ORGAN AT RISK DURING PELVIC RADIATION AND IT'S COMPLICATION AND MANAGEMENT......

1. DR.HARSH GOYAL
PG JR-2
SRI AUROBINDO MEDICAL COLLEGE AND SCIENCE AND
REASERCH CENTERE, INDROE (M.P.)
RADIOTHERAPY DEPARTMENT

2.  These are normal tissues whose radiation
may significantly influence the treatment
planning or prescribed dose. It is divided into
three classes.
1. Class I-Radiation lesions are fatal or result in
severe morbidity.

3. 2. Class II-Radiation lesion result in mild to
moderate morbidity.
3. Class III-Radiation lesion are mild, transient
and reversible or result into no significant
morbidity.

4. Organ at risk during pelvic radiotherapy are:
1. Bladder
2. Rectum
3. Urethra & Ureter
4. Small bowel
5. Vagina
6. Bone and bone marrow
7. Gonads

6.  Radiation effects on the bladder have been
documented during treatment of various
pelvic malignancies including cervical
cancers, prostate cancers, and bladder
cancers.
 The urinary bladder and ureters are covered
by urothelium—mucosa made of transitional
epithelium of several cells.

7.  For whole-bladder irradiation, doses in excess
of 60 Gy, particularly with fraction sizes >2 Gy
or accelerated radiation regimen, result in a
significant risk of grade 3 or higher late
toxicity.
 Risks are lower when the whole bladder
receives 45 to 55 Gy followed by a boost to
>60 Gy to a portion of the bladder.

8.  Acute side effects of bladder irradiation are
common and include urinary frequency, urgency,
and dysuria.
 Late effects include hematuria, fistula,
obstruction, ulceration, contracted bladder,
vesicovaginal fistula, necrosis, spasm, reduced
flow, and incontinence.
 Median onset of late complications after
radiation is 13–20 months.

11.  Prior pelvic surgery can result in increased
risk of bladder toxicity as a direct result of
bladder or urethral trauma or by denervation
of the bladder, which can cause urinary
hesitancy or retention, resulting in overflow
incontinence.
 Patients receiving anticoagulants may be at
greater risk of hematuria.

12.  Cyclophosphamide, independently or with
radiation, can cause chronic hemorrhagic
cystitis, incontinence, contractions, and
vesicoureteral reflux.
 Radiation-sensitizing chemotherapy may
increase risk of acute and late bladder
toxicity.

13.  Recommended Dose–Volume Limits- for
whole bladderV80 < 15%,V75<25%,
V70<35%,V65<50%.
 For whole-bladder radiation, the reported
risks of grade 3 or higher toxicity in doses of
50 to 60 Gy range from < 5% to 40%.

14.  In early reactions-Symptomatic frequency and
urgency are best treated with anticholinergic agents.
These agents are thought to act primarily by
inhibiting involuntary detrusor muscle contractions.
 Oxybutynin chloride is an antispasmodic that relaxes
the bladder smooth muscle and may relieve the
symptoms of frequency and urgency.
 Detrol has a greater inhibitory effect on bladder
contraction and it has fewer side effects as compare
to oxybutynin (eg, dryness of mouth), usual adult dose
is 2 mg bd till symptomatic relief is obtained.

15.  Phenazopyridine (Pyridium) can be used to
provide symptomatic relief in dysuria. It is
a azo dye, it acts directly on urinary tract
mucosa to produce local analgesic effect.
 The usual adult dose of pyridium is 100 to
200 mg tds for 5 to 7 days.
 If dysuria associated with UTI, then proper
antibiotic should be added.

16.  Percutaneous posterior tibial nerve
stimulation (PTNS):PTNS is a minimally invasive
neuro modulation method designed to deliver
retrograde electrical stimulation to the sacral nerve
plexus through percutaneous electrical stimulation of
the posterior tibial nerve.
 By using a battery-powered,hand-held stimulator and
a 34-gauge needle electrode, the tibial nerve is
accessed and stimulated. Patients receive a 30-minute
weekly treatment for 12 weeks.

18. Botulinum toxin-
 Detrusor injections of botulinum toxin are approved
by the FDA for the treatment of adults with over
active bladder who do not adequately respond to
anticholinergic medication.
 Most of the effects of botulinum toxin are thought to
be the result of inhibition of the release of
acetylcholine from the presynaptic nerve terminal,
which prevents stimulation of the detrusor muscle.
 Recommended total dose is 100 Units injection across
20 sites into the detrusor muscles by cystoscope in
every 12 weeks.

19.  The primary treatment modality for hematuria is
bladder irrigation.Intravesical treatments with silver
nitrate, prostaglandins or formalin have also been
used.
 Other treatment involves the injection of a sclerosing
agent (1% ethoxysclerol) into the bleeding areas to
control the severe hematuria in patients with
hematuria that is not responding to simpler methods.
 More serious interventions can include embolization
of the hypogastric arteries or urinary diversion and
cystectomy.

20.  Contracted bladder-Treated by reconstruction
of bladder with a segment of small or large
bowel (by sigmoid colon).
 Cystectomy- This procedure is used as a last
resort for contracted bladder and involves
removing the bladder and surgically
constructing a replacement or an opening in the
body (stoma) to attach a bag on the skin to
collect urine.

21.  Enterovesical fistula managed by surgically.The
aim of operative management is to resect and
reanastomose the offending bowel segment and
to close the bladder.
 The treatment may involve single-stage or
multistage procedures.
 The single stage procedure involves resection
and primary anastomosis without a protective
colostomy.

23.  Urethral injury usually consists of stricture
formation and Incontinence.
 For patients undergoing radiation to the
prostate, most reports have documented
increased risk of stricture and Incontinence in
patients who have had previous transurethral
resections of the prostate (TURP).

24.  Therapeutic doses of radiation ranging from
60 to 70 Gy, patients with priorTURP
demonstrated stricture rates of 10-20%
compared to patients with out priorTURP
who had stricture rates ranging from 0% to
5%.

25.  Many factors can affect incontinence in addition
to damage to the urethral sphincter including
age,weight,comorbid medical conditions,
bladder irritability, and pelvic floor weakening.
 Urethral damage causes stenosis, necrosis, and
reflux from radiation.
 The most frequent cause of ureteral injury after
treatment for cancer is a progressive disease.

26.  Mild stenosis may be treated by placement of
a ureteral stent.
 Other procedures to divert the urinary stream
may be used including placement of ileal
conduits.
 Nephrectomy may be required with recurrent
urinary tract infections and a non-functional
kidney.

28.  Early injury to rectum at the cellular level is
characterized by mucosal cell loss, acute
inflammation, eosinophilic crypt abscesses, and
endothelial swelling in the arterioles which can be
seen following radiation to the rectum.
 A thickened and edematous lamina propria with
patchy fibroblastic proliferation with decreased
mitotic rate seen in the mucosa with
radiotherapy.

29.  According to quantec dose guidelines-
recommended Dose–Volume Limits are-
V50<50%,V60<35%,V65<25%,V70<20%.
 At 50 Gy doses (administered in 20 fractions over 1
month @ 2.5 Gy/#) in addition to mucosal cell
injury and crypt shortening, infiltration of
inflammatory cells occurs.
 The development of delayed tissue injury starts to
be apparent as early as at 6 months post
treatment and may gradually worsen.

30.  The pathogenesis of the delayed injury is a result
of the development of fibrosis in the stroma and
in the blood vessels, causing ischemia.
 This fibrosis can lead to relative ischemia, and
mucosal capillaries attempt to compensate for
this develop telangiectasia with friable vessels
that are prone to bleeding.
 More severe ischemia can lead to ulceration,
perforation fistula, or abscess formation.

31.  Acute symptoms of the rectum can be seen
early in the course of radiation therapy for
cancers in the pelvic region.
 Symptoms usually begin following 20Gy of
standard fractionation.
 Acute proctitis usually with in three months of
radiation.
 Early symptoms includes tenesmus, bleeding,
and diarrhea.

32.  Late reactions result in bleeding, ulcers,
strictures, and fistula formation.
 Patients typically present with painless rectal
bleeding.
 Other symptoms include evacuation difficulties,
frequent elimination, fecal incontinence, and
urgency which may also develop from
alterations in anorectal function.

33.  Grade 0- No symptoms and no intervention required.
 Grade 1 -Mild symptoms (mucus discharge or minimal
bleeding & rectal discomfort) and self-limiting , not
required analgesics, or other medications.
 Grade 2 –It is managed by conservatively, lifestyle not
affected- Intermittent rectal bleeding not required
regular use of pads, erythema seen in rectal lining on
proctoscopy, diarrhea requiring medications.

34.  Grade 3- Severe reactions occurs which alters patient
lifestyle or rectal ulceration present- Rectal bleeding
required regular use of pads and minor surgical
intervention, rectal pain requiring narcotics.
 Grade 4- Life threatening reactions occurs which
causes bowel obstruction, fistula formation may
occur. Bleeding required hospitalization, surgical
intervention required.
 Grade 5- Death directly related to radiation effects.

35.  At sigmoidoscopy, a spectrum of mucosal changes
can be seen including mucosal pallor or erythema,
prominent telangiectasia,friability, or fistula.
 The onset of radiation proctitis is typically seen in 12–
18 months following treatment.
 Patient-related factors that may increase the risk of
proctitis include hypertension, diabetes, and
cerebrovascular disease that can all affect the vascular
supply in the radiated field.

36.  Acute symptoms of urgency and tenesmus can be
treated with an antispasmodic such as Lomotil ( 5mg
tds).
 Steroid enemas (predinisolone enema) also useful to
decrease inflammation.
 Biopsy of mucosal changes should be discouraged if
they occur in an area that likely received a high dose
of radiation such as the anterior rectal wall. Biopsy
may cause persistent inflammation, decrease healing,
and precipitate fistula formation.

37.  SUCRALFATE- It mechanically protects the
gastrointestinal mucosa by forming a protective
coating on inner surface of the bowel and stimulate
healing by increasing angiogenesis. Administration of
sucralfate enema given as 2 gm/day bd.
 METRONIDAZOLE- It is a antiprotozoal and
immunomodulator drug which inhibits anaerobic
Organism growth in rectum.The usual adult dose is
400 mg tds.

38.  FORMALIN-Formalin is an aldehyde which induces
coagulative tissue necrosis on contact. Endorectal
formalin instillation has been used successfully in
several studies.
 ENDOSCOPICTHERAPY-The goal of endoscopic
therapy is to provide cessation of rectal bleeding, to
decrease the need for transfusion or hospitalization,
and thus improve the patient’s quality of life.These
techniques should be considered after medical
management fails, and the patient experiences
persistent symptoms.
 These techniques includes endscopic application of
clips, use of bending devices by endoscopy.

39.  Balloon therapy- Patients with radiation
proctitis can develop a lower gastrointestinal
stricture with resultant obstructive
symptoms.
 Mechanical dilation via an endoscopically
passed balloon is a simple and effective
treatment for patients with radiation-induced
rectal strictures.

40.  ARGON PLASMA COAGULATION-Argon
plasma coagulation (APC) is a non-contact
thermal method of coagulation and hemostasis.
 This modality utilizes a jet of sprayed argon gas,
which is ionized by a high voltage spark into
plasma.
 Once ionized, it produed coagulation and
hemostasis in bledding mucosa.

41.  PROCTECTOMY/PELVIC EXENTERATION-In
patients with persistently refractive radiation
proctitis, the most extreme intervention is complete
rectal excision with possible removal of adjacent
pelvic organs.
 This treatment can be considered the most definitive
treatment for radiation proctitis, in that it removes
the offending tissue and gives feacal diversion though
a permanent ostomy and this treatment should be
offered to patients who are refractory to all
treatment.

43.  Mucosa above the anal orifice is made of
stratified squamous epithelial cells which show a
rapid turnover and hence are very radiosensitive.
 This mucosa is involved in the pathology of the
early radiation injury.
 Sustained radiation injury to muscle, stromal,
and vascular cells are the cause of the delayed
anal radiation injury.

44.  Tolerance dose of the normal tissue is
considered to be above 65Gy.
 Acute grade 3 toxicity with 2-Gy fractions is
40%, while it is 75% with 2.5-Gy fractions.
 Acute effects include epithelial discomfort
which may be aggravated by radiation-
induced diarrhea.

45.  Epithelial effects follow a sequential
progression from erythema to desquamation.
Shallow erosions and ulcerations can develop
which can lead to tenesmus.
 Late effects which includes strictures of the
anus or ulceration, fibrosis required
intervention.

46.  Therapeutic interventions usually include
antidiarrheal medications such as loperamide or
codeine.
 Care of the skin includes cleansing ointments,
Application of gentian violet,lidocaine which can
help in manage symptoms.
 Biopsy of the anus following high dose radiation
can result in non-healing ulceration. Avoidance
of this procedure is preferred.

47.  If a non-healing ulceration develops,
conservative management is generally used
initially.This involves stool softeners, sitz baths,
and wound care.
 Some studies reports that use of hyperbaric
oxygen is beneficial in the management of non
healing ulcers.
 There are limited therapeutic interventions for
incontinence with the primary treatment being
colostomy.

49.  The small bowel may incidentally irradiated during
radiation therapy to the pelvis. It is particularly
evident in the treatment of prostate cancer and in
gynecological cancers.
 As a consequence of the radiation changes on the
bowel, it may develop serious complications.
 prospective trials demonstrated that approximately
30% of postoperative patients with endometrial
cancer who received radiation, experienced with
acute diarrhea which persisted in approximately 10%
of patients, up to 5 years after treatment.

50. FACTORS AFFECTING RISK-
 Use of concurrent chemotherapy increase acute toxicity
like 5 FU, docetaxel, etoposide and bevacizumab.
 Previous surgery causes the development of adhesions
that tend to fix the intestines, which may become involved
in the radiation field.
 Patients with hypertension, diabetes mellitus, and
generalized atherosclerosis are at an increased risk for
vascular occlusive disease.
 patients with underlying inflammatory bowel disease may
be at a higher risk for severe toxicity.

51.  Recommended Dose–Volume Limits for
small bowel isV45 <195 cc.
 TheTD5/5 andTD50/5 estimate for 1/3 small-
bowel irradiation is 50 Gy and 60 Gy
respectively.

54.  Radiation induced small-bowel mucositis can be
expressed as cramping and diarrhea and weight
loss from interference with nutrient absorption,
typically developing 1 to 2 weeks after the start
of Radiation.
 Chronic small-bowel injury from RT can include
persistent diarrhea, obstruction, ulceration,
perforation and bleeding, majority of symptoms
occur with in 3 years of post radiation.

55. Acute toxicity is managed by
 Diet- A low-residue diet and a diet low in fats and
lactose are helpful. In more severe cases, an elemental
diet may improve diarrhoea while maintaining
nutrition.
 Drugs-Antispasmodics, anticholinergics and opiates
can improve symptoms of pain and diarrhoea by
reducing motility. Oral antibiotics may improve
diarrhoea in patients with bacterial colonisation of the
small bowel.

56.  Total parenteral nutrition-Bowel rest and
total parenteral nutrition (TPN) may be used
for severe symptomatic disease and for
enterocutaneous fistulas, although
spontaneous closure is uncommon.
 Total parenteral nutrition is also valuable in
malnourished patient prior of surgery.

57. Surgical management-
 Indications for surgery include bowel
obstruction, perforation, abscess, intractable
bleeding or diarrhoea, and occasionally
malabsorption.

59.  The testis is one of the most radiosensitive
tissues in the body with a radiation dose as low
as 15 cGy causing a significant depression in the
sperm count.
 The testis may be directly in the radiation field
or receive scattered dose from a nearby field.
 Recommended Dose–Volume Limits of testis is
V3<50%.

60.  Azoospermia after low doses (<2 Gy) takes 60-70 days
due to damage to spermatogonia, after higher doses
(>4 Gy), azoospermia develops much faster due to
concurrent damage to spermatids.
 Low doses of radiation kill spermatogonia which are
differentiating into spermatocytes.
 Therefore, low doses of radiation deplete the stem
cells of these developing sperm which result in
decreased sperm production during the first 50–60
days after radiation.

61.  Complete recovery takes place with in 9–18 months
after less than 1 Gy, 30 months for 2–3 Gy, and 5 or
more years after 4–6 Gy.
 Direct testicular irradiation of 24 Gy results in ablation
of the germinal epithelium which is responsible for
sperm development and Leydig cell function which is
responsible for testosterone,which is seriously
affected in most men.

62. Symptoms of low testosterone includes:
 Loss of libido
 Erectile dysfunction
 Fatigue
 Decreased muscle mass
 Body and facial hair loss
 Difficulty in concentrating
 Depression
 Irritability
 Low sense of well-being

63.  When testes present directly in the irradiation
field, it cannot be protected.
 The dose from scattered irradiation from
nearby beams, can be reduced by moving the
gonad away from or by applying thick
shielding cups directly over the scrotum.

64. (Front view of gonadal shield)
The shield has aV cut for inserting the testis and to hold in position,wax
coating is done on the inner surface of the shields. It makes the inner
surface smooth and avoid back-scattered electron dose from the shield.

65.  Androgen replacement therapy to enable normal
pubertal development and future sexual function is
required for patients with deficient testosterone
production.
 Inj testesterone 200 mg (I.M.) in every 2 week should
be given till regression of symptoms occurs.
 Pre treatment sperm banking may be preferable in
patients who want continue their fertality.

67.  The lining of the vagina is made of stratified
squamous epithelium over a connective tissue
lamina propria and longitudinal muscle fibers
and elastic fibers.
 Radiosensitivity of the squamous epithelium is
significant and early vaginal injury is marked by
acute epithelial denudation with endothelial
injury that may lead to thrombosis,edema,and
smooth muscle necrosis.

68.  Delayed injury involves severe fibrosis that may
obliterate portions of the muscle and vasculature
potentially resulting in vaginal stenosis and
ulceration.
 Vaginal mucosa is reasonably tolerant to radiation.
 An irradiation tolerance level of the proximal vagina
was suggested by Hintz in 1980.None of the patients
treated to a maximum dose of 140 Gy developed
severe complications or necrosis of the upper vagina.

69.  The distal vagina (introitus) and posterior wall are
more sensitive to radiation.
 Hintz suggested doses to the distal vagina not to be
greater than 98 Gy.
 Serious complications include mucosal necrosis or
fistula formation.
 Less serious complications included vaginal stenosis
or shortening, formation of telangiectasia (which can
lead to bleeding) or thinning of the vaginal mucosa,
and dryness.

70.  If soft tissue necrosis is observed, symptomatic
management with antibiotics, debridement,
estrogen cream, and gentle irrigation may heal
the area.
 The strategy for prevention of vaginal stenosis
or shortening has been to encourage sexual
intercourse or use of vaginal dilators.
 Estrogen cream or systemic estrogen may also
aid in the rejuvenation of cells and increase the
elasticity of the vagina.

72.  Radiation to the ovaries can damage oocytes
and result in premature menopause because
of ovarian failure of estrogen production.
 Oocytes undergo meiosis and are relatively
radioresistant (single dose LD50 is 4 Gy)
however, proliferating granulosal cells are
very radiosensitive.

73.  Therefore, a total dose of 24Gy (fractionated
in 2-Gy single doses) leads to ablation of
ovaries due to the loss of granulosa cells.
 Immediate ovarian failure will be produced by
16.5 Gy in females of 20 years, while 14 Gy is
sufficient in 30-year-olds or in elderly group.

74.  Early radiation injury then comprises of
necrotic changes in proliferating granulosa
cells, while early changes include
microvascular thrombi and endothelial cell
swelling.
 Late radiation effects include atrophy and
fibrosis, with thick walled and hyaline
arterioles and venules.

75.  The effects on the ovary are dependent on the
age of the patient and total dose to the ovary.
Low doses of radiation (4–7 Gy in 1–4 fractions)
can result in permanent menopause in women
over 40 years of age.
 However, permanent sterility in young women
may not result until a total dose of 20 Gy .

76. Symptoms of ovarian irradiation includes-
 Amenorrhea
 Hot flashes
 Night sweats
 Vaginal dryness
 Irritability
 Difficulty in concentrating
 Loss of libido
 Infertility

77.  Harmonal therapy-Estrogen therapy can
help prevent osteoporosis and relieve hot
flashes and other symptoms of estrogen
deficiency. Estrogens can be administered
orally or transdermally.
 The usual adult dose for transdermal
estradiol is 100-150 mcg and oral estradiol 2
to 4 mg.

78.  Progestins should be administered cyclically,
10-14 days in each month, to prevent
endometrial hyperplasia.
 The recommended regimens include
medroxyprogesterone 10 mg daily for 10-12
days in each month.
 Preservation of fertility by egg storage (oocyte)
is a useful technique prior to treatment.

80.  Radiation can affect the microvasculature of the
mature bone.This injury causes decreased blood
supply to the periosteum which compromises
osteoblastic function and can result in an
insufficiency fracture (IF).
 Insufficiency fractures of bone occur as a result of
physiological stress on bones with deficient elastic
resistance.
 Irradiation can damage osteoblasts, osteocytes, and
osteoclasts and leave an acellular matrix that appears
radiographically normal.

81.  Such radiation-induced atrophy reduces the
number of functional and structural components
of a tissue.
 These two processes can result in clinically and
radiographically significant bone atrophy.
 In addition, previously irradiated atrophic bone
is at risk for fracture, second malignancy, or
infection, leading to true necrosis of bone.

82.  Resulting injuries include atraumatic femoral
neck fracture, and osteonecrosis of the
femoral head or of the acetabulum.
 Abe et al. reported that asymptomatic
Insufficiency Fracture was found in 34% of
postmenopausal patients treated with
adjuvant postoperative radiation for
endometrial cancer.

83.  The incidence of symptomatic pelvic fractures in
several series of women treated for gynecologic
malignancies ranges from 1.7% to 6% following
doses of 46–50 Gy to the whole pelvis.
 Pain in the pelvic area is the initial complaint of
patients.The average time to onset of
symptoms is usually 11–12 months after
radiation therapy.

84.  CT scans can reveal radiological findings of IF,
although MRI is currently the most sensitive
modality for detecting these lesions.
 Most IF is multiple and the most common
location for them is in the sacrum and pubic
bones.

85.  The tolerance doses for the femoral head
have been estimated to be 52Gy for the
TD 5/5 and 65 Gy for theTD 50/5.
 No fracture occurred below doses of 42Gy.
 Treatment for bone fractures following
radiation has included calcium supplements,
and pain management, and surgically.

87.  The bone marrow is one of the most
radiosensitive organs in the pelvis.
 Approximately 40% of the total body bone
marrow reserve lies with in the pelvic bones.
 Hematologic toxicity can be seen acutely
during radiation and exposure to radiation
can result in long-term myelotoxicity.

88.  The radiation dose, dose rate, and volume all
affect the acute response of the bone marrow
to radiation therapy.
 With exposure to large bone marrow
volumes, neutropenia occurs in 2–3 weeks
followed by thrombocytopenia and then
anemia in 2–3 months.

89.  The management of patients with bone marrow
toxicity can be divided into supportive and
preventive.
 Growth factor administration is now a common
supportive measure in patients with white cell
deficiencies.
 BloodTransfusion is typically reserved for
patients with hemoglobin levels below 8 g/dl.

91.  The aim of modern radiotherapy is to ensure a high
level of accuracy in tumour targeting, to reduce normal
tissue exposure, and to minimise side effects.
 Normal organ reactions depends on various factors,
such as the type of radiotherapy, the size and site of the
treatment field, and the dose delivered.
 A variety of different strategies have been proposed
which includes improved radiotherapy delivery
techniques, other aspects like timing of radiation
delivery, patient positioning , pharmacological
interventions, and non-pharmacological interventions
who reduces radiation impact on normal tissue and to
prevent side effects.

92. Radiotherapy delivery techniques-
 3D conformal radiotherapy (3D-CRT) is intended to
improve tumour targeting and reduce the amount of
radiation to the surrounding tissues by aiming shaped
radiotherapy beams from several different directions
at the tumour.
 It uses pre-treatment imaging with computerised
tomography (CT) to plan the radiotherapy treatment
area in three dimensions (width,height and depth)
matching the radiation beams to the 3D shape of the
tumour.

93. Intensity-modulated radiotherapy (IMRT)-
uses computerised methods to orientate
multiple small beams of different intensities to
the volume of tumour tissue that needs to be
treated.
 IMRT potentially conform more precisely to the
tumour than 3D-CRT as it allows the dose of
radiation to be adjusted for different parts of the
treatment area and can reduce exposure to
organ at risk.

94. Image-guided radiotherapy (IGRT)
 IGRT includes imaging (e.g. CBCT) performed at pre-
treatment and treatment delivery that improves or
verifies the target accuracy of radiotherapy.
 It causes reduction in CTV to PTV margins thus
reducing the volume of normal tissue receiving high
radiation doses.
 MRI-based planning with its greater soft tissue
definition can reduce the clinical target volume (CTV)
by approximately 20% compared to CT-based
planning and reduces radiation exposures to OARs.

95.  Stereotactic body radiotherapy (SBRT)
SBRT involves the use of a high and precise
radiation dose in a small number of fractions.
 Radiotherapy beams are orientated from many
different positions around the body to minimise
the radiation dose to the surrounding tissues.
 SBRT is currently mainly used for small tumours
of the brain, prostate, liver, lung and spinal cord.

96. Patient positioning-
 The position of a patient during radiotherapy delivery
might influence the dose of radiation delivered to
normal pelvic structures and subsequent GI injury.
 A systematic review of prospective and retrospective
studies of patient positioning and the use of belly
boards, it suggests that delivering radiotherapy to
patients positioned in the prone position, and using
positioning devices such as belly boards, displaces the
small bowel away from the treatment field and can
reduce the volume of small bowel radiation.

97.  Timing of delivery (Physiological clocks)- According
to Buchi day-night cycle is the core clock that
influences response to anti-cancer treatments and the
development of treatment side effects.
 It regulate the timing of physiological processes
through gene expression exist in every organ and cell
of the human body.
 Evidence from animal and human laboratory studies
suggests that gastrointestinal cellular and mucosal
proliferation being greatest in the morning and lowest
in the evening.

98.  As proliferating cells are most radiosensitive, it is
plausible that radiotherapy delivered in the morning
may be more likely to cause damage to
gastrointestinal mucosal cells than radiotherapy
delivered in the evening.
 Findings from a clinical study of women receiving
radiotherapy for cervical cancer, which found that
severe diarrhoea occurred less frequently with
evening radiotherapy than morning radiotherapy,
appear to support this theory (Shukla et al 2010).

99.  Fractionation-Certain cancers such as prostate
cancer have been shown to be more sensitive to
fraction size.
 Therefore, increasing the fraction size
(hypofractionation) per treatment, which allows
the total dose to be delivered in fewer
treatments, might improve the treatment
outcome or therapeutic ratio but associated with
late gastrointestinal and genitourinary toxicity.

100.  Other interventions-Various surgical
techniques, such as the surgical placement of
absorbable mesh slings to exclude the small
bowel from the field of radiation, have been
proposed to reduce the gastrointestinal
effects of pelvic radiotherapy.
 Using daily endorectal balloons filled with air
or water or gel might be beneficial for men
undergoing prostate radiotherapy.

101.  Amifostine is thought to mediate a protective effect
with in normal cells by free-radical scavenging, DNA
protection and repair acceleration.The usual adult
dose of amiofostine is 500 mg in 50 ml normal saline
over 6 minute before 30 minute of radiotherapy.
 Antioxidants, such as vitamins C, D, and E, helps to
reduce radiotherapy-induced injury by reducing
antioxidant stress with in radiating tissue and
facilitating tissue repair.
 Glutamine, a non-essential amino acid and other
agents with antioxidant properties could also
potentially to be protective.

102.  Probiotics-Probiotic preparations contain live and defined
micro-organisms , when administered in sufficiently large
amounts, it causes increased secretion of protective
mucins and stimulate the immune response.
 Nutrition- Malnutrition can occur as a consequence of
radiotherapy-induced impaired gastrointestinal
absorption and digestive functioning, and can cause
radiation associated reactions.
 Dietary modification of fat, lactose, or fibre intake, or
combinations of these dietary modifications probably
reduces diarrhoea and plays a protective role in
radiotherapy.