the User Manual for the IVB 1000 Chamber, in PDF Format
Contents
1. 10 11 Measure the atmospheric temperature and pressure For well chambers measure the temperature in the well of the chamber Turn on or insert the radiation source s and take at least 3 measurements Generally the measurements should not be moving in only one direction i e three readings that continue to drop and hence may not yet be stabilized If a current measurement is done allow sufficient time for value to stabilize Analyze the data taking into account the average of the readings system leakage temperature pressure correc tions calibration factors and any other appropriate corrections to be made Keep in mind that the calibration factor consists of the electrometer cali bration factor and the ionization chamber calibration factor When all measurements are completed set bias volt age to OVDC turn off the electrometer and disconnect the ionization chamber Overview The Standard Imaging IVB 1000 Ionization chamber is a well type ionization chamber It is specifically designed for measurement of Intravascular brachytherapy sources with the appropriate calibration It is recommended that the cham ber be calibrated every two years as is standard practice for other ionization chambers Initially the calibration factor is given in the calibration report from the Accredited Dosim etry Calibration Laboratory ADCL The appendix provided with the calibration report discusses the calibration factors in greate2. The step by step procedure for measurement of intravascular brachytherapy sources follows If measuring Ir the cham ber can be left with the lead rings on it at all times Generally the chamber is calibrated with the lead rings on it If the cham ber was calibrated without the lead rings it should be used in that manner DO NOT use lead rings when calibrating Sr seed trains NOTE Thereis a 1 difference in calibration factor whether or not the lead rings are present since the lead rings contrib ute scatter into the chamber Procedures for calibration of IVB Sr sources REF 70036 Strontium IVB Source Holder for Sr sources 1 If necessary let the IVB 1000 Chamber equilibrate to ambient temperature and pressure for at least 30 min utes before the measurement WARNING NEVER cut the catheter for Sr source trains manufactured by Novoste 11 Connect the IVB 1000 Chamber to a suitable electrom eter such as the MAX 4000 from Standard Imaging and apply 300 V bias voltage Allow the system to sta bilize for at least 10 minutes Be sure to use the bias voltage with which the IVB 1000 was calibrated Set the Source Holder to the length of source to be mea sured 30 40 or 60mm This is indicated by the lowest number visible on the Source Holder See Figure 1B Insert the Source Holder into the IVB 1000 Carefully slide the Source Catheter into the top open ing in the knurled knob on the Source Holder In
3. air kerma strength can be compared to your expected RAPID Strand average seed air kerma strength Note this is a QA measurement assuming the ten seeds are the same activity If the total air kerma strength for the 10 seeds together is desired do not divide by N REF 70049 IBt InterStrand Source Holder This source holder is designed for QA measure ments of International Brachytherapy InterStrand source trains These consist of 10 model 1031L 103Pd seeds or 10 model 1251L I seeds with an absorbable suture contained within the open an nulus of each seed This source holder works only with the IVB 1000 Well Chamber One IBt InterStrand containing 10 I seeds and one containing 10 Pd seeds was evaluated with the IVB 1000 and the InterStrand Source Holder 21 Following measurement individual seeds of the InterStrand were removed from the suture material The collective seed measurements were compared with individual seed measure ments in the Single Seed Source Holder REF 70043 to ob tain a correction factor This factor was found to be approxi mately 0 97 times the model 1251L I seed calibration fac tor from the University of Wisconsin ADCL and 0 92 times the model 1031L Pd seed calibration factor The IBt InterStrand Source Holder REF 70049 can be gas sterilized or steam sterilized autoclaved Refer to the policy of the institution performing the measurements To measure an InterStrand source train prepare th
4. all of the beta particles Thus it allows only the x rays created in the encapsulation of the seeds to be detected l After the calibration measurement of a Sr source train with the Strontium source holder REF 70036 loosen the knurled knob and remove the calibration catheter and source holder from the IVB 1000 2 Place the X Ray Contamination Test Tool into the IVB 1000 Slide the catheter into the opening in the knurled knob on the source holder and insert it until it bottoms within the source holder 3 Secure the catheter by tightening the knurled knob until the catheter no longer moves up and down easily Do not tighten too far so the seed train is unable to pass completely into the source holder 4 Inject the source following the source manufact urer s instructions 5 Read and record the measured current or charge 6 Calculate the ratio of this reading with the calibra tion reading taken with the Strontium source holder REF 70036 A representative value is 2 76 x 10 0 5 16 REF 70043 IVB Single Seed Source Holder l Insert an individual seed into the center tube of the source holder The source holder will place the seed at the most active area of the chamber Take a measurement A seed can be removed by removing the source holder and inverting The center tube will allow the seed to easily slide out ADCL calibrations are available for LDR iridium iodine and palladium seeds ADCL calibrations a
5. autoclaved Refer to the policy of the institution where the measurements are being performed To measure a pre loaded isosleeve needle first follow all applicable sterility procedures as required by your institu tion Prepare the IVB 1000 Well Chamber and an appropri ate Electrometer as described in the General Procedures for Medical Measurements section of this manual Place the sterilized Source Holder into the IVB 1000 Well Chamber Then remove the polyimide amber colored sleeve from the needle hub and insert the sleeve into the opening on top of the Source Holder Measure and record the air kerma strength of the seeds This may be repeated as needed with other pre loaded isosleeve needles A formula can be used to determine the average air kerma strength AKS per seed as a QA measurement of the sum of N seeds Average air kerma strength per seed R CF C EF a R reading CF cal factor The ADCL iodine calibration factor for Imagyn isostar seeds obtained with Single Seed Source Holder REF 70043 N number of seeds Cip correction for temperature and pressure EF electrometer correction factor OZ For Example You receive a needle with a stated air kerma strength per seed of 0 3uGym h Five seeds are measured and an iodine 11 2 1 1 calibration factor of 2 6 x 10 uGymh A is used Assume R 0 5321x10 A N 5 CF 2 6x 10 C 1014 EF 0 998 T P Average air kerma strength per s
6. 0 uGym HA is used Assume R 10971x10 A N 10 Cy 1 014 EF 0 998 CF 0 97 2 6 x 10 Average air kerma strength per seed 1 0971 x 10 A 1 014 0 998 97 2 6 x 10 10 0 28 uGym h This average air kerma strength per seed can be compared to your stated InterStrand air kerma strength per seed Note this is a QA measurement assuming the ten seeds are the same activity If the total air kerma strength for the 10 seeds to gether is desired do not divide by N REF 70050 Imagyn isosleeve Source Holder This source holder is designed for QA measurements of the isosleeve prostate brachytherapy needle de livery system from Imagyn Medical Technologies Each isosleeve needle is provided sterilized and custom loaded according to the treatment plan The polyimide sleeve within the isosleeve needle con tains the seeds and spacers and may be removed from the needle hub so that the seeds can be assayed in the source holder This source holder works only with the Standard Im aging IVB 1000 Well Chamber 93 An isosleeveTM needle containing 7 iodine seeds and spacers was evaluated with the IVB 1000 and the Imagyn isosleeveTM Source Holder The collective seed measurements were com pared with individual seed measurements in the Single Seed Source Holder REF 70043 and the correction factor was found to be the same The Imagyn isosleeve Source Holder can be gas sterilized or steam sterilized
7. 3Q2 where Q is the charge or current measured at 300 V and Q3 is the charge or current measured at 150 V See Med Phys 11 714 1984 9 7 Knurled Knob rotate to secure catheter E Indexer indicates of seeds in train 14 yA 7 Ring interfaces to IVB 1000 i Support clear plastic tube _ Inner Cotheter Guide aluminum Figure 1A REF 70034 Source Holder for Iridium IVB seed trains Markings show the number of seeds in the train 6 10 14 18 or 22 As shown above the Source Holder is set for a seed train with 10 seeds the lowest number visible on the sliding portion of the Holder Knurled Knob rotate to secure catheter Indexer shows length of source in cm Ring interfaces to IVB 1000 Catheter Guide ensures proper location plastic Figure 1B REF 70036 Source Holder for Strontium IVB source trains Markings show the length of source in cm As shown above the Source Holder is set for 30 cm the lowest number visible on the sliding portion of the Holder 10 IVB 1000 Response Curve for LDR Ir 105 0 100 0 95 0 90 0 Percent Response 85 0 80 0 o 20 40 60 80 100 120 140 160 180 Distance mm Figure 2 Typical axial response shown as a percent with distance from the bottom of the chamber
8. N This device should never be submerged to clean or scrubbed with an abrasive cleaner AUTION Do not drop mishandle or disassemble unit since it may result in change of calibration factor Refer all servicing to qualified individuals JTION Do not sharply bend triax cable Damage to the cable may result in high leakage currents CAUTION Insure source freely moves within secured cath eter Proper location of source is necessary to assure proper calibration Q gt E polz Peer Features and Specifications Active Volume 475 cm ADCL Calibrations Various single seed Sr Y beta Isotope Source Holders Iridium IVB Source Holder REF 70034 Strontium IVB Source Holder REF 70036 X Ray Contamination Test Tool REF 70042 IVB Single Seed LDR Source Holder REF 70043 IVB HDR Source Holder REF 70044 IVB Cesium 5mm Source Holder REF 70045 IVB Cesium 7mm Source Holder REF 70046 Mick Source Holder REF 70047 Seed Strand Source Holder REF 70048 IBt InterStrand Source Holder REF 70049 Imagyn isosleeve Source Holder REF 70050 Connector Two lug triax standard TNC or Type M Cable 1 meter 3 feet Bias Voltage Applied 300 volts typical Leakage Less than 50 fA Stability 0 2 Reproducibility Response 0 3 over 100mm at center of axis typical Sensitivity 2 4 pA U typ for Ir 38 5 nA Gy s typ for Sr im 1 000 Case Rugged carrying case Dimensions Height 25 9 cm 10 2 in Diameter 10 2 cm 4 0
9. NA Categorical Course in Brachytherapy Physics 1997 pp 143 153 Specification of Brachytherapy Source Strength Report of Task Group 32 American Association of Physicists in Medicine AAPM Report No 21 1987 New York American Institute of Phys ics Intravascular brachytherapy physics Report of the AAPM Radiation Therapy Committee Task Group No 60 Ravinder Nath Howard Amols Charles Coffey Dennis Duggan Shirish Jani Zuofeng Li Michael Schell Christopher Soares James Whiting Patricia E Cole Ian Crocker and Robert Schwartz Med Phys 26 pp 119 152 1999 Clinical implementation of AAPM Task Group 32 recommen dations on brachytherapy source strength specifications Williamson J F and Nath R 1991 Med Phys 18 439 448 The American Brachytherapy Society Perspective on Intravas cular Brachytherapy Subir Nag MD et al 15 additional authors Cardiovascular Radiation Medicine 1 1 1999 8 19 Radiation Safety Requirements for Cardiovascular Brachytherapy Billy G Bass PhD Cardiovascular Radiation Medi cine 1 3 1999 297 306 Comprehensive QA for radiation oncology Report of AAPM Radiation Therapy Committee Task Group 40 Medical Physics 21 4 581 618 1994 Remote Afterloading Technology Report of Task Group 41 American Association of Physicists in Medicine AAPM Report No 41 1993 New York American Institute of Physics sy E Customer Responsib
10. SeeDOS User Manual IVB 1000 Ionization Chamber Table of Contents General Precautions ccccccccccceceesessnscecececeesessnseaeees 2 Features and Specifications 2 00 eeseeseesseceseeeeeeeenees 3 General Procedures for Medical Measurements 4 ADV ELVICW E E E E AE aon 6 Calibration of IVB 1000 occcnnnnnconnannncnoninanannanonononnons 8 Constancy Check of IVB 1000 sonses 8 OCOPETAUION s ssieseverszenatiasdasaevegcoeacteseere green 9 Procedures for Calibration of IVB ot SOUICES 11 Procedures for Calibration of IVB Ir sources 13 Procedures for Other Source Holders o o oo 16 MELENA caodedtsseoussuescteccsseseesanetes 25 EVI irte load 25 Brachytherapy Parts List ooooconnccnonccnoccconnnonnonancnnnnnn 26 Bibliography Brachytherapy Measurements 27 Customer Responsibility 0 0 eee eeeeeeeeeeeeeereeees 28 A O O 29 O 2002 Standard Imaging Inc Distributed by SeeDOS Ltd Please contact cwalters seedos com General Precautions Warnings and Cautions alert users to dangerous con ditions that can occur 1f instructions in the manual are not obeyed Warnings are conditions that can cause injury to the operator while Cautions can cause damage to the equip ment WARNING Electrical shock hazard when connected to 300 V bias supply Do not remove cover CAUTION Proper use of this device depends on careful read ing of all instructions and labels CAUTIO
11. autoclaved To measure a RAPID Strand source raise the lift knob on the top of the source holder as far as possible and insert the strand in its amber colored spacing jig There is a plastic key on the bottom of the housing to guide the spacing jig so the seeds are in the center of the well chamber Lower the lift knob and measured activity of all ten seeds in the strand Inverting the RAPID Strand is not necessary To measure more Rapid Strand sources simply raise the lift knob and remove the measured RAPID Strand from the holder A formula can be used to determine the average seed air kerma strength AKS as a QA measurement of the sum of 10 seeds Average seed air kerma strength R CF C EF N R reading CF correction factor 1 07 times the ADCL iodine calibration factor for Amersham 6711 seeds obtained with Single Seed Source Holder REF 70043 N number of seeds C correction for temperature and pressure EF electrometer correction factor 20 For Example You receive a strand with an average air kerma strength of 0 3uGym h per seed Ten seeds are measured and an io dine calibration factor of 2 6 x 10 uGym h A is used Assume R 0 9914x10 A N 10 CF 1 07 2 6 x 10 C 1 014 EF 0 998 Average seed air kerma strength 0 9914 x 10 A 1 07 2 6 x 10 1 014 0 998 q _____ l Average seed air kerma strength 0 28 uGym h This average seed
12. cally during use Suppliers of sources usu ally provide calibration certificates that can have an uncer tainty of 4 or more necessitating an independent calibra tion for better accuracy This point is addressed in the article published in Brachytherapy Dosimetric Assessment Source Calibration RSNA Categorical Course in Brachytherapy Phys ics 1997 pp 143 153 The IVB 1000 is convenient for fre quent use If your measurement differs significantly from the manufacturer you should resolve the difference before use Please note that the factors that are used in the cali bration of these chambers are the most current and in some cases may be different than those used in treatment planning computers This difference 1f present should be accounted for during your treatment planning activities To avoid con fusion the American Association of Physicists in Medicine has recommended that air kerma strength calibrations be used for gamma emitting brachytherapy sources AAPM Reports No 56 60 40 and 32 instead of source activity Because of the difficulty of beta calibrations using an extrapolation cham ber both the absorbed dose at 2mm in water and contained activity are presently in use It is desired that only the ab sorbed dose at 2mm will be used in the future The only NIST traceable calibration quantity is air kerma strength for gamma rays and this is the calibration factor provided for the IVB 1000 Any other quantity desired for e
13. corrected for decay should remain within 0 5 Operation The IVB 1000 ionization chamber has a vent hole to maintain the internal air at ambient atmospheric pressure Thus the readings obtained must be corrected for ambient temperature and pressure to the temperature and pressure of calibration 22 C and 760 mm Hg at normal relative hu midity 50 25 non condensing in the usual accepted manner The IVB 1000 has variable inserts available that can be set for different seed lengths Figure 1A shows the Tr insert and Figure 1B shows the Sr insert Figure 2 shows a typical axial response curve for the IVB 1000 as determined by a single Ir source There is only a 0 3 variability in sensitivity within 100 mm around the center 50 mm on each side The axial response curve is similar for the Sr source The IVB 1000 utilizes a conventional triax connec tor and cable to be connected to a suitable electrometer A bias of 300 volts must be applied to the electrometer low impedance connection relative to chassis ground such that the guard of the ionization chamber is at this voltage relative to ground The voltage polarity effect is less than 0 1 If desired a second bias level of 150 volts can also be used to determine the ionic recombination loss at 300 V The ionic recombination loss is less than 0 05 and thus can be con sidered negligible or equal to a correction of 1 000 1 The equation used is Ajon 4 3 Q1
14. d is marked For use in the IVB 1000 only on the top label For measurement in the HDR 1000 Figure 6 Plus Well chamber use Source Holder REF REF 70047 70023 See Figure 6 REF 70048 Seed Strand Source Holder This source holder is designed for QA measurements of RAPID Strand 6711 Iodine seed strands prior to use and is designed for use only with the IVB 1000 Well Chamber A RAPID Strand containing 10 iodine seeds was evaluated with the IVB 1000 and the Seed Strand Source Holder Fol lowing the evaluation seeds of the RAPID Strand were cut from the strand The collective seed measurements were com pared with individual seed measurements in the Single Seed Source Holder REF 70043 to obtain a correction factor This factor was found to be approximately 1 07 times the 6711 Iodine seed calibration factor from the University of Wis consin Accredited Dosimetry Calibration Laboratory 19 The results of the above testing apply specifically to the sub mitted strand type and well chamber Application of these results to any well chamber and its associated holder may result in errors due to differences in manufacturing processes component composition and the effects of different stranded seed trains to those variations It is recommended that this investigation be repeated by users upon initial receipt of this holder to verify this number The Seed Strand Source Holder REF 70048 can be gas sterilized or steam sterilized
15. e IVB 1000 Well Chamber and an appropriate Electrometer as described in the General Procedures for Medical Measurements sec tion of this manual Following sterility and radiation safety procedures remove the cover from the InterStrand Stainless Steel Shielding Container Invert the Source Holder and thread the exposed portion of the Container into the Source Holder Return the Source Holder to the upright position This should cause the InterStrand to slide out of the container directly into the Source Holder which should be visually verified Insert the Source Holder into the VB Well Cham ber and measure and record the air kerma strength of the seed train To remove the train simply reverse the above steps This may be repeated as needed with other InterStrand sources A formula can be used to determine the average air kerma strength AKS per seed as a QA measurement of the sum of N seeds Average air kerma strength per seed R Cp EF CF i R reading N number of seeds w correction for temperature and pressure EF electrometer correction factor 22 CF correction factor 0 97 times the ADCL calibration factor for IBt model 1251L I seeds or 0 92 times the model 1031L Pd seed cal factor obtained with Single Seed Source Holder REF 70043 For Example You receive an I InterStrand with a stated air kerma strength per seed of 0 3 uGym h Ten seeds are measured and an iodine calibration factor of 2 6 x 1
16. eed 0 5321 x 10 A 2 6 x 10 1 014 0 998 5 0 28 uGym h This average air kerma strength per seed can be compared to your stated isosleeve air kerma strength per seed Note this is a QA measurement assuming the five seeds are the same strength If the total air kerma strength for the 5 seeds together is desired do not divide by N Maintenance Exterior cleaning of the device can be done with a soft brush and a cloth Gently brush all surfaces to remove dirt and dust Remove any remaining dirt with a cloth slightly dampened with a solution of mild detergent and water or a liquid disinfecting agent Be especially careful that this is an external cleaning only and do not permit any liquid to seep into the IVB 1000 in any manner during cleaning Service There are no serviceable parts on the IVB 1000 If the IVB 1000 is disassembled the calibration factor will become invalid and necessitate recalibration Also the warranty will become void if the IVB 1000 is disassembled If the triax connector and external cable are modified the value of the leakage may be af fected Notice We welcome your evaluation of this manual Your comments and suggestions help us improve our publications 25 Brachytherapy Measurement System Parts and Accessories List REF Description 80289 Instruction Manual 70034 Iridium IVB Source Holder for LDR Ir 70036 Strontium IVB Source Holder for Sr 70042 X Ray Contamination Test Tool 70043 IVB Si
17. hich are returned to Standard Imaging promptly after discovery of the defect and 4 which are found to be defective upon Standard Imaging s examination Transportation charges are the buyer s responsibility This warranty extends to every part of the product except fuses batteries or glass breakage Standard Imaging Inc shall not be otherwise liable for any damages including but not limited to incidental damages conse quential damages or special damages Repaired or replaced products are warranted for the balance of the original warranty period or at least 90 days This warranty is in lieu of all other warranties express or implied whether statutory or otherwise including any implied warranty of fitness for a particular purpose In no event shall Standard Imaging Inc be liable for any incidental or consequential damages resulting from the use mis use or abuse of the product or caused by any defect failure or malfunc tion of the product whether a claim of such damages is based upon the warranty contract negligence or otherwise This warranty represents the current standard warranty of Standard Imaging Inc Please refer to the labeling or instruction manual of your Standard Imaging Inc product for any warranty conditions unique to the product Doc No 80289 09 03 04 02 29 pgs Distributed by SeeDOS Ltd
18. his manual may be copied or reproduced in any form or by any means without prior written consent of Standard Imaging Inc 28 Warranty Standard Imaging Inc sells this product under the warranty herein set forth The warranty is extended only to the buyer purchasing the prod uct directly from Standard Imaging Inc or as a new product from an authorized dealer or distributor of Standard Imaging Inc For a period of twenty four 24 months for well chambers and twelve 12 months for all other Standard Imaging Inc products from the date of original delivery to the purchaser or a distributor this product is war ranted against functional defects in materials and workmanship pro vided it is properly operated under conditions of normal use and that repairs and replacements are made in accordance herewith The forego ing warranty shall not apply if the product has been dissembled altered or repaired other than by Standard Imaging Inc or if the product has been subject to abuse misuse negligence or accident Standard Imaging s sole and exclusive obligation and the purchaser s sole and exclusive remedy under the above warranties are limited to repairing or replacing free of charge at Standard Imaging s option a product 1 which contains a defect covered by the above warranties 2 which are reported to Standard Imaging Inc not later than seven 7 days after the expiration date of the 12 or 24 month warranty period 3 w
19. ility This product and its components will perform properly and reliably only when operated and maintained in accordance with the instructions contained in this manual and accompanying labels A defective device should not be used Parts which may be broken or missing or are clearly worn distorted or contaminated should be replaced immediately with genuine replacement parts manufactured by or made available from Stan dard Imaging Inc Caution Federal law in the U S A and Canada restricts the sale distribution or use of this device to by or on the order of a licensed medical practitioner The use of this device should be restricted to the supervision of a qualified medical physicist Measurement of high ac tivity radioactive sources is potentially hazardous and should be per formed by qualified personnel Should repair or replacement of this device become necessary after the warranty period the customer should seek advice from Standard Imaging Inc prior to such repair or replacement If this device is in need of repair it should not be used until all repairs have been made and the product is functioning properly and ready for use After repair the chamber may need to be calibrated The owner of this device has sole responsibility for any malfunction resulting from abuse improper use or maintenance or repair by anyone other than Standard Imaging Inc The information in this manual is subject to change without notice No part of t
20. in Insert Diameter 3 5 cm 1 4 in Insert Height 22 4 cm 8 8 in Weight 3 6 kg 8 0 lbs ee General Procedures for Medical Measurements The following procedures should be used any time that measurements are to be made with an ionization chamber and electrometer system This applies only to the setup of the ionization chamber and electrometer not to the setup of the ionization source 1 With nothing connected to the input jack of the elec trometer turn the power on and wait at least 15 minutes for warm up Verify the leakage of the electrometer is within the manufacturer s stated acceptable limits Connect the ionization chamber to the electrometer and apply 100 voltage bias Allow the electrometer and the ionization chamber sys tem at least 10 minutes to stabilize making certain that all cabling is lying flat and unkinked Verify the leakage of the ionization chamber is within the manufacturer s stated acceptable limits If measured in the presence of background sources note that this signal will add to the leakage of the chamber Some electrometers such as the Standard Imaging MAX 4000 Electrometer allow the user to zero the device at any time If desired perform this system zeroing now Check the system leakage Take a reading without ex posing the chamber to radiation This reading should be less than 0 1 of the final signal expected If it is not the leakage should be subtracted from the signal
21. ngle Seed Source Holder 70044 IVB HDR Source Holder 70045 IVB Cesium 5mm Source Holder 70046 IVB Cesium 7mm Source Holder 70047 Mick Source Holder 70048 Seed Strand Source Holder 70049 IBt InterStrand Source Holder 70050 ImagynisosleeveTM Source Holder 70125 One Inch thick lead rings to surround IVB 1000 set of six 80010 ADCL Calibration for High Dose Rate Ir 80020 ADCL Calibration for Cesium 80025 A ADCL Calibration for low dose rate Ir Alpha Omega Services 80025 B ADCL Calibration Ir Best 80035 ADCL Calibration for Palladium 80036 ADCL Calibration Sr Novoste Medical 80040 A ADCL Calibration for Iodine Amersham 6702 80040 B ADCL Calibration for Iodine Amersham 6711 80040 C ADCL Calibration for Iodine Mentor loGold 80040 D ADCL Calibration for Iodine Best Industries 80040 E ADCL Calibration for Iodine Bebig Uromed 80040 F ADCL Calibration for Iodine Mills Biopharmaceuticals 80040 G ADCL Calibration for Iodine Syncor 80040 H ADCL Calibration for Iodine Imagyn 80040 I ADCL Calibration for Iodine Implant Sciences 80040 J ADCL Calibration for Iodine International Brachytherapy 80040 K ADCL Calibration for Iodine Source Tech 80040 L ADCL Calibration for Iodine DRAXIMAGE Inc Other Calibrations available Optional Equipment 90015 MAX 4000 Electrometer 26 Bibliography Brachytherapy Source Measurements Brachytherapy Dosimetric Assessment Source Calibration L A DeWerd RS
22. ode is used and the charge is accumulated while the source is in transit account for the transit time error of the source by making the standard timer end effect measure ments as described in High Dose Rate Brachytherapy A Textbook Nag ed Futura 1994 Note This value will differ depending on the length of the catheter The timer feature of Standard Imaging electrometers can be used to collect charge for set times and eliminate this effect REF 70045 IVB Cesium 5mm Source Holder For Cs calibrations verify the plastic spacer inside the source holder insert is gt at the bottom of the source holder Insert the cesium source into the source holder using safe handling procedures Take measurements using the method de scribed in the General Procedures for Medical Measurements Section of this manual See Figure 4 18 REF 70046 IVB Cesium 7mm Source Holder Insert the cesium source into the source SD holder using safe handling procedures Take measurements using the method described in the General Procedures for Medical Measurements Section of this manual See Figure 5 Figure 5 REF 70046 REF 70047 MICK Source Holder for IVB 1000 This source holder allows for a constancy QA check of seeds loaded into a MICK cartridge Screw a loaded cartridge into the holder from the bottom as shown and make sure the seeds are not blocked by the metal posts This holder is to be used only in the IVB 1000 an
23. r detail Calibration factors should be obtained from an ADCL for each brachytherapy source that is being mea sured The ionization current expected from the IVB 1000 is approximately 2 4 pA U for Ir brachytherapy sources and 38 6 nA Gy s for Sr U is the unit for air kerma strength and is uGym7h Thus the measurement of all brachytherapy sources requires an electrometer with a calibrated scale for measuring currents in the range from pA tonA Alternatively a calibrated charge scale may be used with timed runs Calibration of all brachytherapy sources with ion ization chambers is important When a brachytherapy source is used it is imperative that there be an accurate and reliable calibration of the source strength by means of a suitable cham ber such as the IVB 1000 Using other inserts low dose rate brachytherapy seeds can also be calibrated with the IVB 1000 Use the appropri ate insert for a given source Additionally do not confuse details in one section of this manual with those of another Some details are specific only for the given application or radionuclide The half life of Ir is 73 83 days The manufacturer for intravascular applications recommends monthly source replacements to maintain the correct output level The half life of Sr is 28 years However the manufacturer recom mends 250 uses or replacement on a six month basis All of these sources must be calibrated when placed in use and may be checked periodi
24. r with the lead rings around it as calibrated If necessary let the chamber stabilize for at least 30 minutes before the measurement to al low it to equilibrate to ambient temperature and pres sure Connect the IVB 1000 Chamber to a suitable electrom eter such as the MAX 4000 from Standard Imaging and apply 300 V bias voltage Allow the system to stabilize for at least 10 minutes Set the Source Holder to the number of seeds to be measured 6 10 14 18 or 22 This is indicated by the lowest number visible on the Source Holder See Fig ure 1A Insert the Source Holder into the IVB 1000 Carefully slide the blue tipped end of the Calibration Catheter into the top opening in the knurled knob on the Source Holder Insert the Catheter until it bottoms within the Source Holder about 7 5 14 Secure the Calibration Catheter by tightening the Knurled Knob until the Catheter no longer moves up and down easily Do not tighten too far so the IVB seed train is unable to pass completely into the Source Holder After performing all manufacturer recommended safety procedures for the IVB seed train run the seed train to the bottom of the Calibration Catheter Verify again that the setting on the Source Holder matches the number of seeds in the train Let the reading stabilize for a mini mum of 20 sec for current measurement or for a repro ducible set time for charge measurement Read and record the measured current or charge Use co
25. re not available for gold REF 70044 IVB HDR Source Holder 1 Place the IVB 1000 Ionization chamber in the same room as the HDR unit for at least 30 minutes before the measurement to allow it to equilibrate to ambient temperature and pressure Connect the IVB 1000 Ionization chamber to a suitable electrometer such as the MAX 4000 from Standard Imaging and apply 300 V bias voltage Allow the system to stabilize for at least 10 min Connect a catheter such as the endobronchial French 6 blue catheter to HDR irradiator Align the black dot on the well insert with the punch mark on the body of the chamber Insert catheter end to bottom of source holder The dead space at the catheter end must be known so that the center of the Ir source can be positioned at the most sensitive spot of the chamber See Figure 2 page 11 for a typical axial response curve for the IVB Use the point determined during calibration as the sensitive spot for the IVB 1000 Secure the catheter by tightening the knurled knob until the catheter no longer moves up and down easily Do not tighten too far so the HDR source is unable to pass completely into the Source Holder 172 7 After performing all manufacturer recommended safety procedures for the HDR after loading device run the Ir source to the radiation sensitive axial point of the chamber for a minimum of 20 sec for current measurement or for a reproducible set time for charge measurement If the charge m
26. rrection factors for temperature pressure elec trometer correction factor electrometer must be cali brated and calibration factor for the IVB 1000 given by the Accredited Dosimetry Calibration Laboratory to calculate the air kerma strength of the source The fol lowing equation can be used S R F E C where S the air kerma strength of the source R the reading in A 1f current scale or in C s 1f charge scale measured for a set time in s F the temperature and pressure correction factor E the correction factor for the electrometer scale C the IVB 1000 calibration factor for air kerma strength Note S can be divided by Ajon if desired to correct for recombination effects Since the IVB 1000 has an Ajon of 1 000 this is not necessary The value of S will give the total air kerma strength for the number of seeds measured within 0 3 For example if R 6 220n A F 1 009 E 0 999 and C 421 U nA then 15 S 6 220nA 1 009 0 999 421U nA 2640 U If the value of air kerma strength is for a number of seeds and the individual value of each seed is desired divide the value by the number of seeds in the train The value for absorbed dose rate at 2mm is determined using AAPM task group 60 report Procedures for Other Source Holders REF 70042 X Ray Contamination Test Tool This tool is designed for use with Sr sources only It con sists of a 7mm radius of material that absorbs nearly
27. sert the Catheter until it bottoms about 7 5 deep Secure the Source Catheter by tightening the Knurled Knob until the Catheter no longer moves up and down easily Do not tighten too far so the source is unable to pass completely into the Source Holder or that the cath eter is kinked or damaged After performing all manufacture recommended safety procedures for the IVB seed train run the seed train to the bottom of the Calibration Catheter Verify again that the setting on the Source Holder matches the number of seeds in the train Let the reading stabilize for a minimum of 20 sec for current measurement or for a reproducible set time for charge measurement Read and record the measured current or charge at five positions e g rotate the Source Holder in the Well cham ber to the compass positions of 0 90 180 270 and 360 for succesive measurments Take the aver age of the readings Use correction factors for temperature pressure elec trometer correction factor electrometer must be cali brated and calibration factor for the IVB 1000 given 12 by the Accredited Dosimetry Calibration Laboratory to cal culate the absorbed dose rate at 2mm for the source The following equation can be used D R F E C where D the absorbed dose rate at 2mm depth in water R the reading in A if current scale or in C s if charge scale measured for a set time in s F the temperature and pressure correction fac
28. tor E the correction factor for the electrometer scale C the IVB 1000 calibration factor Note D can be divided by Ajon if desired to correct for recombination effects Since the IVB 1000 has an Ajon of 1 000 this is not necessary The value of D will give the total absorbed dose rate at 2mm for the source length measured For example if R 6 220n A F 1 009 E 0 999 and C 42 Gy s nA then D 6 220nA 1 009 0 999 42Gy s nA 263Gy s Note A calibration factor is also given for contained activ ity The equation above is still used with C being replaced by the calibration factor for contained activity The result obtained is then the contained activity instead of D Procedures for calibration of IVB Ir sources REF 70034 Iridium IVB Source Holder for LDR Ir seeds 1 Convert a Treatment Catheter to a Calibration Catheter if required WARNING This is only applicable for IVB Ir sources and only if a Calibration Catheter has not been provided or fabricated 13 fe Catheter after tip is shertened fl ls 1 mm Figure 3 Converting a Treatment Catheter to a Calibration Catheter for Ir IVB sources Using a sharp exact o knife cut off the blue tip of a Ir treatment catheter as shown in Figure 3 Retain this Calibration catheter and use with all future source calibrations A Warning This procedure is only for IVB Ir sources Place the IVB 1000 Chambe
29. xample apparent activity will have to be derived using agreed upon constants Further details are provided in the appendix included with the calibration report a Calibration of IVB 1000 As is standard practice for other ion chambers it is rec ommended that the IVB 1000 be calibrated every 2 years It should be calibrated with the source insert used for the cham ber This calibration should be performed by an Accredited Dosimetry Calibration Laboratory Standard Imaging offers calibrations from the University of Wisconsin Accredited Do simetry Calibration Laboratory You need only one purchase order to cover calibrations shipping and handling and ser vice Standard Imaging hand carries all instruments to and from the ADCL Constancy Check of IVB 1000 Regular constancy checks should be performed by us ing a procedure such as the following The source holder may be removed to allow the stability of the IVB 1000 to be checked by means of a constancy check source e g using a low dose rate Cs brachytherapy source with the insert in place Alternatively the stability can be monitored with the use of an external Co beam This value should be obtained upon receipt of the chamber and monitored for consistency thereafter Either place the chamber in the Co beam at a known distance with a standard field such as 10 cm x 10 cm or place the Cs source in a reproducible position and take a current reading A graph of the response
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