Introduction to Basic Radiotherapy

8/13/2019 Introduction to Basic Radiotherapy

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Basic of

radiotherapy/radiation

oncology

dr. Narno Budianto, Sp. R (K) Onk. Rad

BAGIAN RADIOLOGI seksi RADIOTERAPI

RSU Dr. SAIFUL ANWAR MALANG

2008


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RADIOTERAPhy

DEFINITION :

- treatment

- ionic rays

- important therapy for cancer

RADIATION ONCOLOGY :

- Application of radiation therapy- single/combination treatment

Ionic ray: X-ray Williem Rontgen


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Basic of radiophysical radiation:

Ionic Ray: - Electromagnetic wave

(photo/particle)- Ionization process

1. Electro Magnetic wave: X and Gamma

E (+), Mass (-), Electricity (-)

deep penetration

2. Particle :

- Mass, electricity (+)

- electricity (+) Proton & helium- electricity (-) Electron

- without electricity Neutron


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IONIC RAY SOURCE :

- Generator : - X-RAY

- Electron- Ionic Particle

- According to Energy level

- Ortho Volt 50300 kv

divided : SuperficialMedium

Deep

Mega Voltage Minimal 1 MV

Output : Photon, Electron, heavy Particle

produced by : Linac, Betatron, Syclotron.


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Natural resources :

- Radio Isotope decay

- produced :Alfa-rayBeta-ray

Gamma-ray

- Radio Isotope that used :1. Co 60

2. Cs 137

3. Iridium 192

4. Radium 255

5. J 131, J 125

- Divided into : - open sources

- closed sources


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RADIO ACTIVE:

- substance become another substance with release E

- atomic number change- can move from room to another in periodic scale.

X rays characteristic:

- Deep penetration- burn film

- causing Ionization effect

- causing biological effect

ELECTRON characteristic :

- max doses 100%, 1 cm under surface

- after max, doses rapidly decrease


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FOTON ELECTRON

1. Gel electro M

2. Mass (-)

3. Energy deep/

sharp4. PDD not rapidly

decrease

5. Low skin reaction

1. Particle

2. Mass (+)

3. Energy absorb by

bone4. PDD rapidly

decrease

5. High skin reaction


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Roentgen equipment for Radiotherapy :

resources :

- natural :- Co 60 T1/2 5- 6 year

- Sc T1/2 2330 year

- Radium T1/2 15501600 year

- Iridium T1/2 72 year

- Generator :

- Lineac: - small Pin point , small penumbra, sharp border- higher Out put

- Constant

- consist of: Photon, Electron

- Betatron: Photon and Electron

- Cyclotron: Neutron

NB : Cobalt : larger focus, larger penumbra

lower Out put


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ENERGY :

Grenz ray Therapy

Contact TherapySuperficial/Low Voltage

Deep/High Voltage/Ortho Voltage

Super Voltage

Mega Voltage

10 20 Kv

15 50 Kv60 - 120 Kv

140400 Kv

4001 Mv

Higher than 1 MV


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RADIO SENSITIZER

Molecule consist of:

- Purin BUDR

increase sensitivity oftumor/healthy tissue

- Electron Affini Component :

increase ionization reaction

- Metro

- Bleo- Fluora


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RADIATION DOSES UNIT:

R = Roentgen ---- Unit of doses in air

Rad = Radiation absorption dose

Gy = Gray 1 Gy = 100 Rad.

1 Rad = 1 cGy

RESTRICTOR OF RADIATION DOSES :

- Radio Sensitizer

- Purpose of Radiation

- Kind of Radiation rays

- Tumor stadium

- soft tissue tolerance


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RADIO PROTECTOR :

- I U R 1721

- Cysteamine- Glutathione

- substance with OH

CYTOSTATICA THAT HAVE RADIO SENSITIZEREFFECT :

- 5 F U

- Actinomycin

- Bleomycin- Metotrexate

- Purine/Pyrimidine


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MEGA VOLTAGE CHARACTERISTIC/MV :

- Sharp

- small side effect

- Effect on bone = tissue

- deep penetration & spin

Radiation Source : - closed

- open

ORTHO VOLT MEGA VOLT

penetration

Max DosesAbsorption

used

-low

-superficial-bone

-Superficial

tissue

-deep

-under skin tissue-bone = tissue

-deep Tumor


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TUMOR MARKER

Body substances ---- Quantity / Quality

- Ca Mamma : Ca 125, CEA, MCA, Estrogen receptor- Ca Cervix : C E A, HCG

- Ca Ovaries : AFP, Ca 125, CEA, FSH, HCG

- Ca Nasopharyngeal : Titer EBV etc

Differences between tumor tissue and healthy tissue :

- Reproduction capability

- Mitosis

- Differentiation- Repair capability

- Oxygenation


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BASIC OF RADIOTHERAPY

- Different radiation effect between tumor and healthy

tissue

- Therapeutic ratio/ T R

Molecular Effect Radiation :

- DNABreak : - Single/Double

- Basa-basa DNA

- Cross Linked DNA and chromosome

Damage followed by :

- Direct Effect DNA Ionization

- Indirect Effect

* Water Molecule Ionization* Free Radical

- Reparation perfect/un perfect


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CELLULER RADIATION EFECT

- Chromosomal abrasion

- inhibition of Reproduction- inhibition of Proliferation cycle

PROLIFERATION ON RADIATION

Growth Factor: - Phase S

- Phase G 2

- Phase M

- Phase G 1Active Proliferation G 2, M


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FACTORS THAT INFLUENCE:

RADIATION RESPON :- Oxygenation- Proliferation

- Heat

- Radio Sensitizer

FRACTINATION ON RADIATION ( DIVIDED DOSES) ;

- Characteristic 4 R :- Reparation

- Reoxygenation- Redistribution

- Repopulation


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RADIOTHERAPY :

- Definitive

- Exact Doses

- Combination

1. surgery: - Radiation before surgery

- Radiation During surgery

- Radiation after surgery

2. Cytostatica :- before Radiation

- during Radiation

- after Radiation

3. Immunology in research


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RADIATION THERAPEUTIC GOAL :- Curative

- Palliative

RADIATION :

1. External Radiation (Telefar)

2. Brachy therapy (short) :- Implants/ Interstitial- Intra Caviter

- Contac

Recent Brachytherapy after Loadingtechnique

3. Radio Farmaka


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FACTOR THAT INFLUENCE RADIATION OUTPUT :

1. Patient condition

2. Continuities

3. Unprecise calculation (ketidak tepatan penentuan)

4. Stage of disease

5. Biological characteristic

EFFORT TO REINFORCE RADIATION EFECT :

- Radio Sensitizer

- Hyperthermia, Hyperbaric

- Depend on cell tumor characteristic

RADIATION SIDE EFECT :

- Acute

- Chronic


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FACTORS THAT MUST BE

UNDERSTOOD IN RADIOTHERAPY

Radiation type (high voltage X ray, uranium,

radium, Co 60 etc.)

Cell type

Bergonie Tribondeau law

Cell environment

Tumor vasculature

Radiation weight


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PLANNING OF RADIOTHERAPY

Decide tumor place and wide Illumination technique and dosagedistribution

Tissue toleration


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SOMATIC EFFECT AND IONIZED

RADIATION

Skin

Acute dermatitis

Level I : erithematosa dermatitis

Level II : bullosa dermatitis

Level III : eschariotic dermatitis

Chronic dermatitis

Late effect of acute dermatitis

Eyes

Konjungtivitis and keratitis

Eyes lens is very sensitive, 400500 rad cataract


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Internal genitalia

Dosage 600 rad sterility ( testis is moresensitive than ovum)

Gravid dead infant, anomaly

Gen mutation Lungs

Cough, hypoxia, chest pain, fibrosis

BoneDisturbance of bone development, osteoporosis


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Neurotic systemMyelitis, neuron tissue degeneration

Radiation disease

Fever, anorexia, headache, nausea,vomiting, weakness, diarrhea

Genetic effect

Gene mutation


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DETERMINISTIC EFFECT

High dosage radiation illumination

Fit with threshold dosage

Time : view minutes after radiation There is automatically healing

Morbidity level is fit with dosage

Ex : - anorexia- vomiting, nausea, weakness

shock dead


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DETERMINISTIC EFFECT

HAPPEN IN :

Dosage > 100 Sv damaged central nervous

system

Dosage 1050 Sv Damaged GIT Dosage 35 Sv Damaged bone marrow

Dosage 3 Sv Women infertility

Dosage 2 Sv Permanent infertility of men

Dosage 2 -5 Sv cataract

Dosage 1 -2 Sv (whole body) nausea


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radiasi


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Energi radiasi

Radiasi mempunyai energi

Max Planck (1900)pertukaran energi

antara radiasi & materi tidak terjadi secara

kontinyu, tapi melalui satuan energi

kwantum

E = h x f

E (erg) = energi radiasi dalam erg

h = konstanta Planck = 6,62 x 10-27erg


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f = frekuensi radiasi

Dan f = C

C = kecepatan gelombang elektromagnetik

= 3 x 1010cm/detik

= panjang gelombang, maka

E = h x C


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Karena h dan C konstan,energi radiasi

berbanding terbalik dengan panjang

gelombang.

B d t d


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Besaran dan satuan dasar

dosimetri Dosimetri : kegiatan pengukuran dosis

radiasi dengan tehnik pengukurandidasarkan padapengukuran ionisasi

yang disebabkan oleh radiasi dalam gas(udara).

Radiasi mempunyai besaran = besaranfisika lain

Dosis radiasi yang diterima/ diberikan bilamedium terkena radiasi.


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Dosis serap

Radiasiionisasi pada jaringan / mediumyang dilalui

Dosis serap D : besarnya energi radiasi

yang diserap tiap satuan massa bahanyang menerima radiasi.

D = dE / dm

dE = energi yang diserap oleh mediumbermassa dm

Dalam sistem SI = joule /kg atau Gray(Gy)


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Sebelumnya digunakan satuan :

erg / gr atau rad (radiation absorbed dose)

1 rad = 100 erg / gr

1 rad = 10-2J /kg

1 Gy = 100 rad

Laju dosis serap : turunan dari dosis serap

terhadap waktu Adalah = dD / dt


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Dosis ekuivalen

Ditinjau dari sudut efek biologi yangditimbulkan : efek yang timbul pada suatu

jaringan akibat penyinaranbermacam-

macam radiasi pengiontidak samadosis radiasi sama, jenis radiasi berbeda.

Digunakan dosis ekuivalen (HT.R)

Menunjukkan kualitas radiasi dalamkaitannya dengan akibat biologi yangditimbulkan.


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International Commission on RadiologicalProtection (ICRP) memperkenalkan faktorbobot radiasi (WR)

HT.R= WR. DT,R DT,R : dosis serap yang dirata-ratakan

organ / jaringan yang menerima radiasi.

Faktor bobot tidak berdemensi , satuandosis ekuivalen = satuan dosis serap =J/kg

Satuan khusus = Sievert (Sv)


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Sebelum digunakan satuan SI :digunakan

satuan REM ( Roentgent equivalent man /

mammal ) : 1 Sv = 100 Rem


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Faktor bobot radiasi

Jenis dan rentang energi radiasi WR

Foton semua energi (gamma,sinar X) 1

Elektron, semua energi 2

Neutron dengan energi EnEn


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Proton energi > 2 MeV 5

Partikel alfa 20


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Dosis efektif

Keefektifan radiasi dalam menimbulkan

efek tertentu pada suatu organ (HE)

Hubungan antara peluang timbulnya efek

biologi tertentu akibat penerimaan dosis

ekuivalen pada suatu jaringan tergantung

pada organ / jaringan yang tersinar.

Digunakan bobot jaringan (WT)

HE= WT. HT

F kt b b t j i t k


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Faktor bobot jaringan untuk

berbagai organ tubuh Jenis jaringan /organ WTGonad 0,20

Sumsum tulang merah 0,12

Usus besar ,paru,lambung 0,12Bladder, payudara,hati 0,05

Oesophagus,thyroid 0,05

Kulit,permukaan tulang 0,01

Adrenal,otak,colon prox,usus kecil, 0,05

Ren, otot,pancreas,spleen,thymus,

Uterus.


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Paparan

Besaranintensitasmenyatakan

intensitas sinar Xmenghasilkan ionisasi

diudarajumlah tertentu

X = dQ / dm

dQ : jumlah muatan elektronakibat

interaksi antara foton dengan atomatom

udara dalam volume udara bermassa dm

Satuan : Roentgen


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1 Rontgen = kuantitas radiasi sinar X / gamma

yang menghasilkan 1 e.s.u ion positif atau

negatif didalam 1 cm3 (NTP)

1 R = 1 esu / cm3 (NTP)Ion bermuatan = 4,8 x 10-10 esu

1cm3 udara = 0,001293 gr

Nilai penyerapan energi = 87,7 erg1 gram udara = 87,7 erg/gr

1 rad = 100 erg/gr udara


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1 erg / gr udara = 0,01 rad

1 R = 0,877 rad


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Efek Stokastik

Paparan radiasi dosis rendah

Somatik

Genetik

Dosis 0,25 s/d 1000 Sv 4 ciri efek stokastik

- tidak ada dosis ambang

- Timbul setelah melewati masa tunda

- Keparahan # dosis radiasi

- Tidak terjadi penyembuhan spontan


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Efek Deterministik

Paparan radiasi dosis tinggi

Sesuai dosis ambang

Waktu : beberapa saat setelah terjadi

radiasi Terjadi penyembuhan spontan

Tingkat keparahan sesuai besarnya dosis

Misal : - nafsu makan kurang- mual, lesu, lemahsyok

kematian.


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Lokal : eritema, pedih, gatal

Limfosit menurunparameter tinggi

rendahnya dosis


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Efek Deterministik terjadi :

Dosis > 100 Svkerusakan susunan saraf

pusat

Dosis 1050 Svkerusakan GIT

Dosis 35Svkerusakan sumsum tulang Dosis 3 Svkemandulan pada wanita

Dosis 2 Svkemandulan pada laki-laki

(permanen) Dosis 25 Svkatarak

Dosis 12 Sv (seluruh tubuh)mual


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3. Tahap biokimia

- secara : ekstra seluler

intra seluler

- terjadi beberapa detik

- Hasil reaksi berinteraksi dengan molekul organik

radikal bebas

oksidatormolekul kompleksbahan dasar (menempel atom, merubah ikatan

molekul).

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Introduction to Basic Radiotherapy

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