Stereotactic Radiosurgery · Dose Tables

Dose Tables

Trial prescription schemes, normal-tissue limits, and a BED/EQD2 calculator

The dose tables behind modern radiosurgery practice, reproduced from the trials and consensus reports that define them: RTOG 90-05, NCCTG N107C, Alliance A071801, AAPM TG-101, HyTEC, RTOG 0631, and CCTG SC.24. Each table names its source so it can be checked. Every value is a starting point for multidisciplinary planning, not a prescription; final dose follows the constraint set adopted by your physics and radiation-oncology team.

Timoteo Almeida, MD, MSc, PhD, FCNS | Departments of Neurological Surgery and Radiation Oncology

Orientation

This page holds the source tables. Representative doses for benign, vascular, and functional targets (vestibular schwannoma, meningioma, pituitary, AVM, trigeminal neuralgia, thalamotomy) are on the Quick Reference, and the reasoning for choosing among them is on Dose Selection & Fractionation. Dose units are Gy; volumes are cc (cm³); fx = fractions.

Part I. Brain metastases, intact
Part II. Postoperative cavity
Part III. Normal-tissue limits
Part IV. Spine SBRT trials
Part V. BED and EQD2

Part I

Brain Metastases, Intact

1.RTOG 90-05: single-fraction maximum tolerated dose

Shaw et al., 2000. Dose escalation in previously irradiated recurrent primary brain tumors and brain metastases. These are ceilings for the setting studied, widely used as the size-based reference for single-fraction SRS. Equivalent spherical volumes from Soltys et al.
Maximum diameter	Equivalent spherical volume	Single-fraction dose
≤ 2.0 cm	≤ 4.2 cc	24 Gy
2.1–3.0 cm	4.3–14.1 cc	18 Gy
3.1–4.0 cm	14.2–33.5 cc	15 Gy

2.Alliance A071801 protocol: unresected lesions

Patients on A071801 (trial described in section 5) could have up to three additional intact metastases, treated in the same arm as the cavity. The single-fraction arm dosed intact lesions by diameter; the fractionated arm used the same schedules as the cavity.

From the A071801 protocol (NCT04114981) as tabulated by Marques et al. Note the split of the smallest RTOG 90-05 tier into < 1 cm (24 Gy) and 1–2 cm (22 Gy).
Maximum diameter	1 fx arm	fSRS arm, cavity < 30 cc	fSRS arm, cavity ≥ 30 cc
< 1.0 cm	24 Gy	27 Gy / 3	30 Gy / 5
1.0 to < 2.0 cm	22 Gy
2.0 to < 3.0 cm	18 Gy
3.0 to < 4.0 cm	15 Gy

3.Common hypofractionated schedules for larger intact lesions

Schedules in routine use for lesions above about 2–2.5 cm or near critical structures. Randomized data for intact lesions are pending: NRG-BN013 (single-fraction vs 3-fraction SRS for 1–3 cm lesions) closed to accrual in 2026.
Schedule	Typical use	Supporting data
27 Gy / 3 (9 Gy × 3)	Lesions > 2 cm; the most widely used 3-fraction schedule	Minniti 2016 (retrospective, 289 patients, > 2 cm): against 15–18 Gy × 1, 1-year local control 91% vs 77% and 1-year cumulative radionecrosis 9% vs 18% (P = .01 for both); crude radionecrosis 8% vs 20% (P = .004)
24 Gy / 3 (8 Gy × 3)	Larger targets or closer OAR proximity	Soltys et al. (2.5–4.0 cm: 8–9 Gy × 3)
30 Gy / 5 (6 Gy × 5)	Largest targets, brainstem or optic proximity	A071801 used it for cavities ≥ 30 cc (no separate intact-lesion outcomes reported); for intact lesions, institutional series

Part II

Postoperative Cavity

4.NCCTG N107C: single-fraction dose by cavity volume

Brown et al., 2017. Eligibility: one resected metastasis, cavity < 5.0 cm maximal extent. Alliance A071801 used the same volume tiers in its single-fraction arm. Approximate equivalent diameters from Soltys et al.
Cavity (target) volume	Approx. equivalent diameter	Single-fraction dose
< 4.2 cc	≤ 2.0 cm	20 Gy
4.2–7.9 cc	2.1–2.4 cm	18 Gy
8.0–14.3 cc	2.5–3.0 cm	17 Gy
14.4–19.9 cc	3.1–3.4 cm	15 Gy
20.0–29.9 cc	3.5–3.8 cm	14 Gy
≥ 30 cc (max extent < 5 cm)	3.9–5.0 cm	12 Gy

5.Alliance A071801: fractionated cavity SRS

Brown, Aizer et al., ASTRO 2026 (LBA 01). Randomized phase III, 242 patients, 1–4 metastases with one resected lesion ≥ 2 cm, cavity < 5 cm; median follow-up 48 months. Single-fraction arm dosed 12–20 Gy by the N107C tiers above.
Cavity volume	fSRS dose	Note
< 30 cc	27 Gy / 3	Intact metastases in this arm received the same schedule (Marques, Table 28.4)
≥ 30 cc	30 Gy / 5

Reported outcomes, fractionated vs single-fraction (abstract; full publication pending). Radionecrosis figures are crude rates; time-to-event analysis has not been reported.
Endpoint	fSRS	1 fx SRS	P
Surgical bed control at 1 year (primary endpoint: time to bed failure)	87%	81%	.046
Median overall survival (secondary endpoint)	29 mo	20 mo	.035 (HR 0.69)
Radionecrosis, grade ≥ 1	14%	10%	NS
Cerebral edema	8%	9%	NS
Failure of treated unresected lesions	4%	11%	.063
Median cavity target volume	16.5 cc	14.8 cc	.41

Reading A071801 For a resected metastasis ≥ 2 cm, fractionated cavity SRS now has randomized phase III support. Read it with five qualifiers. The gain is modest: about 6 points of 1-year surgical bed control. The typical cavity was moderate, not very large: median 14.8–16.5 cc by arm. Small lesions were not studied: cavities from metastases under 2 cm were ineligible, so single-fraction SRS remains reasonable there, and for patients who prefer one visit. The survival difference is a secondary endpoint without a clear mechanism; treat it as hypothesis-generating. All numbers are from the abstract; the full paper is pending.

Inference, pending the full paper The abstract does not report the single-fraction dose distribution. The single-fraction median cavity of 14.8 cc falls in the N107C 15 Gy tier, just above the 14.4 cc lower bound of that tier, so at least half of that arm would have received 15 Gy or less. The typical comparison was therefore probably closer to 15 Gy × 1 against 27 Gy / 3 (BED₁₀ 37.5 vs 51.3 Gy) than many readers assume. This is a reading of the median volume against the protocol tiers, not a reported result.

Part III

Normal-Tissue Limits

6.AAPM TG-101: CNS and neural structures

Benedict et al., 2010, Table III, original values (some handbooks reproduce institutionally modified versions under the TG-101 name). Vol = threshold dose: no more than the listed volume may receive more than this dose. Max = point maximum. Most values were not validated and many were extrapolated; see the HyTEC updates in section 7. A 2023 erratum corrected the report; check the corrected tables before clinical use.
Structure	Volume	1 fx		3 fx		5 fx		Endpoint (≥ G3)
Structure	Volume	Vol	Max	Vol	Max	Vol	Max	Endpoint (≥ G3)
Optic pathway	< 0.2 cc	8	10	15.3	17.4	23	25	Neuritis
Cochlea	–	–	9	–	17.1	–	25	Hearing loss
Brainstem (not medulla)	< 0.5 cc	10	15	18	23.1	23	31	Cranial neuropathy
Spinal cord and medulla	< 0.35 cc	10	14	18	21.9	23	30	Myelitis
Spinal cord and medulla	< 1.2 cc	7	14	12.3	21.9	14.5	30	Myelitis
Cord subvolume (5–6 mm above and below level)	< 10%	10	14	18	21.9	23	30	Myelitis
Cauda equina	< 5 cc	14	16	21.9	24	30	32	Neuritis
Sacral plexus	< 5 cc	14.4	16	22.5	24	30	32	Neuropathy
Brachial plexus	< 3 cc	14	17.5	20.4	24	27	30.5	Neuropathy

7.HyTEC refinements and the QUANTEC brainstem limit

HyTEC (2021) pooled outcome data to refine the TG-101 era limits. Point maxima in Gy. The optic limit loosened at 3 fractions; the de novo cord limit tightened at 3 and 5 fractions, although HyTEC’s lower cord values derive from thecal-sac point maxima rather than the TG-101 true cord.
Structure	1 fx	3 fx	5 fx	Estimated risk / note	Source
Optic pathway, Dmax	10	20	25	About 1% or less without prior RT (10 Gy is the HyTEC single-fraction recommendation; risk levels in the next table). Prior irradiation carried about a tenfold higher crude risk	Milano 2021 (HyTEC)
Spinal cord, de novo SBRT, Dmax	12.4–14	20.3	25.3	1–5% myelopathy; 2 fx 17.0, 4 fx 23.0. Applies to the thecal sac as a cord PRV; 14 Gy derives from myelogram-defined cord	Sahgal 2021 (HyTEC)
Brainstem, Dmax	12.5	–	–	< 5% risk; higher doses accepted for brainstem metastases by prognosis	Mayo 2010 (QUANTEC)

Optic nerve and chiasm: modeled risk of optic neuropathy by point maximum dose, no prior RT (HyTEC optic, Milano 2021, NTCP model across all studies, α/β = 1.6 Gy). A model built only from single-fraction series gives lower 1-fraction values: 10.0, 11.1, and 14.0 Gy for 1%, 2%, and 5%.
Risk	1 fx Dmax	3 fx Dmax	5 fx Dmax
1%	12.1 Gy	20.0 Gy	25.1 Gy
2%	13.8 Gy	23.0 Gy	28.9 Gy
5%	16.1 Gy	26.9 Gy	33.9 Gy

Normal brain and radionecrosis in metastasis SRS (HyTEC brain, Milano 2021). V12, V20, and V24 include the target; the 3-fraction V18 and V23 figures refer to normal brain outside the target and come from the single-institution series HyTEC drew on (Minniti, Inoue). AVMs showed modestly lower necrosis rates at the same V12. Earlier QUANTEC guidance kept single-fraction V12 under 5–10 cc.
Schedule	Dose-volume metric	Estimated risk
1 fx	V12 = 5 cc	~10% symptomatic radionecrosis
	V12 = 10 cc	~15%
	V12 > 15 cc	~20%
3 fx	V20 < 20 cc	< 10% any necrosis or edema; < 4% necrosis requiring resection
5 fx	V24 < 20 cc
3 fx	Normal brain V18 < 30 cc and V23 < 7 cc	< 10% radionecrosis

Part IV

Spine SBRT Trials

8.Randomized schedules and their cord limits

The two randomized spine trials most often cited for dose (RTOG 0631, phase III; SC.24, phase II/III). Cord limits are protocol-specific; do not interchange true-cord, thecal-sac, and PRV contours.
Trial	Arms	Cord limit (protocol)	Primary result
RTOG 0631 (Ryu 2023)	16 or 18 Gy / 1 vs 8 Gy / 1 cEBRT	Cord D0.35 cc ≤ 10 Gy, or ≤ 10 Gy to 10% of the partial cord 5–6 mm above and below; point max ≤ 14 Gy (protocol)	3-month pain response favored 8 Gy (41.3% vs 60.5%; 2-sided P = .01); no spinal cord complications at 24 months
CCTG SC.24 (Sahgal 2021)	24 Gy / 2 vs 20 Gy / 5 cEBRT	Protocol values not reproduced here; the HyTEC 2-fraction cord Dmax of 17.0 Gy is the usual reference	Complete pain response at 3 months 35% vs 14% (P = .0002)

9.SBRT re-irradiation after conventional RT

Sahgal et al., 2012. Thecal sac point maximum for SBRT given at least 5 months after conventional palliative RT (prior courses about 30–50 Gy EQD2): SBRT course 20–25 Gy EQD2, no more than about half of the cumulative total, cumulative about 70 Gy EQD2 or less (α/β = 2). Doses below are the physical dose that equals 25 Gy EQD2.
Fractions	1	2	3	4	5
Thecal sac point max (Gy)	9.0	12.3	14.6	16.4	17.9

For other prior doses, other structures, or several structures at once, use the re-irradiation budget on the Dose Calculator.

Part V

BED and EQD2

10.Calculator

BED = n · d · (1 + d / [α/β]); EQD2 = BED / (1 + 2 / [α/β]). Enter any α/β or pick a preset; the comparison line shows the same schedule at α/β 10 (tumor) and 2 (late CNS effects).

Dose per fraction (Gy)

Fractions

α/β (Gy)

Total dose

27.0 Gy

BED

51.3 Gy

EQD2

42.8 Gy

α/β 10: BED 51.3, EQD2 42.8 Gy · α/β 2: BED 148.5, EQD2 74.3 Gy

Full calculator The Dose Calculator adds isoeffective conversion between fraction numbers, a re-irradiation module that sums the dose to a structure against published CNS cumulative levels, and a pre-plan estimate of dose 1–3 mm outside a target and of brain V12, V20, or V24 from target size, platform, and gradient index.

11.Common schedules in BED₁₀ and EQD2

Tumor effect (α/β = 10) beside late-CNS cost (α/β = 2). 27 Gy / 3 matches the 18 Gy single-fraction tier for tumor (BED₁₀ 51.3 vs 50.4) at a lower late-CNS EQD2 (74.3 vs 90.0 Gy). Single fractions above about 10 Gy are shown at α/β = 2 for comparison only; the LQ model may overstate their effect, although some argue the opposite. Load sends a schedule to the calculator above.
Schedule	Use in the tables above	BED₁₀	EQD2₁₀	EQD2₂
Single fraction
24 Gy × 1	RTOG 90-05 ceiling ≤ 2 cm; A071801 intact < 1 cm	81.6	68.0	156.0
22 Gy × 1	A071801 intact 1–2 cm	70.4	58.7	132.0
20 Gy × 1	N107C and A071801 cavity < 4.2 cc	60.0	50.0	110.0
18 Gy × 1	RTOG 90-05 2.1–3 cm; cavity 4.2–7.9 cc	50.4	42.0	90.0
17 Gy × 1	Cavity 8.0–14.3 cc	45.9	38.3	80.8
15 Gy × 1	RTOG 90-05 3.1–4 cm; cavity 14.4–19.9 cc	37.5	31.3	63.8
14 Gy × 1	Cavity 20.0–29.9 cc	33.6	28.0	56.0
12 Gy × 1	Cavity ≥ 30 cc	26.4	22.0	42.0
Fractionated
27 Gy / 3	A071801 cavity < 30 cc; large intact metastasis	51.3	42.8	74.3
24 Gy / 3	Large intact metastasis, institutional series	43.2	36.0	60.0
30 Gy / 5	A071801 cavity ≥ 30 cc; large intact metastasis	48.0	40.0	60.0
25 Gy / 5	Targets near the optic apparatus or brainstem, institutional series	37.5	31.3	43.8
24 Gy / 2	Spine SBRT, CCTG SC.24	52.8	44.0	84.0

LQ caveat The linear-quadratic model is least certain at the single-fraction doses used in radiosurgery: it may overstate the effect as cell-survival curves straighten at high dose, while vascular and immune effects proposed by Kirkpatrick and colleagues could act the other way; Brenner argues the model remains appropriate. Use BED and EQD2 to compare schedules and reason about trends, not to set a prescription or to sum doses for re-irradiation without physics review.

Key points

RTOG 90-05 gives the single-fraction ceiling by diameter: 24, 18, and 15 Gy for ≤ 2, 2.1–3, and 3.1–4 cm.
N107C doses the cavity by volume, from 20 Gy (< 4.2 cc) down to 12 Gy (≥ 30 cc). A071801 used the same tiers.
A071801 (abstract) supports 27 Gy / 3 (or 30 Gy / 5 for ≥ 30 cc) after resection of a lesion ≥ 2 cm: a modest gain in bed control, small lesions untested, survival result hypothesis-generating.
Read TG-101 alongside HyTEC: optic Dmax 10 Gy / 1 fx, 20 Gy / 3 fx, 25 Gy / 5 fx for about 1% risk or less (the all-study model puts 5% at about 16, 27, and 34 Gy); de novo cord Dmax 20.3 Gy / 3 fx and 25.3 Gy / 5 fx.
Track brain-plus-target V12 for single-fraction plans (about 10%, 15%, and 20% symptomatic necrosis at 5, 10, and > 15 cc). For fractionated plans, keep brain-plus-target V20 (3 fx) or V24 (5 fx) under 20 cc; at 3 fx, normal-brain V18 under 30 cc and V23 under 7 cc are the alternative markers.

Last updated November 2026.

References

Shaw E, Scott C, Souhami L, et al. Single dose radiosurgical treatment of recurrent previously irradiated primary brain tumors and brain metastases: final report of RTOG protocol 90-05. Int J Radiat Oncol Biol Phys. 2000;47(2):291–298. PubMed
Brown PD, Ballman KV, Cerhan JH, et al. Postoperative stereotactic radiosurgery compared with whole brain radiotherapy for resected metastatic brain disease (NCCTG N107C/CEC.3): a multicentre, randomised, controlled, phase 3 trial. Lancet Oncol. 2017;18(8):1049–1060. PubMed
Brown PD, Ballman KV, Aizer AA, et al. Alliance A071801 phase III trial: postoperative single fraction stereotactic radiosurgery (SRS) vs fractionated SRS (fSRS) for resected brain metastasis. LBA 01. Int J Radiat Oncol Biol Phys. 2026;126(1 Suppl):e832. Abstract; full publication pending. ASTRO abstract
Minniti G, Scaringi C, Paolini S, et al. Single-fraction versus multifraction (3 × 9 Gy) stereotactic radiosurgery for large (> 2 cm) brain metastases: a comparative analysis of local control and risk of radiation-induced brain necrosis. Int J Radiat Oncol Biol Phys. 2016;95(4):1142–1148. PubMed
Soltys SG, Pollom E, Gibbs IC. Brain metastases: intact and postoperative radiotherapy and radiosurgery. In: Halasz LM, Lo SS, Chang EL, Sahgal A, eds. Intracranial and Spinal Radiotherapy: A Practical Guide on Treatment Techniques. Springer; 2021:147–154.
Marques C, et al. Brain metastases. In: Lee NY, Lu JJ, Yu Y, eds. Target Volume Delineation and Field Setup: A Practical Guide for Conformal and Intensity-Modulated Radiation Therapy. 2nd ed. Springer; 2022.
Benedict SH, Yenice KM, Followill D, et al. Stereotactic body radiation therapy: the report of AAPM Task Group 101. Med Phys. 2010;37(8):4078–4101. PubMed
Milano MT, Grimm J, Niemierko A, et al. Single- and multifraction stereotactic radiosurgery dose/volume tolerances of the brain (HyTEC). Int J Radiat Oncol Biol Phys. 2021;110(1):68–86. PubMed
Milano MT, Grimm J, Soltys SG, et al. Single- and multi-fraction stereotactic radiosurgery dose tolerances of the optic pathways (HyTEC). Int J Radiat Oncol Biol Phys. 2021;110(1):87–99. PubMed
Sahgal A, Chang JH, Ma L, et al. Spinal cord dose tolerance to stereotactic body radiation therapy (HyTEC). Int J Radiat Oncol Biol Phys. 2021;110(1):124–136. PubMed
Correction to: Stereotactic body radiation therapy: the report of AAPM Task Group 101. Med Phys. 2023:3885. PubMed
Mayo C, Yorke E, Merchant TE. Radiation associated brainstem injury (QUANTEC). Int J Radiat Oncol Biol Phys. 2010;76(3 Suppl):S36–S41. PubMed
Lawrence YR, Li XA, el Naqa I, et al. Radiation dose-volume effects in the brain (QUANTEC). Int J Radiat Oncol Biol Phys. 2010;76(3 Suppl):S20–S27. PubMed
Sahgal A, Ma L, Weinberg V, et al. Reirradiation human spinal cord tolerance for stereotactic body radiotherapy. Int J Radiat Oncol Biol Phys. 2012;82(1):107–116. PubMed
Kirkpatrick JP, Meyer JJ, Marks LB. The linear-quadratic model is inappropriate to model high dose per fraction effects in radiosurgery. Semin Radiat Oncol. 2008;18(4):240–243. PubMed
Brenner DJ. The linear-quadratic model is an appropriate methodology for determining isoeffective doses at large doses per fraction. Semin Radiat Oncol. 2008;18(4):234–239. PubMed
Ryu S, Deshmukh S, Timmerman RD, et al. Stereotactic radiosurgery vs conventional radiotherapy for localized vertebral metastases of the spine: phase 3 results of NRG Oncology/RTOG 0631 randomized clinical trial. JAMA Oncol. 2023;9(6):800–807. PubMed
Sahgal A, Myrehaug S, Siva S, et al. Stereotactic body radiotherapy versus conventional external beam radiotherapy in patients with painful spinal metastases: an open-label, multicentre, randomised, controlled, phase 2/3 trial (CCTG SC.24). Lancet Oncol. 2021;22(7):1023–1033. PubMed