Phantoms for Quality Control — Complete Guide
Quality control phantoms are indispensable physical devices in modern clinical practice across radiology, radiotherapy and nuclear medicine. They simulate the properties of human tissues — attenuation, scattering, and electron density — enabling rigorous, reproducible, and safe verification of equipment performance. Interphysix is the exclusive distributor of Sun Nuclear in Portugal, as well as a distributor for Fluke Biomedical and other leading QA phantom manufacturers.
What Are Phantoms and What Are They Used For?
The term phantom refers to any object that mimics the physical properties of biological tissue for the purpose of medical equipment testing. In clinical practice, phantoms are used for:
- Dosimetric calibration — absolute dose determination under reference conditions (TG-51/TRS-398 protocols)
- Treatment plan verification — comparing the dose distribution measured in the phantom with the dose calculated by the treatment planning system (TPS)
- Acceptance testing and commissioning — verification of new equipment before clinical use
- Periodic quality control — daily, monthly, and annual tests required by standards and regulations
- Imaging performance testing — assessment of spatial resolution, contrast, noise, and artefacts in CT, MRI, mammography, and nuclear medicine
Radiotherapy Phantoms
Plan Verification Phantoms (Patient-Specific QA)
IMRT/VMAT plan verification is a fundamental requirement before each complex radiotherapy treatment. These phantoms integrate detector arrays that measure 2D or 3D dose distributions and compare them with the calculated plan.
| Product | Type | Detectors | Application |
|---|---|---|---|
| ArcCHECK® | 3D Cylindrical | 1386 diodes | IMRT, VMAT, Tomotherapy |
| MapCHECK®3 | 2D Planar | 1527 diodes | Static and dynamic field verification |
| SRS MapCHECK® | 2D Planar (high density) | 1013 diodes (2.47 mm spacing) | SRS/SBRT, small fields |
| ArcCHECK®-MR | 3D Cylindrical (MR-safe) | 1386 diodes | MR-Linac (ViewRay, Elekta Unity) |
Absolute Dosimetry Phantoms
For photon and electron beam calibration per AAPM TG-51 and IAEA TRS-398 protocols, solid water phantoms are used to reproduce reference conditions with high accuracy:
- Solid Water® HE (Sun Nuclear/Gammex) — water-equivalent material for dosimetric calibration; certified electron densities; available in slabs of various thicknesses
- Liquid water phantom — the gold standard for primary calibrations; the SunSCAN™ 3D is Sun Nuclear's 3D water scanning system
- PMMA (acrylic) phantoms — used in CT dosimetry (CTDI) and fluoroscopy tests
SRS/SBRT Phantoms
Stereotactic radiosurgery demands the highest geometric and dosimetric precision. The StereoPHAN™ (Sun Nuclear) is the reference phantom for end-to-end SRS QA:
- Compatible with SRS MapCHECK® for high-resolution 2D verification
- Supports image-guided localisation (CBCT, kV-kV) and isocentric alignment
- Inserts for small-field ionisation chambers (Exradin A16, PTW 31016)
- Validated for CyberKnife, Gamma Knife, and LINAC-based SRS
Anthropomorphic Phantoms
Anthropomorphic phantoms reproduce human anatomy with radiological fidelity. The ATOM® Phantom family (Sun Nuclear/CIRS) includes head, neck, thorax, and pelvis models with tissue-equivalent inserts (lung, bone, soft tissue). Applications include:
- End-to-end verification of stereotactic radiotherapy plans
- External dosimetric audits (IAEA, ROSIS)
- Training of medical physicists and radiation therapists
- IGRT system validation
Beam Profile Phantoms
The IC PROFILER™ (Sun Nuclear) is an ionisation chamber array for beam profile measurement, output factor determination, and beam/light coincidence tests. Ideal for LINAC commissioning and periodic QA.
Diagnostic Imaging Phantoms
In diagnostic quality control, the reference standard is IEC 61223, which sets requirements for acceptance testing, commissioning, and constancy testing of X-ray equipment.
CT (Computed Tomography) Phantoms
| Phantom | Parameters Assessed | Standard |
|---|---|---|
| ACR CT Phantom 464 | Spatial resolution, low contrast, uniformity, noise, slice thickness, CT number | ACR CT Accreditation |
| Catphan® (The Phantom Laboratory) | MTF, low-contrast resolution, geometry, uniformity, noise | IEC 61223-3-5 |
| CTDI Phantom | Volumetric dose (CTDIvol), axial dose profile | IEC 60601-2-44 |
Mammography Phantoms
Quality control in mammography is critical for breast cancer screening programmes. Key phantoms include:
- ACR Mammography Phantom — evaluates simulated microcalcifications, masses, and fibrous structures; standard for ACR accreditation and national screening
- Mammo 156 Phantom (CIRS/Fluke) — for digital mammography (FFDM) and tomosynthesis systems; includes variable-contrast inserts
- Spectral Mammography Phantom — specific to contrast-enhanced mammography (CEM)
General Radiography and Fluoroscopy Phantoms
Fluke Biomedical provides phantoms for acceptance testing and quality control in conventional radiography and fluoroscopy, including spatial resolution, contrast, geometric distortion, and entrance skin dose assessments. These comply with IEC 61223-3-1 (general radiography) and IEC 61223-3-2 (fluoroscopy).
MRI Phantoms
- ACR MRI Phantom — assesses spatial resolution, signal uniformity, SNR, slice thickness, and geometric alignment; required for ACR MRI accreditation
- MRI Distortion Phantom — maps magnetic field geometric distortion; essential for MRI-guided radiotherapy planning
Nuclear Medicine Phantoms
SPECT Phantoms
- Jaszczak Phantom — cylinder with rod and sphere inserts for resolution, contrast, and uniformity assessment of gamma cameras; NEMA standard for SPECT performance evaluation
- Uniformity phantom — intrinsic and extrinsic uniformity assessment of scintillation detectors
- UN Thyroid Phantom — simulates I-131 uptake for dosimetry in thyroid therapy
PET Phantoms
- NEMA IEC Body Phantom — standard for PET performance evaluation (sensitivity, resolution, scatter fraction) per NEMA NU 2
- Activity calibration phantom — determination of activity calibration factors (KBq/count) for absolute PET quantification
- PET uniformity phantom — periodic verification of detector field-of-view uniformity
Standards and Regulatory Framework
| Standard/Protocol | Area | Scope |
|---|---|---|
| AAPM TG-51 | Radiotherapy | Dosimetric calibration of external photon and electron beams |
| AAPM TG-142 | Radiotherapy | Linear accelerator QA (daily, monthly, annual) |
| IAEA TRS-398 | Radiotherapy | IAEA code of practice for external beam dosimetry |
| IEC 61223 | Diagnostic Radiology | Evaluation and constancy testing of X-ray equipment |
| NEMA NU 2 | Nuclear Medicine | PET system performance; tests with NEMA IEC Body phantom |
Sun Nuclear Products Available from Interphysix
As the exclusive Sun Nuclear distributor in Portugal, Interphysix offers the complete range of phantoms and QA systems for radiotherapy:
- ArcCHECK® — 3D verification of IMRT/VMAT plans
- ArcCHECK®-MR — MR-compatible version for MR-Linac
- MapCHECK®3 — 2D treatment plan verification
- SRS MapCHECK® — high-precision QA for SRS/SBRT
- StereoPHAN™ — end-to-end phantom for radiosurgery
- IC PROFILER™ — beam profile measurement
- SunSCAN™ 3D — 3D water scanning system
- Solid Water® HE — reference material for calibration
Our technical team is available to support phantom selection tailored to your institution's equipment, clinical protocols, and regulatory requirements.
Última actualização: 26/04/2026