ICRT รศ.พญ.เยาวล กษณ ชาญศ ลป

ICRT รศ.พญ.เยาวล กษณ ชาญศ ลป

Brachytherapy การร กษาด วยร งส ระยะใกล Insertion การสอดใส แร Implantation การฝ งแร Surface application การวางแร

physical benefit of brachytherapy - very high dose of radiation to the tumor - very rapid fall off of dose to the surrounding normal tissue

Properties of radioisotope Radioisotope Half life Energy (MeV) HVL (mm. of Lead) Max. Concentration available (GBqmm -3 ) Ra-226 1600 years 0.24-2.4 17 ~0.05 Cs-137 30 years 0.66 6.5 1.2 Co-60 5.27 years 1.17, 1.33 12 130 Ir-192 74.02 days 0.3-0.61 4.5 330 Au-198 2.696 days 0.41 3 7.4 I-125 60.14 days 0.035 0.03 3.7

Loading System Preloading tech. Afterloadin tech. Manual afterloading Remote afterloading

Afterloading system

Radioactive sources Activity (ICRU 38) Low dose rate (LDR) 0.4-2 Gy/hr Cs-137, Ra-226 Medium dose rate (MRD) 2-12 Gy/hr Cs-137 High dose rate (HDR) more than 12 Gy/hr Co-60, Ir-192

Intracavitary Insertion

Surface mould

Interstitial implantation Radioactive sources are inserted directly into the tumors. Temporary implantation Permanent implantation

Permanent implantation Isotopes with short half-life and low photon energies Radioisotope Half life Energy (MeV) Rn-222 3.84 days 0.24-2.4 Au-198 2.7 days 0.41 I-125 60.14 days 0.035

Brachytherapy For Gynaecologic Malignancy

Cervical Cancer

Extension of cervical cancer lymph nodes body Parametrium Vagina

Paraaortic node metastasis

Degree of invasion 1. Carcinoma in situ 2. Microinvasive Carcinoma 3. Invasive carcinoma Lesions invaded less than 3 mm rarely metastasize Tumors invaded 3-5 mm have positive pelvic nodes about 5% to 10%

Modality of Treatment Teletherapy - Megavoltage : 10 + MV Co-60, 4-6 MV Brachytherapy - Intracavitary Insertion - Implantation - Mould

E X T E R N A L B E A M RT

The classical Manchester system A line source inserted into the uterus Two ovoids placed in the lateral vaginal fornices creates a pear-shaped volume around cervix, lower uterus, upper vagina and immediate parametria equivalent to Radical Hysterectomy type II

Reference points of dose in RT of cervical cancer The dose is prescribed to Manchester point A 2 cm above the lateral vaginal fornices and 2 cm lateral to the central uterine tube. = medial parametrium ** uterine art. X ureter ** Point B - 5 cm lateral to the midline. = obturator node and lateral parametrium

ICRU 38 : rules on critical organ dose consideration In practice, the rectal dose is often the dose limiting factor Rules are given as to where one should assume rectum and bladder to be Space visible on X-ray due to radio-opaque packing material

Early Radium System for Cervix Cancer 40-70 mgra 30 mgra 15 mgra 10 mgra 10 mgra 70 mgra Stockholm 2 (1-day) tx, 3 wks apart 30 mgra Paris 1 (5-day) tx 20 mgra 20 mgra Manchester 2 (3-day) tx 1 wk apart

Manchester Applicators

Manchester method (Paterson, Todd M, 1938, 1950) Two insertion each of 72 hrs delivered over 10 days Three uterine sources available 6 cm 35 mg 4 cm 25 mg 2 cm 20 mg Three vaginal ovoids available large 22.5 mg medium 20 mg small 17.5 mg

Afterloading applicators (Fletcher-Suit Applicator)

HDR and LDR : same result of treatment : same complications : shorter treatment time : better immobilization : OPD cases except PDR : more patients treated : more fractions : higher work load : more expense

Changing in fractionation will affect the late responding tissue much more than early responding tissue

American Brachytherapy Society (ABS) recommendations for HDR Int J Radiat Oncol Biol Phys 2000;48:201-211 Goals = treat point A to at least a total LDR equivalent of - 80-85 Gy for early-stage disease (nonbulky, stage I/II, <4 cm in diameter) - 85-90 Gy for advanced-stage disease (stage I/II & >4 cm in diameter or stage IIIB) Pelvic sidewall dose recommendations - 50-55 Gy for early lesions - 55-65 Gy for advanced lesions - Keep bladder dose <80 Gy LDR-equivalent dose - Keep rectal dose <75 Gy LDR-equivalent dose - Keep overall treatment time (EBRT + brachy.) <8 weeks ( 55 days) - EBRT not given on the day of a HDR treatment

Abnormal Point A

Bulky barrel-shaped carcinoma of the cervix Invasion of myometrium of the uterine isthmus, producing a bulky barrelshaped lesion. Tumor cells in the periphery of the tumor may receive an inadequate dose to achieve central tumor control. Fletcher GH: Textbook of radiotherapy. Philadelphia, Lee & Febiger, 1966, p479

For successful Intracavitary Therapy Good geometry of the applicator to prevent underdose region around cervix Adequate dose to paracervical tissue Mucosal tolerance has to be respected XRT prior to ICRT can provide the good geometry, especially with CCRT

Brachytherapy after hysterectomy

Surgical Management for Cervical cancer 1. Conization 2. Extrafascial Hysterectomy (Total Abdominal Hysterectomy with Bilateral Salpingo-Oophorectomy TAH.BSO ) 3. Radical Hysterectomy type II 4. Radical Hysterectomy type III with pelvic node dissection ( Wertheim s operation )

Extrafascial Hysterectomy Radical Hysterectomy III Radical Hysterectomy II

Intracavitary Brachytherapy with tandem and ovoids is as effective as type II Radiacal Hysterectomy

Treatment for Cervical cancer (I) CIS - Conization/TAH - ICRT Stage Ia1 - Extrafascial Hysterectomy (TAH with/without BSO) - ICRT Stage Ia2 - Radical Hysterectomy type II - ICRT Stage Ib - Radical Hysterectomy type III with pelvic node dissection ( Wertheim s operation ) - XRT + ICRT

Treatment for Cervical cancer (II)

Treatment for Cervical cancer (II) Postoperative RT - positive LN - parametrial involvement - T > 4 cm - deep stromal invasion - angiolymphatics invasion - inappropriate surgery

Treatment for Cervical cancer (III) Stage II - XRT ( + Concurrent chemotherapy ) + ICRT Stage III - XRT + Concurrent chemotherapy + ICRT Stage IV IVa - XRT + Concurrent chemotherapy (+ ICRT) IVb - palliative RT or Chemotherapy

Brachytherapy in subtotal hysterectomy

Special type of applicators - Miami

Miami

Miami

Miami

Endometrial carcinoma or Ca corpus

Radical Hysterectomy Ca Cervix Ca Endometrium

Spreading Local extension - endometrium, myometrium - cervix - vaginal - parametrial - uterine tube and ovary Pelvic and paraaortic nodes Intraperitoneal spreading Hematogenous spreading

Pathology Adenocarcinoma endometrioid type non-endometrioid type

Treatment Stage I-II TAH.BSO+PAN sampling + peritoneal washing Postop. Chemo/RT for - Grade II-III - myometrial invasion - vagina / ovary / parametrial + - peritoneal washing + Stage III-IV RT and/or Chemotherapy

RT technique XRT whole pelvic RT ICRT - postop. : vaginal ovoid - RT alone : special applicator