X-ray examination of blood products as a security measure at the time of their delivery

A blood banker in Florida works at a medical center that has conveyor belt x-ray machines at every entrance for security purposes. The x-ray machines are like those used in airports for examination of passenger carry-on articles. The hospital's blood products are provided by an outside blood center, and as a security measure, all blood products are examined by x-ray machines at the time of their delivery. There is concern, however, that this x-ray examination may affect the viability of some of the blood products or change their expiration dates. The inquiring blood banker wants to know if any other medical center has encountered this issue, or if there is published guidance. The dose recorded as being released by the x-ray machines is one millirad. Based on this low dose, the inquiring blood banker is of the opinion that there is probably no harm being done to the blood products, however, the inquiring blood banker is not certain if this can be proven. Is anyone aware of FDA guidance on this issue? The same scenario may occasionally occur at airports.

The following replies were submitted in response to the above:

1. A blood banker from the Hoosier state (Indiana) reported that the National Marrow Donor Program (NMDP) has been studying this very issue with hematopoietic stem cell products. According to the responding blood banker, since 9/11/01, there have been incidents where airport security has required these products to be passed through an airport x-ray machine. Apparently, the NMDP Donor and Patient Safety Monitoring Committee investigated these incidents and determined that, based on the doses of x-rays delivered, the risk to hematopoietic stem cell product was nil. Also, the responding blood banker states that a group of Austrian investigators reported having passed products up to 10 times through a standard airport security x-ray machine and showed no decrease in cell viability, colony forming cells (CFC) or long-term culture initiating cells (LTC-IC). It was stated that during an air flight, the "cosmic radiation exposure (~5uSieverts(uSv) per hour of flight) actually exceeds that from the airport security x-ray (<2uSv per run).
   
   
2. A blood banker from Texas also reported that information from the NMDP may be of interest here, if the machines being used for x-ray security are similar to those in airports. As critical as hematopoietic stem cells are, the responding Texan states that the NMDP has determined that routine security x-rays are permissible (if the airport insists). As in reply #1 above, the Texan mentions an abstract from Austrian investigators (EBMT, Maastricht, 2001) that reports on products passed up to 10 times through a standard security x-ray and showed no decreases in viability, colony forming cells (CFC) or long-term culture initiating cells (LTC-IC). The abstract authors apparently state that "Further, during an air flight, the cosmic radiation exposure (approximately 5 uSieverts per hour of flight) actually exceeds that from the airport security x-ray (less than 2 uSv per run)." This information obviously addresses a sort of obverse of the question posed by the inquiring blood banker, and addresses only stem cells. However, it provides some additional data on the low levels of radiation of standard x-ray security devices. The NMDP publication citing by the Texan is a memo dated October 26, 2001, to Donor, Collection, Transplant, and Apheresis Centers personnel from Dennis L. Confer, the NMDP Chief Medical Officer.
   
   
3. A scientist from Canada reports that his basic knowledge of radiation physics is that the energy level used would not be enough to affect the lymphocyte DNA or create damage to the rbc membranes, however, this hypothesis requires testing. The hospital may have an HLA typing lab where lymphocyte function assays are done, or can send out some aliquots for this testing. If the lymphocyte function is not affected, then the RBC membrane is going to be ok. Even if the lymphocyte function is affected by the x-ray machine, the RBC membrane is likely still fine, but this would then require testing, i.e., osmotic fragility, hemolysis, etc.
   
   
4. A blood banker from Virginia states that laboratorians "control" everything from daily temperature checks to centrifuge speed. The responding blood banker comments that if blood is sent through x-ray machines, then there would be a need to periodically perform an assessment of dosage emitted. What happens when the machines malfunction?
   
   
5. A blood banker from Chicago asked "Are overnight shipped blood products getting x-rayed by the couriers? You might want to ask the National Marrow Donor Program and/or the Red Cross about what's going on at the airports these days. Several years ago an overzealous (!) airport security guard put one of our donor center's NMDP bone marrow products through the carry-on x-ray. We determined that the amount of radiation was minuscule, and the NMDP said this had come up before and was not a problem. So my inference would be that this would not be an issue for carry-on blood products, although cargo luggage x-ray machines are stronger."
   
   
6. Another blood bank physician raised a very interesting side issue, mainly, will the U.S. Post Office implement a plan to irradiate mail with very high doses of radiation to kill anthrax spores? He adds that this question will be discussed at an upcoming DHHS Advisory Committee on Blood Safety and Availability at the end of the month.
   
   
7. A blood banker in Bethesda reported that the NMDP has investigated this question in great detail, since unrelated donor hematopoietic stem cell components (marrow and PBSC) are transported nationally and internationally by hand-held courier and must go through airport security. As long as there is a system for periodic QC of the x-ray device (to make sure the components are exposed to the expected dose), the extremely low exposure (less than one millirad) should not damage, inactivate, or cause carcinogenic transformation of any cells in the component. There has been no problem with hematopoietic engraftment of marrow or blood stem cells that went through airport security x-ray devices.

ADDENDA Jan. 7, 2002

8. A blood bank physician in Sacramento commented that he would not worry about the X-raying of blood products by security equipment. Much more irradiation is given when we use irradiation to prevent TA-GVHD and then only the RBCs are somewhat afffected. He comments that his facility used to worry about marrow and peripheral blood stem cell collections which were transporting for the NMDP to transplant recipients; they had their messengers carry a letter saying that the contents were not to go through the X-ray machines at the airport. Since Sept. 11, however, this has changed. These now go through the X-ray machines like all hand carried items and they don't think twice about it. If these are not appreciably affected, then regular components should not be.

ADDENDA Jan. 10, 2002

9. A blood bank physician from the city that gave us Motown music wrote that "Michiganders might be a bit sensitive about this issue at the moment, as one of our Congressmen recently had to partially disrobe when his metal hip implant set off the metal detector and the security personnel didn't believe him". Given the overzealous and somewhat inconsistent screening taking place at airports, even after September 11, I agree with the respondent from Virginia that periodic monitoring of the carry on baggage devices needs to be done & documented. I think any QC done needs to be public information. It is easy to speak of this in generalities, yes, stem cells and bone marrow have evidently come through these devices ok, but what about malfunctions? Are these machines, or the larger cargo x-ray machines, ever tested for dosage or leaks? We don't really think about the blood that is air cargo shipped every day. Surely these boxes are subjected to cargo x-rays. How do we know with certainty that these machines are consistent in dose of radiation? This is a question that the FDA should be looking into, as it could be something that could affect the purity and potency of blood products, particularly if there was a machine malfunction. Is there an NRC or other requirement to do QC on dose or leaks?" If it were my stem cells or bone marrow, I'd want a hand search at security, if this is doable.

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