Search

Radiotherapy is recognized as an effective method of cancer treatment and management that employs ionizing radiation to produce lethal effects to localized malignant cells. In employing radiotherapy, it is important to verify that the dose administered to the patient during treatment delivery is the same as sought during the treatment planning phase. This is typically done using phantoms and dosimeters. However, most phantoms in use are static, they do not simulate respiratory motion which occur during treatment. In lieu of this, we a developing a dynamic thorax phantom which simulates the respiratory motion of a lung lesion in 4D. This paper specifically focuses on the motion mechanism for our 4D respiratory motion phantom system. To keep the cost down, we 3D printed all of mechanisms structure to house the off-shelf electro-mechanical components. Respiratory motion of a lung lesion approximated through the translational and rotational movement of a cylinder. Both these motions are actuated independently and by a linear and servo motor respectively. A simple user interface (UI) was designed to test the motion mechanism by manual control of the motors or selecting waveforms to simulate respiratory motion of the lesion. This proof of concept shows that the mechanism can be fabricated at low cost and improved upon in the future for the full 4D respiratory motion phantom system.

BackgroundThe accessibility to radiotherapy facilities may affect the willingness to undergo treatment. We sought to quantify the distance and travel time of Malaysian population to the closest radiotherapy centre and to estimate the megavoltage unit (MV)/million population based on the regions.Materials & methodsData for subdistricts in Malaysia and radiotherapy services were extracted from Department of Statistics Malaysia and Directory of Radiotherapy Centres (DIRAC). Data from DIRAC were validated by direct communication with centres. Locations of radiotherapy centres, distance and travel time to the nearest radiotherapy were estimated using web mapping service, Google Map.ResultsThe average distance and travel time from Malaysian population to the closest radiotherapy centre were 82.5km and 83.4mins, respectively. The average distance and travel were not homogenous; East Malaysia (228.1km, 236.1mins), Central (14.4km, 20.1mins), East Coast (124.2km, 108.8mins), Northern (42.9km, 42.8mins) and Southern (36.0km, 39.8mins). The MV/million population for the country is 2.47, East Malaysia (1.76), Central (4.19), East Coast (0.54), Northern (2.40), Southern (2.36). About 25% of the population needs to travel >100 km to get to the closest radiotherapy facility.ConclusionOn average, Malaysians need to travel far and long to reach radiotherapy facilities. The accessibility to radiotherapy facilities is not equitable. The disparity may be reduced by adding centres in East Malaysia and the East Coast.