PV-0565 - Dosimetric response maps of diode and diamond detectors in kilovoltage synchrotron beams

At a Glance

Metadata	Details
Publication Date	2016-04-01
Journal	Radiotherapy and Oncology
Authors	T. Wright, D.C.D. Butler, A. W. Stevenson, Jayde Livingstone, JC Crosbie
Analysis	Full AI Review Included

6CCVD Technical Documentation: High-Resolution Diamond Dosimetry

Analysis of PV-0565: Dosimetric response maps of diode and diamond detectors in kilovoltage synchrotron beams

Executive Summary

This research validates the use of MPCVD diamond detectors for high-spatial-resolution dosimetry in kilovoltage synchrotron beams, a critical application in radiotherapy. 6CCVD provides the necessary high-purity Single Crystal Diamond (SCD) material with precise thickness control required for replicating and advancing this technology.

Application Validation: Confirms the suitability of solid-state diamond detectors (microDiamond) for high-resolution spatial mapping of kilovoltage X-ray beams (95 keV).
High Resolution Achieved: Dosimetric maps were created with a spatial resolution of approximately 0.1 mm, utilizing a 0.1 mm collimated beam.
Active Volume Isolation: The microDiamond response was found to be almost exclusively due to the active detector area, minimizing signal contribution from surrounding materials—a key advantage over conventional diodes.
Critical Dimension: The high spatial resolution relies on an ultra-thin active volume thickness of only 1 µm for the diamond detector.
6CCVD Core Value: 6CCVD specializes in growing and processing high-purity SCD wafers with thickness control down to 0.1 µm, perfectly matching the requirements for next-generation microDiamond detectors.
Customization: 6CCVD offers custom metalization (e.g., Ti/Pt/Au contacts) essential for fabricating functional solid-state diamond detectors.

Technical Specifications

The following hard data points were extracted from the analysis of the dosimetric response mapping experiment:

Parameter	Value	Unit	Context
Detector Type Tested	microDiamond (PTW 60019)	N/A	Compared against Diode P and Diode E
Radiation Source	Kilovoltage Synchrotron X-rays	N/A	Imaging and Medical Beamline (IMBL)
Weighted-Average Beam Energy	95	keV	Energy used for dosimetric mapping
Beam Collimation Diameter	0.1	mm	Achieved using a tungsten pinhole
Spatial Resolution Achieved	0.1	mm	Resolution of the spatial uniformity map
Diamond Active Volume Thickness	1	µm	Critical dimension for high spatial resolution
Diode Active Volume Thickness	27	µm	Comparison point (significantly thicker)
Diamond Sensitive Spot Response	30	% Higher	Response found in the central 1.5 mm
Response Uniformity (Diodes)	3	% Variation	Across the central 1.5 mm

Key Methodologies

The spatial dosimetric response maps were generated using a high-precision scanning technique at a synchrotron facility:

Detector Selection: Three solid-state detectors (PTW 60016 Diode P, PTW 60017 Diode E, and PTW 60019 microDiamond) were analyzed.
Beam Generation: A low-divergence, high dose-rate beam of kilovoltage synchrotron X-rays was utilized, with a weighted-average energy of 95 keV.
Collimation: The beam was tightly collimated to 0.1 mm in diameter using a tungsten pinhole to achieve sub-millimeter resolution.
Scanning Technique: Continuous line scans were performed to create two-dimensional maps of the detector response.
Orientation Testing: Dosimetric maps were collected for both side-on and end-on orientations to fully characterize the spatial response and contributions from surrounding materials.
Internal Analysis: Detectors were radiographed to identify internal components (e.g., wires) that could affect the measured response.

6CCVD Solutions & Capabilities

6CCVD is an expert supplier of MPCVD diamond materials essential for high-performance radiation detectors like the microDiamond used in this study. Our ability to control thickness, purity, and surface finish directly enables the fabrication of next-generation dosimeters.

Applicable Materials

To replicate or extend this high-resolution dosimetry research, high-purity Single Crystal Diamond (SCD) is required.

Material: Optical Grade Single Crystal Diamond (SCD)
Purity Requirement: High purity is essential to minimize defects and ensure a stable, reproducible signal response (charge collection efficiency) under high dose-rate synchrotron radiation.
Alternative for High-Dose Applications: For applications requiring higher conductivity or specific doping profiles, Boron-Doped Diamond (BDD) PCD or SCD can be engineered.

Customization Potential

The success of the microDiamond detector hinges on the precise control of the active volume thickness (1 µm). 6CCVD’s advanced MPCVD growth and processing capabilities directly address this critical requirement.

Requirement from PV-0565	6CCVD Capability	Technical Advantage
Ultra-Thin Active Layer (1 µm)	SCD Thickness Control: 0.1 µm - 500 µm	Enables precise replication of the 1 µm layer, or exploration of thinner layers (e.g., 0.5 µm) for even higher spatial resolution.
Detector Contacts	Custom Metalization: Au, Pt, Pd, Ti, W, Cu	We provide in-house deposition of electrode structures (e.g., Ti/Pt/Au stacks) optimized for ohmic or Schottky contacts on diamond.
Detector Size	Custom Dimensions: Plates/wafers up to 125 mm (PCD)	Allows for scaling up detector arrays or manufacturing large-area detectors for different medical physics applications.
Surface Quality	Polishing: Ra < 1 nm (SCD)	Ultra-smooth surfaces are critical for minimizing charge trapping and ensuring uniform contact deposition across the active area.

Engineering Support

6CCVD’s in-house PhD engineering team specializes in material science for extreme environments and radiation detection. We can assist researchers and manufacturers with:

Material Selection: Optimizing SCD grade and thickness for specific beam energies (e.g., kilovoltage vs. megavoltage beams).
Doping Profiles: Designing custom Boron-Doped Diamond (BDD) layers for specific conductivity or p-type semiconductor requirements.
Device Integration: Consulting on optimal metalization schemes and surface preparation for reliable electrode integration in high-resolution dosimeters.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Original Source

DOI: https://doi.org/10.1016/s0167-8140(16)31815-1