Beam direction techniques are used to accurately direct radiation beams towards the tumor while sparing surrounding healthy tissues. Key steps include patient localization using imaging like CT/MRI to delineate the tumor and organs, patient positioning and immobilization, field selection using beam directing devices like lasers, collimators and pointers, and dose distribution analysis to calculate and verify the prescribed dose. Proper beam direction allows obtaining conformal dose distributions and reproducible treatments for better therapeutic outcomes.

13. Lateral height method H 1 H 2 d d H 1 + H 2 2 d =

15. Tube shift principles Marker d 2 y f S Tumor x 1 x 2 d 1

16. Calculation d 1 f y d 2 x 1 x 2 x 1 S = d 1 f – d 1 S x 2 S = d 2 f – d 2 y = d 2 – d 1 = f x 2 + S x 2 - x 1 + S x 1 Tumor Marker

24. Positioning aids… Pelvic Board Prone Support Breast Board

26. Breast boards… Modern Breast Board Indexed Arm supports Indexed wrist support Head rest Carbon fiber tilt board Wedge to prevent sliding

27. Belly boards

28. Mould making

29. Mould making : Contd..

30. Mould making : Contd..

50. SAD calculations Total Tumor dose Number of fields x Number of #s = T Incident dose = T x 100 TMR/TAR Time = ID Output

63. Applicators: Design Lead Sheet Box Plastic Cap Metal Plate with hole

66. Jaws: Disadvantages Disadvantages Remedy Size and shape of field remain unknown Light beam shining through the jaws Patient to source distance unknown SSD indicator used. Compression not possible A Perspex box may be applied to the head

73. Pin & Arc Pin Arc Bubble