capable of reconstructing individual protons in a high flux environment. GEANT4 simulations have been performed to examine the performance of such a system at a modern commercial cyclotron facility using aσ≈ 10 mm beam for currents in the range 10-50 pA at the nozzle.Main results.Apart from low-density lung tissue, a discrepancy of less than 1% on the Relative Stopping Power is found for all other considered tissues when embedded within a 150 mm spherical Perspex phantom in the 10-30 pA current range, and for some tissues even up to 50 pA.Significance.By removing the need for the calorimeter system to provide spatial information, it is hoped that the de-averaging approach can facilitate clinically relevant, cost effective and less complex calorimeter systems for performing high current pCTs.

Review of the validity of DOPS as an assessment tool for the procedural skills of surgical trainees

INTRODUCTION

Surgical trainees at all stages are mandated to use workplace-based assessments (WBAs) to gain feedback from their trainers. Direct observation of procedural skills (DOPS) is a tool to assess hands-on surgical skills. This review of the literature seeks to ascertain how valid DOPS are as an assessment tool for the procedural skills of surgical trainees according to the American Psychology Association (APA) validity framework.

METHODS

Relevant literature was identified through a structured search of Medline, CINAHL and Web of Science databases, with further papers included on citation review. Following this, papers meeting the inclusion and exclusion criteria were included in the final review specifying those investigating WBAs including DOPS, assessments in practice rather than simulation and specifically for postgraduate surgical trainees.

FINDINGS

Sixteen papers were included in the final analysis. Extracted data from the returned papers were assessed for evidence of validity in each of the five domains on the APA framework: validity based on consequence, response process, reliability, content and relationship to other variables. There are studies that show good parameters for reliability and validity for specific DOPS used in endoscopy and otolaryngology. However, there is confusion over the purpose of DOPS among trainers and trainees as to whether they should be used formatively or summatively. Recent changes to the surgical curriculum have sought to address this, and further work into the impact of this needs to be done.

'Why would we not want to keep everybody safe?' The views of family members of people who use drugs on the implementation of drug consumption rooms in Scotland

BACKGROUND

People who use drugs in Scotland are currently experiencing disproportionately high rates of drug-related deaths. Drug consumption rooms (DCRs) are harm reduction services that offer a safe, hygienic environment where pre-obtained drugs can be consumed under supervision. The aim of this research was to explore family member perspectives on DCR implementation in Scotland in order to inform national policy.

METHODS

Scotland-based family members of people who were currently or formerly using drugs were invited to take part in semi-structured interviews to share views on DCRs. An inclusive approach to 'family' was taken, and family members were recruited via local and national networks. A convenience sample of 13 family members were recruited and interviews conducted, audio-recorded, transcribed, and analysed thematically using the Structured Framework Technique.

RESULTS

Family members demonstrated varying levels of understanding regarding the existence, role, and function of DCRs. While some expressed concern that DCRs would not prevent continued drug use, all participants were in favour of DCR implementation due to a belief that DCRs could reduce harm, including saving lives, and facilitate future recovery from drug use. Participants highlighted challenges faced by people who use drugs in accessing treatment/services that could meet their needs. They identified that accessible and welcoming DCRs led by trusting and non-judgemental staff could help to meet unmet needs, including signposting to other services. Family members viewed DCRs as safe environments and highlighted how the existence of DCRs could reduce the constant worry that they had of risk of harm to their loved ones. Finally, family members emphasised the challenge of stigma associated with drug use. They believed that introduction of DCRs would help to reduce stigma and provide a signal that people who use drugs deserve safety and care.

CONCLUSIONS

Reporting the experience and views of family members makes a novel and valuable contribution to ongoing public debates surrounding DCRs. Their views can be used to inform the implementation of DCRs in Scotland but also relate well to the development of wider responses to drug-related harm and reduction of stigma experienced by people who use drugs in Scotland and beyond.

'Why would we not want to keep everybody safe?' The views of family members of people who use drugs on the implementation of drug consumption rooms in Scotland

BACKGROUND

People who use drugs in Scotland are currently experiencing disproportionately high rates of drug-related deaths. Drug consumption rooms (DCRs) are harm reduction services that offer a safe, hygienic environment where pre-obtained drugs can be consumed under supervision. The aim of this research was to explore family member perspectives on DCR implementation in Scotland in order to inform national policy.

METHODS

Scotland-based family members of people who were currently or formerly using drugs were invited to take part in semi-structured interviews to share views on DCRs. An inclusive approach to 'family' was taken, and family members were recruited via local and national networks. A convenience sample of 13 family members were recruited and interviews conducted, audio-recorded, transcribed, and analysed thematically using the Structured Framework Technique.

RESULTS

Family members demonstrated varying levels of understanding regarding the existence, role, and function of DCRs. While some expressed concern that DCRs would not prevent continued drug use, all participants were in favour of DCR implementation due to a belief that DCRs could reduce harm, including saving lives, and facilitate future recovery from drug use. Participants highlighted challenges faced by people who use drugs in accessing treatment/services that could meet their needs. They identified that accessible and welcoming DCRs led by trusting and non-judgemental staff could help to meet unmet needs, including signposting to other services. Family members viewed DCRs as safe environments and highlighted how the existence of DCRs could reduce the constant worry that they had of risk of harm to their loved ones. Finally, family members emphasised the challenge of stigma associated with drug use. They believed that introduction of DCRs would help to reduce stigma and provide a signal that people who use drugs deserve safety and care.

CONCLUSIONS

Reporting the experience and views of family members makes a novel and valuable contribution to ongoing public debates surrounding DCRs. Their views can be used to inform the implementation of DCRs in Scotland but also relate well to the development of wider responses to drug-related harm and reduction of stigma experienced by people who use drugs in Scotland and beyond.

Drug Consumption Rooms and Public Health Policy: Perspectives of Scottish Strategic Decision-Makers

There is widespread support for the introduction of Drug Consumption Rooms (DCRs) in Scotland as part of a policy response to record levels of drug-related harm. However, existing legal barriers are made more complex by the division of relevant powers between the UK and Scottish Governments. This paper reports on a national, qualitative study of key decision-makers in both local and national roles across Scotland. It explores views on the political barriers and enablers to the adoption of Drug Consumption Rooms and the potential role of these facilities in the wider treatment system. It also considers approaches to evidence, especially the types of evidence that are considered valuable in supporting decision-making in this area. The study found that Scottish decision-makers are strongly supportive of DCR adoption; however, they remain unclear as to the legal and political mechanisms that would make this possible. They view DCRs as part of a complex treatment and support system rather than a uniquely transformative intervention. They see the case for introduction as sufficient, on the basis of need and available evidence, thus adopting a pragmatic and iterative approach to evidence, in contrast to an appeal to traditional evidence hierarchies more commonly adopted by the UK Government.

Stress and Wellbeing during the COVID-19 Pandemic: A Mixed-Methods Exploration of Frontline Homelessness Services Staff Experiences in Scotland

Staff working in homelessness services often find the work rewarding yet challenging, and the sector experiences high levels of staff burnout and staff turnover. During the COVID-19 pandemic, staff working in these services faced particularly stressful working conditions. This study explored the experiences of stress and wellbeing among those working in frontline homelessness service roles during the early stages of the pandemic in Scotland. Semi-structured interviews were conducted with 18 participants, 11 of whom completed the Maslach Burnout Inventory (MBI). Qualitative data were analysed using Framework Analysis in NVivo, informed by the Revised Transactional Model of occupational stress and coping. MBI data were analysed using descriptive statistics. The COVID-19 pandemic positively and negatively impacted participants’ lives and roles. Organisational culture acted as a magnifying glass for pre-pandemic practices: for some, the pandemic brought teams and staff closer together, creating a better working environment. For others, it led to fragmentation and frustration. Participants discussed coping strategies and recommendations for the future to protect staff wellbeing. Quantitative data suggested that participants were not experiencing burnout, although some were at heightened risk. Future research should explore the longer-term impact of the pandemic on homelessness service staff outcomes.

A novel range telescope concept for proton CT

Proton beam therapy can potentially offer improved treatment for cancers of the head and neck and in paediatric patients. There has been a sharp uptake of proton beam therapy in recent years as improved delivery techniques and patient benefits are observed. However, treatments are currently planned using conventional x-ray CT images due to the absence of devices able to perform high quality proton computed tomography (pCT) under realistic clinical conditions. A new plastic-scintillator-based range telescope concept, named ASTRA, is proposed here to measure the proton’s energy loss in a pCT system. Simulations conducted using GEANT4 yield an expected energy resolution of 0.7%. If calorimetric information is used the energy resolution could be further improved to about 0.5%. In addition, the ability of ASTRA to track multiple protons simultaneously is presented. Due to its fast components, ASTRA is expected to reach unprecedented data collection rates, similar to 108 protons/s. The performance of ASTRA has also been tested by simulating the imaging of phantoms. The results show excellent image contrast and relative stopping power reconstruction.

Assessing the feasibility, acceptability and accessibility of a peer-delivered intervention to reduce harm and improve the well-being of people who experience homelessness with problem substance use: the SHARPS study

BACKGROUND

For people experiencing homelessness and problem substance use, access to appropriate services can be challenging. There is evidence that the development of trusting relationships with non-judgemental staff can facilitate service engagement. Peer-delivered approaches show particular promise, but the evidence base is still developing.

METHODS

The study used mixed methods to assess the feasibility, acceptability and accessibility of a peer-delivered, relational intervention to reduce harms and improve health/well-being, quality of life and social functioning, for people experiencing homelessness and problem substance use. Four Peer Navigators were employed to support individuals (n = 68 total, intervention participants). They were based in outreach services and hostels in Scotland and England. Qualitative interviews were conducted with intervention participants, Peer Navigators and staff in services, and observations were conducted in all settings. Quantitative outcomes relating to participants' substance use, physical and mental health, and quality of the Peer Navigator relationship, were measured via a 'holistic health check' with six questionnaires completed at two time-points.

RESULTS

The intervention was found to be acceptable to, and feasible and accessible for, participants, Peer Navigators, and service staff. Participants reported improvements to service engagement, and feeling more equipped to access services independently. The lived experience of the Peer Navigators was highlighted as particularly helpful, enabling trusting, authentic, and meaningful relationships to be developed. Some challenges were experienced in relation to the 'fit' of the intervention within some settings. Among participants there were reductions in drug use and risky injecting practices. There were increases in the number of participants receiving opioid substitution therapy. Overall, the intervention was positively received, with collective recognition that the intervention was unique and highly valuable. While most of the measures chosen for the holistic health check were found to be suitable for this population, they should be streamlined to avoid duplication and participant burden.

CONCLUSIONS

The study established that a peer-delivered, relational harm reduction intervention is acceptable to, and feasible and accessible for, people experiencing homelessness and problem substance use. While the study was not outcomes-focused, participants did experience a range of positive outcomes. A full randomised controlled trial is now required to assess intervention effectiveness.

TRIAL REGISTRATION

Study registered with ISRCTN: 15900054.

Comparison of Oxidizing Solutions in the Evaluation of Metmyoglobin Reducing Activity in Dark-Cutting Beef

ObjectivesMetmyoglobin reducing activity (MRA) is an inherent muscle biochemical property that can influence color stability. Hence, MRA is used in color research to better understand meat color changes. A greater postmortem muscle pH can affect inherent biochemical properties, including the conventional methodologies to determine MRA. The MRA methodology described in the American Meat Science Association Color Guide utilize changes in nitric oxide induced-metmyoglobin level pre- and post-incubation. However, a greater muscle pH can limit initial metmyoglobin formation. Hence, the methodology discussed in the AMSA color guide may not provide accurate results. Therefore, the objectives of this research were to compare different conditions to induce initial metmyoglobin formation.Materials and MethodsIn the first objective, normal-pH and dark-cutting steaks were dipped in 0.3%s (level recommended in the AMSA color guide) and 1% nitrite solution to induce metmyoglobin formation. Metmyoglobin formed steaks were blotted dry, vacuum packaged, and incubated at 30°C to induce metmyoglobin reduction. In the second experiment, 1% ferricyanide solution was used as an oxidizing agent. The methodology used in objective 1 was used to measure MRA. The experiments were replicated three times and the data were analyzed using the Mixed Procedure of SAS.ResultsThere was no effect (P > 0.05) of nitrite concentration on MRA of dark-cutting beef. However, when 1% ferricyanide was used as an oxidizing agent, initial metmyoglobin was more (P < 0.05) in dark-cutting beef compared with 0.3% sodium nitrite solution.ConclusionThe results suggest that the use of a strong oxidizing agent can impart more metmyoglobin formation in high-pH/dark-cutting beef.

Hypertension as a predictor of advanced colorectal cancer outcome and cetuximab treatment response

Background

Adrenergic receptor stimulation is involved in the development of hypertension (htn) and has been implicated in cancer progression and dissemination of metastases in various tumours, including colon cancer. Adrenergic antagonists such as beta-blockers (bbs) demonstrate inhibition of invasion and migration in colon cancer cell lines and have been associated with decreased mortality in colorectal cancer (crc). We examined the association of baseline htn and bb use with overall (os) and progression-free survival (pfs) in patients with pretreated, chemotherapy refractory, metastatic crc (mcrc). We also examined baseline htn as a predictor of cetuximab efficacy.

Methods

Using data from the Canadian Cancer Trials Group co.17 study [cetuximab vs. best supportive care (bsc)], we coded baseline htn and use of anti-htn medications, including bbs, for 572 patients. The chi-square test was used to assess the associations between those variables and baseline characteristics. Cox regression models were used for univariate and multivariate analyses of os and pfs by htn diagnosis and bb use.

Results

Baseline htn, bb use, and anti-htn medication use were not found to be prognostic for improved os. Baseline htn and bb use were not significant predictors of cetuximab benefit.

Conclusions

In chemorefractory mcrc, neither baseline htn nor bb use is a significant prognostic factor. Baseline htn and bb use are not predictive of cetuximab benefit. Further investigation to determine whether baseline htn or bb use have a similarly insignificant impact on prognosis in patients receiving earlier lines of treatment remains warranted.

Multiple breath washout in pediatric patients after lung transplantation

Forced expiratory volume in 1 second (FEV₁ ) from spirometry is the most commonly used parameter to detect early allograft dysfunction after lung transplantation (LTx). There are concerns regarding its sensitivity. Nitrogen-multiple breath washout (N₂ -MBW) is sensitive at detecting early global (lung clearance index [LCI]) and acinar (S_acin ) airway inhomogeneity. We investigated whether N₂ -MBW indices indicate small airways pathology after LTx in children with stable spirometry. Thirty-seven children without bronchiolitis obliterans syndrome [BOS] at a median of 1.6 (0.6-3.0) years after LTx underwent N₂ -MBW and spirometry, 28 of those on 2 occasions (≤6 months apart) during clinically stable periods. Additional longitudinal data (11 and 8 measurements, respectively) are provided from 2 patients with BOS. In patients without BOS, LCI and S_acin were significantly elevated compared with healthy controls. LCI was abnormal at the 2 test occasions in 81% and 71% of patients, respectively, compared with 30% and 39% of patients with abnormal FEV₁ /forced vital capacity (FVC). Correlations of LCI with FEV₁ /FVC (r = 0.1, P = .4) and FEV₁ (r = -0.1, P = .6) were poor. N₂ -MBW represents a sensitive and reproducible tool for the early detection of airways pathology in stable transplant recipients. Moreover, indices were highly elevated in both patients with BOS. Spirometry and LCI showed poor correlation, indicating distinct and complementary physiologic measures.

Prospective randomized trial of neoadjuvant chemotherapy during the 'wait period' following preoperative chemoradiotherapy for rectal cancer: results of the WAIT trial

AIM

The aim was to determine whether the addition of additional cycles of chemotherapy during the 'wait period' following neoadjuvant chemoradiotherapy for rectal cancer improves the pathological complete response (pCR) rate.

METHOD

Rectal cancer patients were randomly allocated either to a standard 10 week wait period before surgery (standard chemoradiotherapy, SCRT) or to receive three cycles of fluorouracil based chemotherapy following chemoradiotherapy during a similar 10 week wait (extended chemoradiotherapy, XCRT). The primary end-point was pCR as determined by blinded pathological assessment.

RESULTS

Forty-nine patients were randomized (SCRTn = 24, XCRTn = 25). pCR occurred in 10 patients overall but there was no significant difference in pCR between the groups (SCRTn = 6, XCRTn = 4, P = 0.49).

CONCLUSION

The addition of three cycles of 5-fluorouracil/leucovorin in a 10 week wait period after conventional chemoradiotherapy seems to result in similar pCR rates in patients with locally advanced rectal cancer based on this small randomized trial.

An experimental demonstration of a new type of proton computed tomography using a novel silicon tracking detector

PURPOSE

Radiography and tomography using proton beams promise benefit to image guidance and treatment planning for proton therapy. A novel proton tracking detector is described and experimental demonstrations at a therapy facility are reported. A new type of proton CT reconstructing relative "scattering power" rather than "stopping power" is also demonstrated. Notably, this new type of imaging does not require the measurement of the residual energies of the protons.

METHODS

A large area, silicon microstrip tracker with high spatial and temporal resolution has been developed by the Proton Radiotherapy Verification and Dosimetry Applications consortium and commissioned using beams of protons at iThemba LABS, Medical Radiation Department, South Africa. The tracker comprises twelve planes of silicon developed using technology from high energy physics with each plane having an active area of ∼10 × 10 cm segmented into 2048 microstrips. The tracker is organized into four separate units each containing three detectors at 60° to one another creating an x-u-v coordinate system. Pairs of tracking units are used to reconstruct vertices for protons entering and exiting a phantom containing tissue equivalent inserts. By measuring the position and direction of each proton before and after the phantom, the nonlinear path for each proton through an object can be reconstructed.

RESULTS

Experimental results are reported for tracking the path of protons with initial energies of 125 and 191 MeV. A spherical phantom of 75 mm diameter was imaged by positioning it between the entrance and exit detectors of the tracker. Positions and directions of individual protons were used to create angular distributions and 2D fluence maps of the beam. These results were acquired for 36 equally spaced projections spanning 180°, allowing, for the first time, an experimental CT image based upon the relative scattering power of protons to be reconstructed.

CONCLUSIONS

Successful tracking of protons through a thick target (phantom) has demonstrated that the tracker discussed in this paper can provide the precise directional information needed to perform proton radiography and tomography. When synchronized with a range telescope, this could enable the reconstruction of proton CT images of stopping power. Furthermore, by measuring the deflection of many protons through a phantom, it was demonstrated that it is possible to reconstruct a new kind of CT image (scattering power) based upon this tracking information alone.

Venous thromboembolism in patients with esophageal or gastric cancer undergoing neoadjuvant chemotherapy

There is a well-established link between cancer and venous thromboembolism (VTE), and patients receiving chemotherapy for esophageal or gastric cancer appear at high risk of developing VTE. The incidence of VTE in the neoadjuvant setting in these patients is poorly understood, as is the role for thromboprophylaxis during neoadjuvant chemotherapy. A PubMed search was conducted using a combination of terms including; esophageal & gastric cancer, deep venous thrombosis (DVT), VTE, neoadjuvant, chemotherapy and chemoradiotherapy. One hundred and fifty-four articles were retrieved and a narrative review was conducted. For patients with esophageal and gastric cancer the incidence of VTE ranged from 4 to 19%. Gastric cancer (Odds Ratio [OR] 6.38, [95% CI: 1.96-20.80]) and Stage III/IV disease, (OR 5.16 [95% CI: 1.29-20.73]) were identified as risk factors for developing VTE. Neoadjuvant chemotherapy was identified as an independent risk factor for developing VTE. Symptomatic and asymptomatic VTE have a similar effect on mortality. Median overall survival for asymptomatic VTE was 13.9 months (95% CI: 5.0-∞) versus 12.8 months (95% CI: 4.7-30.3) if the VTE was symptomatic. Neoadjuvant chemotherapy is a significant risk factor for VTE in patients with esophageal and gastric cancer. Intervention to minimize the risk using pharmacological and mechanical thromboprophylaxis should be considered, and this should start in the neoadjuvant period.

A new silicon tracker for proton imaging and dosimetry

For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction around the world today. The Proton Radiotherapy, Verification and Dosimetry Applications (PRaVDA) consortium are developing instrumentation for particle therapy based upon technology from high-energy physics. The characteristics of a new silicon micro-strip tracker for particle therapy will be presented. The array uses specifically designed, large area sensors with technology choices that follow closely those taken for the ATLAS experiment at the HL-LHC. These detectors will be arranged into four units each with three layers in an x-u-v configuration to be suitable for fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of tracing the path of ~200 MeV protons entering and exiting a patient allowing a new mode of imaging known as proton computed tomography (pCT). This will aid the accurate delivery of treatment doses and in addition, the tracker will also be used to monitor the beam profile and total dose delivered during the high fluences used for treatment. We present here details of the design, construction and assembly of one of the four units that will make up the complete tracker along with its characterisation using radiation tests carried out using a 90Sr source in the laboratory and a 60 MeV proton beam at the Clatterbridge Cancer Centre.

'Shrink' losses in commercially sized corn silage piles: Quantifying total losses and where they occur

Silage 'shrink' (i.e., loss of fresh chopped crop between ensiling and feedout) represents a nutrient loss which can degrade air quality as volatile carbon compounds, degrade surface waterways due to seepage, or degrade aquifers due to seepage. Virtually no research has documented shrink in large silage piles. The term 'shrink' is often ill defined, but can be expressed as losses of wet weight (WW), oven dry matter (oDM), and oDM corrected for volatiles lost in the drying oven (vcoDM). Corn silage piles (4 wedge, 2 rollover/wedge, 1 bunker) from 950 to 12,204 tonnes as built, on concrete (4), soil (2) and a combination (1) in California's San Joaquin Valley, using a bacterial inoculant, covered within 24 h with an oxygen barrier inner film and black/white outer plastic, fed out using large front end loaders through an electronic feed tracking system, and from the 2013 crop year, were used. Shrink as WW, oDM and vcoDM were 90±17, 68±18 and 28±21 g/kg, suggesting that much WW shrink is water and much oDM shrink is volatiles lost during analytical oven drying. Most shrink occurred in the silage mass with losses from exposed silage faces, as well as between exposed face silage removal and the total mixed ration mixer, being low. Silage bulk density, exposed silage face management and face use rate did not have obvious impacts on any shrink measure, but age of the silage pile during silage feedout impacted shrink losses ('older' silage piles being higher), but most strongly for WW shrink. Real shrink losses (i.e., vcoDM) of large well managed corn silage piles are low, the exposed silage face is a small portion of losses, and many proposed shrink mitigations appeared ineffective, possibly because shrink was low overall and they are largely directed at the exposed silage face.

CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography

Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs.

Proton tracking for medical imaging and dosimetry

For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy, where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction - including two in the U.K.. The characteristics of a new silicon micro-strip detector based system for this application will be presented. The array uses specifically designed large area sensors in several stations in an x-u-v co-ordinate configuration suitable for very fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of giving information on the path of high energy protons entering and exiting a patient. This will allow proton computed tomography (pCT) to aid the accurate delivery of treatment dose with tuned beam profile and energy. The tracker will also be capable of proton counting and position measurement at the higher fluences and full range of energies used during treatment allowing monitoring of the beam profile and total dose. Results and initial characterisation of sensors will be presented along with details of the proposed readout electronics. Radiation tests and studies with different electronics at the Clatterbridge Cancer Centre and the higher energy proton therapy facility of iThemba LABS in South Africa will also be shown.