I'm writing software that needs to differentiate the following "isotopes" for a dose calibrator (as used in nuclear medicine). My software needs to normalize various inputs for "isotopes", so I'd like to parse the suffixes provided and have names for what they mean, so I can document this in the code.

I use the term "isotopes" because that's how they are being referred to in my organization, but Wikipedia says that the difference between Tc-99 and Tc-99m would be termed an isomer.

I have the following examples of isotopes with and without suffixes.

  • Ir-196
  • Ir-196p
  • Y-80
  • Y-90s
  • Y-90ss
  • Y-90v
  • P-32s
  • Tc-99m

So the suffixes I have to work with are

  • m: I know this means metastable.
  • p
  • s
  • ss: I think this means "sphere sources".
  • v

What do these various suffixes mean? Is there a general term to group their meanings (eg: metastable is a "state")?

  • 2
    $\begingroup$ Where, and in what context, have you seen those? $\endgroup$
    – Jon Custer
    Commented Aug 10, 2021 at 2:19
  • 7
    $\begingroup$ These might be calibration used for a specific container... my research indicates Y-90s might refer to measuring the source inside a syringe, and Y-90v, inside a vial. Atomlab lists calibration sources by index: biodex.com/sites/default/files/086330man_17355_0_opt.pdf , but there is no explanation. In this case, it should not be an embarrassment to ask your employer for more information; this is not readily found information. $\endgroup$ Commented Aug 10, 2021 at 2:28
  • 2
    $\begingroup$ @DrMoishePippik Great find! A little tip: a multipage PDF might be a pain to browse for the keyword, so one can append #page=<page_number> to the URL for PDF, e.g. biodex.com/sites/default/files/… will open the file on the Appendix H: Atomlab 500 Isotope Index list where the aforementioned symbols are located. $\endgroup$
    – andselisk
    Commented Aug 10, 2021 at 11:51
  • 1
    $\begingroup$ @andselisk, thanks for the tip! Until now, I just used Ctrl-F to find a key word - but Y90 might have been written 90Y, requiring multiple searches. $\endgroup$ Commented Aug 10, 2021 at 18:26
  • $\begingroup$ @ DrMoishe Pippik: As andselisk commented, Appendix H has listed about 98 isotopes, including Y-90s (syringe), Y-90v (vial), and Y-90s-s (sir-spheres). No other ways are written. $\endgroup$ Commented Aug 10, 2021 at 19:05

1 Answer 1


These might be calibration used for a specific container... my research only found mention of those items in an Atomlab manual for radiation calibration sources by index, starting on p. 195, and show on p. 190 how to enter that ISOtope index. Appendix E, p 183, lists the following formats for 90Y sources:

Bremsstra[h]lung only, 10cc plastic syringe 
Bremsstra[h]lung only, NIST vial
Bremsstrahlung only, [SIR]-Spheres

(Typos corrected above, in "SIP-spheres" and in Bremsstrahlung (or Bremßtrahlung, if you prefer).

So it appears that:

  • Y-90s is calibrated for (plastic) syringe,
  • Y-90v is calibrated for vial, and
  • Y-90ss is calibrated for SIR-Spheres, i.e., encapsulated in Sirtex resin microspheres.
  • And all the calibrations appear to be for the X-rays produced by Bremsstrahlung from β− decay... [with] energy of 2.28 MeV with an average beta energy of 0.9336 MeV. This is likely because the container blocks the β− radiation (that's beta particle, electron, not eszett ;-), so only X-rays escape the container. Since some containers are plastic, containing no heavy elements, likely the X-ray spectrum is towards the low end of the spectrum, because electrons penetrate farther, spreading their energy loss over multiple collisions.

However, since you are working on an interface for a device used in nuclear medicine, be very cautious about any assumptions. Deaths have been attributed to computational errors leading to radiation overdose, such as with the Therac-25 linac. Therefore, it should not be an embarrassment to ask your employer for more information. This is not readily found information, my answer is imprecise, and human safety is involved.

  • $\begingroup$ +1 For words of caution. For this particular question, the meanings don't affect the behavior of the software (just comments in the code), but duly noted. $\endgroup$
    – duckbrain
    Commented Aug 11, 2021 at 19:49
  • $\begingroup$ Apparently there are people who write "Bremßtrahlung"...? I wonder where that came from. This spelling would be >100% orthographically wrong in the German language where the word originates. $\endgroup$
    – Antimon
    Commented Aug 11, 2021 at 22:33
  • $\begingroup$ @Antimon, yes, the eszett or scharfes S (a double "s"), I was taught, was the original spelling. However, languages change - Neanderthal has lost its "h", also. In any event, it's the electromagnetic radiation resulting from acceleration of a charge, as when an electron in an X-ray valve smacks into the tungsten anode. So Röntgen was making heavy-metal vibrations many years ago. $\endgroup$ Commented Aug 12, 2021 at 0:32
  • $\begingroup$ I highly doubt that the ß version would ever have been correct in German. It's a compound term and those two "s" belong to different words within it. In addition, the letter ß is a sharp "s" sound and that's not how you pronounce that word. I'm really confused where this came from... if you have any more historic pointers, I'd be really interested. $\endgroup$
    – Antimon
    Commented Aug 12, 2021 at 1:33
  • $\begingroup$ @Antimon, just search "Bremßtrahlung" online - it's in use by NASA, Elsevier, AAAS, and numerous other authoritative sites. Did they all make up the word? $\endgroup$ Commented Aug 12, 2021 at 15:44

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