Neutral Density Filter OD Measurements

Transcription

1 Neutral Density Filter OD Measurements Note: Check and adjust the absorbtion scale before ND filter measurements (Section 1.2.1) Form-SIT-1 Reader serial number: 3312 Filter setting 600 nm Date Time Optical Density (OD) Remarks Operator ND1 ND2 ND3 Yellow Green Blue : Just before dosimetry system calibration AGP : Just after dosimetry system calibration AGP : Background reading AGP : AGP

2 Background OD for the Batch of Dosimeters Note: Check and adjust the absorbtion scale before ND filter measurements (Section 1.2.1) Form-SIT-2 Lot ID: Date: Dose: 0 (zero) Gy Operator: AGP Dosimeter OD (600 nm) Mean OD Standard Dev OD(bkgd) = Mean OD for the present batch of dosimeters Note: This value is valid for 6 months only. If the batch last longer, these measurements should be repeate

3 Dose Rate Measurement with Transfer Standard Dosimeters Note: Also attach here copies of the data sheets Form-SIT-3 Date: Co 137Cs Operator: AGP Halflife days Dosimeter type set number IDAS alanine Reference field Irradiator Gammacell 220 Dosimeter holder ID 1 Holder location Field centre Irradiation Temperature ( C) Controlled? Yes No X Measured Before= 23 After= 23 Other Irradiation time (secs) 1, Dose from reading certificate Gy Dose rate Gy/sec Dose rate uncertainty [u dr (%)] 1.7 % 1 How and when was the timer calibrated: Not calibrated - quartz 2 Is the measurement based on an automatic timer? Yes If it is done manually, when was the time started and stopped? 3 Dose rate = Dose (from reading certificate, Section 2.4)/Irradiation time Note it is assumed that the transit dose is negligible compared to the dose value When was the last time the dose rate was measured: Same irradiation conditions? What was the value then? Any other remarks:

4 Gafchromic Dosimetry System Calibration: Irradiation Form-SIT-4A Date: Reference field and dosimeter holder: Field centre, holder 1 (should be the same as those used for the dose rate measurement with alanine (Form-SIT-3)) Dose rate of today (from section 3.1): Operator: Ouatara Dose (Gy) Calculated Irrad Actual Irrad. Nominal Min. Temp. Max. Temp Temp(eff) 3 time (sec) time (sec) 1,2 Dose T(cal)= When and how was the timer calibrated Not calibrated 2 Is this measurement based on an automatic timer? Yes If it is done manually, when was the timer started and stopped? Automatic 3 Temp(eff) = Temp(min) + 2/3{T(max) - T(min)} Range of Temp(eff), from the last column =

5 Gafchromic Dosimetry System Calibration: Response Determination Note: Check and adjust the absorbtion scale every 30 minutes. Measure the OD values for the three ND filters just before and just after the following measurements and enter the values here and in Form-SIT-1 Form-SIT-4B Date: Analysed by: Ouatara OD of the three ND filters Before the measurements: After the measurements: Dose OD OD OD CV(%) Resp. 1 R(corr) 2 R(mean) 3 (Gy) 3 values for each strip (mean) (std dev) (R) 40 A: % B: % C: % A: % B: % C: % A: % B: % C: % A: % B: % C: % A: % B: % C: % A: % B: % C: % Response = OD(mean) - OD(bkgd), where OD(bkgd) is from FORM-SIT-2 2 R(corr) = R( x T), where T = T(eff) - T(cal), where T(eff) and T(cal) are from Form-SIT-4A 3 R(mean) = Average of the three response values in column 5 NOTE Calculate the coefficient of variation (CV) for each dosimeter strip (A, B and C) as: CV(%) = {OD(std dev)/od(mean)} x 100 This value should be less than 2%

6 Gafchromic Dosimetry System Calibration: Transit Dose Determination Note: Check and adjust the absorbtion scale every 30 minutes. Measure the OD values for the three ND filters just before and just after the following measurements and enter the values here and in Form-SIT-1 Form-SIT-4C Date: Analysed by: Ouatara Transit dose calculation Calculate transit dose Don't calculate transit dose OD of the three ND filters Before the measurements: After the measurements: Time (sec) OD OD OD Resp. 1 R(corr) 2 R(mean) 3 Temp 3 values for each strip (mean) (std dev) (R) T1 125 A: B: Temp 22.0 C: T2 250 A: B: Temp 23.8 C: T3 370 A: B: Temp 23.0 C: T4 490 A: B: Temp 22.5 C: T1 125 A: N1 7 B: Temp 22.3 C: T1 125 A: N2 15 B: Temp 22.3 C: Response = OD(mean) - OD(bkgd), where OD(bkgd) is from FORM-SIT-2 2 R(corr) = R( x T), where T = T(eff) - T(cal), where T(eff) and T(cal) are from Form-SIT-4A 3 R(mean) = Average of the three response values in column 5 NOTE Calculate the coefficient of variation (CV) for each dosimeter strip (A, B and C) as: CV(%) = {OD(std dev)/od(mean)} x 100 This value should be less than 2% Transit time= 4.5 seconds

7 0.7 Transit time calculation Calibration points Regression fit Transit dose points O.D Time (Seconds)

8 Gafchromic Dosimetry System Calibration: Relationship Form-SIT-4D Date: Irradiation Temperature: range of Temp(eff) from Form-SIT-4A Operator: Ouatara Transit time: Transit dose: 4.5 sec Gy Nominal Dose Actual Dose Corrected R(mean) (Gy) (Gy) 1 Response A: B: C: A: B: C: A: B: C: A: B: C: A: B: C: A: B: C: Actual dose = Nominal dose + transit dose Graphical analysis: Plot 'actual dose' on the x-axis and 'R(mean)' on y-axis Regression Analysis: X-variable = Actual dose Y-variable = Response, thus there are 3 y-values for each x-value Fit the data to linear as well as quadratic relationship Attach all the graphs to this form

9 1.00 Linear Dose x Response Response (OD) Dose / Gy 2.50 Linear fit Residuals Residual % Dose / Gy y= a + bx a= b=

10 1.00 Quadratic Dose x Response Response (OD) Dose / Gy 2.00 Quadratic fit Residuals Residual (%) Dose / Gy y = a + bx + cx 2 a= b= c=

11 1.00 Power Series fit, Dose X Response Response (OD) Dose / Gy 2.00 Power Series fit Residual(%) Residual(%) Dose / Gy ln(y) = a + b*ln(x) a= b=

12 Gafchromic Dosimetry System Calibration: Residual behaviour For regression analysis Select Fit Date: Linear Operator: Ouatara Quadratic Power Series Form-SIT-4E Actual Linear Rel. Quadratic Rel. Power Series Rel. dose 1 (Gy) D calc 2 Resid.(%) 5 D calc 3 Resid.(%) 5 D calc 4 Resid.(%) 5 A: A: A: A: A: A: B: B: B: B: 0.20 B: B: 0.33 C: C: C: C: C: C: A: A: 1.90 A: A: 1.81 A: A: B: B: 0.21 B: B: 0.13 B: B: 0.13 C: C: C: C: C: C: A: A: 0.52 A: A: 0.30 A: A: B: B: B: B: B: B: C: C: C: C: C: C: A: A: 1.12 A: A: 0.95 A: A: B: B: 0.40 B: B: 0.24 B: B: 0.26 C: C: 0.07 C: C: C: C: A: A: A: A: A: A: B: B: B: B: B: B: C: C: 0.83 C: C: 0.81 C: C: 0.79 A: A: A: A: A: A: B: B: B: B: B: B: C: C: 1.20 C: C: 1.36 C: C: 1.28 U fit Values from column 2, Form-SIT4D 2 D calc = Calculated dose for the corresponding value of 'Response' from Form-SIT-4D, and using the linear calibration relationship 3 D calc = Calculated dose for the corresponding value of 'Response' from Form-SIT-4D, and using the quadratic calibration relationship 4 D calc = Calculated dose for the corresponding value of 'Response' from Form-SIT-4D, and using the power series calibration relationship 5 Residual(%) = 100 x (D calc - D actual )/D actual Note: Residual(%) value may be positive or negative. Plot 'Residual(%)' as y-parameter and 'Actual dose' as x-parameter for both the fits. Select the relationship that yields random distribution of the residual values as a function of dose. If they show similar random distribution, select the linear function as the calibration relationship. Attach all the graphs to this Form.

13 Dose Determination Form-SIT-5 Date: Dose rate (Gy/sec): OD(bkgd) Calibration out of date Dosimetry system Calibration out of date Lot ID: Transit time/sec: 4.5 Calibration relationship: Linear Target dose/gy: 100 From Form-SIT-4C Irradiation time/sec: 430 Operator: AGP OD of the three ND filters Before the measurements: After the measurements: Dosimeter 1 Temp( o C) 2 OD 3 Respo. 4 Corr Res 5 Dose(Gy) 6 Remarks Identification of the dosimeter. This information should appear on the small envelope in which the dosimeter was irradiated and where it is stored. 2 Estimated temperature of the dosimeter during irradiation. 3 Measured OD of the dosimeter 4 Response = measured OD - OD(bkgd) 5 Corrected Response (for temperature) = Response (column 4) x [ x dt] where dt = Temperature (column 2) - calibration temp (See Section 3.6) 6 Dose calculated using the Corrected Response (column 5) and the calibration relationship (Form-SIT-4C) 7 Enter information re: product run, product batch, location of dosimeter, etc.

14 Homogeneity for the Batch of Dosimeters Note: Check and adjust the absorption scale before these measurements. Form-SIT-6 Lot ID: Dose Rate: Gy/sec Date: Transit time: 4.5 Dose/Gy: 100 Time/sec: 308 Operator: AGP Dosimeter Response (600nm) Mean Response Standard Deviation Coefficient of Variation (%) CV(%) = {standard deviation/mean value} x 100

15 Dose Mapping Form-SIT-7 Date: Product: G. pallidipes Container: 1.1 Operator: AGP OD of the three ND filters Before the measurements: After the measurements: Dosimeter 1 Temp( C) 2 OD 3 Respo. 4 Corr Res 5 Dose(Gy) 6 Remarks 7 Reference For routine monitoring Top Middle NOTE: This is the same form as Form-SIT-5, except that there should be a dosimeter "reference" location which will be used later for routine monitoring (see Section 4.4). 1. Identification of thedosimeter. This information should also appear on the small envelope in which the dosimeter was irradiated and where it is stored. 2. Estimated temperature of the dosimeter during irradiation. 3. Measured OD of the dosimeter 4. Response=Measured OD - OD(bkgd) 5. Corrected Response (for temperature) = Response (column 4) [ x T] Where T = Temperature (column 2) - calibration temp (See Section 3.6) 6. Dose calculated using the corrected Response (column 5) and the calibration relationship (Form-SIT-4C) 7. Enter information re: product run, product batch, location of dosimeter, etc.

16 Process Control: Routine Dosimetry Form-SIT-8A Date: Irradiation batch/run ID: G. pallidipes 100Gy Analysed by: AGP OD of the three ND filters Before the measurements: After the measurements: Dosimeter 1 Temp( C) 2 OD 3 Dose(Gy) 6 95% CI 7 Mean 95% CI Remarks 8 1a Ref ± 4.6 Reference location 1b ± ± 4.5 1c ± 4.6 2a ± Minimum dose 2b ± ± 2c ± 3a Centre ± 5.1 3b ± ± 4.9 3c ± 5.0 4a ± 4b ± ± 4c ± NOTE: This is the same form as Form-SIT-5 and -7. However the dosimeters are placed either at the location of minimum dose or at the reference location identified during dose mapping (see Section 4.4 and Form-SIT-7) Up to four sets of 1, 2 or 3 dosimeters placed at a single location can be recorded. The results for each dosimeter are shown together with the average of the three with confidence interval. 1. Identification of the dosimeter. This information should also appear on the small envelope in which the dosimeter was irradiated and where it is stored. 2. Estimated temperature of the dosimeter during irradiation. 3. Measured OD of the dosimeter 4. Response=Measured OD - OD(bkgd) 5. Corrected Response (for temperature) = Response (column 4) [ x T] Where T = Temperature (column 2) - calibration temp (See Section 3.6) 6. Dose calculated using the corrected Response (column 5) and the calibration relationship (Form-SIT-4C) 7. 95% confidence interval (= 2 * U Total ) 8. Enter information re: product run, product batch, location of dosimeter, etc.

17 Process Control: Process Parameter Monitoring Form-SIT-8B Date: Irradiation batch/run ID: Gp100Gy Analysed by: AGP Please add any other parameters that are relevant to your process Parameter Description / Value Species G. pallidipes Insect density (g/cc) 0.48 Source (location, activity) (if different than normal) GC220 Canister ID 1.1 Canister rotated? No Yes Speed= RPM Canister location Centre Irradiation duration / Conveyor speed 377

18 Characteristics of the Current Lot of Dosimeters Form-SIT-9 Gafchromic dosimeter Lot ID Gafchromic dosimeter sheets received on: Calibration of Gafchromic dosimetry system Date of calibration (valid for only one year) Irradiation temperature T(cal) 22.6 Relationship Linear, O.D. = * dose Background response Date of measurement (valid for 6 months) OD(bkgd) Uncertainty Values Arising from dose rate u dr (%)= 1.7 date= Arising from calibration u fit (%)= 0.94 date= Arising from lot non-homogeneity (n = 1) u lot (%)= 0.77 date= Arising from uncertainty in read-out temperature u temp-r (%)= 1.00 Arising from uncertainty in the temperature T max (est) 24 T min (est) 21 of the dosimeter during irradiation u temp-i (%)= 0.63 u total (%)= 2.40