idgenössisches Justiz- und Polizeidepartement JPD Bundesamt für Metrologie MTAS xperimental k Q,Q0 lectron Beam Quality Correction Factors for the Types NACP02 and PTW34001 Plane-parallel Chambers Gerhard Stucki, Sandor VörösV Federal Office of Metrology
xperimental k Q,Q0 lectron Beam Quality Correction Factors for the Types NACP02 and PTW34001 Plane-parallel Chambers 1) Irradiation facilities 2) Primary standard (electron beam) 3) Ionisation chamber calibration 4) Results for k Q,Q Q,Q 0 5) Comparison with TRS 398 6) Conclusions AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 2
1) MTAS Irradiation Facilities lectron accelerator (microtron) M22 lectron energies 5.3 to 22.5 MeV Conventional treatment head 10 photon beams: TPR 20,10 = 0.639 to 0.802 10 electron beams: R 50 = 1.75 to 8.54 g cmg -2 60 Co irradiation unit ALCYON II AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 3
AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 4 MTAS microtron M22
MTAS Standard Radiation Qualities for High - nergy lectron Beams Nominal electron energy [MeV] Radiation index Q (=R 50 ) [gcm -2 ] z ref [gcm -2 ] 5.5 1.75 0.95 6.0 1.95 1.07 7.5 2.62 1.47 9.0 3.31 1.89 10.0 3.70 2.12 12.0 4.35 2.51 15.0 5.67 3.30 18.0 6.90 4.04 20.5 7.52 4.41 22.5 8.54 5.02 AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 5
2) Primary Standard : Chemical Dosimeter (Fricke) Total Absorption xperiment Irradiation experiment: D = F abs m (1) Fricke solution abs = e N e - pencil beam 5.3-22.5 MeV AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 6
2) Primary Standard : Chemical Dosimeter (Fricke) Total Absorption xperiment UV- spectrometer read-out: Fricke solution D F ε Δ A T G ρ = (2) l T e - pencil beam 5.3-22.5 MeV AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 7
2) Primary Standard : Chemical Dosimeter (Fricke) Total Absorption xperiment Irradiation experiment: UV- spectrometer read-out: D = F abs m (1) Fricke solution D F = ε Δ A T G ρ l T (2) abs = e N e - pencil beam 5.3-22.5 MeV (1) + (2) G = Δ A T ε ρ l T m abs (3) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 8
Total absorption experiment, 6 MeV vessel AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 9
Total absorption experiment, 22 MeV vessel AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 10
Magnetic spectrometer beam exit NMR probe beam entrance AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 11
Corrections 1) abs = e N F T Bremsstrahlung (about 8 % @ 22 MeV) Backscattering Fringe field spectrometer nergy losses (entrance- and exit windows, air gap, beam line) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 12
2) Primary Standard : Chemical Dosimeter (Fricke) Total Absorption xperiment Irradiation experiment: UV- spectrometer read-out: D = F abs m (1) Fricke solution D F = ε Δ A T G ρ l T (2) abs = e N F T e - pencil beam 5.3-22.4 MeV (1) + (2) G = Δ A T ε ρ l T m abs (3) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 13
1.015 G / <G> versus Beam nergy Measurements June 1999 to March 2000 1.010 G / <G> [1] 1.005 1.000 0.995 0.990 0.985 1999-2000 Norm 5 7 9 11 13 15 17 lectron nergy [ MeV ] G f() within the given uncertainties AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 14
G / <G> versus Beam nergy Measurements June 1999 to March 2000 + 2007 1.015 1.010 G / <G> [1] 1.005 1.000 0.995 0.990 0.985 1999-2000 Norm 2007 5 7 9 11 13 15 17 lectron nergy [ MeV ] AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 15
3) Ionisation Chamber Calibration Against Fricke Solution e - Fricke e - IC Monitor Monitor z ref z ref z ref = 0.6 R 50-0.1 gcm -2 D F = ΔA ε Gρl (3) D W = N M (4) D, W, Q Q AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 16
NACP02 chamber P bag PMMA holder AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 17
Corrections 2) Fricke solution -> > water -> f e Perturbations / wall effect due to P foil, PMMA holder etc -> f e Temperatue, air pressure, humidity etc. -> Π f i AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 18
3) Ionisation Chamber Calibration Against Fricke Solution D W = ΔA S εgρl S f e (5) e - Monitor z ref = 0.6 R 50-0.1 gcm -2 Fricke = ΔA ΔA S T l T l S N e m f f T e (6) G cancels out, since G does not depend on beam energy e - Monitor IC N D,W,Q = ΔA S ΔA T l T 1 l M Πf S Q i N e f f m T e (7) z ref AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 19
4) Results k Q,Q0 lectron Beam Quality Correction Factors Definition of k Q,Q0 (experimental): k = Q, Q 0 N N D D, w, w, Q, Q 0 Definition of k Q,Q0 k Q, Q0 ( s = ( s w, air w, air ) ) Q Q0 (theoretical): ( W ( W air air ) ) Q Q0 p p Q Q0 AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 20
Measurements in 60 Co beam: Primary standard: water calorimeter Measurements in electron beams: Primary standard: chemical dosimeter (total absorption in Fricke solution) No correlations between primary standards u kq = 1 %, (k = 1) u k Q,Q0 = 0.5 %, (k = 1) u kq > u > u kq,q Q,Q0 AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 21
xperimental k Q,Q0 Factors NACP02 (13 chambers) Q 0 = 60 Co 0.96 0.95 0.94 0.93 0.92 k Q [1] 0.91 0.90 0.89 0.88 0.87 TRS 398 <xp> Fit to xp 0.86 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] u kq = 1 %, (k = 1) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 22
xperimental k Q,Q0 Factors NACP02 (13 chambers) Q 0 = 60 Co Q 0 = 7.523 gcm -2 0.96 1.08 0.95 1.07 0.94 1.06 0.93 1.05 0.92 1.04 k Q [1] 0.91 0.90 k Q,7.523 [1] 1.03 1.02 0.89 1.01 0.88 0.87 TRS 398 <xp> Fit to xp 1.00 0.99 TRS 398 <> Fit 0.86 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] 0.98 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] u kq = 1 %, (k = 1) u kq,q0 = 0.5 %, (k = 1) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 23
xperimental k Factors Q,Q0 NACP02 Chambers, Q 0 =7.523 gcm -2 1.08 1.07 1.06 1.05 kq,7.523 [1] 1.04 1.03 1.02 1.01 chamber to chamber variation: 1.9 % 1.00 0.99 Individual Chambers <> Fit 0.98 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 24
xperimental k Q,Q0 Factors PTW 34001 (18 Chambers) Q 0 = 60 Co 0.97 0.96 0.95 0.94 0.93 kq [1] 0.92 0.91 0.90 0.89 0.88 TRS 398 <xp> Fit to xp 0.87 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] u kq = 1 %, (k = 1) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 25
xperimental k Q,Q0 Factors PTW 34001 (18 Chambers) Q 0 = 60 Co Q 0 =7.523 gcm -2 0.97 1.08 0.96 1.07 0.95 1.06 0.94 1.05 kq [1] 0.93 0.92 0.91 kq,7.523 [1] 1.04 1.03 1.02 0.90 1.01 0.89 0.88 TRS 398 <xp> Fit to xp 1.00 0.99 TRS 398 <xp> Fit to xp 0.87 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] 0.98 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] u kq = 1 %, (k = 1) u kq,q Q,Q0 = 0.5 %, (k = 1) AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 26
1.08 xperimental k Factors Q,Q0 as a Function of R 50 Individual PTW34001 Chambers, Q 0 =7.523 gcm -2 1.07 1.06 1.05 kq,7.523 [1] 1.04 1.03 1.02 1.01 chamber to chamber variation: 1.2 % 1.00 0.99 Individual Chambers <xp> Fit to exp 0.98 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 27
5) Comparison with TRS 398 k Q, Q = ( s w, air ) ( W air 0 ( s ) ( W ) w, air Q 0 air Q ) Q Q 0 p p Q Q 0 Assumptions IAA TRS 398, Appendix II: (W air ) Q :=(W air ) Q0 p Q := p cav p dis p wall p cel and p cav =p dis =p cel :=1 p Q = p wall p wall := 1, in electron beams p wall 1, if Q = 60 Co k = Q,Q 0 (s (s w,air w,air ) ) Q Q 0 k Q = (s (s w,air w,air ) ) 60 Q Co 1 p wall AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 28
0.96 NACP02: k Q Factors, xperiment <> TRS 398 0.95 0.94 0.93 0.92 kq [1] 0.91 0.90 0.89 0.88 0.87 TRS 398 <xp> Fit to xp 0.86 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 R 50 [g/cm 2 ] u kq = 1 %, (k = 1) <p wall (exp)> = 1.022, σ = 0.004 p wall (TRS 398, V_12, 5 June 2006) ) = 1.024 AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 29
1.010 NACP02: k Q,Q0 - exp / k Q,Q0 -TRS398 kq,q0 - exp / k Q,Q0-TRS 398 [1] 1.005 1.000 0.995 0.5 % xp / IAA 398, Q0=Co-60 xp / TRS 398, Q0=7.523 gcm-2 Linear ( xp / IAA 398, Q0=Co-60) Linear ( xp / TRS 398, Q0=7.523 gcm-2) 0.990 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 <>=1.0021, σ=0.0026 Q 0 = 60 Co AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 30 R 50 [g/cm 2 ] <>=1.0028, σ=0.0024 Q 0 = 7.523 gcm -2
PTW 34001 : k Q Factors, xperiment <> TRS 398 0.97 0.96 0.95 0.94 0.93 kq [1] 0.92 0.91 0.90 0.89 0.88 TRS 398 <xp> Fit to xp 0.87 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 u kq = 1 %, (k = 1) R 50 [g/cm 2 ] <p wall (exp)> = 1.013, σ = 0.004 p wall (TRS 398, V_12, AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 31 V_12, 5 June 2006 5 June 2006) ) = 1.010
PTW 34001: k Q,Q0 - exp / k Q,Q0 -TRS398 1.010 xp / IAA 398, Q0=Co-60 xp / TRS 398, Q0=7.523 gcm-2 Linear ( xp / IAA 398, Q0=Co-60) Linear ( xp / TRS 398, Q0=7.523 gcm-2) kq - exp / k Q-TRS 398 [1] 1.005 1.000 0.995 0.5 % 0.990 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 <> = 0.9967, σ = 0.0027 Q 0 = 60 Co 60 Co AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 32 R 50 [g/cm 2 ] <> = 1.0026, σ = 0.0027 Q 0 = 7.523 gcm -2
Conclusions <P Q > (electron beams) : constant (within uncertainty) <k Q,Q0 (exp)> in agreement with k Q,Q 0 NACP02 chamber: <P wall (exp)> = 1.022 in agreement with p wall (TRS 398 (V_12)) ) = 1.024 mean ratio k (exp)/k Q,Q0 Q,Q (TRS), Q 0 0 = 60 Co: 1.0021 (σ:( : 0.26 %) mean ratio k (exp)/k Q,Q0 Q,Q (TRS), Q 0 0 = 7.523 gcm -2 : 1.0028 (σ:( : 0.24 %) chamber to chamber variation: 1.9 %! (TRS 398 (V_12) (V_12)) PTW34001 chamber: <P wall (exp)> = 1.013 in agreement with p wall (TRS 398 (V_12)) ) = 1.010 mean ratio k (exp)/k Q,Q0 Q,Q (TRS), Q 0 0 = 60 Co: 0.9967 (σ:( : 0.27 %) mean ratio k (exp)/k Q,Q0 Q,Q (TRS), Q 0 0 = 7.523 gcm -2 : 1.0026 (σ:( : 0.27 %) chamber to chamber variation: 1.2 %! AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 33
AbsDos 2007 I Gerhard Stucki I 11.05.2007 I 34 Thank you for your attention!