PO-0801 - Large area 2D polycrystalline CVD diamond dosimeter under intensity modulated beams
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-04-01 |
| Journal | Radiotherapy and Oncology |
| Authors | C. Talamonti, Andrea Baldi, M. Scaringella, M. Zani, D. Pasquini |
| Institutions | Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, University of Florence |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Large Area MPCVD Diamond Dosimeters
Section titled âTechnical Documentation & Analysis: Large Area MPCVD Diamond DosimetersâReference Paper: PO-0801: Large area 2D polycrystalline CVD diamond dosimeter under intensity modulated beams (Talamonti et al., ESTRO 35 2016)
Executive Summary
Section titled âExecutive Summaryâ- Application Validation: Polycrystalline CVD (pCVD) diamond is confirmed as a highly suitable, tissue-equivalent material for advanced radiotherapy quality assurance (QA) detectors, specifically for Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT).
- High Spatial Resolution: The DIAPIX prototype, utilizing a 2 mm pixel pitch, successfully demonstrated the capability for high spatial resolution dose mapping, crucial for verifying complex modulated beams.
- Accuracy: Measured dose profiles compared favorably with Treatment Planning System (TPS) calculations (Monaco/Pinnacle), showing general dose differences within 5%.
- Scalability Requirement: The research identifies the need for larger, monolithic pCVD matrices (future target area 7.5 x 2.5 cm2) to cover typical IMRT fields completely.
- 6CCVD Value Proposition: 6CCVD specializes in providing the necessary large-area, detector-grade PCD wafers (up to 125 mm) and custom metalization services required to scale this technology into clinical-grade, high-density dosimeters.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the analysis of the pCVD diamond dosimeter prototype:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Material Used | Polycrystalline CVD Diamond (pCVD) | N/A | Detector-grade |
| Individual Sample Dimensions | 2.5 x 2.5 | cm2 | Two adjacent samples used in prototype |
| Pixel Matrix (Per Sample) | 12 x 12 (144 contacts) | N/A | Bidimensional detector structure |
| Pixel Pitch | 2 | mm | Defines spatial resolution |
| Total Future Target Area | 7.5 x 2.5 | cm2 | Required for 432-pixel monolithic device |
| Dose Difference (Accuracy) | < 5 | % | Compared to TPS (general region) |
| Distance-to-Agreement (DTA) | < 3 | mm | Achieved in high dose gradient (penumbra) regions |
| Irradiation Source | Elekta Synergy LINAC | N/A | Used for IMRT, VMAT, and conventional photon beams |
| TPS Algorithms Used | Monaco v3.2 (MonteCarlo), Pinnacle v9.2 (Collapsed Cone Convolution) | N/A | Used for QA plan computation |
Key Methodologies
Section titled âKey MethodologiesâThe performance verification of the large-area pCVD diamond dosimeter (DIAPIX) involved the following steps:
- Material Fabrication: Two detector-grade pCVD diamond samples (2.5 x 2.5 cm2) were prepared.
- Electrode Patterning: Each sample was equipped with a 12x12 contact matrix, featuring a 2 mm pitch, connected to a custom electronic read-out system.
- Experimental Setup: The dosimeter was placed at the isocenter and sandwiched within a water-equivalent phantom.
- Initial Calibration: Measurements were performed under a conventional flat radiotherapy beam to verify matrix uniformity and derive a flatness correction factor for each pixel.
- Modulated Beam Testing: Dosimetric maps were acquired using clinical IMRT (prostate/breast) and VMAT (lung) fields.
- Data Acquisition: Due to the prototypeâs smaller size, measurements involved shifting the dosimeter in the Latero-Lateral direction to cover the field area.
- Verification: Measured dose maps and profiles were compared against QA plans computed by the Monaco and Pinnacle Treatment Planning Systems (TPS).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful development of large-area diamond dosimeters hinges on the ability to source high-quality, large-format pCVD material and execute precise micro-patterning. 6CCVD is uniquely positioned to supply the necessary components to replicate and advance this research.
Applicable Materials
Section titled âApplicable Materialsâ| Research Requirement | 6CCVD Material Recommendation | Technical Rationale |
|---|---|---|
| Detector-grade Polycrystalline CVD (pCVD) | Electronic Grade PCD Wafers | Optimized for charge collection efficiency and high carrier mobility, essential for accurate, real-time dosimetry. |
| Large Area Coverage (Future 7.5 x 2.5 cm2) | Custom PCD Plates (up to 125 mm) | Enables the fabrication of monolithic, inch-size detectors, eliminating the need to stitch smaller samples and ensuring uniform response across the entire field. |
| High Spatial Resolution (2 mm pitch) | Ultra-Thin PCD (0.1 ”m - 500 ”m) | Control over thickness allows optimization of detector sensitivity and spatial resolution, minimizing volume averaging effects. |
Customization Potential
Section titled âCustomization Potentialâ6CCVD offers comprehensive services to transition research prototypes into scalable, high-performance devices:
- Custom Dimensions: We can supply PCD plates up to 125 mm in diameter, easily accommodating the required 75 mm x 25 mm area for the future 432-pixel matrix, ensuring a monolithic device structure.
- Precision Patterning: Our in-house laser cutting and etching capabilities allow for the precise definition of the 2 mm pixel pitch and the creation of complex 12x12 or larger electrode matrices with high geometric accuracy.
- Advanced Metalization: We provide custom metal contact deposition, critical for stable ohmic contacts and reliable signal readout. Available metals include Ti/Pt/Au (common for diamond detectors), as well as W, Pd, and Cu.
- Surface Preparation: We offer high-quality polishing services for PCD, achieving surface roughness (Ra) < 5 nm on inch-size wafers, which is essential for subsequent lithography and reliable electrode adhesion.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the material science and engineering of diamond for radiation detection. We can assist researchers and engineers with:
- Material Selection: Optimizing PCD grade and thickness for specific clinical requirements (e.g., maximizing sensitivity while maintaining tissue equivalence).
- Design Consultation: Advising on optimal metalization schemes and electrode geometries for high-resolution Radiotherapy Dosimetry projects.
- Global Logistics: Providing reliable global shipping (DDU default, DDP available) to ensure timely delivery of custom wafers for critical clinical research timelines.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.