Fig 1.
Add-on collimator and Gammacell irradiator.
A) Add-on collimator components including the top lid, 1cm aperture, internal chamber, and the steel container to hold the collimator inside the irradiator. B) Collimator placed in the Gammacell 40 Exactor, prepared for irradiation.
Fig 2.
Illustration of MC modelling of the irradiation system.
MC modelling of the 137Cs source and collimator top lid are demonstrated using BEAMnrc components. The scoring surface is positioned right below the collimator’s lid (red line). The top and bottom red arrows represent the phase-space file used multi-directionally employed at beam angel of 0° and 180°.
Fig 3.
Illustration of the EBT3 film sandwiched between PMMA slabs and irradiation setup.
A) The GAFchromic film dosimeter sandwiched between PMMA phantom slabs. B) The PMMA phantom was placed inside the collimator and the tumour model was situated within the marked collimated beam on the polystyrene platform for irradiation. C) The irradiated film from the phantom irradiation is shown. Irradiation field and profile line selection are marked. D) Cutaway drawing of the collimator with the PMMA phantom positioned at the midplane of the collimator and the film dosimeter sandwiched between phantom slabs irradiated with Cs-137 beam. Film dosimeter, phantom slabs, and the collimator’s components are marked.
Fig 4.
Image A demonstrates the transversal view of a slice of the original mouse CT image set with the maximum xenographic tumour diameter of 1 cm. Images B and C demonstrate the modified tumours with diameters of 0.75 cm, and 0.5 cm, respectively. The xenographic tumour and the rubber band that distances the tumour from the mouse healthy tissue are marked in image A.
Fig 5.
Measured and calculated dose profiles.
A) The blue line is the dose profile sampled measured across PMMA tumour phantom exposure. The purple line is the corresponding calculated dose profile results from the EGSnrc simulation, B) The cyan line shows the resultant gamma index trend determined between the two relative GAFchromic film measurements and EGSnrc calculation dose profiles.
Table 1.
Measured and calculated doses and MC dose calculation errors.
Fig 6.
Dose distribution colourwash demonstration on micro-CT images in CERR.
Doses are normalized to Dmax. The rubber band squeezes the mouse body out of the field and the accurate irradiation modelling of the tumour is demonstrated. The dose colourwash shows approximately 60%-100% of Dmax to the whole tumour and maximum 7% of Dmax to the normal tissue.
Fig 7.
Isodose demonstration on micro-CT images in CERR.
The sagittal (left) and coronal (right) isodose lines are demonstrated. Doses are normalized to the Dmax. Isodose lines within the tumour show an increase in dose level from the edge to the centre of the tumour. The purple isodose encircling the mouse body indicates the constant dose level of 7% of Dmax to the mouse body.
Fig 8.
DVHs of the tumours and OARs for 0.5 cm, 0.75 cm, and 1 cm tumour irradiations are demonstrated in dash, dot, and solid lines, respectively. DVHs of the tumours are in black and colours of the DVHs for OARs are presented in the graph.
Table 2.
Minimum, maximum, and mean doses for the tumour and OARs.