What is the potential for extremity doses in this X-ray exposure incident?

[Badgeronimous]

Homework Statement

A research worker is irradiating some drug samples in an x–ray beam.

The tube is running at 60kVp with a tube current of 4mA.

Although the ‘shutter open’ lamp is extinguished, indicating the shutter is closed , it is faulty and the researcher loads his samples with the shutter open.

The samples are 12cm from the tube and it takes the operator 45 seconds to align his samples. Calculate his potential extremity doses assuming

(a) no filtration and
(b) 2mm Al filtration.

Assume area of skin exposed to scattered x-rays is 100sq cm.

What are the likely symptoms for the potential skin dose received and the prognosis for short and long-term radiation injuries?

What actions, in compliance with IRR99, would you take as a result of this incident?

Homework Equations

Attached in solution - I do not have appropriate textbook.

The Attempt at a Solution

see attachment

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Hi there, I am a Radiation Protection Technician working in Nuclear Power with no experience at all of X-Rays. As part of a Professional Development course I am doing, I have this question - it isn't really relevant to my work but it is part of the course regardless. I don't have access to an Academic Library and I am severely struggling to find appropriate text to help me answer this question (any texts I have all relate to Nuclear Power, not X-Ray sets). I feel I have probably approached the question incorrectly making it more complicated than it needs to be.

I'm looking to be pointed in the right direction with some links to referable material. I'm absolutely fine with the latter part of the question, it is just the actual calculation of the dose received to the extremities I am having difficulty with. I can see that the dose to the extremities is likely to be very high, in the order of several Sieverts.

Any hints, or links to similar problems that will give me appropriate information will be greatly appreciated.

Thanks

 

[mfb]

Well, you have large parts of the solution attached already. What exactly is unclear?

0.047% should be 4.7% or 0.047, but the following line uses the correct value again.

 

[Badgeronimous]

Thank you for your reply.

The issue is that I'm struggling on how to make the step from joules to grays.

The course isn't particularly well planned in that regard, I'm given no access to a library or detailed enough study material. I've spent quite a bit of time going over all the material given and cannot find a list of the formula or text relevant to this question, I can't really find anything in my (3rd party) textbooks either - but they all relate to nuclear power, not X-rays. Filtration also will add another facet that has not been covered with the notes I've been given. TBH, the rest of the course has been fine, but I feel this question is almost an afterthought.

I can tell the dose is going to be very high, I suspect it is going to be beyond a threshold that is going to cause local radiation injury - but can't quantify it into grays without knowing the mass deposited into. 1Gy is 1J per KG of a material. All I can see is 0.81J deposited over 100cm² and I need help getting to the next step.

If somebody can point me to a book, or online resource where I can get the relevant information. I work in nuclear power, but the people at work don't really deal with X-rays and I'm googling for things I can't find or even know exactly what to look for.

A worked example for instance would be brilliant.

Thanks
Alex

 

[PSRB191921]

Hi,
for a X-rays generator (60 kVp) it comes:
with no filtration 155 mGy/mA/min at 1 meter
with 2mm Al 4 mGy/mA/min at one meter
so at 12 cm and 4 mA it comes:
43 Gy/min (no filtration)
1.1 Gy/min (2 mm Al)
these results come from the book's abacus "Applied Physics of External Radiation Exposure: Dosimetry and Radiation Protection, Springer, 2017"
http://www.springer.com/us/book/9783319486581
Calculations are not so simple because of the continuous Bremsstrahlung spectrum on which is superimposed the tungsten characteristic X rays,
PSR