There is a demonstrated need for improved access to radiation therapy in the developing world. Part of the limiting factor to the creation of new facilities is the cost. Immobilization devices are necessary for radiation therapy clinics to ensure successful dosing and minimal damage to healthy tissue, but the exorbitant cost of these devices supported within the US healthcare system is unrealistic for countries such as Tanzania. Breast boards specifically are a crucial immobilization device due to the high incidence of breast and thoracic cancers, the treatment of which utilizes breast boards. A modified breast board which could still perform the crucial elements of immobilization without beam attenuation, while being designed for local manufacturing capabilities and locally available materials, is a vital component of an affordable radiation therapy clinic in Tanzania.
Step 1: Materials, Tools and Cuts
1 Pine 2x12x12
1 Pine 4x4x6
1 Pine 1x4x10
1 1in diameter x 18in long dowel rod
~10oz of wood glue
4 10x3 1/2in deck screws
12 8x1 5/8in deck screws
Electric Powered Handsaw
8 inch Metal File
2x12x12 cut to:
2 x 42 inches length (using table saw)
2 x 21.5 inches length
4x4x6 cut to:
1 x 22" length (or whatever twice the exact width of the 2x12 board is)
2 x 9.74" back to 10.87" front (using chop saw at angle of 15 degrees for first cut and then 0 degrees for second one so that length and angle are exactly the same as first)
2 x 6.58" back to 7.29" front (using chop saw at angle of 10 degrees for first cut and then 0 degrees for second one so that length and angle are exactly the same as first)
2 x 3.31" back to 3.66" front (using chop saw at angle of 5 degrees for first cut and then 0 degrees for second one so that length and angle are exactly the same as first)
1x4x10 cut to:
3 x 22 inches length (using table saw)
Dowel rod cut to:
8 x 2 inches length (using chop saw)
Step 2: Notching, Teeth, and Butt Stop
Using the mill, make notches that are the entire width of the board, about 3.5" in length (or whatever exact width dimension of 1x4 is), and about 3/4" deep (or whatever exact thickness of 1x4 is) by covering the entire area with at about 1/10" of depth at a time. (Alternatively you can raise the blade on a table saw the correct thickness and go 1/8 in of length at a time down the width.)
Do this at the following locations:
10" from one end of both 42" 2x12's *ensuring they line up exactly on both boards
7 1/2" from the other end of both 42" 2x12's *ensuring they line up exactly on both boards
9" from one end of both 21 1/2" 2x12's *ensuring they line up exactly on both boards
Using the vertical band saw, rectangular pieces were cut out of all four 2x12's (on the 7 1/2" end of the long boards and the other side from which you measured the notch on the short board). These pieces were 2.2" (or 1/5 the width of these boards) wide and 1.5" long into the length of the board. In each case, the entire depth of the board was cut out. Only every other 2.2" section was removed leaving "teeth" intact and attached to the boards that are the same dimension as the holes. Three teeth (two holes) were cut for each short board and two teeth (three holes) were cut for each long board.
*Ensure that you cut on the same sides of measured lines on the top piece and bottom piece that go together so that they will fit together.
Use metal file to significantly round the bottom side of all teeth on the long boards.
3. Butt Stop
Looking at the 4x4 side of the 4x4x22", mark about 1/2" or 3/4" along one edge and the same along the adjacent edge but measured from the opposite corner. Draw a line between the points and use the electric powered hand saw to cut down that line for the entire 22" length.
Step 3: Holes, Dowels, and First Paint
Cut holes that are 1 inch deep and 1 inch in diameter with centers in the following locations:
The exact centers of the angled sides of all angled length 4x4s so that the holes are perpendicular to the angled surface (use the mill or drill but secure the piece so that that angled side is level to the ground while the hole is being drilled).
2", 6", 10", and 14" from the non-teeth end of the short boards on the top side and centered width wise.
On one of the intact sides of the 22" 4x4 and 1/3 of the exact width of this side from the other intact side, make two holes at the exact distance apart that the holes in the short boards were such that there is also equal remaining length on the outsides of the holes.
1.75" from the non-teeth end of the long boards and centered width wise.
Use wood glue to put 2" long dowel pieces into each of the 8 holes drilled into different pieces of 4x4. Let stand for 3 days.
3. First Paint
Paint all sides of just teeth area of all four 2x12 board pieces and let dry.
Step 4: Assembly
Position one short board and one long board so that teeth are intertwined. There should be approximately 3/4" between the end of the tooth of one board and the end of the hole of the other board. Maintain this position while turning board on their sides.
Do the same for the other short and long board and position them on their sides next to the first set so that all appropriate notches line up. Mark spot equal distance in thickness and length for each set and use drill and 3 1/2" deck screw to screw through two teeth for each set of boards.
Flip boards to other side and do the same at the same location on the other side for each set.
2. Screw and Glue
Put wood glue between two sets of boards so that the notches all line up. Put wood glue into the notches and then add the cut 1x4 boards to each notch. Screw the 1x4 boards into place with 4 screws per board.
Allow to sit for 3 days.
Step 5: Paint
1. After the wood glue has set, remove screws from cross boards.
2. Paint entire board and all parts.
*Be careful not to paint dowels or holes so that they still fit together or drill slightly larger holes to account for paint thickness.*
3. Add letters to each set of holes in short board and write degree of cut on each set of angled 4x4's.