1. DOSIMETRY COMMISSIONING OF THE LNS-INFN PROTON THERAPY FACILITY THE DOSIMETRIC CHARACTERISTICS OF NARROW PROTON BEAMS USED IN EYE THERAPY HAVE BEEN DEFINED BY USING DIFFERENT RADIATION DETECTORS  IONIZATION CHAMBERS (parallel-plate,minithimble chambers) SILICON DIODES RADIOCHROMIC AND RADIOGHRAPHIC FILMS THERMOLUMINESCENCE DETECTORS  1) CENTRAL AXIS DEPTH-DOSE DISTRIBUTIONS 2) LATERAL (TRANSVERSE) PROFILES 3) OUTPUT FACTORS (FSDF)  TO PROVIDE INPUT TO THE TPS AND FOR M.U. CALCULATIONS.  QUALITY CONTROL PROCEDURES  DOSIMETRIC COMMISSIONING OF 60 MeV PROTON BEAMS PRODUCED AT LNS FOR EYE THERAPY SHAPED WITH 5 - 30 mm CIRCULAR BRASS COLLIMATORS. INFN-LNS

2. PROTON DEPTH-DOSE DISTRIBUTIONS THE PTW MARKUS PLANE-PARALLEL ION CHAMBER WAS USED IN THE COMMISSIONING AS THE REFERENCE DETECTOR FOR DEPTH-DOSE MEASUREMENT IN PROTON BEAMS (ICRU 59, IAEA 398)  THE DESIGN OF THE MARKUS CHAMBER  1) Active volume=0.05 cm 3, 2) Electrode separation=2 mm, 3) Collector diameter=5.4 mm 4) t entrance window =2.3 mg/cm 2 5) Exact Location of p eff.  PROVIDES DEPTH-DOSE DISTRIBUTIONS WITH HIGH SPATIAL RESOLUTION AND HIGH PRECISION  ) PMMA CUP IS PROVIDED TO SEAL THE CHAMBER FOR USE IN WATER  ) A SPACER IS PROVIDED FOR USE IN A SOLID PHANTOM, WHICH ALSO SERVES AS A HOLDER FOR A RADIOACTIVE SOURCE FOR STABILITY CHECKS. INFN-LNS

3. PTW MARKUS PLANE-PARALLER ION CHAMBER IN WATER PHANTOM INFN-LNS

4. ^ taken from BJR Supplement 25 (1996) CENTRE MAXIMUM RANGE (mm) EQUIVALENT ENERGY (MeV) PEAK PLATEAU RATIO F.W.H.M. (mm ) Distal-dose falloff d 90%-10% (mm) CATANA 30.60 60.2 4.68 3.29 0.81 CCO^ 31.0 60.4 4.85 3.65 0.80 PSI^ 30.0 60.0 4.47 1.10

5. THE NEW SCANDITRONIX Si-DIODE IN PROTON BEAMS (Proton Field waterproof Detector-narrow beam no.DZA192 1001) INFN-LNS

6. THE NEW SCANDITRONIX Si-DIODE IN PROTON BEAMS (Proton Field waterproof Detector-narrow beam no.DZA192 1001) CYLINDRICAL MINIDIODE SPECIFICATIONS Detector Material: Hi-pSi, high doped p-type silicon (preirradiated for use in proton beams). Detector diameter: 0.6 mm (t = 60  m) DETECTOR PEAK DEPTH (mm) PEAK- PLATEAU RATIO F.W.H.M (mm) Distal-dose falloff (1) d 90%-10% (mm) Distal-dose falloff (2) d 80%-20% (mm PRACTICAL RANGE (d 10%, ICRU 59) MARKUS PTW 30.14 4.68 3.19 0.71 0.50 31.15 DIODE SCANDITRON IX 30.07 4.89 3.07 0.80 0.60 31.06 INFN-LNS

7. MODULATED PROTON DEPTH DOSES FOR EYE THERAPY MODULATOR RANGE SHIFTER MODULATION (SOBP) (mm eye tissue) DISTAL-DOSE FALLOFF (1) d 90%-10% (mm eye-tissue) DISTAL-DOSE FALLOFF (2) d 80%-20% (mm eye tissue) MAXIMUM DOSE IN SOBP % BEAM RANGE (90% DISTAL) (mm eye-tissue) MOD: 000/00 RS: 14 mm 14.5 0.91 0.65 101.6 14.38 MOD: 010/02 RS: 10 mm 10.5 0.90 0.60 104 18.27 MOD: 009/02 RS: 1.8 mm 20.30 0.80 0.55 103.9 27.04 CCO  17 0.900.75< 102 INFN-LNS

8. 15 MM SOBP vs RANGE SHIFTER MODULATED PROTON DEPTH DOSES FOR EYE THERAPY

9. BEFORE EACH TREATMENT PERIOD TREATMENT DEPTH DOSE PROFILES HAVE TO BE VERIFIED.  TO VERIFY RANGE MODULATION AND MAXIMUM RANGE OF THE BEAM  DEPTH-DOSE MEASUREMENT WHEEL (CCO DIODE SCANNER)  WHEEL IS COMPUTER CONTROLLED, AND RELATIVE DOSE MEASURED AS RATIO BETWEEN WHEEL’S DETECTOR AND REFERENCE DETECTOR TOLERANCES 1)  [(MEASURED RANGE) / (REQUIRED RANGE)]:   0.2 mm 2)  [(MEASURED MODULATION) / (REQUIRED MODULATION)]: [ -0.1 mm // +0.9 mm ] INFN-LNS

10. LATERAL OFF-AXIS BEAM PROFILES 1) LATERAL PENUMBRA: d 80%-20% 2) Field ratio: 3) L 95% 4) SIMMETRY (AREA RATIO): 5) FLATNESS: MD-55-2 RADIOCHROMIC FILMS WERE USED IN COMMISSIONING tissue equivalence – dose rate indipendence Linear dose response – high spatial resolution  ONLY ONE CALIBRATION FILE IS NEEDED TO EVALUATE FILMS EXPOSED AT DIFFERENT DEPTHS Energy indipendence 1.3 mm

11. PMMA Phantom He-Ne Scanning Laser Densitomiter

12. INFN - LNS EXPERIMENTAL SET-UP (  =25 mm) SOBP (WIDTH)HL 95% (mm) S r% (simmetry) R t% (flatness) Lateral penumbra (mm) d 80%-20% MOD: 000/00 RS: 14 mm 14 mm z irr. =7 mm 0.9223  3% 1.40 MOD: 010/02 RS: 10 mm 10 mm z irr. = 12 mm 0.9223  2%  3% 1.30 MOD: 009/02 RS:1.8 mm 20 mm z irr. = 14 mm 0.9323  3% 1.15 CCO  18 z irr. = ½ SOBP  3% 1.10 CAL  18 z irr. = ½ SOBP 1.50

13. KODAK XV FILMS AND SCANDITRONIX DIODE WERE USED IN COMMISSIONING  IF CALIBRATION FILES PRODUCED FOR KODAK XV FILMS AT DEPTH OF SOBP ARE USED FOR TRANSVERSE BEAM MEASUREMENTS  GAF MD55-2 = KODAK XV FILM MOD 010/02 RS:10 MM z irr. =12 mm Lateral penumbra (mm) d 80%-20% H L 95% (mm) S r% (simmetry) KODAK XV 1.300.9222.80.50 MD-55-2 1.270.9222.70.90 INFN-LNS

14. BEFORE EACH TREATMENT  PROTON BEAM PROFILES AT ISOCENTRE ARE TO BE CHECKED  IN AIR X-Y DIODE SCANNING COMPUTER CONTROLLED DEVICE  PLANNED TOLERANCES  1)LATERAL PENUMBRA (d 80%-20% )  1.50 mm 2) BEAM SIMMETRY (S r )  3% 3) BEAM FLATNESS: R t %  3% 4) FIELD RATIO: H  0.90 INFN-LNS

15. DOSE MONITORING SYSTEM (IN-BEAM DOSE MONITORS)  THE PROTON DOSE IS MONITORED BY TWO INDEPENDENT TRANSMISSION UNSEALED ION CHAMBERS, PLACED IMMEDIATELY UPSTREAM OF THE PROTON NOZZLE.  TRANSMISSION CHAMBERS HAVE SEPARATE CABLING, BIAS SUPPLIES (800 V) AND CURRENT INTEGRATORS AND ARE ARRANGED AS A REDUNDANT COMBINATION TO TERMINATE THE BEAM.  TRANSMISSION ION CHAMBERS ARE CALIBRATED DAILY AGAINST A REFERENCE PARALLEL-PLATE MARKUS ION CHAMBER, LOCATED AT THE ISOCENTRE. COMMISSIONING TESTS 1) PRECISION 1a) SHORT TERM PRECISION: (CV) OF THE RATIO R OF DOSE MONITOR UNITS TO DOSIMETER SCALE READING FOR n=5 CONSECUTIVE IRRADIATIONS OF 15 Gy.  MEASURED CV = 0.1% 1b) LONG TERM PRECISION (WEEKLY STABILITY):  MEASURED [  (cGy/U.M.) WEEK ] :  1.5%. 2) LINEARITY THE RATIO V BETWEEN THE MEASURED PROTON DOSE AND DOSE MONITOR UNITS SHALL BE WITHIN  1% AT ALL MONITOR SCALE READINGS, i.e. IN THE CLINICAL RANGE UP TO 15–20 Gy.  MEASURED RATIO INFN-LNS

16. DOSE MONITORING SISTEM TRANSMISSION ION CHAMBER INFN - LNS

17. DOSE RATE MONITORING (BEAM INTENSITY MONITOR)  THE PROTON BEAM RATE IS MONITORED BY THE VOLTAGE SIGNAL (V SF ) PROVIDED BY THE FIRST SCATTERING FOIL, LOCATED IN VACUUM IMMEDIATELY UPSTREAM OF THE EXIT WINDOW. I BEAM (nA) = 0.0412 + 6.0835  V SF (R 2 =0.9999)  (V SF ) IS USED BY THE C.S. TO STOP THE BEAM IF THE RATE XCEEDS A PRESET LIMIT.   NORMAL TREATMENT BEAM CURRENT  4 nA  CLINICAL DOSE RATE =12  20 Gy/min. Normal current Alarm current Z markus = 1 mm Full energy beam U.M. =K INFN-LNS

18. ABSOLUTE DOSIMETRY (BEAM CALIBRATION, cGy/U.M.) FOR REFERENCE DOSIMETRY, AT LNS, A PLANE-PARALLEL MARKUS ION CHAMBER IS USED IN A WATER PHANTOM, BY EXTENDING TO PROTON BEAMS THE FORMALISM OF THE IAEA 381 CODE OF PRACTICE ON THE USE OF PLANE-PARALLEL ION CHAMBERS IN HIGH ENERGY ELECTRON DOSIMETRY. cGy (nC) cGy/nC (s w,air ) q p Q = 1.00 (ICRU 59, IAEA TRS-398, MED.PHYS. 1995 :22) ( TAB. 7.1 ICRU 59) (W air /e) c p = 1.031 (ICRU 59) FOR DOSE CALIBRATIONS OF INDIVIDUAL PATIENTS, THE CALIBRATION IS MADE IN A UNIFORM DOSE REGION AT THE MIDDLE OF SOBP, AT ISOCENTRE, WITH THE 25 mm DIAMETER REFERENCE COLLIMATOR ON BEAM DELIVERY NOZZLE. FOR DAILY DOSE CHECKS, A PMMA PHANTOM BLOCK IS USED: A RADIOACTIVE CHECK DEVICE ( 90 Sr) IS USED FOR OPERATIONAL AND CONSTANCY CHECKS OF DOSIMETRY SYSTEM (  1%, NCRP).

19. AN EXRADIN T1 THIMBLE ION CHAMBER [A-150 TE, 0.05 cm 3, N K ( 60 Co)] CAN BE USED AT LNS IN THE WATER PHANTOM, ACCORDING TO ICRU 59   BECAUSE OF THE Cavity length AND Outer diameter of the chamber, USE IS LIMITED TO (  )  15 mm AND (SOBP WIDTH)  12 mm. WORK IN PROGRESS  NOW AVAILABLE BY PTW N D,w, 60 Co FOR T1 EXRADIN AND MARKUS LNS CHAMBERS  ADOPTION OF IAEA TRS-398 CODE OF PRACTICE  D w, Q = M Q N D,w,Q0 k Q,Q0  ESTIMATED UNCERTAINTY OF D w, Q UNDER REFERENCE CONDITIONS (1 S.D.) ICRU 59 (  N k =1%) IAEA TRS-398 (  N D,w,Q0 =1%) EXRADIN T1 2.6% 2.1% PTW MARKUS 3.1% 2.5% INFN-LNS

20. PROTON DOSIMETRY INTERCOMPARISON (ECHED, ICRU 59)  BEFORE STARTING LNS PROTON THERAPY FACILITY  ) INTERCOMPARISON (1) AT CCO (PHYSICA MEDICA, VOL.XV, N.3)  LNS (PTW MARKUS, T1-EXRADIN)  CCO (A-150 FW-IC18, REFERENCE DOSE)   (D w ) [(PTW MARKUS) / (FW-IC18)]:  1%  (D w ) [(T1-exradin) / (FW-IC18)]:  1.4%  ) INTERCOMPARISON (2) AT PSI (PHYSICA MEDICA VOL.XVII, S.3, PTCOG XXX 1999)  1) CCO (FW-IC18, MARKUS) 2) LNS (MARKUS, EXRADIN-T1, PTW PMMA FARMER) 3) PSI (PTW GRAPHITE FARMER, MARKUS) 4) TERA ( MARKUS, EXRADIN-T1)   % = 1.2%   max (%) = 3.5% INFN-LNS

21. DOSIMETRY INTERCOMPARISON AT PSI (FULLY MODULATED BEAM) INFN-LNS

22. OUTPUT FACTORS (FSDF)  ) AT THE INITIAL CALIBRATION OF CYCLOTRON THE OUTPUT DOSE RATE HAS BEEN MEASURED FOR ALL COLLIMATORS AREA ENCOUNTERD IN THE CLINICAL PRACTICE.   ) TO EVALUATE IF THERE ARE SIGNIFICANT DROPS OF DOSE PER MONITOR UNIT WHEN COLLIMATOR DIAMETER DECREASES TO A FEW MILLIMETERS.   ) THE MOST RELIABLE RELATIVE OUTPUT VALUES ARE PROVIDED FROM RADIOCHROMIC DETECTORS, ESPECIALLY FOR NARROWEST BEAMS (VATNITSKY).  NO SIGNIFICANT DECREASE OF BEAM OUTPUT (cGy/U.M.) FOR COLLIMATOR DIAMETER UP TO 5 mm INFN-LNS

23. OUTPUT FACTORS (FSDF)  ) FROM EXPERIMENTAL RESULTS WE CAN STATE THE LOWER BOUND OF COLLIMATOR DIAMETER FOR WHICH FRELATIVE OUTPUT IS MEASURED ACCURATELY WITH EACH DETECTOR  1) MARKUS CHAMBER CAN BE USED IN PROTON BEAMS WITH  12 mm 2) TLDs AND SCANDITRONIX DIODE CAN BE USED UP TO  =8 mm IN CLINICAL PRACTICE AT LNS  GAF-DETECTOR IS USED FOR EVALUATION OF OUTPUT FACTOR  FOR SHAPED NARROWEST BEAMS INFN-LNS

24. PATIENT DOSES (STRAY RADIATION) (PERSONAL MONITORING, TWO PATIENTS TESTED) A) TWO PERSONAL BADGE-DOSIMETERS WERE PLACED ON THE CHEST OF PATIENTS DURING THE WHOLE PROTON TREATMENT. 1) ENEA FILM BADGE PERSONAL DOSIMETER ( , , x)   0.05 mSv 2) NRPB PADC NEUTRON PERSONAL DOSEMETER  0.20 mSv PATIENTS COMPLETING TREATMENT  INDUCED DOSE RATE   15  Sv/h  (10’)  1.5  Sv/h INFN-LNS