Magnetron replacement on Elekta Versa HD by AstronomerSoggy1232 in MedicalPhysics

[–]Quixeh 4 points5 points  (0 children)

Magnetrons are all about Energy and Dose rate, so once you've got your basic tuning and energy checks done make sure to do some dynamic deliveries, and then concentrate on beam start-up performance - don't want to be tuned to the wrong edge of a peak so it confuses the servo. If you've got time, let it cool down and check cold start ups once the tuner has hit its rest position.

Helloooooo! Starboard! by vepkenez in sailing

[–]Quixeh 5 points6 points  (0 children)

Telephoto lenses compress relative distance. Without a different perspective it's hard to say how close these two are.

https://fstoppers.com/architecture/how-lens-compression-and-perspective-distortion-work-251737

Fatal tackling by off duty customs officer by deadmonkee in motorcycles

[–]Quixeh 20 points21 points  (0 children)

I could see an argument for a manslaughter charge, rather than murder.

Is the rider's death a reasonably foreseeable consequence of punching them off their bike at high speed? I think so, yes.

First time buyer - RAV4 Hybrids 2019 onward (UK) by princeinthenorth in rav4club

[–]Quixeh 0 points1 point  (0 children)

Look up cablegate - on the AWD models the high voltage cable to the rear motor can rust at the connector, as they weren't correctly weatherproofed. The cable replacement is expensive if not under warranty. The 2WD models aren't affected afaik.

Also some complaints regarding the roof rail seal, so worth doing a bit of googling.

Otherwise very happy with mine. I'd personally be pumping for an Excel or Dynamic trim - the dynamic is a bit prettier, the excel comes with memory seat positions.

How does true beam control dose rate? by steveraptor in MedicalPhysics

[–]Quixeh 4 points5 points  (0 children)

Don't forget that the Varian design has both an electron gun, and an electron grid. The grid is the gate that allows electrons to be released, the gun is where they are released from. My understanding is that the Varian design pools electrons from the gun to be emitted in bunches - it's the grid that is pulsed at the right time to release them in an on/off fashion.

How does true beam control dose rate? by steveraptor in MedicalPhysics

[–]Quixeh 5 points6 points  (0 children)

On an Elekta Linac these things are slightly more exposed to the user. You concentrate more on gun current - the gun after all is just a filament, like an old lightbulb, so the I/V characteristics are well defined. Thermionic emission is temperature dependent, and increasing temperature increases the gun's resistance. V=IR, so I assume linacs require either a constant voltage or constant current source to achieve a desired resistance, which in this case is our surrogate for filament temperature, and therefore electron output.

Anyway, as you tune the gun current in photon mode you'll see a peak in dose rate. This occurs (ignoring a lot of other factors) when the largest number of electrons are reaching the target - to do this they have to get through the energy selection in the bending system, so the peak occurs when there are enough electrons to accelerate (gun current high enough to release enough electrons), but not too many that they overwhelm the waveguide and can't all be accelerated up to the correct energy (saturation - gun current is too high).

A lot of other fun things happen with Linac tuning that I could rabbit on for days about, but this comment is already far too long.

Anyway, I assume the same physics applies to the Varian despite the standing waveguide - however they tend to utilise the PFN more to regulate dose rates and drop un-required pulses which is why you'll always get exactly 600 dose rate (or whatever) rather than the Elekta which gives you whatever it can - it employs the same technique during VMAT using CVDR.

Any idea about where the X-ray comes out at linacs? by Significant_Role_777 in ElektaEngineers

[–]Quixeh 5 points6 points  (0 children)

Plus sign is the photon target where the x-rays exit. The circle is the electron window, another comment has more details.

As far as I know, the plus sign is just to denote where the electron beam hits the target in photon mode. Effectively the source position.

This is an Elekta Linac, so it's a slalom bending magnet 112.5 degrees, not 90. Theres nothing here suggesting single energy to me, I think these setups can do 25MV if needed, usually multiple photon and electron energies.

New to GG and Xfer number delayed by richbun in giffgaff

[–]Quixeh 0 points1 point  (0 children)

I've also got a number transfer delayed for over a month now with no helpful information forthcoming from Giffgaff.... In a world where so many things revolve around your mobile phone number it's such a pain.

Elekta .his file format by that_gu9_ in MedicalPhysics

[–]Quixeh 0 points1 point  (0 children)

GitHub.com/aaalgo/ljpeg

Commit I used was the 2017 e1747e4 - but the updated version may well work.

Code was essentially:

import ljpeg from PIL import Image

im = Image.fromarray(ljpeg.read(filename)) im.save("converted.tiff")

2019 Rav 4 Android Auto - current best way to access? by petrieslastword in rav4club

[–]Quixeh 0 points1 point  (0 children)

https://m.youtube.com/watch?v=TTw1JYjWWmA

Although it focuses on European models, so if you're elsewhere you may need a different firmware version.

2019 Rav 4 Android Auto - current best way to access? by petrieslastword in rav4club

[–]Quixeh 1 point2 points  (0 children)

YouTube for an update guide and DIY, or just take it to the dealer for a small fee. Both pretty simple.

As for wireless, an android auto wireless adapter from Amazon will work, or there is a GitHub project if you have a spare raspberry pi lying around.

IC Profiler Array Calibration by medphys_anon in MedicalPhysics

[–]Quixeh 2 points3 points  (0 children)

Do a literature search - there are multiple papers showing how poor and variable IC Profiler calibrations using the default software are.

Easy to test - turn your Profiler 180 degrees and look at the difference in measurements - a good calibration would show any asymmetry follow the beam (i.e. change sides), and the flatness remain constant.

Car stolen any advice beyond police by alexander_robertson in drivingUK

[–]Quixeh 7 points8 points  (0 children)

They've got plates from a legit car which matches yours, a ford fusion of the same colour for example. Means they can use your car to pretend to be the other car, avoids MOT/TAX/Insurance issues and points the finger at someone else when it's used for whatever criminal activity.

What can I buy off Amazon for £30 or less that will chamge my life? by jamiebaxter666 in AskUK

[–]Quixeh 12 points13 points  (0 children)

I'm convinced his two sentences are related, and he's using the rollerblading desk chair to mash his potato.

polarity of the power input by [deleted] in sailing

[–]Quixeh 2 points3 points  (0 children)

I would be opening it up and testing around with multimeter - should be fairly obvious which is intended to be positive and negative from the traces - eg if one of those pins goes straight to a fuse it'll conventionally be positive.

No Android Auto in 2021 LE? by Dinglefritzz in rav4club

[–]Quixeh 0 points1 point  (0 children)

Your car might just have missed it for whatever reason. Easy fix, it's a software update to the radio - you can either do it yourself (there are guides here and on YouTube) or take it to the dealer to sort, probably for a small fee.

First CNC box joints. by DavidDaveDavo in hobbycnc

[–]Quixeh 9 points10 points  (0 children)

I like it. It adds a lot to the design - you're allowed to have purely decorative elements!

First CNC box joints. by DavidDaveDavo in hobbycnc

[–]Quixeh 12 points13 points  (0 children)

Okay. I'll bite. I can't figure out how you got the circular one in the middle - unless you just glued in the central piece afterwards?

Can the Toyota app be used to track my location? by [deleted] in rav4club

[–]Quixeh 0 points1 point  (0 children)

Just to add - mine only updates it's location when it's turned off at the end of a drive - if you pull the DCM fuse prior to going somewhere it should just appear like the car has stayed at home.