There are a lot of good resources available for radiation medicine online. Here are some helpful links:
Associazione Italiana di Radioterapia Oncologica (AIRO, Italy)
American Society for Radiation Oncology (ASTRO, USA)
Deutschen Gesellschaft für Radioonkologie (DEGRO, Germany)
Sociedade Brasiliera de Radioterapia (SBRT, Brazil)
Canadian Partnership for Quality Radiotherapy (CPQR)
International Atomic Energy Agency (IAEA, Austria)
i.treatsafely (treatment planning)
Radiation Oncology Institute (ROI)
Belgian Radiation Oncology Awareness and Visibility Organization (BRAVO)
Pelvic Radiation Disease Association (UK)
Miranda Fielding – The Crab Diaries
Tere M. Migueláñez – Carpe Diem
Radiation Nation – Multi-author
Virginia Ruiz – Un Rayo de Esperanza
Radiation Oncology Professionals (LinkedIn)
American Joint Committee on Cancer (AJCC)
Union of International Cancer Control (UICC)
World Health Organization (WHO)
American College of Radiation Oncology (ACRO)
American College of Radiology (ACR)
American Society for Radiation Oncology (ASTRO)
Asociación ibero Latinoamericana de Terapia Radiante Oncológica (ALATRO)
Association of Radiation Oncologist of India (AROI)
Associazione Italiana di Radioterapia Oncologica (AIRO, Italy)
British Institute of Radiology (BIR, UK)
Canadian Association of Radiation Oncology (CARO-ACRO)
Dansk Selskab for Klinisk Onkologi (DSKO, Denmark)
Deutschen Gesellschaft für Radioonkologie (DEGRO, Germany)
EΛΛHNIKH ETAIPEIA AKTINOΘEΡAΠEYTIKHΣ OΓKOΛOΓIAΣ (EEAO, Greece)
European Society for Radiation Oncology (ESTRO)
Hrvatsko Onkološko Društvo (HOD, Croatia)
האיגוד לאונקולוגיה קלינית ורדיותרפיה (ISCORT, Israel)
Japanese Society for Radiation Oncology (JASTRO)
Korean Society for Radiation Oncology (KOSRO)
Nederlandse Vereniging voor Radiotherapie en Oncologie (NVRO, Netherlands)
Norsk Onkologisk forening (NOF, Norway)
Österreicher Gesellschaft für Radioonkologie (ÖGRO, Austria)
Phillipines Radiation Oncology Society
Polski Towarzystwo Radioterapii Onkologicznej (PTRO, Poland)
РОССИЙСКАЯ АССОЦИАЦИЯ ТЕРАПЕВТИЧЕСКИХ РАДИАЦИОННЫХ ОНКОЛОГОВ (RATRO, Russia)
Royal College of Radiologists, Clinical Oncology (UK)
Royal Australia and New Zealand College of Radiologists (RANZCR)
Scientific Association of Swiss Radiation Oncology (SASRO)
Sino-American Network for Therapeutic Radiology and Oncology (SANTRO)
Sociedad Española de Oncología Radioterápica (SEOR, Spain)
Sociedad Mexicana de Oncologica AC (SMEO, Mexico)
Sociedade Brasiliera de Radioterapia (SBRT, Brazil)
Sociedade Portuguesa de Radioterapia Oncologia (SPRO, Portugal)
Société Française de Radiothérapie Oncologique (SFRO, France)
South African Society of Clinical and Radiation Oncology (SASCRO, South Africa)
Southeast Asian Radiation Oncology Group (SEAROG)
Svensk Onkologisk Förening (SOF, Sweden)
สังคมไทยรังสีวิทยารักษาและมะเร็งวิทยา (THASTRO, Thailand)
TÜRK RADYASYON ONKOLOJİSİ DERNEĞİ (TROD, Turkey)
American Society for Radiologic Technologists (ASRT)
Associazione Italiana Tecnici Sanitari di Radioterapia e Fisica Sanitaria (AITRO, Italy)
Australian Institute of Radiography (AIR)
Canadian Association of Medical Radiation Technologists (CAMRT)
International Society of Radiographers and Radiological Technologists (ISRRT, Unknown)
Nederlandse Vereniging Medische Beeldvorming en Radiotherapie (NVMBR, Netherlands)
Norsk Radiograffborund (Norway)
Sociêté Française de Physique Médicale (France)
Society and College of Radiographers (SCoR, UK)
Svenska Sjukhusfysiker Förbundet (Sweden)
Radyoterapi Teknisyenleri Derneği (RTTDER, Turkey)
American Association of Medical Dosimetrists (AAMD)
American Association of Physicists in Medicine (AAPM)
Associazione Italiana di Fisica Medica (AIFM, Italy)
Australasian College of Physical Scientists & Engineers in Medicine (ACPSEM)
Canadian Organization of Medical Physics (COMP-OCMP, Canada)
Dansk Selskab for Medicinsk Fysik (DSMF, Denmark)
Nederslandse Vereniging voor Klinische Fysica (NVKF, Netherlands)
Norsk forening for medisinsk fysikk (NFMF, Norway)
Polskie Towarzystwo Fizyki Medycznej (PTFM, Poland)
Schweizerische Gesellschaft für Strahlenbiologie und Medizinische Physik (SGSMP, Switzerland)
Cancer Nurses Society of Australia (CSNA, Australia)
European Oncology Nursing Society (EONS, UK)
International Society of Nurses Cancer Care (ISNCC, Canada)
Oncology Nursing Society (ONS, USA)
UK Oncology Nursing Society (UKONS, UK)
If you think there are resources we should add, please let us know.