Radiation Therapy

PATHARAKRIT TEEWASUTRAKUL(DVM )

ONCOLOGY CLINICSSMALL ANIMAL HOSPITAL

CHULALONGKORN UNIVERSITY

Radiation Therapy

Introduction to Radiation TherapyHistory 1895 Wilhelm Conrad Röntgen -Diagnosis &Therapeutic purposes 1902 Radiation induced cancer was reported 1903 suggestion to treat cancer w implanting radium 1930 Initial clinical use of radiation dose fractionation 1972 Computed Tomography and Radiation therapy 1990 3D setting w tumor hypoxia and the tumor environment 1994 Am College of Veterinary Radiology 2009 -Currently about 70 board-certified veterinary radiation oncologists -Residency programs in USA -Veterinary Technicians

(Barbara Kaser- Hotz. ,36thWSAVA 2011) (Elizabeth McNiel.,29th Annual conference of the VCS 2009)

What is the Radiation Therapy

รงัสท่ีีใชร้กัษาได้แก่ รงัสเีอกซ์ รงัสแีกมมา นิวตรอน และพวกอนุภาคต่างๆ สว่นใหญ่แล้วมกันิยม ใชร้งัสี

แกมมาจากเครื่องโคบอลต์-60 รงัสเีอกซพ์ลังงานสงู จากเครื่องเรง่อนุภาค และนิยมใชอ้นุภาคอิเล็กตรอน รกัษาบรเิวณพื้นผิวต้ืน ๆ การเลือกชนิดและพลังงาน ของรงัสรีกัษา ต้องพจิารณาลักษณะรูปรา่ง ตลอดจนตำาแหน่งท่ีตัง้ของก้อนมะเรง็

Types of radiation

1. Electromagnetic Radiation 1.1 รงัสเีอกซ์ (x-rays) source : high energy x-ray

equipments

1.2 รงัสแีกมมา (gamma-rays) :radioactive isotopes nucleus

2. Particle Radiation:Linear Accelerator 2.1 อนุภาคอิเล็กตรอน (Electrons)

2.2 อนุภาคอ่ืน ๆ เชน่ โปรตรอน(Photons)

How does radiation kill cells?

Relative radiosensitivity of common animal tumours

response Type of tumors

High Lymphoproliferative disordersMyeloproliferative disordersTransmissible venereal tumourMast cell tumours (variable)

Sensitive Squamous cell carcinomaBasal cell carcinomaAdenocarcinoma (various)

Moderate Oral melanoma

low FibrosarcomaOsteosarcomaChondrosarcomaHaemangiopericytoma

Radiation therapy and Biological response of tumor and normal tissue

Relative radiosensitivity of normal animal tissue

How radiation dose is measured?

The Absorbed dose :Gray(Gy)= SI unit1Gray(Gy)=1joule(j) of energy absorbed by 1

kg tissue1Gray(Gy)=100 Rad1Rad =100ergs/g

1 Fraction =Individual radiation treatment dose

Total dose= Fraction X Time of RT treatment.

Principles of Radiation Oncology

The concept of therapeutic ratio for radiation therapy

Principles of Radiation Oncology

The concept of therapeutic ratio for radiation therapy

Ideal X ORadiosensitive tumor Limited sensitive tumor Radioresistant

tumor

Details Treatment procedure

1.Total dose (Gy)2.Fraction size (Gy)3.Duration of Tx.

Fractionation

Fractionation effect

Radiation dose(Gy)

Cumulation Dose(Gy)

Cells present

Fraction killed

Cell s Remaining

X 1X 1,000,000,000

10% 100,000,000

X 2X 100,000,000 10% 10,000,000

X 3X 10,000,000 10% 1,000,000

X 4X 1,000,000 10% 100,000

X 5X 100,000 10% 10,000

Exponential tumor cell killing by radiation

4R’s radiobiology

1.Repair2.Repopulation3.Redistribution4.Reoxygenation

Fraction ation and Tumor biology

Radiation therapy

Types of Radiation Therapy

1. Teletherapy or External beam therapy

2. Plesiotherapy or Brachytherapy

3. Unsealed source therapy or Nuclear medicine

Model Linac Linear Accelerator (4-20MeV)

1.Teletherapy or External beam therapy

Stand Mask

Different types of animal immobilization

Tooth block Cat and tooth block

Different type of animal immobilization

Position of dog during RT Dog and tooth block

Different type of animal immobilization

Animal immobilization

Different types of animal immobilization

Vacuum bag

1.Measures of tumor volume CT scan

Equipment CT or MRI X-rays

Radiotherapy treatment planning

CT &MRI CT&MRI



Hand &Computer planning

Radiotherapy treatment planning3D Virtual Simulation

Computer planning

Radiotherapy treatment planning3D Virtual simulation

Computer planning

Multileaf collimator Other devices

Radiation therapy:Beam control

Virtual Simulation : multiple fields RT

Monitoring RT procedure

Dog and oronasal mass: canine oral melanoma

Radiation Therapy

multiple fields RT

Cat : CT scan for RT preparation

Cat with nasal lymphoma

Radiation therapy

Common tumours amenable to radiation therapy

Iridium-192 Strontium-90

2. Plesiotherapy or Brachytherapy

Iodine-131

3. Unsealed source therapy or Nuclear medicine

Acute side effects Delay side effects

Common radiation therapy side effects

Acute moist desquamation

Delay effect :Depigmentation


1.Radiation therapy alone

Radiation Therapy in Veterinary Medicine

Curative Treatment Local and small tumor

size Almost radiosensitive

tumor types

Palliative Treatment Reduce cancer pain Destroy cutaneous

metastasis tumor Slowly tumor growth

rate

1. Combined Radiation and Surgery

2.Combined Radiation and Systemic therapy

Preoperative irradiation

Intraoperative irradiation

Postoperative irradiation

Chemotherapy: Synergistically improve Doxorubicin Carboplatin Gemcitabine Paclitaxel

are all shown to improve the effects of radiation Adjuvant chemotherapy Neoadjuvant Chemotherapy

Immunotherapy Melanoma vaccine

Combined Radiation with Other modalities

Weak point


IMRT : Intensity modulated RT Rapid Arc : 4D RT

Future Direction of Radiation Therapy

CLINICAL APPLICATION


Dog and oronasal mass: canine oral melanoma

Radiation Therapy

multiple fields RT

Cat : CT scan for RT preparation

Cat with nasal lymphoma

Radiation therapy

Use of strontium-90 plesiotherapy for the treatment of a lingual plasmacytoma in a dog. K. Ware and T. Gieger etal. Journal of Small Animal Practice (2011) 52, 220–223

1.Plasmacytoma

2.cytology

3.Therapeutic Planing

5.Post RT

4.RT 150Gy

Prognostic significance of specific magnetic resonance imaging features in canine nasal tumours treated by radiotherapy . P. AGTHE*, A. R. CAINE, R. N. A. GEAR et al., Journal of Small Animal Practice (2009) 50, 641–648

Intensity-Modulated and Image-Guided Radiation Therapy forTreatment of Genitourinary Carcinomas in Dogs

M.W. Nolan, L. Kogan, L.R. Griffin, et al. J Vet Intern Med 2012;26:987–995

UB target



Colon

UB

Questions

Radiation Therapy

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