title: Evaluation of two Compton camera models for scintimammography

authors: Uche, Chibueze Zimuzo

subjects: Compton camera

abstract: We study the performance of a Si/LaBr3:Ce Compton camera model for scintimammography, and compare it with a Si/NaI(Tl) model of similar geometry. The GEANT4 simulation toolkit was used to study the behaviour of the cameras at 511 keV. Certain simulation steps, such as the modelling of radionuclide decay times, scintillation photon transport and interactions with photomultipliers, as well as detector dead time corrections were included to make the modelling of the cameras more realistic than previous studies. The Si/LaBr3:Ce Compton camera shows superior efficiency of 2.0×10⁻³ and resolution of 5.3 mm over the Si/NaI(Tl) Compton camera model which has the efficiency of 1.6×10⁻³ and resolution of 6.9 mm at a source-to-scatterer distance of interest, 2.5 cm. A similar result sequence is obtained for two breast tumours of 5 mm diameter embedded in the medial region of an average-size breast phantom of thickness 5 cm. Notably, the signal-to-noise ratios (SNR) obtained for the Si/LaBr3:Ce camera are 9.7 and 3.4 for tumour/background radiation uptakes of 10:1 and 6:1, whereas 6.8 and 2.4 were obtained for the Si/NaI(Tl) camera model for the same tumour/background radiation uptakes respectively. It is therefore envisioned that with lower cost, LaBr3:Ce could replace NaI(Tl) as the Compton camera absorber.

text: Evaluation of two Compton camera models for scintimammography We study the performance of a Si/LaBr3:Ce Compton camera model for scintimammography, and compare it with a Si/NaI(Tl) model of similar geometry. The GEANT4 simulation toolkit was used to study the behaviour of the cameras at 511 keV. Certain simulation steps, such as the modelling of radionuclide decay times, scintillation photon transport and interactions with photomultipliers, as well as detector dead time corrections were included to make the modelling of the cameras more realistic than previous studies. The Si/LaBr3:Ce Compton camera shows superior efficiency of 2.0×10⁻³ and resolution of 5.3 mm over the Si/NaI(Tl) Compton camera model which has the efficiency of 1.6×10⁻³ and resolution of 6.9 mm at a source-to-scatterer distance of interest, 2.5 cm. A similar result sequence is obtained for two breast tumours of 5 mm diameter embedded in the medial region of an average-size breast phantom of thickness 5 cm. Notably, the signal-to-noise ratios (SNR) obtained for the Si/LaBr3:Ce camera are 9.7 and 3.4 for tumour/background radiation uptakes of 10:1 and 6:1, whereas 6.8 and 2.4 were obtained for the Si/NaI(Tl) camera model for the same tumour/background radiation uptakes respectively. It is therefore envisioned that with lower cost, LaBr3:Ce could replace NaI(Tl) as the Compton camera absorber.

year: 2011

title: Characterizing an image intensifier in an full-field range image system

authors: Payne, Andrew D.

subjects: image intensifier

abstract: We are developing a high precision full-field range imaging system. An integral component in this system is an image intensifier, which is modulated at frequencies up to 100 MHz. The range measurement precision is dictated by the image intensifier performance, in particular, the achievable modulation frequency, modulation depth, and waveform shape. By characterizing the image intensifier response, undesirable effects can be observed and quantified with regards to the consequence on the resulting range measurements, and the optimal operating conditions can be selected to minimize these disturbances. The characterization process utilizes a pulsed laser source to temporally probe the gain of the image intensifier. The laser is pulsed at a repetition rate slightly different to the image intensifier modulation frequency, producing a continuous phase shift between the two signals. A charge coupled device samples the image intensifier output, capturing the response over a complete modulation period. Deficiencies in our measured response are clearly identifiable and simple modifications to the configuration of our electrical driver circuit improve the modulation performance.

text: Characterizing an image intensifier in an full-field range image system We are developing a high precision full-field range imaging system. An integral component in this system is an image intensifier, which is modulated at frequencies up to 100 MHz. The range measurement precision is dictated by the image intensifier performance, in particular, the achievable modulation frequency, modulation depth, and waveform shape. By characterizing the image intensifier response, undesirable effects can be observed and quantified with regards to the consequence on the resulting range measurements, and the optimal operating conditions can be selected to minimize these disturbances. The characterization process utilizes a pulsed laser source to temporally probe the gain of the image intensifier. The laser is pulsed at a repetition rate slightly different to the image intensifier modulation frequency, producing a continuous phase shift between the two signals. A charge coupled device samples the image intensifier output, capturing the response over a complete modulation period. Deficiencies in our measured response are clearly identifiable and simple modifications to the configuration of our electrical driver circuit improve the modulation performance.

year: 2008

title: He Pikinga Waiora Kimi Ora lifestyle programme: Case study of a successful community-based indigenous diabetes intervention.

authors: Masters-Awatere, Bridgette

subjects: Diabetes

abstract: ABSTRACT 
AIM: To co-design and implement a whānau-centred, community-based lifestyle programme (Kimi Ora) intended to ensure no worsening of HbA1c and to improve wellbeing for Māori whānau and communities with diabetes or pre-diabetes. 
METHODS: Māori healthcare providers, community members, research advisors and wider stakeholders used a co-design process underpinned by He Pikinga Waiora to collaboratively develop and implement Kimi Ora Control group comparisons and participants were recruited from Te Kōhao Health. Multi-method monitoring and collection captured individual, whānau and community data. 
RESULTS: Kimi Ora was run in two communities in Aotearoa New Zealand. In total, there were 35 participants who took part in an eight-week programme offered five times alongside a comparison group comprising 21 participants. Kimi Ora resulted in significant improvements on all biomedical measures compared to baseline, and participants had gains relative to the comparison group for variables including weight, BMI, blood pressure and waist measurement. Of particular note was the 100% retention rate and sustained community support for Kimi Ora. 
CONCLUSIONS: Outcomes from Kimi Ora demonstrate this programme, which was actively tailored for and worked with Māori communities in a responsive and flexible manner, resulted in successful biomedical outcomes, high engagement and high retention.

text: He Pikinga Waiora Kimi Ora lifestyle programme: Case study of a successful community-based indigenous diabetes intervention. ABSTRACT 
AIM: To co-design and implement a whānau-centred, community-based lifestyle programme (Kimi Ora) intended to ensure no worsening of HbA1c and to improve wellbeing for Māori whānau and communities with diabetes or pre-diabetes. 
METHODS: Māori healthcare providers, community members, research advisors and wider stakeholders used a co-design process underpinned by He Pikinga Waiora to collaboratively develop and implement Kimi Ora Control group comparisons and participants were recruited from Te Kōhao Health. Multi-method monitoring and collection captured individual, whānau and community data. 
RESULTS: Kimi Ora was run in two communities in Aotearoa New Zealand. In total, there were 35 participants who took part in an eight-week programme offered five times alongside a comparison group comprising 21 participants. Kimi Ora resulted in significant improvements on all biomedical measures compared to baseline, and participants had gains relative to the comparison group for variables including weight, BMI, blood pressure and waist measurement. Of particular note was the 100% retention rate and sustained community support for Kimi Ora. 
CONCLUSIONS: Outcomes from Kimi Ora demonstrate this programme, which was actively tailored for and worked with Māori communities in a responsive and flexible manner, resulted in successful biomedical outcomes, high engagement and high retention.

year: 2021-11-12