Atomic Radiations in the Decay of Medical Radioisotopes: A Physics Perspective

Table 1

Calculated Auger electron yields for selected medical radioisotopes.

	RADAR [10, 11]	DDEP [12]	Eckerman and Endo [13]	Howell [14]	Stepanek [15]	Pomplun [16]	Present study
Nuclear decay data^(a)	ENSDF	DDEP	ENSDF	ENSDF	ENSDF	ICRP38	ENSDF
Conversion coefficients	[17]	[8, 18]	[18, 19]	[18]	[15]	[17, 20, 21]	[8]
Electron capture ratios	[22]	[23]	[24]	[22, 25]	[22, 25]	[22]	[23]
Atomic shells	K, L	K, L	K–O	K–O	K–N	K–N	K–R
Atomic transition rates^(b)	[7, 26]	[27–29]	[30, 31]	[32–35] (A)	[30]	[32–34] (A)	[30]
	RADLST	EMISSION	EDISTR04	[27, 36] (X)		[37, 38] (X)
Atomic transition energies^(c)	NAB [39]	SE [40]	NAB [30]	𝑍/𝑍 + 1(A)	DF	DF [41]	DF [42]
				NAB (X)
Vacancy propagation^(d)	DET	DET	DET++	MC	MC	MC	MC
Charge neutralization	No	No	No	Yes	No	No	No
	Auger electron yield per nuclear decay
99mTc (6.007 h)	0.122	0.13	4.363	4.0		2.5	3.37
^111In (2.805 d)	1.136	1.16	7.215	14.7	6.05		5.75
^123I (13.22 h)	1.064	1.08	13.71	14.9		6.4
^125I (59.4 d)	1.77	1.78	23.0	24.9	15.3
^201Tl (3.04 d)	0.773	0.614	20.9	36.9

(a)ENSDF: evaluated nuclear structure file [43]; DDEP: decay data evaluation project [12]; ICRP38: international commission on radiological protection [44].
(b)Computer codes: RADLST by Burrows [26], EMISSION by Schönfeld and Janßen [45], and EDISTR04 by Endo et al. [46]; (A): Auger electrons, (X): X-rays.
(c)Transition energies deduced from: NAB: neutral atom binding energies; SE: semiempirical Auger energies Z/Z + 1 approximated from neutral atom binding energies [47]; DF: relativistic Dirac-Fock calculations.
(d)Approach to treat vacancy cascades: DET: deterministic, using closed formulae; DET++: deterministic, using up to 3000 possible transitions; MC: Monte Carlo approach.