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Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
I’m starting a new project which has the absolute priority at the moment. I received a torso of an old X-ray machine which was routinely used 5years ago in the experimental physics department. I desperately need an X-ray machine for my biological laboratory which I’m starting now in Czech Republic and this could be a pretty cheap option…In case it will work again. (I need an irradiator of cultured cells to induce defined amount of DNA damage. Basically it is simple lead shielded box with doors where the cells are placed and exposed to the X-rays for defined time.)
The X-ray machine story: It was assembled in 1984 in Dresden (Germany - Zeiss) and released from service in 2003. It is 60KV machine designed for 1500W X-ray tubes for continuous operation.
The reason for releasing it was not a malfunction but dramatic changes in the department of Experimental physics (moving into a new building). The X-ray machine was disassembled and sent for specialized destruction process. 5 extra X-ray tubes were included! However, my good friend is chief of the destruction commission and he saved the machine (for me). Problem was that in the time when he started to be involved, the machine was already heavily damaged by the workers cleaning the old building. In fact the control panel was lost and only the HV generator (on the picture) and the X-ray tubes with X-ray tube holder and HV cables were saved. Moreover, the HV generator was sitting outside the building for few weeks with one opened oil refilling lid so it’s very likely some water got inside and is mixed with oil….
The project issues:
1. Refilling the generator with new oil 2. Make very simple control panel for operating the HV generator 3. Make a new water cooling system for the tube 4. Make the shielded box for irradiation of the cells 5. Get an approval from Czech atom law authorities for operating the device
At the moment I’m becoming slowly familiar with this crazy beast. It is a three phase transformer with bridge rectifier. I’m studying the wiring diagrams and it looks PITA work to make it run again. I will give a try and share my progress with you guys. I hope for your help! Remember - I'm only a biologist
Thanks Mates
Pumping the oil out is not easy - there is minimum 100L of oil inside... On the picture you see the generator. You can see the HV plugins. I'll send the pictures of the parts which are inside of the box very soon!!!
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
Nice job getting that stuff!
Ok, now before embarking on this project, I would be asking myself, how big do I need my x-ray machine to be?
If its just for irradiating cell cultures (in petri dishes I presume), I think a massive 3 phase transformer is overkill. You will get much longer tube life, a safer,simpler and a more portable machine, by running the tube at a few 10`s of watts.
A few 10`s of watts is even good enough for taking some decent sized x-ray photos, so I would put the transformer aside, for some later project for now (obviously, dont throw it out! :) )
For the power supply,I would use a Royer driven, flyback supply, with a multiplier attached to get the 60kV, (this is how I now run the tubes in my more recent x-ray machines, its small, and efficient, and hardly breaks a sweat).
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
plazmatron wrote ...
Nice job getting that stuff!
Ok, now before embarking on this project, I would be asking myself, how big do I need my x-ray machine to be?
If its just for irradiating cell cultures (in petri dishes I presume), I think a massive 3 phase transformer is overkill. You will get much longer tube life, a safer,simpler and a more portable machine, by running the tube at a few 10`s of watts.
A few 10`s of watts is even good enough for taking some decent sized x-ray photos, so I would put the transformer aside, for some later project for now (obviously, dont throw it out! :) )
For the power supply,I would use a Royer driven, flyback supply, with a multiplier attached to get the 60kV, (this is how I now run the tubes in my more recent x-ray machines, its small, and efficient, and hardly breaks a sweat).
Do you have the heater specs for your tube?
Leslie
Dear Leslie, You are completely wrong... You need very powerful X-ray machine to induce DNA damage in decent time period. At the moment (in my old lab in Denmark) I'm using 150KV 15mA X-ray machine and the irradiation times are varying between 3-10minutes!!!(Corresponds to the dose 2-10Gy). Actually the X-ray machine on the picture is quite weak and looks like a litle baby to my scale. But it should be enough (I hope…)
Regarding the X-ray photographs - that's the kind of X-ray fun where few tens of watts are enough. But that's not mine business - unfortunately
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I know nothing about DNA and cell damage, but I would guess that the damage caused by the 60KVP photons of this proposed set up will be that much greater than the 150KVP you are now using, because far more of the lower energy photons will be absorbed and interact.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Harry wrote ...
I know nothing about DNA and cell damage, but I would guess that the damage caused by the 60KVP photons of this proposed set up will be that much greater than the 150KVP you are now using, because far more of the lower energy photons will be absorbed and interact.
You are right, but difference in damaging potential of 150KeV photons and 60KeV are only minor for the thin layer of cells grown on surface of plastic Petri dish (BTW it is something what is difficult to find out exactly even for me who is working and doing research in this field). In the X-ray therapy of cancer there is a trend to use as high photon energies as possible (the 150KV X-ray device I mentioned is a therapeutic device). The latest cancer therapies are based on X-rays generated by accelerators and photon energies up to 25MeV are used. What I think is definitely the determine factor for the amount of damage in my case is the density of photons and that's something what is directly dependent on the power of the device...
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
Then I stand corrected! I had just figured that your samples would be physically closer to the tube, than one would expect in a radiographic setup, and that time would be on your side (in terms of exposure length).
Harry also elucidated a point, that I had factored in, that of photon energy.
High energy photons are used in Radiotherapy, so as to avoid excessive damage to healthy tissue, as would be seen using sub 100keV x-rays. 100keV+ photons will practically drift through even the thickest body tissues, leaving most of them unscathed. Cancer cells have a much higher vulnerability to radiation than healthy tissue (they have difficulty repairing themselves), so they are more likely to be permanently damaged during the exposure.
If you were to try to irradiate an internal tumour on a patient using 60keV x-rays, you would cause severe damage to healthy tissue, as well as very visible skin burns.
Since when a cell is exposed to ionizing radiation,most of the damage is caused by secondary ionization (ie the DNA is attacked by free radicals, notably the hydroxyl ion, due to the ionization of water). I would have thought that lower energy photons would have a much greater `quality factor` when exposing thin layers of cells like this.
Indeed there was a heated debate some years back about Mammography machines, actually causing cancer, on account of the low energy (30keV) used to image the soft tissues of the breast. A whole series of studies was conducted on the `relative biological effectiveness` (RBE) of x-ray photons at different energies. As I recall, 30keV photons, are TWICE as effective at inducing aberrations in DNA, than 120keV photons.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
plazmatron wrote ...
Then I stand corrected! I had just figured that your samples would be physically closer to the tube, than one would expect in a radiographic setup, and that time would be on your side (in terms of exposure length).
Leslie
Even if I would be irradiating only one dish (which is a bit impractical due the variations between doses) the size of the "middle" dish is 10cm in diameter. I need 100-90% photon intensity distribution within this area. It practically means to keep the x-ray tube at least 40cm (rather more) away.
I remember that some time ago in my old lab we wanted to buy a new X-ray device which would be table based construction (all standing on the table). The irradiation surface was just for one 10cm dish which was rotating. The irradiation time for 10Gy was over 20minutes! The time was unacceptable because of the type of research we are doing (studies on the early response to DNA damage) so we had to give up that product. There is no way for me how to avoid the necessity for a big generator - unfortunately.
Otherwise you are pretty right in the other things - the penetration ability of the low and high energy photons and their different damaging potential. It is only something which is more suitable for general science discussion forum... Maybe I'll start thread like that, I'm doing some interesting research in this field - for example now I'm studying differences in DNA damage induced by X-rays and Alpha particles from Americium241 source. But that's a bit of this thread...
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I must say I am surprised to learn that the study of radiation damage to cells and DNA is within the possible grasp of any single individual, let alone the amateur scientist. I had imagined the radiobiologist approaching this kind of problem with the resources and equipment of an entire institution - electron microscopes, optical tweezers, a biochemical laboratory for sample preparation and DNA amplification, with technicians and postgraduate students to undertake the many routine procedures, control experiments, and so on.
But this is not my field, and I have perhaps misunderstood some simple fundamental of the plan proposed.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Harry wrote ...
I must say I am surprised to learn that the study of radiation damage to cells and DNA is within the possible grasp of any single individual, let alone the amateur scientist. I had imagined the radiobiologist approaching this kind of problem with the resources and equipment of an entire institution - electron microscopes, optical tweezers, a biochemical laboratory for sample preparation and DNA amplification, with technicians and postgraduate students to undertake the many routine procedures, control experiments, and so on.
But this is not my field, and I have perhaps misunderstood some simple fundamental of the plan proposed.
Harry, that’s my job - not a hobby . I work in a biochemical lab which is part of University research institute. I became the director of this small lab recently and I have all the equipment that you mentioned (even more - I have access to confocal microscopes also). The only thing I miss at the moment is the X-ray machine and I have not enough money to buy a new one...It complicates my research because I have to use radio-mimicking drugs which brings a lot of practicall problems...
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Industrial X-ray machine - will it work?
. I work in a biochemical lab which is part of University research institute. I became the director of this small lab recently and I have all the equipment that you mentioned (even more - I have access to confocal microscopes also). The only thing I miss at the moment is the X-ray machine and I have not enough money to buy a new one...It complicates my research because I have to use radio-mimicking drugs which brings a lot of practicall problems... 