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Biological Effects of Ionizing RadiationBiological Effects of Ionizing Radiation Deterministic effectsDeterministic effects
Radiation injury of Radiation injury of
Gastrointestinal tract Gastrointestinal tract LectureLecture
IAEA Post Graduate Educational Course Radiation Protection and Safe Use of Radiation Sources
IAEA Post Graduate Educational Course in Radiation Protection and Safety of Radiation Sources
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IntroductionIntroduction
Damage of gastrointestinal tract by Damage of gastrointestinal tract by ionizing radiation – one of the typical ionizing radiation – one of the typical consequence of whole body exposureconsequence of whole body exposure
Development of damage had different Development of damage had different stagesstages
Symptoms of gastrointestinal syndrome Symptoms of gastrointestinal syndrome could help for diagnosis and treatmentcould help for diagnosis and treatment
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ContentContent
Structure of gastrointestinal systemStructure of gastrointestinal system Gastrointestinal syndromeGastrointestinal syndrome Pathophysiology of gastrointestinal syndromePathophysiology of gastrointestinal syndrome Phases and symptoms of gastrointestinal Phases and symptoms of gastrointestinal
syndromesyndrome Differential organ response in gastrointestinal Differential organ response in gastrointestinal
syndromesyndrome Radiation-induced diarrhoeaRadiation-induced diarrhoea Diagnosis and treatment of gastrointestinal Diagnosis and treatment of gastrointestinal
syndromesyndrome
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Gastrointestinal syndromeGastrointestinal syndrome
Phases of GIT injury after exposure:Phases of GIT injury after exposure: ProdromalProdromal Manifest Manifest
SymptomsSymptoms NauseaNausea VomitingVomiting AnorexiaAnorexia DiarrhoeaDiarrhoea
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Pathophysiology of Pathophysiology of gastrointestinal syndromegastrointestinal syndrome
Depletion of the epithelian cells Depletion of the epithelian cells lining the lumen of the lining the lumen of the gastrointestinal tractgastrointestinal tract
Intestinal bacteria gain free access to Intestinal bacteria gain free access to the bodythe body
Hemorrhage through the denuded Hemorrhage through the denuded areasareas
Loss of absorptive capacityLoss of absorptive capacity
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Phases and symptoms of GISPhases and symptoms of GIS
PhasePhase SymptomsSymptoms Time of onsetTime of onset
ProdromalProdromal Nausea, vomiting, Nausea, vomiting, diarrhoeadiarrhoea
Immediate – hoursImmediate – hours
SubacuteSubacute Vomiting, Vomiting, diarrhoeadiarrhoea
Hours – daysHours – days
AcuteAcute Diarrhoea, Diarrhoea, toxaemia, toxaemia,
septicaemiasepticaemia
Days – weeksDays – weeks
ChronicChronic Fibrosis, bleeding, Fibrosis, bleeding, fistulasfistulas
Months - yearsMonths - years
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Differential organ responses in Differential organ responses in GISGIS
Parts of GIT could be exposed Parts of GIT could be exposed during radiotherapyduring radiotherapy
Segmental difference in Segmental difference in radiosensitivity of GIT existsradiosensitivity of GIT exists
Radiosensitivity order of different Radiosensitivity order of different parts of the GIT: parts of the GIT: duodenum, duodenum, jejunum, ileum, oesophagus, jejunum, ileum, oesophagus, stomach, colonstomach, colon,, and rectum and rectum
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OesophagusOesophagus
May be irradiated by radiotherapy of May be irradiated by radiotherapy of oesophagus itself or lungoesophagus itself or lung
Symptoms:Symptoms: Denudation of the mucosaDenudation of the mucosa Burning sensationsBurning sensations Difficulty in swallowingDifficulty in swallowing Changes in motilityChanges in motility Loss of mucosal barrierLoss of mucosal barrier Increased possibility of infectionIncreased possibility of infection
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StomachStomach
Symptoms of radiation injury:Symptoms of radiation injury: decreased gastric motility, decreased gastric motility, emptying and decreased fluid outputemptying and decreased fluid output nauseanausea dyspepsiadyspepsia gastritisgastritis
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Small intestineSmall intestine
Most sensitive part of the GITMost sensitive part of the GIT Has a Has a high proliferative activity high proliferative activity
which results in damage within a which results in damage within a short time after exposureshort time after exposure
Exposure in dose 0.01 Gy may Exposure in dose 0.01 Gy may increase the apoptotic yieldincrease the apoptotic yield
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Colon and rectumColon and rectum
Main symptom – diarrhoeaMain symptom – diarrhoea Diarrhoea may arise from Diarrhoea may arise from small small
intestinal dysfunction, colo-rectal intestinal dysfunction, colo-rectal dysfunction and/or bothdysfunction and/or both
Colon has strong compensatory Colon has strong compensatory function and adaptive capacityfunction and adaptive capacity
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Radiation-induced diarrhoea – Radiation-induced diarrhoea – multifactorial naturemultifactorial nature
Effects on intestinal fluid and electrolyte Effects on intestinal fluid and electrolyte transporttransport
Effects of exposure:Effects of exposure: increased basal chloride secretionincreased basal chloride secretion release of mediators from cells of the release of mediators from cells of the
epithelium, surrounding tissue or from nervesepithelium, surrounding tissue or from nerves
Later effects:Later effects: reduced stem cell activity and capacity to reduced stem cell activity and capacity to
replace the epitheliumreplace the epithelium
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Radiation-induced diarrhoeaRadiation-induced diarrhoea
Was investigated in experimentsWas investigated in experiments Observations:Observations:
Changes in motor activity, which can lead to:Changes in motor activity, which can lead to: Change in absorption of some nutrients Abdominal cramping Associated pain
Changes in motor activity are likely to be related Changes in motor activity are likely to be related with altered neuronal activitywith altered neuronal activity
Modifications in colon’s motor activity can Modifications in colon’s motor activity can contribute to contribute to altered transit, altered transit, mmalabsorption alabsorption and diarrhoeaand diarrhoea
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Radiation-induced diarrhoeaRadiation-induced diarrhoea
One of the reason - dysfunction of One of the reason - dysfunction of regularity mechanismsregularity mechanisms
Ionizing radiation influences Ionizing radiation influences the the synthesis, metabolism, release and synthesis, metabolism, release and actions of regulatory mediators actions of regulatory mediators ((hormones, neurotransmitters or hormones, neurotransmitters or paracrine agentsparacrine agents))
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Diagnosis of gastrointestinal Diagnosis of gastrointestinal damage - clinical observationdamage - clinical observation
Main aspect – clinical observationMain aspect – clinical observation Important observations:Important observations:
Description of the diarrhoea:Description of the diarrhoea: Time of onset, Duration, and Severity
Characteristics of diarrhoea may Characteristics of diarrhoea may indicate the prognosisindicate the prognosis
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Diagnosis of gastrointestinal Diagnosis of gastrointestinal damage - other diagnostic methodsdamage - other diagnostic methods Estimation of rEstimation of radiation-induced adiation-induced
gastrointestinal dysfunction by standard gastrointestinal dysfunction by standard functional testfunctional tests:s: intestinal permeability (sucrose/lactulose ratio for the intestinal permeability (sucrose/lactulose ratio for the
proximal intestine; lactulose/mannitol ratio for the distal proximal intestine; lactulose/mannitol ratio for the distal intestine), intestine),
intestinal transit time and bile acid or vitamin B12 intestinal transit time and bile acid or vitamin B12 absorptionabsorption
MMeasurement of some gastrointestinal easurement of some gastrointestinal regulatory peptides as site-specific markersregulatory peptides as site-specific markers
MMeasurement of certain easurement of certain inflammatory inflammatory mediators in stool samples, gut lavage or mediators in stool samples, gut lavage or biopsy materialbiopsy material
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Treatment of gastrointestinal Treatment of gastrointestinal damagedamage
Purpose - Purpose - correction of altered intestinal correction of altered intestinal physiological functionsphysiological functions
Treatment - Treatment - antiemetics, antispasmodics, antiemetics, antispasmodics, antibiotics as well as anti-inflammatory antibiotics as well as anti-inflammatory agents (mainly steroids) agents (mainly steroids)
Purpose - Purpose - to promote the restoration of to promote the restoration of the epithelium and/or the surrounding the epithelium and/or the surrounding tissuetissue
Treatment – use of growth factorsTreatment – use of growth factors
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SummarySummary
This lecture presented materials about This lecture presented materials about radiation injury of gastrointestinal tractradiation injury of gastrointestinal tract
The following topics were covered in the The following topics were covered in the lecture: lecture: structure of gastrointestinal system; structure of gastrointestinal system; gastrointestinal syndrome (pathophysiology, gastrointestinal syndrome (pathophysiology, phases and symptoms, differential organ phases and symptoms, differential organ response); radiation-induced diarrhoea; response); radiation-induced diarrhoea; diagnosis and treatment of gastrointestinal diagnosis and treatment of gastrointestinal syndrome.syndrome.
Comments are welcomedComments are welcomed
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Where to Get More InformationWhere to Get More Information
Gunter-Smith PJ. Effect of ionising Gunter-Smith PJ. Effect of ionising radiation on gastrointestinal physiology. radiation on gastrointestinal physiology. ConardConard RA,RA, Walker RI, eds. Military Walker RI, eds. Military Radiobiology, Orlando: Academic Press, Radiobiology, Orlando: Academic Press, 1987: 135-151.1987: 135-151.
Barber J, James RD, Radiation effects on Barber J, James RD, Radiation effects on the human gastrointestinal tract. Potten CS, the human gastrointestinal tract. Potten CS, Hendry JH, eds. Radiation and Gut. Hendry JH, eds. Radiation and Gut. Amsterdam: Elsevier, 1995; 231-52.Amsterdam: Elsevier, 1995; 231-52.