This case-sensitive code system http://hl7.eu/fhir/ig/idea4rc/CodeSystem/cs-generic-eu-i4rc defines the following codes:

Code	Display	Definition
orthovoltage	Orthovoltage	Orthovoltage / kilovoltage usually 200 - 300kv X rays/photons
linac-mv	Linac MV	(Linear Accelerator) megavoltage MV X Rays/photons
linac-el	Linac electrons	Linac (Linear Accelerator) electrons
cobalt	Cobalt MV	Cobalt - MV gamma rays / photons
proton-beam	Proton Beam	Proton Beam
surface-brachytherapy	Surface brachytherapy	Surface brachytherapy
interstitial-brachytherapy	Interstitial brachytherapy	Interstitial brachytherapy
intra-brachytherapy	Intracavitary or intraluminal brachytherapy	Intracavitary or intraluminal brachytherapy
unk-brachytherapy	Unknown brachytherapy	Unknown brachytherapy
cumulativeDose	Cumulative dose received by a patient for a specific drug.