accidents with radiotherapy

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accidents with radiotherapy

  1. 1. ACCIDENTS IN RADIATIONACCIDENTS IN RADIATIONONCOLOGY PRACTICEONCOLOGY PRACTICEDR. ASHUTOSH MUKHERJIDR. ASHUTOSH MUKHERJIASST. PROFESSOR OF RADIOTHERAPY,ASST. PROFESSOR OF RADIOTHERAPY,REGIONAL CANCER CENTRE, JIPMERREGIONAL CANCER CENTRE, JIPMER
  2. 2. RADIATIONRADIATION ONCOLOGYONCOLOGY• Radiation therapy is that branch ofRadiation therapy is that branch ofmedicine thatmedicine that deals with use ofdeals with use ofradiation in the treatment ofradiation in the treatment ofmalignant diseasesmalignant diseases ..• Goal of radiation therapy is toGoal of radiation therapy is to killkillcancerous cells, while sparingcancerous cells, while sparingnormal tissue.normal tissue.• Radiation therapy can be eitherRadiation therapy can be eithercurative, or palliative.curative, or palliative.• In contrast to diagnosticIn contrast to diagnosticprocedures, therapeutic doses ofprocedures, therapeutic doses ofradiation are high; for example:radiation are high; for example:5000 cGy in post operative cases5000 cGy in post operative casesvs 10 cGy (CAT scan).vs 10 cGy (CAT scan).
  3. 3. RADIATION ONCOLOGY IN THE USRADIATION ONCOLOGY IN THE US• In the US in 1995, 41% of the 1,252,050 newly diagnosed cases ofIn the US in 1995, 41% of the 1,252,050 newly diagnosed cases ofcancer were treated with radiation.cancer were treated with radiation.• These radiation treatments relieved suffering and extended the livesThese radiation treatments relieved suffering and extended the livesof the patients being treated.of the patients being treated.• Along with early diagnosis, radiation treatments contributed to aAlong with early diagnosis, radiation treatments contributed to a1.1% decrease in annual cancer death rates from 1993 through1.1% decrease in annual cancer death rates from 1993 through2002.2002.• In 1996 in the US there were 1,893 Linear Accelerators and 504 Co-In 1996 in the US there were 1,893 Linear Accelerators and 504 Co-60 machines. Present estimates put the number at 4492.60 machines. Present estimates put the number at 4492.
  4. 4. RADIATION ONCOLOGY IN THE USRADIATION ONCOLOGY IN THE USRadiotherapy Trends: 1975-199005001000150020001970 1975 1980 1985 1990 1995YearNumberFacilitiesAcceleratorsCobalt
  5. 5. RADIATION ONCOLOGY IN INDIARADIATION ONCOLOGY IN INDIA• In India, it is estimated that over 1 million cancer cases are detected everyyear and a majority of them require radiotherapy at one time or other duringtheir course of the treatment.• In India as per IAEA figures, there are 218 radiotherapy centres with 354teletherapy units as of year 2004.• About 131 of these centres have brachytherapy facilities, either manual,remote or both.• Also there are about 140 nuclear medicine centres in the country, of which25 centres have facilities for treatment of cancer of thyroid
  6. 6. Break-up of Radiation Therapy Facilities inIndia:(during the period 1980 – 2004)•Radiotherapy Centres in India: 218•Radionuclide Therapy Units: 283•Linear Accelerators: 71•Remote Afterloading LDR/MDR Units: 37•Remote Afterloading HDR Units: 45•Manual Afterloading Intracavitary Kits: 76•Manual Afterloading Interstitial Kits: 27•Radiotherapy Simulators: 40•Treatment Planning Systems: 80•Nuclear Medicine Centres: 140•Nuclear Medicine Therapy Centres: 25
  7. 7. Year-wise distribution of growth of radiationtherapy facilities in India
  8. 8. CASE HISTORIES OF RADIATIONCASE HISTORIES OF RADIATIONACCIDENTSACCIDENTS
  9. 9. Case 1:Case 1: Use of an incorrect decay curve forUse of an incorrect decay curve for6060Co (USA, 1974-76)Co (USA, 1974-76)Initial calibration of aInitial calibration of a 6060Co beam was correct, but ..Co beam was correct, but ..• A decay curve forA decay curve for 6060Co was drawn: by mistake, the slope wasCo was drawn: by mistake, the slope wassteeper than the real decay and the curve underestimated thesteeper than the real decay and the curve underestimated thedose ratedose rate• Treatment times based on it were longer than appropriate, thusTreatment times based on it were longer than appropriate, thusleading to overdoses, which increased with time reaching up toleading to overdoses, which increased with time reaching up to50% when the error was discovered50% when the error was discovered• There were no beam measurements in 22 months and a total ofThere were no beam measurements in 22 months and a total of426 patients were affected426 patients were affected• Of these 183 patients who survived one year, 34% had severeOf these 183 patients who survived one year, 34% had severecomplicationscomplications
  10. 10. Case 2: Incomplete understanding & testingCase 2: Incomplete understanding & testingof a treatment planning system (TPS)of a treatment planning system (TPS)(UK, 1982-90)(UK, 1982-90)• In a hospital, most of the treatments were with a SSD of 100 cmIn a hospital, most of the treatments were with a SSD of 100 cm• For treatments treatments with SSD different from standard (100 cm),For treatments treatments with SSD different from standard (100 cm),corrections for distance were usually done by the technologistscorrections for distance were usually done by the technologists• When a TPS was acquired, technologists continued to apply manualWhen a TPS was acquired, technologists continued to apply manualdistance correction, without realising that the TPS algorithm alreadydistance correction, without realising that the TPS algorithm alreadyaccounted for distanceaccounted for distance• As a result, distance correction was applied twice,As a result, distance correction was applied twice, leading to under-leading to under-dosage (up to 30%)dosage (up to 30%)• The procedure was not written, and therefore, it was not modified whenThe procedure was not written, and therefore, it was not modified whennew TPS was usednew TPS was used• Problem remained undiscovered during eight years and affected 1,045Problem remained undiscovered during eight years and affected 1,045patients andpatients and 492 patients developed local recurrence492 patients developed local recurrenceprobably due to the underexposureprobably due to the underexposure !!!!!!
  11. 11. Case 3: Untested change of procedureCase 3: Untested change of procedurefor data entry into TPS (Panama, 2000)for data entry into TPS (Panama, 2000)• A TPS allowed entry of four shielding blocks for isodose calculations,A TPS allowed entry of four shielding blocks for isodose calculations,one block at a timeone block at a time• Need for five shielding blocks led to deviation from standardNeed for five shielding blocks led to deviation from standardprocedure for block data entry: several blocks were entered in oneprocedure for block data entry: several blocks were entered in onestepstep• Instructions for users had some ambiguity with respect to shieldingInstructions for users had some ambiguity with respect to shieldingblock data entryblock data entry• TPS computer calculated treatment time, which was double theTPS computer calculated treatment time, which was double thenormal one (leading to 100% overdose)normal one (leading to 100% overdose)• There was no written procedure for the use of TPS, and therefore, aThere was no written procedure for the use of TPS, and therefore, achange of procedure was neither written nor tested for validitychange of procedure was neither written nor tested for validity• Computer output was not checked for treatment time with manualComputer output was not checked for treatment time with manualcalculationscalculations• TheThe error affected 28 patientserror affected 28 patients and one year after the eventand one year after the event,, andandat least five had died from the overexposureat least five had died from the overexposure !!!!
  12. 12. Case 3:Case 3:Colonoscopy of a patientColonoscopy of a patienttreated with overdosestreated with overdosesof 100% with:of 100% with:• Necrotic tissueNecrotic tissue• TelangiectasiaTelangiectasia
  13. 13. Case 4: Accelerator software problemsCase 4: Accelerator software problems(USA & Canada, 1985-87)(USA & Canada, 1985-87)• Software from an older accelerator design was used for a new,Software from an older accelerator design was used for a new,substantially different, designsubstantially different, design• Software flaws were later identified in the software used to enterSoftware flaws were later identified in the software used to entertreatment parameters, such as type of radiation and energytreatment parameters, such as type of radiation and energy• Six accidental exposuresSix accidental exposures occurred in different hospitals andoccurred in different hospitals andthree patients died from overexposure!!three patients died from overexposure!!
  14. 14. Case 5: Reuse of outdated computer file forCase 5: Reuse of outdated computer file for6060Co treatments (USA, 1987-88)Co treatments (USA, 1987-88)• After source change, TPS computer files were updated…After source change, TPS computer files were updated…• Except a computer file, which was no longer in use (this wasExcept a computer file, which was no longer in use (this wasintended for brain treatments with trimmer bars)intended for brain treatments with trimmer bars)• The computer file was not removed although no longer in useThe computer file was not removed although no longer in use• A new radiation oncologist decided to treat with trimmer bars andA new radiation oncologist decided to treat with trimmer bars andtook the file corresponding to the priortook the file corresponding to the prior 6060Co sourceCo source• There was no double or manual check for dose calculationThere was no double or manual check for dose calculation• 33 patients received 75% higher overexposure33 patients received 75% higher overexposure
  15. 15. Case 6: Incorrect accelerator repair &Case 6: Incorrect accelerator repair &communication problems (Spain, 1990)communication problems (Spain, 1990)• Accelerator fault followed by an attempt to repair it by local softwareAccelerator fault followed by an attempt to repair it by local softwarefirmfirm• Electron beam was restored but electron energy was misadjustedElectron beam was restored but electron energy was misadjusted• Accelerator delivered 36 MeV electrons, regardless of energyAccelerator delivered 36 MeV electrons, regardless of energyselectedselected• Treatments resumed without notifying physicists for beam checksTreatments resumed without notifying physicists for beam checks• There was a discrepancy between energy displayed and energyThere was a discrepancy between energy displayed and energyselected, and which was attributed to a faulty indicator, instead ofselected, and which was attributed to a faulty indicator, instead ofinvestigating the reason for the discrepancyinvestigating the reason for the discrepancy• A total ofA total of 27 patients were affected with massive27 patients were affected with massiveoverdosesoverdoses and by distorted dose distribution due to wrong electronand by distorted dose distribution due to wrong electronenergy of whom at leastenergy of whom at least 15 patients died15 patients died from the accidentalfrom the accidentaloverexposure and two more died with overexposure as majoroverexposure and two more died with overexposure as majorcontributorcontributor
  16. 16. Case 7: Malfunction of HDR brachytherapyCase 7: Malfunction of HDR brachytherapyequipment (USA, 1992)equipment (USA, 1992)• HDR brachytherapy source detached from the driving mechanismHDR brachytherapy source detached from the driving mechanismwhile still inside the patientwhile still inside the patient• While the console display indicated that the source was in retractedWhile the console display indicated that the source was in retractedto the shielded position, an external radiation monitor was indicatingto the shielded position, an external radiation monitor was indicatingthat there was radiationthat there was radiation• Staff failed to investigate the discrepancy with available portableStaff failed to investigate the discrepancy with available portablemonitormonitor• The source remained in the patient for several days and the patientThe source remained in the patient for several days and the patientdied from overexposuredied from overexposure
  17. 17. Case 8: Beam miscalibration ofCase 8: Beam miscalibration of 6060CoCo(Costa Rica, 1996)(Costa Rica, 1996)• Radioactive source of a teletherapy unit was exchangedRadioactive source of a teletherapy unit was exchanged• During beam calibration, reading of the timer was confused, leadingDuring beam calibration, reading of the timer was confused, leadingto underestimation of the dose rateto underestimation of the dose rate• Subsequent treatment times were calculated with the wrong doseSubsequent treatment times were calculated with the wrong doserate and were about 60% longer than requiredrate and were about 60% longer than required• 115 patients were affected115 patients were affected ; two years after the event, at least; two years after the event, at least17 patients had died17 patients had died from the overexposurefrom the overexposureThus there was in this case……………………Thus there was in this case……………………• Failure to perform independent calibrationFailure to perform independent calibration• Failure to notice that treatment times were too long for a new sourceFailure to notice that treatment times were too long for a new sourcewith higher activitywith higher activity
  18. 18. Child affected by overdoses to brain and spinal cord lost his ability tospeak and walk
  19. 19. Further recent instances in the US (A study by theFurther recent instances in the US (A study by theNew York Times dated 24New York Times dated 24ththJanuary 2010)January 2010)In a study of the number of radiation therapy accidents in the US betweenIn a study of the number of radiation therapy accidents in the US between2000-2008, following instances were highlighted:2000-2008, following instances were highlighted:October 2008 — Prostate Glands MisidentifiedOctober 2008 — Prostate Glands Misidentified::• Five prostate cancer patients were treated incorrectly after a faultyFive prostate cancer patients were treated incorrectly after a faultyultrasound machine misidentified their prostate glands.ultrasound machine misidentified their prostate glands.• One patient was irradiated incorrectly on 32 of 38 treatments; another onOne patient was irradiated incorrectly on 32 of 38 treatments; another on19 of 45 treatments19 of 45 treatments. After the ultrasound was repaired, quality checks. After the ultrasound was repaired, quality checkswere performed by the vendor, and not the consulting physics group thatwere performed by the vendor, and not the consulting physics group thatwas servicing the facility. The therapist warned the oncologist that thewas servicing the facility. The therapist warned the oncologist that thetreatment position appeared incorrect, but nothing was done about it.treatment position appeared incorrect, but nothing was done about it.
  20. 20. June 2008 — Therapist Mistakes Treatment on Alternate DaysJune 2008 — Therapist Mistakes Treatment on Alternate Days::• A 63-year-old woman was to undergo two different treatments onA 63-year-old woman was to undergo two different treatments onalternate days — one to the upper lung and the other to thealternate days — one to the upper lung and the other to themediastinum — an area in the chest.mediastinum — an area in the chest.• But because of a therapist’s error,But because of a therapist’s error, her upper lung received one-her upper lung received one-tenth the prescribed dose and her mediastinum got 10 times thetenth the prescribed dose and her mediastinum got 10 times theprescribed dose.prescribed dose. The patient died of cancer later in the yearThe patient died of cancer later in the year..• The hospital now requires two radiation therapists to attendThe hospital now requires two radiation therapists to attendwhenever a complex treatment plan is being delivered. Thewhenever a complex treatment plan is being delivered. Thetherapists must also use a checklist to verify the patient’s identity,therapists must also use a checklist to verify the patient’s identity,the type of treatment, the dose and the site to be treated.the type of treatment, the dose and the site to be treated.
  21. 21. December 2007 — Radioactive Seeds Implanted in Wrong LocationDecember 2007 — Radioactive Seeds Implanted in Wrong Location::• A patient’s prostate cancer was underdosed by 50 percent —A patient’s prostate cancer was underdosed by 50 percent —increasing the odds that cancer would recur — because a doctorincreasing the odds that cancer would recur — because a doctorimplanted radioactive seeds in the wrong location. Consequently,implanted radioactive seeds in the wrong location. Consequently,the rectum and urethra received more radiation than intended.the rectum and urethra received more radiation than intended.• Also the radiation oncologist then failed to promptly interpret a post-Also the radiation oncologist then failed to promptly interpret a post-implant CT scan, which would have revealed the error sooner.implant CT scan, which would have revealed the error sooner.
  22. 22. March 2007 — Radioactive Seeds Measured IncorrectlyMarch 2007 — Radioactive Seeds Measured Incorrectly::• A 31-year-old woman with vaginal cancer was overdosed becauseA 31-year-old woman with vaginal cancer was overdosed becauseof confusion over the method of measuring the strength ofof confusion over the method of measuring the strength ofradioactive seeds.radioactive seeds.• The operator failed to enter the correct information into theThe operator failed to enter the correct information into thetreatment planning software, causing an overdose to her rectum andtreatment planning software, causing an overdose to her rectum andvagina.vagina.• The patient faced anThe patient faced an increased risk of radiation cystitis, rectalincreased risk of radiation cystitis, rectalproctitisproctitis, and the formation of a fistula between the rectum and the, and the formation of a fistula between the rectum and thevagina. Neither the physicist nor the radiation oncologist hadvagina. Neither the physicist nor the radiation oncologist hadprepared a treatment plan using iridium-192 — an isotope — in sixprepared a treatment plan using iridium-192 — an isotope — in sixyears.years.
  23. 23. March 2006 — Wrong Patient Receives TreatmentMarch 2006 — Wrong Patient Receives Treatment::• Patient A had just completed treatment for a brain tumor receivedPatient A had just completed treatment for a brain tumor receivedadditional radiation intended for Patient B, who had breast cancer.additional radiation intended for Patient B, who had breast cancer.Patient A did not realize that treatment had been completed when aPatient A did not realize that treatment had been completed when atherapist closed the patient’s electronic chart and pulled up the charttherapist closed the patient’s electronic chart and pulled up the chartfor Patient B. A second therapist arrived, saw the breast cancerfor Patient B. A second therapist arrived, saw the breast cancertreatment had not been administered, and mistakenly administeredtreatment had not been administered, and mistakenly administeredit to the first patient.it to the first patient.
  24. 24. December 2005 — Therapist Overrides a Computer MalfunctionDecember 2005 — Therapist Overrides a Computer Malfunction::• A patient undergoing I.M.R.T. for prostate cancer was irradiatedA patient undergoing I.M.R.T. for prostate cancer was irradiatedincorrectly after a therapist overrode a computer malfunction.incorrectly after a therapist overrode a computer malfunction.• After the guidance system froze, the therapist manually entered co-After the guidance system froze, the therapist manually entered co-ordinates but left out a negative sign, shifting the aim in the wrongordinates but left out a negative sign, shifting the aim in the wrongdirection.direction.• Hospital policy required that a second therapist review the dataHospital policy required that a second therapist review the databefore treatment, but that was not done!!before treatment, but that was not done!!
  25. 25. A Breast Cancer Patient who received massive overdose toA Breast Cancer Patient who received massive overdose tothe chest wall resulting in sloughing off of the skin!!the chest wall resulting in sloughing off of the skin!!
  26. 26. New Delhi radiation accident, 1967New Delhi radiation accident, 1967• Date:Date: May 1967 May 1967• Location:Location: Safdarjang Hospital, New Delhi, India Safdarjang Hospital, New Delhi, India• Type of event:Type of event:  accidental exposure to source accidental exposure to source• Description:Description: While replacing a Co-60 source in a teletherapy unit,While replacing a Co-60 source in a teletherapy unit,an employee received a localized radiation exposure of about 800an employee received a localized radiation exposure of about 800rads to the hand while pushing the source into place. The employeerads to the hand while pushing the source into place. The employeenoticed an immediate burning sensation but no other symptoms untilnoticed an immediate burning sensation but no other symptoms until12 days later, when burning pain and itching developed. A blistering12 days later, when burning pain and itching developed. A blisteringburn developed while the employee was hospitalized.burn developed while the employee was hospitalized.• Consequences:Consequences:  1 injury. 1 injury.
  27. 27. India x-ray accident, 1974India x-ray accident, 1974• Date:Date: 9 August 1974 9 August 1974• Location:Location: India India• Type of event:Type of event:  x-ray accident x-ray accident• Description:Description: A worker using an x-ray crystallography unit wasA worker using an x-ray crystallography unit wasexposed to the x-ray beam. After returning from a lunch break, heexposed to the x-ray beam. After returning from a lunch break, heoperated the unit for 15 minutes before realizing that one shutteroperated the unit for 15 minutes before realizing that one shutterwas open, exposing his right forearm to the beam. A woundwas open, exposing his right forearm to the beam. A wounddeveloped on the arm after 14 days which healed after 3 months,developed on the arm after 14 days which healed after 3 months,leaving a white scar. Dose was on the order of 8,000-12,000 rads toleaving a white scar. Dose was on the order of 8,000-12,000 rads tothe skin or more.the skin or more.• Consequences:Consequences:  1 injury. 1 injury.
  28. 28. Mayapuri orphaned source, 2010Mayapuri orphaned source, 2010• A cobalt-60 source at a scrap metal shop in Mayapuri area of DelhiA cobalt-60 source at a scrap metal shop in Mayapuri area of Delhicaused radiation injuries to several individuals.caused radiation injuries to several individuals.• The University of Delhi disposed off a Gammacell 220 researchThe University of Delhi disposed off a Gammacell 220 researchirradiator unused since 1985 which was auctioned on 26 Februaryirradiator unused since 1985 which was auctioned on 26 February2010 to a scrap metal dealer. By late March the shop owner2010 to a scrap metal dealer. By late March the shop ownerdeveloped diarrhea followed by skin legions; and on 4 April wasdeveloped diarrhea followed by skin legions; and on 4 April washospitalized with radiation sickness. Authorities found the source onhospitalized with radiation sickness. Authorities found the source on5 April. By 14 April a5 April. By 14 April a total of 7 people had been hospitalized withtotal of 7 people had been hospitalized withradiation injuriesradiation injuries. One person died on 26 April from multiple organ. One person died on 26 April from multiple organfailure. Six individuals, including the owner of the scrap dealer shop,failure. Six individuals, including the owner of the scrap dealer shop,remained hospitalized on 28 April at three hospitals; two individualsremained hospitalized on 28 April at three hospitals; two individualswere in critical condition.were in critical condition.• Authorities recovered 8 sources at the original shop, two at a nearbyAuthorities recovered 8 sources at the original shop, two at a nearbyshop, and one from the dealers wallet. Indias Atomic Energyshop, and one from the dealers wallet. Indias Atomic EnergyRegulatory Board announced on 28 April having traced the origin ofRegulatory Board announced on 28 April having traced the origin ofthe source to the University of Delhi. On 5 May the AERB stated thatthe source to the University of Delhi. On 5 May the AERB stated thatall material from the Gammacell unit was accounted for. Furtherall material from the Gammacell unit was accounted for. Furthercleanup of the scrap metal site in Mayapuri was conducted 15-16cleanup of the scrap metal site in Mayapuri was conducted 15-16May.May.• Consequences:Consequences: 1 fatality, 7 injuries 1 fatality, 7 injuries
  29. 29. CLINICAL CONSEQUENCESCLINICAL CONSEQUENCES
  30. 30. Side effects and complications inSide effects and complications inradiotherapyradiotherapy• Side effects are usually minor and transientSide effects are usually minor and transient– e.g : xerostomia and localised subcutaneous fibrosise.g : xerostomia and localised subcutaneous fibrosis– Relatively high frequency acceptable to achieve cureRelatively high frequency acceptable to achieve cure• Complications are more severe and long lastingComplications are more severe and long lasting– e.g : radiation myelitise.g : radiation myelitis– Expected only at very low frequencyExpected only at very low frequency
  31. 31. Impact of accidental underexposureImpact of accidental underexposure• Accidental underdosage may jeopardise tumour control probabilityAccidental underdosage may jeopardise tumour control probability• They are difficult to discover, may only be detected after relativelyThey are difficult to discover, may only be detected after relativelylong time and, therefore, may involve a large number of patientslong time and, therefore, may involve a large number of patientsImpact of overdoses on early (or acute)Impact of overdoses on early (or acute)complicationscomplications• Usually observed in tissues with rapid cell turnover (skin, mucosa,Usually observed in tissues with rapid cell turnover (skin, mucosa,bone marrow)bone marrow)• Overexposure may increase the frequency and severity (up toOverexposure may increase the frequency and severity (up tonecrosis)necrosis)
  32. 32. Early (acute) complicationsEarly (acute) complications• Determinant factors for acute complications are:Determinant factors for acute complications are:– 1) total delivered dose1) total delivered dose– 2) total duration (protraction)2) total duration (protraction)– 3) size and location of irradiated volume3) size and location of irradiated volume• Little correlation of early complications with fraction size and doseLittle correlation of early complications with fraction size and doserate (except if the latter is very high)rate (except if the latter is very high)
  33. 33. Late complicationsLate complications• Mainly observed in tissues withMainly observed in tissues withslowly proliferating cellsslowly proliferating cells(arteriolar narrowing which(arteriolar narrowing whichoccurs with a time delay)occurs with a time delay)• Can also become manifest inCan also become manifest inrapidly proliferating cells (inrapidly proliferating cells (inaddition to and after acuteaddition to and after acuteeffects)effects)• Manifest more than six monthsManifest more than six monthsafter irradiation and even muchafter irradiation and even muchlaterlater• Usually irreversible and oftenUsually irreversible and oftenslowly progressiveslowly progressive• Eg:- Picture showing case ofEg:- Picture showing case ofeextensive fibrosis of the left groinxtensive fibrosis of the left groinwith limitation of hip motion as awith limitation of hip motion as aresult of accidental overexposureresult of accidental overexposure
  34. 34. Impact of overexposure on lateImpact of overexposure on latecomplicationscomplications• Determinant factors:Determinant factors:– 1) total delivered dose1) total delivered dose– 2) fraction size and dose rate2) fraction size and dose rate• In the case of accidental exposure, increased fraction size mayIn the case of accidental exposure, increased fraction size mayamplify the effects (as occurred in some accidents)amplify the effects (as occurred in some accidents)• In serial organs (spinal cord, intestine, large arteries), a lesion ofIn serial organs (spinal cord, intestine, large arteries), a lesion ofsmall volume irradiated above threshold may cause majorsmall volume irradiated above threshold may cause majorincapacity, for example paralysisincapacity, for example paralysis• In organs arranged in parallel (e.g. lung and liver), severity is relatedIn organs arranged in parallel (e.g. lung and liver), severity is relatedto the tissue volume irradiated above thresholdto the tissue volume irradiated above threshold
  35. 35. Clinical detection of accidental medicalClinical detection of accidental medicalexposureexposure• Careful clinical follow-up may lead to detect accidental overdoseCareful clinical follow-up may lead to detect accidental overdosethrough early enhanced reactionsthrough early enhanced reactions• Experienced radiation oncologists can detect overdoses of 10 %Experienced radiation oncologists can detect overdoses of 10 %during regular weekly consultationsduring regular weekly consultations• Some overdoses may cause late severe effects without abnormalSome overdoses may cause late severe effects without abnormalearly effectsearly effects• In the case of unusual reactions in a single patient, other patientsIn the case of unusual reactions in a single patient, other patientstreated in the same period may need to be recalledtreated in the same period may need to be recalled
  36. 36. Recommendations forRecommendations forPreventionPrevention
  37. 37. List of Recommendations for preventionList of Recommendations for prevention• Overall preventive measure: a Quality Assurance Programme,Overall preventive measure: a Quality Assurance Programme,involvinginvolving– OrganisationOrganisation– Education and trainingEducation and training– Acceptance testing and commissioningAcceptance testing and commissioning– Follow-up of equipment faultsFollow-up of equipment faults– CommunicationCommunication– Patient identification and patient chartsPatient identification and patient charts– Specific recommendations for teletherapySpecific recommendations for teletherapy– Specific recommendations for brachytherapySpecific recommendations for brachytherapy
  38. 38. Quality Assurance Programme for RadiationQuality Assurance Programme for RadiationTherapy (QART)Therapy (QART)• Quality assurance programmes have evolved from equipmentQuality assurance programmes have evolved from equipmentverifications to include the entire process, from the prescription toverifications to include the entire process, from the prescription todelivery and post treatment follow-updelivery and post treatment follow-up• Major accidental exposures occurred in the absence of writtenMajor accidental exposures occurred in the absence of writtenprocedures and checks (QART); either because a QART did notprocedures and checks (QART); either because a QART did notexist or it was not fully implemented (checks omitted)exist or it was not fully implemented (checks omitted)
  39. 39. OrganizationOrganization• Comprehensive QAComprehensive QAIs crucial in prevention and involve clinical, physical and safetyIs crucial in prevention and involve clinical, physical and safetycomponents.components.• QA implementation requiresQA implementation requires– complex multi-professional team workcomplex multi-professional team work– clear allocation of functions and responsibilitiesclear allocation of functions and responsibilities– functions and responsibilities understoodfunctions and responsibilities understood– number of qualified staff, commensurate to workloadnumber of qualified staff, commensurate to workload
  40. 40. Education and trainingEducation and training• The most important component of QA is qualified personnel,The most important component of QA is qualified personnel,including radiation oncologists, medical physicists, technologistsincluding radiation oncologists, medical physicists, technologistsand maintenance engineersand maintenance engineers• Comprehensive education together with specific training onComprehensive education together with specific training on– procedures and responsibilitiesprocedures and responsibilities– everyone’s role in the QART programmeeveryone’s role in the QART programme– lessons from typical accidents with a description of methods forlessons from typical accidents with a description of methods forpreventionprevention– additional training when new equipment and techniques areadditional training when new equipment and techniques arebeing introducedbeing introduced
  41. 41. Acceptance testing & commissioningAcceptance testing & commissioning• Errors in these phases may affect many patientsErrors in these phases may affect many patients• Acceptance testing:Acceptance testing:– Should include test of safety interlocks, verification of equipmentShould include test of safety interlocks, verification of equipmentspecifications, as well as understanding and testing TPSspecifications, as well as understanding and testing TPS• Commissioning:Commissioning:– Should includes measuring and entering all basic data for futureShould includes measuring and entering all basic data for futuretreatments into computertreatments into computer• Systematic acceptance and commissioning, including a cross checkSystematic acceptance and commissioning, including a cross checkand independent verification, form a major part of accidentand independent verification, form a major part of accidentpreventionprevention
  42. 42. Follow-up on equipment faultsFollow-up on equipment faults• Experience has shown that some equipment faults areExperience has shown that some equipment faults aredifficult to isolate and to correctdifficult to isolate and to correct• If an equipment fault or malfunction has not been fullyIf an equipment fault or malfunction has not been fullyunderstood and corrected, there is a need forunderstood and corrected, there is a need for– communication and follow-up with manufacturercommunication and follow-up with manufacturer– dissemination of information and experience to otherdissemination of information and experience to othermaintenance engineersmaintenance engineers
  43. 43. Communication and repairsCommunication and repairs• Need for a written communication policy, including:Need for a written communication policy, including:– Reporting of unusual equipment behaviourReporting of unusual equipment behaviour– Notification to the physicist and clearance by beforeNotification to the physicist and clearance by beforeresuming treatments (because of possible need forresuming treatments (because of possible need forcontrol checks after repairs)control checks after repairs)– Reporting of unusual patient reactionsReporting of unusual patient reactions
  44. 44. Patient identification and patient chartPatient identification and patient chart• Effective patient identification procedures and treatmentEffective patient identification procedures and treatmentcharts (consideration of photographs for identification …)charts (consideration of photographs for identification …)• Double check of chart data at the beginning of treatment,Double check of chart data at the beginning of treatment,before changes in the course of treatment (for example,before changes in the course of treatment (for example,a new field) and once a week at leasta new field) and once a week at least
  45. 45. Specific items for external beam therapySpecific items for external beam therapy• CalibrationCalibration– Provisions for initial beam calibration and follow-upProvisions for initial beam calibration and follow-upcalibrationscalibrations– Independent verification of the calibrationIndependent verification of the calibration– Following an accepted protocolFollowing an accepted protocol– Participation in dose quality auditsParticipation in dose quality audits• Treatment planningTreatment planning– Include TPS in the programme of acceptance testingInclude TPS in the programme of acceptance testingcommissioning and quality assurancecommissioning and quality assurance– Cross-checks and manual verificationCross-checks and manual verification• Adequate in-vivo dosimetry would prevent mostAdequate in-vivo dosimetry would prevent mostaccidental exposuresaccidental exposures
  46. 46. Specific items for brachytherapySpecific items for brachytherapy• Provisions for checking source activity and sourceProvisions for checking source activity and sourceidentification before useidentification before use• Dose calculation and treatment planningDose calculation and treatment planning– Provisions for dose calculation and cross-checksProvisions for dose calculation and cross-checks• Source positioning and source removalSource positioning and source removal– Provisions to verify source positionProvisions to verify source position– Provisions to ensure that sources do not remain in theProvisions to ensure that sources do not remain in thepatient (including monitoring patients and clothes)patient (including monitoring patients and clothes)
  47. 47. Summary………Summary………• Radiotherapy has unique features from the point of viewRadiotherapy has unique features from the point of viewof the potential for accidental exposureof the potential for accidental exposure• Consequences of accidental exposure can be veryConsequences of accidental exposure can be verysevere and affect many patientssevere and affect many patients• Careful clinical follow up may detect overdoses fromCareful clinical follow up may detect overdoses fromabout 10%about 10%• A quality assurance programme is the key element inA quality assurance programme is the key element inprevention of accidental exposureprevention of accidental exposure

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