Characterization of a new commercial single crystal diamond detector for photon- and proton-beam dosimetry
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-08-12 |
| Journal | Journal of Radiation Research |
| Authors | Yuichi Akino, Archana Gautam, Len Coutinho, Jan WĂŒrfel, Indra J. Das |
| Institutions | Indiana University Health, Indiana University Bloomington |
| Citations | 34 |
| Analysis | Full AI Review Included |
Technical Documentation and Analysis: MPCVD Diamond for High-Precision Dosimetry
Section titled âTechnical Documentation and Analysis: MPCVD Diamond for High-Precision DosimetryâExecutive Summary
Section titled âExecutive SummaryâThis documentation analyzes the characterization of the commercial PTW 60019 Synthetic Single Crystal Diamond Detector (SCDD) used for radiation dosimetry. The findings confirm the superior performance of MPCVD SCD for clinical applications requiring high spatial resolution.
- Superior Resolution: The detectorâs sensitive volume, featuring an ultra-thin 1 ”m SCD layer (1.1 mm radius), delivers excellent spatial resolution and sharp profile penumbrae, outperforming traditional ionization chambers by minimizing volume-averaging effects.
- Broad Application Suitability: Demonstrated excellent performance across multiple beam types: 6 MV and 15 MV photon beams (IMRT/VMAT relevance) and 208 MeV uniform-scanning proton beams (Proton Therapy relevance).
- High Stability and Linearity: The SCDD showed consistent linearity (within 1% for photons, excellent for protons â„100 MU) and robust temperature stability (variation <0.7%) in the critical range of 4-41 °C.
- Critical Material Requirement: Accurate measurements require a significant pre-irradiation dose of at least 1000 cGy (1200 cGy recommended for 0.2% stability), highlighting the importance of tailored MPCVD growth and post-processing.
- 6CCVD Value Proposition: 6CCVD specializes in providing SCD substrates with customized thickness down to 0.1 ”m, precisely matching the ultra-thin layer needed for next-generation micro-dosimeters, coupled with full metalization capabilities.
Technical Specifications
Section titled âTechnical SpecificationsâThe following key material and performance metrics were extracted from the characterization study of the PTW 60019 SCD detector:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| SCD Layer Thickness (Sensitive Volume) | 1 | ”m | Essential for high spatial resolution |
| SCD Sensitive Volume Radius | 1.1 | mm | Circular area (0.004 mmÂł volume) |
| Operational Mode | Photovoltaic | N/A | No external bias applied (passive detection) |
| Photon Beam Energies Tested | 6, 15 | MV | Linear accelerator dosimetry |
| Proton Beam Energy Tested | 208 | MeV | Uniform-scanning proton beam (USPB) |
| Temperature Stability Range | 4 to 41 | °C | Response variation maintained within ±0.7% |
| Minimum Pre-Irradiation (0.5% Stability) | 900 | cGy | Dose required for chamber stabilization |
| Recommended Pre-Irradiation (0.2% Stability) | 1200 | cGy | Required for highly accurate clinical use |
| Maximum PDD Difference (SCDD vs. Ion Chamber) | <0.6 | % | Smallest variation among tested detectors (30x30 cm2 field) |
Key Methodologies
Section titled âKey MethodologiesâThe characterization relied on stringent procedures typical for clinical accelerator commissioning and high-resolution beam profiling.
- Detector Operation: The Synthetic Single Crystal Diamond Detector (SCDD, PTW 60019) was exclusively operated in photovoltaic mode (zero bias voltage).
- Photon Beam Testing: Measurements were conducted using 6 MV and 15 MV photon beams (Varian Clinac 2100C/D) in an MP3 water phantom system.
- Proton Beam Testing: Characterization utilized a 208 MeV uniform-scanning proton beam (USPB) in a Blue Phantom scanning water phantom system, focusing on pristine Bragg peaks (8, 16, and 24 cm ranges).
- Dose Linearity Assessment: Evaluated response across 3-1000 Monitor Units (MU) for photon beams and 10-1000 MU for proton beams, typically measured at 10 cm depth (photons) or the Spread-Out Bragg Peak (SOBP) center (protons).
- Pre-Irradiation Stabilization: The detector, if un-irradiated for the day, was subjected to repeated 100 MU exposures (measured every 20 s) to monitor and quantify the pre-irradiation dose necessary to achieve stability levels (900 cGy for 0.5% tolerance, 1200 cGy for 0.2% tolerance).
- Temperature Dependence Study: Chamber response to 100 MU (6 MV photons) was tested in water environment ranging from 4 °C up to 60 °C, confirming suitability across typical clinical and laboratory environments.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research validates the critical role of ultra-thin, high-purity SCD in advanced radiation dosimetry. 6CCVDâs specialization in MPCVD growth allows researchers to replicate or surpass the material specifications used in the PTW 60019 commercial device.
| Requirement/Application | 6CCVD Applicable Material | 6CCVD Customization Potential |
|---|---|---|
| Ultra-High Spatial Resolution | Optical Grade SCD (Electronic/Dosimetry Purity) | Custom Thickness: 6CCVD provides SCD active layers from 0.1 ”m up to 500 ”m, allowing precise control over the sensitive volume size for micro-dosimetry or advanced profiling. The 1 ”m layer used in the study is a standard capability. |
| Minimizing Volume Averaging | SCD Substrates with Ra < 1 nm polished surface. | Polishing: SCD polished to ultra-smooth Ra < 1 nm ensures uniform material properties and optimal surface preparation for contact formation, crucial for sharp penumbra measurement. |
| Electrode Integration (Photovoltaic/Schottky) | High-Purity SCD or PCD (if larger area is needed). | Custom Metalization: We offer in-house deposition of standard and custom electrode stacks (Au, Pt, Pd, Ti, W, Cu), facilitating the precise Ohmic and Schottky contacts required for stable photovoltaic mode operation. |
| Large-Field/Novel Detector Arrays | PCD Wafers (Polycrystalline Diamond) | Custom Dimensions: While the paper used SCD, 6CCVD can supply PCD plates up to 125 mm diameter for large-area detectors or experimental arrays, maintaining high uniformity and quality. |
| Stabilization & Material Expertise | SCD and light Boron-Doped Diamond (BDD) formulations. | Engineering Support: Our in-house PhD team provides technical consultation to tailor MPCVD recipes, potentially investigating controlled doping profiles to reduce the high pre-irradiation dose (e.g., 1000 cGy) needed for chamber stabilization. |
Engineering Support & Delivery
Section titled âEngineering Support & Deliveryâ6CCVD understands the urgent need for reliable, high-performance materials in medical physics and radiation research. We provide the material quality assurance and customization necessary to move from successful characterization studies (like this PTW 60019 analysis) to new detector designs.
We guarantee global DDU shipping, with DDP available upon request, ensuring rapid delivery to research institutions worldwide.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
A synthetic single crystal diamond detector (SCDD) is commercially available and is characterized for radiation dosimetry in various radiation beams in this study. The characteristics of the commercial SCDD model 60019 (PTW) with 6- and 15-MV photon beams, and 208-MeV proton beams, were investigated and compared with the pre-characterized detectors: Semiflex (model 31010) and PinPoint (model 31006) ionization chambers (PTW), the EDGE diode detector (Sun Nuclear Corp) and the SFD Stereotactic Dosimetry Diode Detector (IBA). To evaluate the effects of the pre-irradiation, the diamond detector, which had not been irradiated on the day, was set up in the water tank, and the response to 100 MU was measured every 20 s. The depth-dose and profiles data were collected for various field sizes and depths. For all radiation types and field sizes, the depth-dose data of the diamond chamber showed identical curves to those of the ionization chambers. The profile of the diamond detector was very similar to those of the EDGE and SFD detectors, although the Semiflex and PinPoint chambers showed volume-averaging effects in the penumbrae region. The temperature dependency was within 0.7% in the range of 4-41°C. A dose of 900 cGy and 1200 cGy was needed to stabilize the chamber to the level within 0.5% and 0.2%, respectively. The PTW type 60019 SCDD detector showed suitable characteristics for radiation dosimetry, for relative dose, depth-dose and profile measurements for a wide range of field sizes. However, at least 1000 cGy of pre-irradiation will be needed for accurate measurements.