This document discusses radiation oncology practice and accidents. It provides background on radiation therapy, its use and growth in the US and India. It then describes 8 case histories of radiation accidents, including overdoses from incorrect decay curves, unverified changes to treatment planning systems, and miscalibrated equipment. These accidents affected thousands of patients and caused many deaths. The document emphasizes the importance of quality assurance measures, independent verification of treatments, and following written procedures to prevent such accidents.

1. ACCIDENTS IN RADIATIONACCIDENTS IN RADIATION
ONCOLOGY PRACTICEONCOLOGY PRACTICE
DR. ASHUTOSH MUKHERJIDR. ASHUTOSH MUKHERJI
ASST. PROFESSOR OF RADIOTHERAPY,ASST. PROFESSOR OF RADIOTHERAPY,
REGIONAL CANCER CENTRE, JIPMERREGIONAL CANCER CENTRE, JIPMER

2. RADIATIONRADIATION ONCOLOGYONCOLOGY
• Radiation therapy is that branch ofRadiation therapy is that branch of
medicine thatmedicine that deals with use ofdeals with use of
radiation in the treatment ofradiation in the treatment of
malignant diseasesmalignant diseases ..
• Goal of radiation therapy is toGoal of radiation therapy is to killkill
cancerous cells, while sparingcancerous cells, while sparing
normal tissue.normal tissue.
• Radiation therapy can be eitherRadiation therapy can be either
curative, or palliative.curative, or palliative.
• In contrast to diagnosticIn contrast to diagnostic
procedures, therapeutic doses ofprocedures, therapeutic doses of
radiation are high; for example:radiation are high; for example:
5000 cGy in post operative cases5000 cGy in post operative cases
vs 10 cGy (CAT scan).vs 10 cGy (CAT scan).

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 of
cancer 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 lives
of 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 a
1.1% decrease in annual cancer death rates from 1993 through1.1% decrease in annual cancer death rates from 1993 through
2002.2002.
• 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. RADIATION ONCOLOGY IN THE USRADIATION ONCOLOGY IN THE US
Radiotherapy Trends: 1975-1990
0
500
1000
1500
2000
1970 1975 1980 1985 1990 1995
Year
Number
Facilities
Accelerators
Cobalt

5. RADIATION ONCOLOGY IN INDIARADIATION ONCOLOGY IN INDIA
• In India, it is estimated that over 1 million cancer cases are detected every
year and a majority of them require radiotherapy at one time or other during
their course of the treatment.
• In India as per IAEA figures, there are 218 radiotherapy centres with 354
teletherapy 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 which
25 centres have facilities for treatment of cancer of thyroid

6. Break-up of Radiation Therapy Facilities in
India:
(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. Year-wise distribution of growth of radiation
therapy facilities in India

8. CASE HISTORIES OF RADIATIONCASE HISTORIES OF RADIATION
ACCIDENTSACCIDENTS

9. Case 1:Case 1: Use of an incorrect decay curve forUse of an incorrect decay curve for
6060
Co (USA, 1974-76)Co (USA, 1974-76)
Initial calibration of aInitial calibration of a 6060
Co beam was correct, but ..Co beam was correct, but ..
• A decay curve forA decay curve for 6060
Co was drawn: by mistake, the slope wasCo was drawn: by mistake, the slope was
steeper than the real decay and the curve underestimated thesteeper than the real decay and the curve underestimated the
dose ratedose rate
• Treatment times based on it were longer than appropriate, thusTreatment times based on it were longer than appropriate, thus
leading to overdoses, which increased with time reaching up toleading to overdoses, which increased with time reaching up to
50% 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 of
426 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 severe
complicationscomplications

10. Case 2: Incomplete understanding & testingCase 2: Incomplete understanding & testing
of 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 manual
distance correction, without realising that the TPS algorithm alreadydistance correction, without realising that the TPS algorithm already
accounted 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 when
new TPS was usednew TPS was used
• Problem remained undiscovered during eight years and affected 1,045Problem remained undiscovered during eight years and affected 1,045
patients andpatients and 492 patients developed local recurrence492 patients developed local recurrence
probably due to the underexposureprobably due to the underexposure !!!!!!

11. Case 3: Untested change of procedureCase 3: Untested change of procedure
for 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 standard
procedure for block data entry: several blocks were entered in oneprocedure for block data entry: several blocks were entered in one
stepstep
• Instructions for users had some ambiguity with respect to shieldingInstructions for users had some ambiguity with respect to shielding
block data entryblock data entry
• TPS computer calculated treatment time, which was double theTPS computer calculated treatment time, which was double the
normal 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, a
change 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 manual
calculationscalculations
• TheThe error affected 28 patientserror affected 28 patients and one year after the eventand one year after the event,, andand
at least five had died from the overexposureat least five had died from the overexposure !!!!

12. Case 3:Case 3:
Colonoscopy of a patientColonoscopy of a patient
treated with overdosestreated with overdoses
of 100% with:of 100% with:
• Necrotic tissueNecrotic tissue
• TelangiectasiaTelangiectasia

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 enter
treatment 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 and
three patients died from overexposure!!three patients died from overexposure!!

14. Case 5: Reuse of outdated computer file forCase 5: Reuse of outdated computer file for
6060
Co 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 was
intended 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 and
took the file corresponding to the priortook the file corresponding to the prior 6060
Co 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. 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 software
firmfirm
• 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 energy
selectedselected
• 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 energy
selected, and which was attributed to a faulty indicator, instead ofselected, and which was attributed to a faulty indicator, instead of
investigating 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 massive
overdosesoverdoses and by distorted dose distribution due to wrong electronand by distorted dose distribution due to wrong electron
energy of whom at leastenergy of whom at least 15 patients died15 patients died from the accidentalfrom the accidental
overexposure and two more died with overexposure as majoroverexposure and two more died with overexposure as major
contributorcontributor

16. Case 7: Malfunction of HDR brachytherapyCase 7: Malfunction of HDR brachytherapy
equipment (USA, 1992)equipment (USA, 1992)
• HDR brachytherapy source detached from the driving mechanismHDR brachytherapy source detached from the driving mechanism
while 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 retracted
to the shielded position, an external radiation monitor was indicatingto the shielded position, an external radiation monitor was indicating
that there was radiationthat there was radiation
• Staff failed to investigate the discrepancy with available portableStaff failed to investigate the discrepancy with available portable
monitormonitor
• The source remained in the patient for several days and the patientThe source remained in the patient for several days and the patient
died from overexposuredied from overexposure

17. Case 8: Beam miscalibration ofCase 8: Beam miscalibration of 6060
CoCo
(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, leading
to 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 dose
rate 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 least
17 patients had died17 patients had died from the overexposurefrom the overexposure
Thus 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 source
with higher activitywith higher activity

18. Child affected by overdoses to brain and spinal cord lost his ability to
speak and walk

19. Further recent instances in the US (A study by theFurther recent instances in the US (A study by the
New York Times dated 24New York Times dated 24thth
January 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 between
2000-2008, 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 faulty
ultrasound 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 on
19 of 45 treatments19 of 45 treatments. After the ultrasound was repaired, quality checks. After the ultrasound was repaired, quality checks
were performed by the vendor, and not the consulting physics group thatwere performed by the vendor, and not the consulting physics group that
was servicing the facility. The therapist warned the oncologist that thewas servicing the facility. The therapist warned the oncologist that the
treatment position appeared incorrect, but nothing was done about it.treatment position appeared incorrect, but nothing was done about it.

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 on
alternate days — one to the upper lung and the other to thealternate days — one to the upper lung and the other to the
mediastinum — 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 the
prescribed 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 attend
whenever a complex treatment plan is being delivered. Thewhenever a complex treatment plan is being delivered. The
therapists 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. 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 doctor
implanted 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. 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 because
of confusion over the method of measuring the strength ofof confusion over the method of measuring the strength of
radioactive seeds.radioactive seeds.
• The operator failed to enter the correct information into theThe operator failed to enter the correct information into the
treatment planning software, causing an overdose to her rectum andtreatment planning software, causing an overdose to her rectum and
vagina.vagina.
• The patient faced anThe patient faced an increased risk of radiation cystitis, rectalincreased risk of radiation cystitis, rectal
proctitisproctitis, and the formation of a fistula between the rectum and the, and the formation of a fistula between the rectum and the
vagina. Neither the physicist nor the radiation oncologist hadvagina. Neither the physicist nor the radiation oncologist had
prepared a treatment plan using iridium-192 — an isotope — in sixprepared a treatment plan using iridium-192 — an isotope — in six
years.years.

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 received
additional 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 a
therapist closed the patient’s electronic chart and pulled up the charttherapist closed the patient’s electronic chart and pulled up the chart
for Patient B. A second therapist arrived, saw the breast cancerfor Patient B. A second therapist arrived, saw the breast cancer
treatment had not been administered, and mistakenly administeredtreatment had not been administered, and mistakenly administered
it to the first patient.it to the first patient.

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 irradiated
incorrectly 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 wrong
direction.direction.
• Hospital policy required that a second therapist review the dataHospital policy required that a second therapist review the data
before treatment, but that was not done!!before treatment, but that was not done!!

26. A Breast Cancer Patient who received massive overdose toA Breast Cancer Patient who received massive overdose to
the chest wall resulting in sloughing off of the skin!!the chest wall resulting in sloughing off of the skin!!

27. 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 800
rads to the hand while pushing the source into place. The employeerads to the hand while pushing the source into place. The employee
noticed an immediate burning sensation but no other symptoms untilnoticed an immediate burning sensation but no other symptoms until
12 days later, when burning pain and itching developed. A blistering12 days later, when burning pain and itching developed. A blistering
burn developed while the employee was hospitalized.burn developed while the employee was hospitalized.
• Consequences:Consequences: 1 injury. 1 injury.

28. 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 was
exposed to the x-ray beam. After returning from a lunch break, heexposed to the x-ray beam. After returning from a lunch break, he
operated the unit for 15 minutes before realizing that one shutteroperated the unit for 15 minutes before realizing that one shutter
was open, exposing his right forearm to the beam. A woundwas open, exposing his right forearm to the beam. A wound
developed 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 to
the skin or more.the skin or more.
• Consequences:Consequences: 1 injury. 1 injury.

29. 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 Delhi
caused 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 research
irradiator unused since 1985 which was auctioned on 26 Februaryirradiator unused since 1985 which was auctioned on 26 February
2010 to a scrap metal dealer. By late March the shop owner2010 to a scrap metal dealer. By late March the shop owner
developed diarrhea followed by skin legions; and on 4 April wasdeveloped diarrhea followed by skin legions; and on 4 April was
hospitalized with radiation sickness. Authorities found the source onhospitalized with radiation sickness. Authorities found the source on
5 April. By 14 April a5 April. By 14 April a total of 7 people had been hospitalized withtotal of 7 people had been hospitalized with
radiation injuriesradiation injuries. One person died on 26 April from multiple organ. One person died on 26 April from multiple organ
failure. 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 individuals
were 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 nearby
shop, and one from the dealer's wallet. India's Atomic Energyshop, and one from the dealer's wallet. India's Atomic Energy
Regulatory Board announced on 28 April having traced the origin ofRegulatory Board announced on 28 April having traced the origin of
the 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 that
all material from the Gammacell unit was accounted for. Furtherall material from the Gammacell unit was accounted for. Further
cleanup of the scrap metal site in Mayapuri was conducted 15-16cleanup of the scrap metal site in Mayapuri was conducted 15-16
May.May.
• Consequences:Consequences: 1 fatality, 7 injuries 1 fatality, 7 injuries

30. CLINICAL CONSEQUENCESCLINICAL CONSEQUENCES

31. Side effects and complications inSide effects and complications in
radiotherapyradiotherapy
• 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

32. 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 relatively
long time and, therefore, may involve a large number of patientslong time and, therefore, may involve a large number of patients
Impact 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 to
necrosis)necrosis)

33. 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 dose
rate (except if the latter is very high)rate (except if the latter is very high)

34. Late complicationsLate complications
• Mainly observed in tissues withMainly observed in tissues with
slowly proliferating cellsslowly proliferating cells
(arteriolar narrowing which(arteriolar narrowing which
occurs with a time delay)occurs with a time delay)
• Can also become manifest inCan also become manifest in
rapidly proliferating cells (inrapidly proliferating cells (in
addition to and after acuteaddition to and after acute
effects)effects)
• Manifest more than six monthsManifest more than six months
after irradiation and even muchafter irradiation and even much
laterlater
• Usually irreversible and oftenUsually irreversible and often
slowly progressiveslowly progressive
• Eg:- Picture showing case ofEg:- Picture showing case of
eextensive fibrosis of the left groinxtensive fibrosis of the left groin
with limitation of hip motion as awith limitation of hip motion as a
result of accidental overexposureresult of accidental overexposure

35. Impact of overexposure on lateImpact of overexposure on late
complicationscomplications
• 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 may
amplify 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 of
small volume irradiated above threshold may cause majorsmall volume irradiated above threshold may cause major
incapacity, 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 related
to the tissue volume irradiated above thresholdto the tissue volume irradiated above threshold

36. Clinical detection of accidental medicalClinical detection of accidental medical
exposureexposure
• Careful clinical follow-up may lead to detect accidental overdoseCareful clinical follow-up may lead to detect accidental overdose
through 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 abnormal
early effectsearly effects
• In the case of unusual reactions in a single patient, other patientsIn the case of unusual reactions in a single patient, other patients
treated in the same period may need to be recalledtreated in the same period may need to be recalled

37. Recommendations forRecommendations for
PreventionPrevention

38. 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

39. Quality Assurance Programme for RadiationQuality Assurance Programme for Radiation
Therapy (QART)Therapy (QART)
• Quality assurance programmes have evolved from equipmentQuality assurance programmes have evolved from equipment
verifications to include the entire process, from the prescription toverifications to include the entire process, from the prescription to
delivery 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 written
procedures and checks (QART); either because a QART did notprocedures and checks (QART); either because a QART did not
exist or it was not fully implemented (checks omitted)exist or it was not fully implemented (checks omitted)

40. OrganizationOrganization
• Comprehensive QAComprehensive QA
Is crucial in prevention and involve clinical, physical and safetyIs crucial in prevention and involve clinical, physical and safety
components.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

41. 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, technologists
and 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 for
preventionprevention
– additional training when new equipment and techniques areadditional training when new equipment and techniques are
being introducedbeing introduced

42. 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 equipment
specifications, 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 future
treatments into computertreatments into computer
• Systematic acceptance and commissioning, including a cross checkSystematic acceptance and commissioning, including a cross check
and independent verification, form a major part of accidentand independent verification, form a major part of accident
preventionprevention

43. Follow-up on equipment faultsFollow-up on equipment faults
• Experience has shown that some equipment faults areExperience has shown that some equipment faults are
difficult 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 fully
understood 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 other
maintenance engineersmaintenance engineers

44. 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 before
resuming treatments (because of possible need forresuming treatments (because of possible need for
control checks after repairs)control checks after repairs)
– Reporting of unusual patient reactionsReporting of unusual patient reactions

45. Patient identification and patient chartPatient identification and patient chart
• Effective patient identification procedures and treatmentEffective patient identification procedures and treatment
charts (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

46. 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-up
calibrationscalibrations
– 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 testing
commissioning 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 most
accidental exposuresaccidental exposures

47. Specific items for brachytherapySpecific items for brachytherapy
• Provisions for checking source activity and sourceProvisions for checking source activity and source
identification 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 the
patient (including monitoring patients and clothes)patient (including monitoring patients and clothes)

49. Summary………Summary………
• Radiotherapy has unique features from the point of viewRadiotherapy has unique features from the point of view
of the potential for accidental exposureof the potential for accidental exposure
• Consequences of accidental exposure can be veryConsequences of accidental exposure can be very
severe and affect many patientssevere and affect many patients
• Careful clinical follow up may detect overdoses fromCareful clinical follow up may detect overdoses from
about 10%about 10%
• A quality assurance programme is the key element inA quality assurance programme is the key element in
prevention of accidental exposureprevention of accidental exposure