Brachytherapy Part 2

1. BRACHYTHERAPY PART 2
PRESENTER- Dr ABHISHEK MEWARA
MODERATOR- Ms. CHANCHAL
Date- 29.2.2024
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2. TOPICS COVERED IN PART 1
 INTRODUCTION
 CLASSIFICATION
 ADVANTAGES AND DISADVANTAGES OF
BRACHYTHERAPY
 INVERSE SQUARE LAW
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3. OVERVIEW
1. RADIONUCLIDES IN BRACHYTHERAPY
2. RADIOBIOLOGY OF BRACHYTHERAPY
3. DOSIMETRY
4. INDIVIDUAL CANCER BASED BRACHYTHERAPY
5. APPLICATORS
6. BRACHYTHERAPY SETUP OF JLN AJMER
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4. I. RADIONUCLIDES IN BRACHYTHERAPY
1. GAMMA EMITTERS-
a. Cesium 137
b. Iridium 192
c. Iodine 125
d. Cobalt 60
2. BETA EMITTERS-
a. Strontium 90
b. Ruthenium 106
3. NEUTRON EMITTERS
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5. PROPERTIES OF AN IDEAL RADIONUCLIDE-
1. Radioactivity-
- Emission energy should be high enough to kill the tumor and treat the patient, but be low
enough to reduce the level of scattered radiation and satisfy radiation safety requirements.
2. Half life-
- Similar to radioactivity, it should be low enough so as there is not much risk of exposure of
radiation to surrounding people, but high enough to treat the patient.
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6. 3. Small and portable, to allow easy delivery.
4. Non toxic.
5. Non soluble.
6. Not prone to breakup or easy dispersal, so as there is minimal gaseous or other
disintegration products.
7. Should be able to undergo frequent sterilization without suffering damage.
8. Should be possible to manufacture the radionuclide in different shapes and sizes,
including rigid tubes, needles, spheres, wires, etc.
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7. Method of Classification Name of the Isotope
Permanent Brachytherapy Sources
(Short Half-life & Low Energy)
Iodine-125, Gold-198, Palladium103,Radon-222,Cesium-131
Temporary Brachytherapy sources
(Long Half-life & Medium Energy)
Radium -226,Caesium-137 ,Iridium-192,Cobalt-60,Ytterbium-169
High Energy Photon Emitters Radium-226: Radon-222: Cesium-137: Cobalt-60: Iridium-192: Gold-198
Low Energy Photon Emitters Iodine-125,Palladium-103: ,Cesium-13,Ytterbium-169
Gamma ray Emitters Caesium-137,Iridium-192,Iodine-125,Cobalt-60
Beta Emitters Strontium-90,Ruthenium-106,Posporus-32
High Dose Rate( > 12Gy/hr) Iridium-192,Cobalt-60
Medium Dose Rate(2>12 Gy/hr)
Low Dose Rate (0.4 Gy/hr to <2Gy/hr) Radium-226,Cesium-137
Pulsed Dose Rate Thulium 107
LDR Intracavitary Radium 226, Cesium 137
Experimental Intracavitary Californium 252, Ytterbium 169, Americium 241
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8. Isotope
Mean Gamma Energy (MeV)
Cobalt 60 1.253
Radium 226 0.83
Cesium 137 0.662
Gold 192 0.415
Iridium 192 0.372
Ytterbium 169 0.143
Palladium 103 0.137
Thulium 170 0.084
Iodine 125 0.035
RADIONUCLIDES AND
THEIR MEAN GAMMA
ENERGY
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9. INDIVIDUAL RADIONUCLIDES-
1. RADIUM 226-
- First isolated radionuclide, no longer used.
- Half life = 226 yrs.
- 0.8 MeV mean gamma energy.
2. CESIUM 137-
- Half life = 30 yrs.
- 0.662 MeV mean gamma energy.
3. IRIDIUM 192-
- Half life = 74 days
- 0.370 MeV mean gamma energy
- Highly malleable, also comes in the form of flexible wires.
NEEDLE RADIUM SOURCES USED IN
INTERSTITIALAND INTRACAVITARY
THERAPY.
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10. IRIDIUM 192 WIRE IMPLANT
WIRE DIAMETER = 0.3
mm
WIRE INSERTION USING NEEDLE GUIDES
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11. HDR AFTERLOADER DOSE DISTRIBUTION AND
IRIDIUM 192 SOURCE
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12. 4. IODINE 125-
- Half life = 60 days.
- 27- 35 KeV mean gamma energy.
- Used mostly in prostate implants.
5. COBALT 60-
- Used in our brachytherapy setup.
- Half life = 5.26 yrs.
- 1.253 MeV mean gamma energy.
6. STRONTIUM 90-
- Half life = 28.7 yrs.
- 2.27 MeV mean gamma energy. SCHEMATIC DIAGRAM OF I 125 SEEDS
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13. 2. RADIOBIOLOGY OF BRACHYTHERAPY
- Brachytherapy exploits differences between intrinsic radioactivity, repair, and repopulation of normal and malignant cells.
- The major difference between brachytherapy and EBRT is seen in marked variation in dose and dose distribution around
the arrangement of radioactive source.
- Close to radiation source in any implant where the dose rate is high enough, both normal and malignant cells will be
killed, regardless of their radiosensitivity.
- In regions of low dose rate farther out from the source, the killing effect will be much smaller, and most radiosensitive
cells will survive.
- Between these 2 extremes, there is a region where differential cell killing occurs.
- Normal cells may undergo cell cycle arrest at G1/ S boundary and p53 mediated repair of radiation damage.
- But in tumor cells, there is continuous proliferation and they enter G2 and M phases of cell cycle. Then the accumulated
radiation damage may lead to death of malignant cells.
- Radioresistant hypoxic cells are often found at the center of tumors, but as the source is normally implanted within the
mass of the tumor, even they are killed because of the high dose levels.
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14. 3. Dosimetry
 Radioactive material is implanted into tissues according to distribution rules, which
vary according to the systems used.
 Commonly used systems are-
1. Parker Paterson System- Planar and Volume Implant
2. Quimby System
3. Memorial System
4. Paris System
5. Computer System
6. Manchester System
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15. EXAMPLES OF THREE PLANAR
IMPLANTS.
A: BOTH ENDS CROSSED.
B: ONE END UNCROSSED.
C: BOTH ENDS UNCROSSED.
EXAMPLE OF A VOLUME
IMPLANT
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16. 4. INDIVIDUAL CANCER BASED BRACHYTHERAPY
A. Gynaecological cancer
B. Prostate cancer
C. Bronchial cancer
D. Oesophagus cancer
E. Bile duct cancer
F. Breast cancer
G. Head and neck cancer
H. Anal and rectal cancer
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17. A. GYNAECOLOGICAL MALIGNANCIES- CA CERVIX-
- HDR is currently the most widely used method of brachytherapy delivery.
- During insertion of applicators and implants, the cervical os is dilated sufficiently to
allow a central rigid tube of nearly 5 cm length to be placed in uterus.
- Ovoid applicators are then placed against cervix in line with the flange on the central
tube.
- Gauze pieces are placed beneath and above the ovoids to reduce the dose, particularly
to bladder and rectum.
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18. B. PROSTATE CANCER-
- Usually restricted to patients with early stage disease with favorable prognostic features.
- These are patients with stage T1 and T2 tumors with pre treatment PSA levels less than 10 mg/ml, and Gleeson scores
of 6 or less.
- Patients with significant outflow obstruction symptoms are unsuitable for this technique owing to high instances of
acute urinary obstruction following the implant process.
- Implantation is performed with the patient in the lithotomy position.
- A needle guidance template attached to ultrasound apparatus is placed against the perineum.
- Hollow needles are inserted through the template under TRUS guidance with supplementary fluoroscopic screening if
necessary.
- Iridium-125 seeds are introduced through these hollow needles in a prearranged pattern.
- Approximately 80 to 100 seeds are used.
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19. PROSTATE BRACHYTHERAPY- SEED IMPLANTS
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20. C. BRONCHIAL CANCER-
- Typical dose is 15 Gy, given in a single fraction.
D. OESOPHAGUS CANCER-
- Tumors can only be treated up to a distance of 1 cm from the source.
- Major use is as a palliative treatment to relieve either bleeding or dysphagia.
- For this purpose, single fraction of 15 Gy is used.
E. BILE DUCT CANCER-
- Mostly used to shrink tumor and relieve obstructive jaundice.
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21. F. BREAST CANCER-
- Flexible polythene tubes are inserted at the time of surgical excision of
the breast lump, i.e. perioperatively.
- Tubing can also be inserted post operatively.
- An advantage of perioperative installation of tubing is that the
radiotherapist knows the exact site of the excised tumor.
- Iridium wires are inserted later.
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22. HDR AFTERLOADER FOR BREAST TREATMENT USING IRIDIUM-192 STEPPING
SOURCE. THE SOURCE TRAVELS ALONG FLEXIBLE POLYTHENE TUBES
WHICH HAVE BEEN INSERTED IN THEATER.
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23. G. BUCCAL CAVITY CANCERS-
- A T1 or T2 tumor on lateral edge of anterior two third of tongue is satisfactorily treated
by iridium hairpins.
- Larger tumors are treated first by EBRT, with or without chemotherapy, and the
implant is merely used as boost treatment.
- Gutter guides, usually 4, are inserted at 12 mm intervals under fluoroscopic guidance,
with 1 cm margin of normal tissue.
- Iridium hairpins are then inserted into the gutter guide wires.
- A typical dose is 65 Gy given over 6-7 days.
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24. H. ANAL CANCER-
- Patients are initially treated with EBRT with 40-45 Gy over 4-5 weeks.
- Patients with tumor greater than 5 cm should also receive concurrent chemotherapy, with
either Mitomycin C and 5 FU or Cisplatin based combinations.
- Then after 1-2 months, a horse shoe shaped jig is placed against the anal skin and up to 8
hollow needles are inserted 1 cm apart through the jig to cover the tumor.
- A hollow syringe barrel is inserted into the anus to allow the flatus or feces to escape.
- A dose of 15-25 Gy is given in 2 - 2 ½ days.
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25. 5. APPLICATORS
- They are devices used to place radiation sources inside the body.
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26. 26 INTRACAVITARY APPLICATORS

27. 27
INTRALUMINAL APPLICATORS
NASOPHARYNX ESOPHAGUS BRONCHIAL

28. 28
INTERSTITIALAPPLICATORS
(HEAD & NECK)

29. 29
INTERSTITIAL APPLICATORS (BREAST)

30. 30 INTERSTITIALAPPLICATORS
(PROSTATE)

31. 31
SURFACE APPLICATORS

32. 6. BRACHYTHERAPY SETUP OF JLN AJMER
WORTH 7-8 CRORES!
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33. C ARM, X RAY PRODUCTION TUBE,
AND INTENSIFIER WITH DETECTORS
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34. CONSOLE ROOM
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35. CHANNELS
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36. EMERGENCY MANUAL
RETRACTOR
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37. CONTROL PANEL OF C ARM
PADDLE
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38. WAVE/ SOURCE GUIDE TUBES
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39. CONTAINER/ SCOOTER FOR SOURCE STORAGE
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40. LAST MAN OUT SWITCH
AREA GAMMA MONITOR
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41. TREATMENT PLANNING SOFTWARE ICON TREATMENT PLANNING SCREEN
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42. TANDOM AND OVOIDS
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43. REFERENCES-
WALTER AND MILLER’S TEXTBOOK OF RADIATION
ONCOLOGY
KHAN’S TEXTBOOK OF RADIATION PHYSICS
PEREZ
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44. SPECIAL THANKS-
Ms. CHANCHAL
Dr. PRANJAL MAHESHWARI
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45. THANK YOU, AND
HAVE A NICE DAY!
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