This document discusses radiology accidents and crises. It summarizes three major radiation accidents that occurred in Panama in 2001, Costa Rica in 1996, and the United States in 1992. The Panama accident resulted in 8 deaths due to overexposure of patients to radiation during treatment planning. The Costa Rica accident led to severe radiation complications in patients due to miscalibration of equipment and poor quality control. The US accident involved a source breaking off during treatment, exposing the patient and others to lethal radiation doses. The document stresses the importance of following written quality assurance procedures and performing manual checks to prevent such accidents.

1. Radiology accidents and crisis
21/11/2012
Dr Belal El Hawwari
Consultant Radiation Clinical Oncologist

2. The Hashemite Kingdom of Jordan

3. • Population
• 6,508,271 (July 2011 est.)
• Age structure
• 0-14 years:
• 35.3% (male 1,180,595/female 1,114,533)
15-64 years:
•
59.9% (male 1,977,075/female 1,921,504)
65 years and over
• : 4.8% (male 153,918/female 160,646) (2011 est.)

4. Trend of cancer in Jordan, 1980-2010

5. Ten most common cancers among
Jordanian Males, 2010
Rank
1
Cancer
No
%
Colorectal
332
14.2
Lung
311
13.3
Prostate
218
9.4
U.Bladder
186
8
5
Leukemia
127
5.5
6
Non- Hodgkin's Lymphoma
120
5.2
Brain & CNS
Stomach
106
4.5
90
3.9
Larynx
74
3.2
Hodgkin's Disease
65
2,8
2
3
4
7
8
9
10

6. Ten most common cancers among Jordanian
Females , 2010
Rank
Cancer
No
%
1
Breast
941
37.4
2
Colorectal
226
9.0
3
136
5.4
4
Thyroid
Non-Hodgkin
lymphoma
130
5.2
5
Uterus
113
4.5
6
Leukemia
91
3.6
7
Ovary
84
3.3
8
Lung
68
2.7
9
Hodgkin disease
67
2.7
10
Stomach
62
2.5

7. Top ten cancers among Jordanian
both sexes, 2010

9. Annual incidence and mortality of the most common cancers
2
5
Stewart, B. World Cancer Report. IARC Press 2003. 2003 International Agency for Research on Cancer.

10. The most prevalent cancers worldwide in 2000, expressed as
thousands of persons dx with ca within the previous 5 yrs
6
4
Stewart, B. World Cancer Report. IARC Press 2003. 2003 International Agency for Research on Cancer.

11. Age-Standardized Incidence Rate per (100,000 )population
for Male cancers ( all sites) , Jordan compared with other
countries .
Egypt-Ghariah
Bahrain
Qatar
Kuwait
Tunisia
Lebanon
Jordan
Malysia
Poland
Norway
Canada
New zealand
UK,Scotland
USA ( White

12. Age-Standardized Incidence Rate per ( 100,000 )population
for Female cancers ( all sites) , Jordan compared with other
countries.
Egypt-Ghariah
Bahrain
Qatar
Kuwait
Tunisia
Lebanon
Jordan
Malysia
Poland
Norway
Canada
New zealand
UK,Scotland
USA ( White

13. Cell Kill by Radiation
-How does radiation kill cells?
-Radiation-induced DNA damage
IDS 502

14. What is radiation?
• Radiation is electromagnetic waves, just like light.
Radiation is made of photons (packets of energy)
each type of radiation has its own energy (which is
closely related to frequency).
• X-rays and -rays are part of the radiation spectrum
that includes visible light. They posses high
frequency.
Light photon
X-ray photon
Gamma photon

15. X-ray Production
• Electrons emit ‘characteristic’ x-ray when they
go from a high atomic energy level to a lower
energy level.
E1
electron
E2
Nucleus
X-ray
E = E1 – E2

16. Continue...
• -rays are emitted
• X-rays can also be
generated by
from the nucleus of a
suddenly stopping
radioactive element.
fast electrons with a
• When protons
target, bremsstahlung
descend from a high
x-rays.
energy level to a
lower energy level
(inside the nucleus)
Diagnostic X-ray
they emit -rays.
machines and
therapeutic radiology
machines.

17. Before discussing the damage
done to cells from radiation
let’s look at how radiation
interacts with material

18. Photoelectric effect
-
+
Result: An energetic electron and a positive ion.

19. Compton Scattering
E
E
ee-
Result: An energetic electron, a positive ion,
and a lower energy photon.

20. Pair Production
?
Nucleus
e-
e+
Result: An energetic electron and a positron

21. • Any of the
above
interactions may
happen directly
with the DNA
molecule
or, most
probably, with
water leading to
the creation of
free radicals.

22. Free Radicals???
They are molecules or atoms carrying an
unpaired e- in their outer orbit. They posses
high degree of chemical reactivity.
• 2/3 of x-ray damage to
mammalian cells is due to
the hydroxy radical (the free
radical produced after
radiation interacts with water).
H 2O
H 2O
e
H 2O
H 2O
H 3O
H2O+: An ion radical
OH : A free radical.
OH

23. Radiation
Fast electrons
Ion radicals
Free radicals
Chemical changes:Broken bonds
Biological effects

24. Radiation-Induced DNA
Damage

25. Non-lethal DNA damage
Single-base
damage
Single-strand
damage
"Of no biological consequence"
NO biological cons.
Carcinogenesis induction
-Translocation
-Deletion

26. Translocation...
A
B
A
B
Interchange of genetic
material between two nearby
chromosomes.
Associated with several
human malignancies, e.g.
A
B
B
A
lymphomas and
leukemias.
Graphs from this slide onward are taken from the book Radiobiology for the
Radiologist, by Eric Hall.

27. Deletion...
Break occurs in the same arm
in an interphase
chromosome. Damage repair
may lead to deletion of parts
of the chromosome.
Carcinogenesis may result if
the deleted part contains a
suppressor gene.
More than 20 solid tumors:
Breast and prostatic adenocarcinoma, lung small cell
carcinoma, ...

28. Lethal DNA damage
Dicentric
Ring
Anaphase bridge
Pre-replication DNA
Pre-replication DNA
Post-replication DNA

29. Dicentric...

30. Ring...

31. Anaphase bridge...
Normal
anaphase

32. Radiation-induced apoptosis
• Radiation increases death by apoptosis.
• If a tumor responds rapidly to a relatively
low dose of radiation, it means that
apoptosis is involved.
• 50% to 60% of a lymphoma die by
apoptosis in the first 3 hours of irradiation.
• Radiation induced apoptosis is p53dependent.

33. Other Radiation-induced damages
• Changes in morphology
“Giant cells”.
Giant cells are ‘dead-cells’ in the waiting.
• Division inhibition
A cancer cell is “as
good as dead” if it doesn’t reproduce.

34. We started with how does radiation kill cells?
BUT more questions arise.
? Specialized cells are less sensitive to radiation, it takes
more radiation dose to kill them. Why?
? Radiation is delivered in small fractions. Everyday a
small dose is given until the entire dose has been
delivered. What are the biological considerations for
fractionations?
? The normal cells surrounding the tumor gets
irradiated as well. How does these cells repair the
damage incurred?
Makes good future talks…

35. Linear accelerator - electron and Xray beams
Rush University Medical Center, Chicago, IL
Courtesy Of Dr. Shada Ramahi, KHCC

36.  Simulator
Rush University Medical Center, Chicago, IL
Courtesy Of Dr. Shada Ramahi, KHCC

37. Co60 machine - ray beam

38.  Three dimensional conformal
radiotherapy - ADAC’s Pinnacle planning system

39.  Three dimensional conformal
radiotherapy - ADAC’s Pinnacle planning system
3D rendering, with a transverse
cut-plane.
Room’s eye view (REV)

40.  Clinical ...
5. Interstitial and intracavitary Implants ->
Brachytherapy procedures
Brachytherapy: Treatment of cancer through implanting
radioactive elements (I125,Ir192, Cs226) inside the body or in a
cavity inside the body in close proximity to the tumor.
Prostate Implant

41. Brachytherapy implants
Recurrent Glioma
Base of tongue
Head and neck

42. Radiation Accidents:
The causes and the prevention

43. Panama, June 2001
IAEA report:
Panama National Institute of Oncology
1. Misuse of the treatment planning system in entering blocks
2. Computer printout appeared normal
3. No manual verification was performed
Result?
28 patients overexposed to radiation, 20%-100% overdose.
8 patients died. 5 deaths related directly to overexposure, 1 related
to cancer, 2 not enough information.
20 survivals: developed persistent bloody diarrhoea, necrosis
(tissue death), ulceration and anaemia. 3/4 expected to develop
serious, ultimately fatal, complications.

44. IAEA recommendations:
Follow written quality assurance procedures,
which include:
Ensuring that the procedures require manual checks of the
doses to the prescription points as calculated by computer, for each
individual patient, before the first treatment;
Performing verification measurements using a phantom in
exceptional cases of complicated treatments, for which manual
calculations may not be practicable.
http://www.iaea.org/worldatom/Press/P_release/2001/panam_adv_info2.shtml

45. Costa Rica, August 1996
NCRP report:
San Juan de Dios Hospital, San José
1. Miscalibration of Co60 unit, by a recent biology grad, with no
training in Medical Physics.
2. Poor quality control protocols.
Result?
Minimum of 60% radiation overexposure to patients, who
developed severe radiation complications.
http://www.acmp.org/newsletters/newsletter_apr99/NCRP.html

46. United States, November 92
Indiana regional Cancer Center, Pennsylvania
1. High dose rate (HDR) treatment for an elderly patient.
2. Cable-head with Ir192 source broke inside the patient.
3. Therapist did not perform patient survey at the end of the
treatment.
4. Therapist completely ignored radiation signals indicating the
source is still ‘outside’. And sent the elderly patient to the
nursing home.
Result?
Patient received lethal dose and died.
Ambulance workers, nurses and other residents at the center
received various amounts of radiation dose.

47. Brazil, September 1987
Cancer Clinic, Goiania
Worst Radiation Accident after Chernobyl
3 doctors owned a private downtown radiation therapy
clinic...when they left [in 1985], they simply abandoned the
radiotherapy machine.
2 yrs later, ‘87, abandoned equipment found. A lead canister
containing 1400 curies of cesium-137, 20 g of cesium
chloride was opened.
The cesium was a "luminous blue powder”. Children and
adults rubbed it on their bodies. 6 yr. old Leide das Neves
Ferreira "rubbed the powder on her body so that she glowed
and sparkled." She reportedly received 5 to 6 times the lethal
dose [of radiation] for adults.

48. Brazil, September 1987
Cancer Clinic, Goiania
Worst Radiation Accident after Chernobyl
The cesium was parceled out to friends and family.
On September 28, a week later, "Devair Ferreira went to
the Goiania public clinic where a health care worker
correctly diagnosed radiation illness and alerted
authorities.”

49. Brazil, September 1987
Cancer Clinic, Goiania
Worst Radiation Accident after Chernobyl
Brazilian Nuclear Energy Commission dispatched a team equipped
to handle a radiation accident. They found:
244 person contaminated, 54 seriously enough to be
hospitalized. 34 were treated and released. The 10 sickest patients
were airlifted to the Navy hospital, Dias, in Rio
Brazilian government requested help from the International
Atomic Energy Commission (IAEC). IAEC found:
1. The patients themselves were radioactive
2. The 20 most seriously irradiated had received doses
ranging from 100 to 800 rads.

50. Brazil, September 1987
Cancer Clinic, Goiania
Worst Radiation Accident after Chernobyl
IAEC report, conti.:
19 of the 20 had radiation-induced skin burns.
Several suffered radiation poisoning, nausea, vomiting,
headaches, diarrhea
Within a week, 4 patients had died, overwhelmed by
pneumonia, blood poisoning and hemorrhaging
!!Money, furniture, homes, businesses and soil were contaminated.
What could not be decontaminated was collected or dismantled and
placed in concrete lined drums for disposal as nuclear waste.

51. Brazil, September 1987
Cancer Clinic, Goiania
CAUSES:
1. The lack of regulation surrounding the use and abandonment of
nuclear materials in Brazil, by both national and international
regulation committees.
2. Lack of adequate preparation for such a disaster -> as a result of
lack of regulations.
Sun, Marjorie. Radiation Accident Grips Goiania. Science. 238; p1028-1031
International Newsletter on Physics Education, Number 35, November 1997

52. What have we learned?
1. The need for regulations governing all
aspects of handling radioisotopes and radiationproducing equipment.
2. The need for a trained medical physicist to
calibrate and assure the performance of the
machines, and to correctly deliver treatment.
3. Physicist, doctors and therapists should
follow regulations.

53. Brazil, December 1983
Centro Médico in Juarez
Vicente Sotelo Alardin was sent to haul away some unused material
from a warehouse operated by the Centro Médico. Among the junk
was a 20-year-old Picker 3000 (Co60) radiotherapy machine
purchased from an American clinic.
Sotelo stole an unmarked capsule, which he later opened to spill
6,010 small, silvery pellets of highly radioactive Co60.
Each pellet in the capsule was capable of producing a dose of 25 rads
per hour.

54. Brazil, December 1983
Centro Médico in Juarez
Some of the pellets rolled into the truck bed and into the road,
others remaind inside the capsule which Sotelo sold as scrap to a
junkyard.
From the junkyard, an estimated 300 curies of radioactive cobalt
found their way to the steel and metal industry.
One shipment of contaminated metals, became metal table legs. It
was shipped to a restaurant-table distributor in the U.S.
The other shipment of produced steel rods used in the reinforcement
of concrete building projects.

55. Brazil, December 1983
Centro Médico in Juarez
About 600 tons of the contaminated steel were shipped to the U.S.
from December 1983 to January 1984
On January 17, 1984, a radiation alarm went off when a delivery
truck took a wrong turn near the gates of Los Alamos National
Laboratory in New Mexico
Later in the month, a different truck--this one transporting table
legs--set off a radiation monitor in an Illinois State Police officer's
patrol car.

56. Brazil, December 1983
Centro Médico in Juarez
Authorities eventually traced the radioactivity to the Juarez
junkyard, which was closed.
It took two months track down the contaminated table legs and steel
rods at sites in Canada, Mexico, and 23 different U.S. states,
including Texas.
Brazil health officials also ordered the demolition of 109 houses
built with reinforcing rods containing the radioactive material.
Because pellets have fallen anywhere on the roads between
Chihuahua and Juarez, officials flew over the area in a special
reconnaissance helicopter. They found 22 radioactive sites and
actually dug eight pellets out of the highway asphalt

57. Brazil, December 1983
Centro Médico in Juarez
In the years since, one worker at the junkyard has died from a rare
bone cancer. Others have suffered sterility, skin discoloration, and
other disorders.
Hundreds of Juarez residents have been tested for radiation
poisoning, and at least a dozen have shown chromosome damage.

58. Brazil, September 1987
Centro Médico, Juarez
CAUSES:
Lack of regulation:
1. Lack of regulation surrounding purchasing and shipping
radioactive sources from outside the country.
2. Lack of regulations on storing nuclear materials in Brazil, by
both national and international regulation committees.
http://www.window.state.tx.us/border/ch09/cobalto.html

59. KEEP IN MIND!
My father was a radiologist and assured
me that radiation was NOT hazardous
Radiation DOES
NOT create
monsters, it
merely
increases the
incidents of the
same mutations
that occur
spontaneously
in a given
population.

60. Radiation Induced Second
Malignancy Following Treatment for
Breast Cancer
Case Presentation
Belal El Hawwari 2006

61. Case
• 66 yr female
• June’04- severe cough which resolved after 23/52 without medication
• Sept/Oct’04- right upper chest abn feeling
with resolution
• Dec ‘04- cough and CXR January’05 RUZ Abn
with widened mediastinum
• CT chest/abdo- RUZ lesion with mediastinal
Lymphadenopathy

62. Case contd
• CT guided biopsy- small cell carcinoma
• PMHx• 1985- R infiltrating ductal adenocarcinoma
LIQ breast, 35x25x25mm, extending macro
to within 0.4cm from skin surface, micro
extending into adipose tissue w/ early
invasion of muscle and perineural invasion.
• Treated with WLE, CMF chemotx and 50Gy in
25# to breast, axilla, internal mammary.

63. Case contd
• PMHx contd• osteopaenia/OA, appendicectomy, tonsillect
omy,hysterectomy and R salpingectomy for
cysts in 1982, menopause during chemo at
age 45.
• Non smoker
• IMPRESSION- Radiation induced small cell ca
• Staging- PET- inrc uptake RUL with evidence
of nodal disease. Consistent with stage IIIA.

64. Case contd
Mx• Carboplatin and Etoposide with post chemo
radiotx of 45 Gy in 25# to mediastinum.
• Decision for Radiotx and field made after
thorough review of imaging and previous
radiotx fields. Acceptance of some overlap in
treatment of lung lesion and small overlap in
skin overlying central chest.

65. Radiation Induced Malignancies
following breast radiotx
• British Journal of Cancer 2004• retospective study using Thames Cancer
Registry database from 1960-2000.
Compared incidence of 2nd primary cancers
in women who received radiotx with those
who did not receive radiotx (pts who
received chemotx were excluded)
• 62,782 women in total (33,763 received post
op radiotx)

66. Rad induced 2nd malignancy contd
• 5217 2nd primary tumours detected.
• 2857 at one of primary sites of interest of study
(lung, colon, oesophagus,thyroid, mal
melanoma, myeloid leukaemia, breast)
• elevated RR in lung ca at >10 yrs of 1.49-1.62 (95%
CI 1.05-2.54)
• elevated RR myeloid leukaemia at 1-5 yrs 2.99 (95%
CI 1.13-9.33)
• elevated RR in oesophageal ca at >15 yrs of 2.19
(95%CI 1.10-4.62)

67. Rad induced 2nd Malignancy contd
• Elevated RR in Breast ca in both grps yet at >5 yrs
excess in RT group with RR 1.34 (95% CI 1.10-1.63)
• no sig differences b/w groups for
colon, thyroid, malignant melanoma
• They concluded that benefits of radiotx still outweigh
risks in appropriate pts, yet aim should be to
minimise radiation dose to surrounding tissues or
volume of exposed tissues
• Also, other factors may contribute such as genetic
predisposition, e’ment exposures, reproductive
factors, incr medical surveillance.

68. Proposed Pathogenesis
• International Journal of Cancer 2003
• study performed at Center for Radiological
Research in NYC
• used immortalised human breast epithelial cell line
(MCF 10F) in combination with oestrogen and
radiation as model- step wise neoplastic
transformation of cell line
• identified 3 regions on chromosone 11- high
incidence of loss of heterozygosity/microsatellite
instability- potential role for carcinogenesis.

69. Proposed Pathogenesis contd
• Same centre published another study using
same cell line in Carcinogenesis 2001
• high rate of allele imbalance at regions on
chromosome 6 and 17- suggests presence
and inactivation of one or more tumour
suppressor genes in these regions.

70. Proposed Pathogenesis contd
• Oncogene 2003- Study at Dept of Molecular
and Cellular Pathology UK
• radiation induced bystander effects from
cells in contact with irradiated cells
(intercellular signalling, cytokine
production, free radical generation)
• radiation induced genomic instability in
descendents of irradiated cells

71. Radiation and Carcinogenesis
• Paper Published in Medical and Paediatric
Oncology 2001
• reviewed 14 cohort studies around world
• important points- linearity in dose response;
risk inversely related to age at exposure;
minimal effect of fractionating dose on risk;
decrease in risk at highest dose levels related
to killing rather than transformation.

72. Sarcoma
• Criteria for diagnosis of Radiation Induced
Sarcoma- prior Hx of radiotx; latency of
several years; sarcoma in previously
irradiated field or adjacent tissues; histologic
confirmation of sarcoma;
• Paper in Cancer Control 1998 (literature r/v)
• Radiation Induced Sarcoma in 0.03%- 0.2% of
patients following treatment for breast ca
• average latency >10 yrs and likely correlates
with dose and technique of radiation Tx

73. Sarcoma Contd
• Of note- improvements in radiotx techniques
last 20 yrs with improved dose distribution
and limitation of lymphatic field irradiationlikely to translate into reduction of future
risk
• important to emphasise that risk of RIS is no
greater than risk of operative death thus risk
of 2nd malignancies should not influence
decision to tx pt with radiotx.

74. Sarcoma contd
• UK Dept of Clinical Radiology in Dundee- Reviewed
post radiation sarcomas in 63 cases- Published in
Clinical Radiology 2001
• did include patients who were treated for primary
breast cancer in addition to lymphoma and head
and neck.
• Mean age 52.8 yrs and mainly osteosarcomas/MFH
• mean radiation dose 50.1 Gy with mean latency of
15.5 yrs.
• They concluded imaging findings not
pathognomonic, yet realising latency may help to
suggest diagnosis.

75. Sarcoma contd
• Large single institution retrospective cohort study
from Institut Curie in Paris and published in Cancer
in Sept, 2005
• reviewed records of 16,705 patients with breast
cancer where 13,472 had MV radiotx and 3233
without between 1981-1997. Median doses 50-55
Gy in 25-27 # +/- boost 16-26 Gy.
• RT pts treated via high energy photons of a cobolt
unit and/or linear accelerator
• after mastectomy- electrons to chest wall ? No
• some pts ? No - axillary and/or internal mamm RT

76. Sarcoma contd
• Results- 35 pts sarcoma with 27/35 fulfilling
criteria for RIS
• mean f/u 9.3 yrs (1-22.4 yrs)
• latency- 3-20.3 yrs
• 13 breast, 5 chest wall, 3 sternum, 2 SC, 1
scapula, 3 axilla
• 13 angiosarcomas, 3 osteosarcomas, 5 undiff
sarcomas, 1 MFH, 2 leiomyomyosarcomas, 1
fibrosarcoma, 1 rhabdomyosarcoma, 1
myosarcoma

77. Sarcoma contd
• Cumulative RIS incidence- 0.07% +/- 0.02 at 5yrs;
0.27% +/- 0.05 at 10 yrs; 0.48 % +/- 0.11 at 15 yrs.
• Incidence ratio for irradiated pts- 10.2 (95%CI 9.0311.59) and for non irradiated pts- 1.3 (95% CI 0.33.6)
• limited no of patients has not allowed study of
different risk factors.
• They concluded shorter latency periods related to
MV rather than orthovoltage and that careful long
term f/u is needed for early detection and
efficacious tx of these malignancies.

78. Oesophageal Carcinoma
• Retrospective analysis published in American
Journal of Epidemiology 2005
• reviewed 1973-2000 data from Population based
surveillance, epidemiology,end results program for
patients who received post mastectomy radiotx
• estimated relative risks- RR 2.83 (95% CI 1.35-5.92)
for SCC oesophageal ca at 5-9yrs and RR 2.17 (95%
CI 1.67-4.02) at >10 yrs
• no increase risk in adenocarcinoma (? Related to
lower 1/3rd oesophagus not being treated)
• stated that risk following radiotx post WLE yet to be
determined

79. Oesophageal carcinoma contd
• An Australian group at Princess Alexandra
Hospital QLD- retrospective cohort using
database of >220,000 women with primary
breast cancer 1973-1993
• published in Radiotherapy and Oncology
2002
• 12 patients identified with second primary
oesphageal ca and 9/12 fitted criteria for
radiation induced malignancy
• all patients had post mastectomy radiotx

80. Oesophageal carcinoma contd
• Mean age at radiotx- 54 yrs
• mean age at diagnosis of oesophageal ca- 72
yrs
• all SCC; RR 5.42 (95% CI 2.33-10.68)
• radiotx techniques were combinations of ant
and post fields with varying boosts
• estimated oesophageal dose- 35-40 Gy MV
in 20#

81. Oesophageal Carcinoma contd
• They concluded main associated factor
identified was previous supraclavicular nodal
irradiation as oesophagus is likely to be
irradiated if direct anterior fields are used.
• Risks assoc with current practices will
become clear with time and further analysis.

82. Oesophageal carcinoma contd
• Population Based retrospective cohort study
using population based US cancer registries
• Published in Annals of Internal Medicine
1998
• 220,806 women with primary breast ca
diagnosed b/w 1973-1993
• RR oesophageal SCC 5.42 (95% CI 2.3310.68) >10 yrs post radiotx

83. Oesophageal Carcinoma contd
• They also found RR for oesophageal
adenocarcinoma 4.22 (95% CI 0.47-15.25)
>10 yrs post radiotx
• no increased RR in those who did not receive
radiotx
• they concluded that future studies required
to determine the role of other risk factors in
oesophageal carcinogenesis such as cigarette
smoking, ETOH, BMI etc. and their interaction
with radiotx.

84. Impact of 3D- CRT and IMRT
• May, 2003 International Journal of Radiation
Oncology, Biology, Physics (Center for Radiological
Reasearch, NY)
• some animal and human data suggest decrease in
2nd malignancies at higher doses due to cell killing
• excess sarcomas in heavily irradiated in- field
tissues and incidence of carcinomas, s’times in sites
remote from tx fields
• 3D-CRT- incr. in dose to target tissue with reduction
of normal tissue receiving dose compared to prior
conventional radiotx

85. IMRT contd
• Paper suggests, move to IMRT involves more
fields and as a consequence a greater
volume of normal tissue is exposed to lower
doses.
• Potential for increase in no of 2nd
malignancies.
• They predict increase of 0.75% for patients
surviving >10 yrs.

86. Conclusions
• Radiation Induced Second Malignancies are a
real risk, yet low risk
• Risk should not interfere with decision to
treat with radiotx in appropriate patients, yet
care should be taken to reduce radiation
exposure to normal tissues.
• Risk likened to risk of operative death
• Inclusion in differential in those patients who
have been treated with radiotx many years
prior with new second malignancy

87. Conclusion contd
• Future studies are required to determine risk
and occurrence in patients treated with
more recent practices
• IMRT may potentially increase risk

88. Calculation of the Shielding Materials
for Mega-Voltage X-Ray Linear
Accelerators

89. Introduction
• Before the installation of a new mega-voltage x-ray
linear accelerator the room should be shielded with
different types of materials. The responsibility of the
calculation for this shielding is one of the physicist
duties. Many theories talked about methods to
consider the scattered radiation and neutrons
contamination.

90. Objective
• The purpose of this paper is to introduce a method
to calculate the shielding for a new mega voltage
linear accelerators taking into consideration
scattered radiation and neutron contamination. In
addition we present a protocol to check the amount
radiation in the areas around and above the
accelerator room and the leakage around the
accelerator inside the room.

91. Method
• ADD: Average Daily Dose (Gy)
• Pno.: Patient number per day for conformal and
conventional radiation therapy.
• PWL: patient work load.
• TPW: total primary work load.
• Total Pno: number of patients of conformal
conventional.
• U.F.: using factor of the accelerator.
• Occ.F.: Occupancy factor.
• L.F.: Leakage factor

92. Beam 4
Beam 3
Beam 2
Beam 1
130 cm
100cm concert
175 cm
150 cm
450 cm
100 cm

93. Use factor for barrier
(U) primary
(U)leakage
1
1
G. down
Floor
G.Up
Ceiling
0.5
1
G. Lat
Wall
0.25
1

94. Occupancy factor
Full Occupancy (offices, nurses station, ----)
Occupancy .Factor (T)
1
Partial Occupancy (corridors, rest rooms, parking)
0.25
Waiting room, toilets.
0.07

95. TVL
cobalt60
6MeV
10MeV
15MeV
Concrete (cm)
28
32
38
41
Lead (cm)
4.2
4.7
5
5
Ilmenite (cm)
14
20
23
23
Steel (cm)
9
9.9
9.7-10.5
10.7

96. Equations
PWL
ADD Pno. (Days/week (weeks/yea
)
r)
TPW
PWL 20%
•
Physics QA =20% ×ADD × (Total Pno./daiy) × (days /week) × (weeks /year)
•
(A)Primary=1000 ×TPW × (d0/d) 2 ×U.F. ×Occ.F × (1/Dose equivalent limit (HL)
•
(B) Secondary=1000 ×TPW (d0/d) 2 ×U.F.(=1) ×Occ.F ×L.F. × (1/Dose equivalent limit (HL)
• No.of (TVL) for primary shielding=log10 (A)
•
Thickness of primary shielding =No.of (TVL) for primary shielding × material (TVL) thickness
• No.of (TVL) for secondary shielding=log10 (B)
• Thickness of secondary shielding =No.of (TVL) for secondary shielding ×
material (TVL) thickness

97. Conclusion
• This study yield to measure accurate values for
different materials thickness that can be used to
avoid the radiation hazarded for both radiation
workers and non radiation workers. However the
amount of radiation checking protocol guarantee the
safety of the stuff working around the medical
radiation facilities

98. Thank you