Stereotac(c Radiosurgery (Rota(on # 9)
Mentor: Edward C Pennington (01/19/2010 – 03/05/2010)
By
Vibha Chaswal, Ph.D.
Contents
Ac(vi(es
• Es(ma(on of mechanical accuracy of the floor-‐stand
• End-‐to-‐end process tes(ng: Absolute phantom based QA: Frame-‐based and Frame-‐less SRS
• Small field dosimetry measurements: TMRs, output factors, profiles, off-‐axis factors
• CT to MRI image registra(on • SRS treatment planning • Pre-‐treatment SRS floor-‐stand QA • Par(cipa(on in treatment delivery
Mechanical QA: Floor-‐stand
End-‐to-‐End: CT-‐Localiza1on
(Frame-‐based)
TILT and SPIN Adjusted on Frame. CT-‐Localiza(on with (lt and spin correc(on
Max error: Ax (0.4 mm) Lat (0.3 mm) A-‐P (0.5 mm) 3D (0.6 mm)
Frame-‐based End-‐to-‐End tes(ng: Floor-‐stand
isocentric localiza(on
Frame-‐Less SRS End-‐to-‐End isocentric localiza(on :
SRS Commissioning: Small field dosimetry TMR and Out-‐put measurement set-‐up
NOT A TRIVIAL AFFAIR !!!!!!!!!
~ 3.5 % lower TMR And dmax ~ 1 cm
Re-‐measurement of TMRs Stereotac1c Chamber-‐valida1on
TMR’s s(ll off but d-‐max depth = 1.5 cm
OUT-‐PUT Factor measurements
Off-‐Axis-‐Factors
Recommenda(on of independent Physics check on TMR measurements
of small fields.
Iden(fied pit-‐falls: SRS stereotac(c chamber response with depth L-‐R (lt on the SRS phantom base (resolved with a (ssue propped at led side)
Par(cipa(on and observa(on in SRS work-‐flow:
Iden(fica(on of Physics QA at all steps
ThankYou!!!!!
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