The Theratron F was a cobalt-60 unit ("Cobalt bomb") for radiotherapy (teletherapy, external beam therapy), manufactured by AECL (Atomic Energy of Canada, Ltd).
The first two Cobalt-60 units were installed in Canada in 1951 - one at the University of Saskatchewan, and the other at the Victoria Hospital in London.
The source of radiation is a Cobalt-60 pellet. The radioactive isotope cobalt-60 has a half-life of around 5.3 years, so the source should be replaced after around 5 years.
Nowadays, cobalt-60 units seem to have come out of fashion.
In fact cobalt-60 units have been largely replaced by linear accelerators (LINACs), and that technique advanced more quickly. However there are still parts in the world with power outtages and / or low/middle income (LMICs) , where LINACs cannot be installed/afforded.
In addition cobalt-60 units are easier to maintain than LINACs. Besides, the technology has caught up, and they should no longer be unterestimated: There are MLC options, and a manifold of treatment options that have been reserved for LINACs such as IMRT can be delivered with a modern cobalt-60 unit.
Cobalt-60 units come in 2 versions: a Beam stopper opposite the treatment head, or a pendulum counterweight (like LINACs).
The former simplifies bunker design (less reinforcement needed in the gantry rotation plane), but the beam stopper may restrict certain table positions and thus have an impact on treatment plans.
This mini model is an Ebay find that was sold off. It looked quite shoddy in the accompanying pics. The counterweight (beamstopper) was somewhat loose, and the head wasn't properly attached.
Some cleaning and fastening of a couple of screws returned it to a healthy state.
Aside from a few scratches the condition is good.
And no, it is not for sale ;-)
Just like the real thing, the model is isocentric. The degrees of freedom are quite amazing.
a) the gantry can be rotated (around the isocenter)
b) the head can be tilted and rotated (moving it out of the isocenter)
c) the table moves
d) the table can be rotated horizontally around the isocenter
e) the table can be swiveled (out of the isocenter)
b) is not possible with LINACs. With respect to b), modern cobalt-60 units can still rotate their head, but there is no tilting anymore.
For all I know:
- The Theratron F was produced from around 1958 to around 1962, but this is based on implicit information.
- The Theratron F was preceded by the Theratron (probably 1953 - ?)and the Theratron Junior (1956-1963)
- The Theratron F was superseeded by the Theratron 60/80 models, which (according to ads I found online) were produced from 1962 onwards.
- In parallel, the Theratron models B and C (C II) were produced.
I assume that the mini model was made around the same time as the Theratron F.
Some more information:
A pendulum type Theratron F and a control panel may be seen here (p. 5):
CancerCare Manitoba - Radiation Therapy Photographs, a collection of annotated photographs commemorating 75 years of cancer care in Manitoba.
This machine was in service for almost 30 years!
A smaller member of the Theratron family was the Theratron Junior (see comment section for an image). This system was produced from 1956 until 1963.
The Biography of an Artifact: The Theratron Junior and Canada’s Atomic Age by David Pantalony describes the fate of one particular system of that type.
Another interesting read with respect to the fact that the Theratrons of the 50s and 60s were normally painted in "Sea Foam Green":
The colour of medicine, also by David Pantalony
Additional information on the Theratron F, its mini model, and the whole family of Theratrons produced by AECL and its successors MDS Nordion and Best Theratronics (esp. with respect to the timeline above), will be highly appreciated.
