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Gamma Ray Dose Constants

The “Specific Gamma Ray Dose Constant”, sometimes known as the “Gamma Factor”, is the dose rate at a specific distance from a given amount of a photon-emitting radionuclide. These constants are used frequently for radiation protection purposes. The following is a listing of Specific Gamma Ray Dose Constants for a variety of radionuclides, in units of Rem per hour (Rem/hr) at a distance of one (1) meter from a one (1) curie point source of that radionuclide.**

Actinium

  • Ac-225 – 0.191364
  • Ac-227 – 0.0087468
  • Ac-228 – 0.84397

Aluminum

  • Al-26 – 1.49739
  • Al-28 – 0.88208

Americium

  • Am-241 – 0.313723
  • Am-242 – 0.202612
  • Am-242m – 0.18315
  • Am-243 – 0.312872
  • Am-244 – 1.17216
  • Am-245 – 0.086617
  • Am-246 – 0.079513

Antimony

  • Sb-117 – 0.304103
  • Sb-122 – 0.304251
  • Sb-124 – 1.06671
  • Sb-125 – 0.38036
  • Sb-126 – 1.7982
  • Sb-126m – 1.04488
  • Sb-127 – 0.444
  • Sb-129 – 0.85655

Argon

  • Ar-41 – 0.69597

Arsenic

  • As-72 – 1.16476
  • As-73 – 0.140008
  • As-74 – 0.54464
  • As-76 – 0.274096
  • As-77 – 0.0062863

Astatine

  • At-211 – 0.22644
  • At-217 – 0.000160247

Barium

  • Ba-131 – 0.46028
  • Ba-133 – 0.45547
  • Ba-133m – 0.124764
  • Ba-135m – 0.110038
  • Ba-137m – 0.39997
  • Ba-139 – 0.0285529
  • Ba-140 – 0.164502
  • Ba-141 – 0.57794
  • Ba-142 – 0.56869

Berkelium

  • Bk-250 – 0.67858

Beryllium

  • Be-7 – 0.0343804

Bismuth

  • Bi-206 – 2.5234
  • Bi-207 – 1.33311
  • Bi-208 – 1.5207
  • Bi-211 – 0.047138
  • Bi-212 – 0.194768
  • Bi-213 – 0.11618
  • Bi-214 – 0.83916

Bromine

  • Br-77 – 0.71151
  • Br-80 – 0.080142
  • Br-80m – 0.703
  • Br-82 – 1.61949
  • Br-83 – 0.0051837
  • Br-84 – 0.88504
  • Br-85 – 0.039183

Cadmium

  • Cd-109 – 0.184371
  • Cd-111m – 0.313131
  • Cd-115 – 1505160000
  • Cd-115m – 0.0127021
  • Cd-117 – 0.6438
  • Cd-117m – 1.08595

Calcium

  • Ca-45 – 2.98664E-08
  • Ca-47 – 0.58497
  • Ca-49 – 1.33755

Californium

  • Cf-248 – 0.045473
  • Cf-249 – 0.41403
  • Cf-250 – 0.044844
  • Cf-251 – 0.42994
  • Cf-252 – 0.041847
  • Cf-253 – 0.0007696
  • Cf-254 – 4.8507E-08

Carbon

  • C-11 – 0.71669

Cerium

  • Ce-139 – 0.205498
  • Ce-141 – 0.073223
  • Ce-143 – 0.255041
  • Ce-144 – 0.0233174

Cesium

  • Cs-126 – 0.80142
  • Cs-129 – 0.359825
  • Cs-131 – 0.124431
  • Cs-132 – 0.57572
  • Cs-134 – 0.99937
  • Cs-134m – 0.070448
  • Cs-136 – 1.34384
  • Cs-137 – 0.38184
  • Cs-138 – 1.26614
  • Cs-139 – 0.15762

Chlorine

  • Cl-38 – 0.71854

Chromium

  • Cr-49 – 0.75073
  • Cr-51 – 0.023384

Cobalt

  • Co-56 – 1.92585
  • Co-57 – 0.151219
  • Co-58 – 0.61383
  • Co-58m – 9.7569E-05
  • Co-60 – 1.37011
  • Co-60m – 0.00335109
  • Co-61 – 0.084582

Copper

  • Cu-61 – 0.56832
  • Cu-62 – 0.7067
  • Cu-64 – 0.131942
  • Cu-67 – 0.087431

Curium

  • Cm-242 – 0.072113
  • Cm-243 – 0.47582
  • Cm-244 – 0.064417
  • Cm-245 – 0.4514
  • Cm-246 – 0.057387
  • Cm-247 – 0.267029
  • Cm-248 – 0.045399
  • Cm-249 – 0.0148259

Dysprosium

  • Dy-157 – 0.309209
  • Dy-165 – 0.0229141
  • Dy-166 – 0.05735

Einsteinium

  • Es-253 – 0.0256077
  • Es-254 – 0.5513
  • Es-254m – 0.56203
  • Es-255 – 0.00315573

Erbium

  • Er-169 – 1.26022E-06
  • Er-171 – 0.29637

Europium

  • Eu-152 – 0.74444
  • Eu-152m – 0.212602
  • Eu-154 – 0.75554
  • Eu-155 – 0.066748
  • Eu-156 – 0.73704

Fermium

  • Fm-254 – 0.041477
  • Fm-255 – 0.322677

Fluorine

  • F-18 – 0.69523

Francium

  • Fr-221 – 0.044141
  • Fr-223 – 0.33041

Gadolinium

  • Gd-153 – 0.172383
  • Gd-159 – 0.039183
  • Gd-162 – 0.308617

Gallium

  • Ga-66 – 1.29648
  • Ga-67 – 0.111148
  • Ga-68 – 0.66193
  • Ga-72 – 1.45632

Germanium

  • Ge-68 – 0.060458
  • Ge-71 – 0.061161
  • Ge-77 – 0.71558

Gold

  • Au-194 – 0.66008
  • Au-195 – 0.087394
  • Au-195m – 0.152884
  • Au-196 – 0.369704
  • Au-198 – 0.291634
  • Au-199 – 0.069042

Hafnium

  • Hf-181 – 0.39257

Holmium

  • Ho-166 – 0.023199
  • Ho-166m – 1.0619

Indium

  • In-111 – 0.50172
  • In-113m – 0.242979
  • In-114 – 0.0230251
  • In-114m – 0.150738
  • In-115m – 0.197173
  • In-116m – 1.3542
  • In-117 – 0.50283
  • In-117m – 0.11322

Iodine

  • I-122 – 0.70337
  • I-123 – 0.276686
  • I-124 – 0.7585
  • I-125 – 0.274984
  • I-126 – 0.39035
  • I-128 – 0.059792
  • I-129 – 0.125837
  • I-130 – 1.40267
  • I-131 – 0.282939
  • I-132 – 1.42746
  • I-133 – 0.40885
  • I-134 – 1.57287
  • I-135 – 0.86099
  • I-136 – 1.26429

Iridium

  • Ir-190 – 0.99197
  • Ir-190m(1.2h) – 2.2644E-07
  • Ir-190m(3.2h) – 0.055463
  • Ir-192 – 0.59163
  • Ir-193m – 0.00037629
  • Ir-194 – 0.061901
  • Ir-194m – 1.61764

Iron

  • Fe-52 – 0.52281
  • Fe-59 – 0.66193

Krypton

  • Kr-79 – 0.60347
  • Kr-81 – 0.43364
  • Kr-83m – 0.118733
  • Kr-85 – 0.00156584
  • Kr-85m – 0.160136
  • Kr-87 – 0.43253
  • Kr-88 – 1.02453
  • Kr-89 – 0.97162
  • Kr-90 – 0.76701

Lanthanum

  • La-141 – 0.0226144
  • La-142 – 1.35272

Lead

  • Pb-203 – 0.67636
  • Pb-204m – 1.3505
  • Pb-205 – 0.251193
  • Pb-210 – 0.251637
  • Pb-211 – 0.0363932
  • Pb-212 – 0.273393
  • Pb-214 – 0.323454
  • Pd-103 – 0.230103
  • Pd-109 – 0.0004847

Lutetium

  • Lu-177 – 0.0282532
  • Lu-177m – 0.78144

Magnesium

  • Mg-27 – 0.53613
  • Mg-28 – 0.87875

Manganese

  • Mn-52 – 2.0091
  • Mn-52m – 1.44411
  • Mn-54 – 0.51134
  • Mn-56 – 0.92352
  • Mn-57 – 0.112147

Mercury

  • Hg-197 – 0.069338
  • Hg-197m – 0.076183
  • Hg-203 – 0.253117

Molybdenum

  • Mo-101 – 0.88467
  • Mo-91 – 0.70226
  • Mo-93 – 0.293632
  • Mo-99 – 0.112924

Neodynium

  • Nd-147 – 0.139453
  • Nd-149 – 0.300144

Neptunium

  • Np-235 – 0.258223
  • Np-236 – 1.04821
  • Np-236m – 0.23643
  • Np-237 – 0.46287
  • Np-238 – 0.55389
  • Np-239 – 0.51282
  • Np-240 – 1.41562
  • Np-240m – 0.42328

Nickel

  • Ni-56 – 1.08817
  • Ni-57 – 1.07707
  • Ni-65 – 0.297406

Niobium

  • Nb-90 – 2.44089
  • Nb-91 – 0.326784
  • Nb-91m – 0.26492
  • Nb-92 – 1.26318
  • Nb-92m – 0.89281
  • Nb-93m – 0.052577
  • Nb-94 – 0.97976
  • Nb-94m – 0.202797
  • Nb-95 – 0.48026
  • Nb-95m – 0.23643
  • Nb-96 – 1.5244
  • Nb-97 – 0.43475
  • Nb-97m – 0.46694

Nitrogen

  • N-13 – 0.71706
  • N-16 – 1.47408

Osmium

  • Os-185 – 0.4847
  • Os-190m – 1.11666
  • Os-191 – 0.067969
  • Os-191m – 0.0053613
  • Os-193 – 0.052318

Oxygen

  • O-15 – 0.7178

Platinum

  • Pt-191 – 0.243756
  • Pt-193m – 0.0172013
  • Pt-195m – 0.075073
  • Pt-197 – 0.0208939
  • Pt-197m – 0.071447

Plutonium

  • Pu-236 – 0.088985
  • Pu-237 – 0.38443
  • Pu-238 – 0.078995
  • Pu-239 – 0.0301365
  • Pu-240 – 0.07511
  • Pu-242 – 0.062308
  • Pu-243 – 0.092833
  • Pu-244 – 0.054094
  • Pu-245 – 0.38702

Polonium

  • Po-209 – 0.00363007
  • Po-210 – 5.2688E-06
  • Po-211 – 0.0049136
  • Po-213 – 1.90402E-05
  • Po-214 – 5.1726E-05
  • Po-215 – 0.000105857
  • Po-216 – 8.9688E-06

Potassium

  • K-40 – 0.081696
  • K-42 – 0.143153
  • K-43 – 0.67007

Praseodynium

  • Pr-142 – 0.0299922
  • Pr-143 – 5.6388E-09
  • Pr-144 – 0.01702
  • Pr-144m – 0.0367521

Promethium

  • Pm-143 – 0.266992
  • Pm-144 – 1.09446
  • Pm-145 – 0.089466
  • Pm-146 – 0.54094
  • Pm-147 – 2.67584E-06
  • Pm-148 – 0.330669
  • Pm-148m – 1.31979
  • Pm-149 – 0.0085729
  • Pm-151 – 0.262182

Protactinium

  • Pa-230 – 0.88319
  • Pa-231 – 0.37407
  • Pa-233 – 0.49395
  • Pa-234 – 1.98172
  • Pa-234m – 0.0102712

Radium

  • Ra-222 – 0.0078255
  • Ra-223 – 0.325193
  • Ra-224 – 0.0109779
  • Ra-225 – 0.154068
  • Ra-226 – 0.0121138

Radon

  • Rn-218 – 0.00050579
  • Rn-219 – 0.052503
  • Rn-220 – 0.000359751
  • Rn-222 – 0.00027343

Rhenium

  • Re-182 – 1.13886
  • Re-182m – 0.73778
  • Re-183 – 0.157509
  • Re-184 – 0.58201
  • Re-184m – 0.284086
  • Re-186 – 0.0181633
  • Re-188 – 0.040478

Rhodium

  • Rh-103m – 0.0255744
  • Rh-105 – 0.058756
  • Rh-105m – 0.157287
  • Rh-106 – 0.138158

Rubidium

  • Rb-81 – 0.83768
  • Rb-82 – 0.77848
  • Rb-83 – 0.77145
  • Rb-84 – 0.86062
  • Rb-86 – 0.053946
  • Rb-88 – 0.321937
  • Rb-89 – 1.0952
  • Rb-90 – 0.94276
  • Rb-90m – 1.63873

Ruthenium

  • Ru-103 – 0.33189
  • Ru-105 – 0.51689
  • Ru-97 – 0.44178

Samarium

  • Sm-151 – 9.0354E-05
  • Sm-153 – 0.09028

Scandium

  • Sc-44 – 1.33274
  • Sc-46 – 1.16735
  • Sc-46m – 0.066933
  • Sc-47 – 0.08029
  • Sc-48 – 1.89329
  • Sc-49 – 0.00052059

Selenium

  • Se-73 – 1.09853
  • Se-75 – 0.85951

Silicon

  • Si-31 – 0.00048322

Silver

  • Ag-106m – 1.93769
  • Ag-108 – 0.0162763
  • Ag-108m – 1.27132
  • Ag-109m – 0.100714
  • Ag-110 – 0.0205646
  • Ag-110m – 1.65242
  • Ag-111 – 0.0197173

Sodium

  • Na-22 – 1.3394
  • Na-24 – 1.93769

Strontium

  • Sr-82 – 0.39405
  • Sr-85 – 0.75924
  • Sr-85m – 0.222148
  • Sr-87m – 0.29637
  • Sr-89 – 8.1585E-05
  • Sr-91 – 0.41366
  • Sr-92 – 0.72002
  • Sr-93 – 1.35605

Tantalum

  • Ta-182 – 0.77182

Technetium

  • Tc-95 – 0.77404
  • Tc-95m – 0.71743
  • Tc-96 – 1.81263
  • Tc-96m – 0.16391
  • Tc-97 – 0.281052
  • Tc-97m – 0.193621
  • Tc-98 – 0.8991
  • Tc-99 – 4.5954E-07
  • Tc-99m – 0.1227
  • Tc-101 – 0.255892

Tellurium

  • Te-121 – 0.53835
  • Te-121m – 0.248011
  • Te-123 – 0.099419
  • Te-123m – 0.194657
  • Te-125m – 0.228216
  • Te-127 – 0.00348836
  • Te-127m – 0.073149
  • Te-129 – 0.067821
  • Te-129m – 0.073889
  • Te-131 – 0.298775
  • Te-131m – 0.90724
  • Te-132 – 0.279313
  • Te-133 – 0.58608
  • Te-133m – 1.36493
  • Te-134 – 0.64047

Terbium

  • Tb-157 – 0.0089762
  • Tb-160 – 0.66156
  • Tb-162 – 0.71188

Thallium

  • Tl-200 – 0.83361
  • Tl-201 – 0.087764
  • Tl-202 – 0.349206
  • Tl-204 – 0.00111518
  • Tl-207 – 0.00130388
  • Tl-208 – 1.70385
  • Tl-209 – 1.29352
  • Tl-210 – 1.70237

Thorium

  • Th-226 – 0.067266
  • Th-227 – 0.42365
  • Th-228 – 0.079254
  • Th-229 – 0.73593
  • Th-230 – 0.068857
  • Th-231 – 0.54501
  • Th-232 – 0.068376
  • Th-233 – 0.095719
  • Th-234 – 0.075406

Thullium

  • Tm-170 – 0.0061901
  • Tm-171 – 0.00096089

Tin

  • Sn-113 – 0.179228
  • Sn-117m – 0.251452
  • Sn-119m – 0.103193
  • Sn-123 – 0.0039294
  • Sn-125 – 0.172938
  • Sn-126 – 0.126096

Titanium

  • Ti-44 – 0.144633
  • Ti-45 – 0.61161
  • Ti-51 – 0.26381

Tungsten

  • W-181 – 0.051393
  • W-185 – 2.02205E-05
  • W-187 – 0.328782
  • W-188 – 0.00133755

Uranium

  • U-230 – 0.091131
  • U-231 – 0.7844
  • U-232 – 0.088911
  • U-233 – 0.0291042
  • U-234 – 0.077589
  • U-235 – 0.338883
  • U-236 – 0.073704
  • U-237 – 0.58793
  • U-238 – 0.065231
  • U-239 – 0.13431
  • U-240 – 0.284382

Vanadium

  • V-48 – 1.70126
  • V-52 – 0.76109

Xenon

  • Xe-122 – 0.180079
  • Xe-123 – 0.52392
  • Xe-125 – 0.356014
  • Xe-127 – 0.345247
  • Xe-129m – 0.228105
  • Xe-131m – 0.093721
  • Xe-133 – 0.102971
  • Xe-133m – 0.112258
  • Xe-135 – 0.189477
  • Xe-135m – 0.320087
  • Xe-137 – 0.123802
  • Xe-138 – 0.62123

Ytterbium

  • Yb-169 – 0.326969
  • Yb-175 – 0.0304621

Yttrium

  • Y-86 – 2.32804
  • Y-87 – 0.68857
  • Y-88 – 1.78303
  • Y-90m – 0.48692
  • Y-91 – 0.00199911
  • Y-91m – 0.38036
  • Y-92 – 0.146927
  • Y-93 – 0.051652

Zinc

  • Zn-62 – 0.33263
  • Zn-65 – 0.330188
  • Zn-69 – 4.3216E-06
  • Zn-69m – 0.295371

Zirconium

  • Zr-86 – 0.88171
  • Zr-88 – 0.6327
  • Zr-89 – 0.98494
  • Zr-95 – 0.46546
  • Zr-97 – 0.108114

**Listing partially extracted from ORNL/RSIC-45, “Specific Gamma-Ray Dose Constants for Nuclides Important to Dosimetry and Radiological Assessment”, May, 1982.  Please note that these constants are for individual radionuclides only and not for decay series (e.g., U-238 plus progeny; Th-232 plus progeny, Ra-226 plus progeny, etc.)