The Modernization of Radiation Therapy Services in Cambodia: A Model of International Collaboration.

PURPOSE: Cambodia is a Southeast Asian low-middle-income country with a population of >15 million. In 2020, Cambodia was estimated to have 18,375 new diagnoses of cancer and 12,638 deaths attributable to cancer. Cambodia was estimated to have a deficit of 16 megavoltage machines in 2012. Cambodia's radiation therapy services have suffered through the tumultuous events of the country's history, with intermittent services until the last decade. In recent years, Cambodia has undergone rapid economic growth and, with this, the development of its first comprehensive cancer center, the National Cancer Centre (NCC). METHODS AND MATERIALS: Planning for NCC began in the early 2000s, with the aim to provide comprehensive care, including modern radiation therapy services, to the public. Funding for the center was supplied primarily by the Cambodian government, assisted by donations from partners including the International Atomic Energy Agency. Training collaborations were formed with international partners, including the Asia-Pacific Radiation Oncology Special Interest Group (APROSIG) of the Royal Australian and New Zealand College of Radiologists and the Asia-Pacific Special Interest Group (APSIG) of the Australasian College of Physical Scientists and Engineers in Medicine. RESULTS: The main model of APROSIG/APSIG collaboration has been in-country training, including the posting of an Australian medical physicist and radiation therapist in Phnom Penh for a year's duration to oversee a safe and sustainable start to the radiation therapy program. The first linear accelerator patient was treated at NCC in March 2018 and the first brachytherapy patient in September 2018. Since that time, the department has treated to capacity, with very little machine downtime. NCC provides comprehensive cancer services including medical oncology, pediatric oncology, hematology, palliative care, surgical oncology, and nuclear medicine. Several challenges to expanding radiation therapy services currently exist, including human resources and cultural stigma. CONCLUSION: Despite many decades of tragedy and suffering, Cambodia serves as an example of successful implementation of modern radiation therapy in a low- and middle-income country. The keys to success have included local champions, support of the Ministry of Health, and willingness to embrace collaboration. The pandemic brings yet another challenge to cancer control in Cambodia, and novel training platforms are being explored.

On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy.

This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments.