Saxsons Group

Clinical evidence library · the manufacturer

Delta4 Phantom+ — what the literature says.

Six peer-reviewed studies anchor this page: error-detection sensitivity (Udee 2024), TG-218 action limits across 275 SRS/SBRT plans (Xia 2020), MR-linac adaptive-RT validation at 0.35 T (Cusumano 2020) and 1.5 T (Houweling 2017), pre-treatment IMRT cohort gamma analysis, and the original Delta4 device characterisation. Filter by use-case to see only the cards that matter to your programme.

6 peer-reviewed studies on this page
275 SRS / SBRT plans, 6 198 γ analyses (Xia 2020)
1 069 p-type diodes on two orthogonal panels
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Sensitivity to introduced plan errors (H&N + lung VMAT)
2 mm
MLC position
2°
Collimator rotation
1.5%
MU change
GPR drops below the 95 % action limit at each of these error magnitudes — a clear stop-go signal for the physicist.
Error detection 2024
95% gamma-passing-rate action threshold — Delta4 crosses it at MLC ≥ 2 mm and collimator rotation ≥ 2°

Delta4-based dosimetric error detection in volumetric-modulated arc therapy: clinical significance and implications

Journal of Medical Physics 49(1):56–63 — Udee et al.

Gamma passing rate at increasing MU error (lower = larger detected error)
MU + 1.5 % (small)
91.7%
MU + 3.0 % (medium)
75%
MU + 4.5 % (large)
49.0%
Error detection 2024
49.0% minimum GPR at MU + 4.5 % — MU error is the most detectable class

Gamma passing rate response to increasing MU error — VMAT

Udee et al., J Med Phys 49(1):56–63 (2024)

TG-218 action-limit application — Delta4 cohort scope
275
plans analysed
1 214
field deliveries
6 198
gamma analyses
Single largest published Delta4 cohort applying AAPM TG-218 statistical action limits to SRS and SBRT.
SRS / SBRT 2020
275 SRS / SBRT plans · 1 214 field deliveries · 6 198 gamma analyses on Delta4 and comparator devices

Application of TG-218 action limits to SRS and SBRT pre-treatment patient-specific QA

Journal of Radiosurgery and SBRT 7(2):135–147 — Xia, Adamson, Zlateva, Giles

Single-target VMAT SRS — GPR by tightening gamma criterion
γ 3 %/3 mm
98.81%
γ 3 %/2 mm
98.06%
γ 3 %/1 mm
93.64%
γ 2 %/1 mm
88.50%
SRS / SBRT 2020
98.81% mean gamma passing rate at 3 %/3 mm — held above 93 % even at the strict 3 %/1 mm criterion

Delta4 gamma passing rate by criterion — single-target intracranial SRS (n = 24)

Xia et al., J Radiosurg SBRT 7(2):135–147 (2020)

SBRT all-sites — Delta4 vs TG-218 action limit
4 %/1 mm
TG-218 action limit
90 % GPR required
vs
90.27%
Delta4 cohort result
0 % plans failed the threshold
SRS / SBRT 2020
0% failure rate at the TG-218 4 %/1 mm action limit across the SBRT cohort

Delta4 holds tolerance at 4 %/1 mm across all SBRT sites (n = 66)

Xia et al., J Radiosurg SBRT 7(2):135–147 (2020)

MR-linac Delta4 validation — clinical readiness
0.35 T
ViewRay MRIdian
1.5 T
Elekta Unity
Daily
adaptive RT cycle
Validated separately in 0.35 T (Cusumano 2020) and 1.5 T (Houweling 2017, PubMed 29176067). The MR-compatible Delta4+ is now the QA standard at UMC Utrecht, Heidelberg, Miami Cancer Institute and other adaptive-RT programmes.
MR-linac 2020
36 plans re-planned on MR-compatible Delta4 and delivered — characteristics comparable to the non-MR version

Clinical validation of the MR-compatible Delta4 QA system in a 0.35 T MR-linac

Physica Medica — Cusumano et al. (PMC8035559)

Pre-treatment IMRT QA — gamma passing-rate range
99.6%
Cohort minimum
lowest plan in the series
vs
100%
Cohort maximum
multiple plans matched the calculated dose
IMRT pre-treatment 2020
99.6% minimum gamma passing rate across the pre-treatment IMRT QA cohort with anatomy-based 3D DVH analysis

Evaluation of Delta4DVH Anatomy in 3D patient-specific IMRT quality assurance

Journal of Applied Clinical Medical Physics (PMC7388137)

Detector hardware (foundational characterisation)
1 069
p-type diodes
5 mm
inner resolution
2 ⊥
orthogonal panels
2.5 mm phantom-shift technique doubles the effective resolution for SRS work. Original Delta4 characterisation continues to underpin the Phantom+ device.
Foundational 2009
1 069 p-type diodes on two near-orthogonal panels · 5 mm spatial resolution in the inner area · the device characterised in the original 2009 validation paper

Evaluation of the Delta4 phantom for IMRT and VMAT verification

Medical Physics — Bedford et al. (PubMed 19384007)

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Brochures & references

Manufacturer comparison material. Peer-reviewed citations are inline on the cards above.

PDF

Delta4 Phantom+ — comparison brochure

Manufacturer comparison brochure covering the Delta4 product family and 3D detector geometry.

127 KB Download

Delta4 Phantom+

More for this product

Each card opens a focused post for a specific specialty — clinical workflow and evidence, written for the persona you select.

For Medical Physicist

Medical Physicist

Sensitivity to introduced plan errors

At what magnitude of MLC, gantry, collimator or MU error does the Delta4 gamma passing rate cross the 95 % action threshold? Per Udee 2024, J Med Phys.

Read this Medical Physicist

50 nGy per-pulse integration — why it matters for FFF and FLASH

Ion chambers under-respond and many diodes drift at high dose-per-pulse. What changes when the detector integrates one pulse at a time at 50 nGy resolution?

Read this Medical Physicist

One phantom — TG-218 patient QA and TG-142 machine QA

Departments routinely run separate equipment for patient-specific QA and routine machine QA. What changes when the same 1,069-detector array runs both workflows under one software ecosystem?

Read this