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Medical uses of ionising radiation
Medical uses of ionizing radiation include radiotherapy, medical imaging like CT scans and X-rays, and nuclear medicine. Radiotherapy uses radiation to treat cancer and can involve external beam techniques like 3D conformal radiation therapy (3D CRT), intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), stereotactic radiosurgery, and brachytherapy. Emerging techniques like proton beam therapy further improve radiation targeting and dose distribution. Precise imaging guidance and computer planning help deliver high radiation doses safely and effectively to tumors while avoiding nearby healthy tissues.
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Medical uses of ionising radiation
- 1. MEDICAL USES OF IONISINGRADIATION Prof Amin E AAmin Dean of the Higher Institute of Optics Technology Prof of Medical Physics Radiation Oncology Department Faculty of Medicine Ain Shams University
- 2. Medical Uses OfIonising Radiation Ionizing Radiation Radiotherapy Medical and Dental Radiology Nuclear Medicine Blood Products Irradiation
- 3.
- 4. What Is Radiotherapy? ❖The medical use of ionizing radiation in the treatment of malignant cancers. ❖ Types: ❑ External Beam Radiotherapy (EBRT) ❑ Brachytherapy
- 5. Different Radiotherapy Modalities Radiotherapy Teletherapy 2Dradiotherapy Electron beam 3DCRT IMRT VMAT Tomotherapy IGRT Stereotactic radiotherapy IORT Proton beam / Heavey charged particles Neutron therapy Flash Radiotherapy Brachytherapy
- 6. Aim of Radiotherapy •The aim of radiotherapy is to kill tumor cells and spare normal tissues Patient Tumor Beam 3 Beam 2 Beam 1
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- 8. How Is 2DRadiotherapy Given? ❖ 2D beams using linear accelerator or cobalt 60 machines from several angles. ❖ Aimed at tumour and sometimes the draining lymph node. LINAC COBALT 60
- 9. 2D Radiotherapy ❖ Simplefield arrangements ➢ Single Beam ➢ Two parallel opposed beams ➢ Multiple beams (three or four) ❖ Uniformly radiate both the target and the surrounding normal tissues. ❖ Includes the use of rectangular blocks to shield normal structures.
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- 12. Introduction ❖ Photon radiationtravels through the whole patient exposing the distal normal tissue. ❖ Electron therapy is suitable for tumors within up to 5 cm of the surface. ❖ H & N , Skin, Breast.
- 13. Electron-beam therapyis advantageous because it delivers a reasonably uniform dose from the surface to a specific depth, after which dose falls off rapidly, eventually to a near-zero value. Using electron beams with energies up to 20 MeV allows disease within approximately 5 cm of the surface to be treated effectively, sparing deeper normal tissues. Why Electron
- 14. Generation and Accelerationof Electron Beam • Linear accelerator is used to generate and accelerate electron beam.
- 15. Characteristics Of ClinicalElectron Beams X-Ray Contamination Surface Dose Depth of 80% Dose Depth of 50 % dose Depth of 90% Dose
- 16. Depth Dose Curveof Electron Beam ❖ A rapid dropoff of dose ❖ X-ray contamination ❖ 90%→E/4 cm 80%→E/3 cm ❖ The percent surface dose for electrons increases with energy.
- 17. Electron Beam vsPhoton Beam Electron Beam Photon Beam
- 18. Electron Beam vsPhoton Beam Electron Beam Photon Beam
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- 22. Electron Arc Therapy •For superficial tumors along curved surfaces
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- 24. Total Skin ElectronTherapy ❖ For superficial lesions covering large areas like mycosis fungoides. ❖ Different methods are possible to expose the whole body. Scatter place is closer to body. ❖ Traditionally, patient on a stretcher. Modified as standing or rotating. ❖ Modified Stanford technique. ❖ 2-9 MeV
- 25. The six-field Stanfordtechnique
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- 27. 3D CRT • 3DCRT, or three-dimensional conformal radiation therapy, is an advanced technique that incorporates the use of imaging technologies to generate three-dimensional images of a patient’s tumor and nearby organs and tissues. • The use of three-dimensional images in the treatment planning process distinguishes 3D CRT from other forms of conventional radiation therapy.
- 28. Conformal Therapy It isdescribed as radiotherapy treatment that creates a high dose volume that is shaped to closely “ Conform” to the desired target volumes while minimizing the dose to critical normal tissues.
- 29. Features of ConformalRadiotherapy 1. Target volumes are defined in three dimensions using contours drawn on many slices from a CT imaging study. 2. Multiple beam directions (2, 3, …, 7) are used to crossfire on the targets. 3. Individual beams are shaped to create a dose distribution that conforms to the target volume and desired dose levels.
- 30. Automated 3-D Conformal RadiationTherapy ❖ Radiation intensity is uniform within each beam ❖ Modulation conferred only by wedges. ❖ Beam shaping automated with multileaf collimators (MLC)
- 31.
- 32. What is IMRT? • IMRT stands for Intensity Modulated Radiation Therapy.
- 33. IMRT ❖ IMRT isan advanced form of 3D CRT ❖ IMRT refers to a radiation therapy technique in which nonuniform fluence is delivered to the patient from any given position of the treatment beam using computer-aided optimization to attain certain specified dosimetric and clinical objectives.
- 34. What is IMRT? • The purpose of IMRT is to shape isodose lines by varying the incident beam intensity spatially in order to conform to clinical requirement i.e. in order to generate a dose distribution that will meet certain clinical specifications. • These clinical specifications usually involves tight tolerances so that the target organs receive high doses and the sensitive organ receives an acceptable level. • The intent of this clinical specification is usually to escalate the normal dose levels to the target.
- 35. Different External BeamRadiotherapy Modalities
- 36. IMRT vs ConformalRT • Conformal radiotherapy is delivering a conformal dose distribution to the shape of the tumour by using uniform beam intensities within each beam portal. • IMRT is delivering a conformal dose distribution to the shape of the tumour by varying the beam intensities within each beam portal. Treated Volume Tumor Tumor Target Volume Treated Volume Critical structure Target Volume Collimator 3DCRT Critical structure IMRT
- 37. IMRT vs ConformalRT • Conformal radiotherapy is planned using manual optimization techniques. • IMRT is planned using inverse treatment planning techniques.
- 38.
- 39. 40 38 40 4038 40 Beam Intensity Map 3 MLC Segments 38 38 38 38 38 38 2 2 2 2 + +
- 40. IMRT - MLCDelivery Methods Converting Intensity Map to Leaf positions (‘Translator’) • Static • beam off during leaf/gantry/couch motion • slower, simpler • Dynamic • beam on during leaf/gantry/couch motion • faster, more versatile, more complicated
- 41. Forward Planning • For3D CRT forward planning is used. • Beam arrangement is selected based on clinical experience. • Using BEV, beam aperture is designed • Dose is prescribed. • 3D dose distribution is calculated. • Then plan is evaluated. • Plan is modified based on dose distribution evaluation, using various combinations of – Beam , collimator & couch angle, – Beam weights & – Beam modifying devices (wedges, compensators) to get desired dose distribution.
- 42. Inverse Planning (IMRTPlanning) • IMRT planning is an inverse planning. • It is so called because this approach starts with desired result (a uniform target dose) & works backward toward incident beam intensities. • Aftercontouring, treatment fields & their orientation dnuora )elgna maeb( si tneitapdetceles. • Next step is to select the parametersused to drive the optimization algorithm to a particular solution. • Optimization refers to mathematical technique of – finding the best physical and technically possible treatmentplan – to fulfill specified physical and clinical criteria, – under certain constraints – using sophisticated computer algorithm
- 43. Inverse Planning 1. Dosedistribution specified Forward Planning 2. Intensity map created 3. Beam Fluence modulated to recreate intensity map Inverse Planning
- 44.
- 45. Volumetric Modulated ArcTherapy (VMAT) ➢VMAT is a new type of IMRT technique. ➢VMAT stands for Volumetric Modulated Arc Therapy ➢The radiotherapy machine rotates around the patient during treatment
- 46. Definition Intensity Modulated Arctherapy where the following three parameters are modulated simultaneously ❖ Gantry rotation with variable speed ❖ Dose rate ❖ Leafe speed
- 47.
- 48. Tomotherapy • Tomotherapy isintensity-modulated rotational radiotherapy utilizing a photon fan beam. • Radiation therapy device designed on a CT scanner-based platform. • Tomotherapy means: slice therapy coined to describe IMRT using fan beam. • Tomo = slice, section (Gk) • Therapy = treatment
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- 50. It is aCt machine in addition to the therapy machine
- 51. Intensity Modulation • Thelinac output can be varied. • The jaw opening can be changed. • The gantry speed can be altered. • The couch speed can be modified. • The leaf states can be changed.
- 52. Helical Delivery Can irradiateup to a 160 cm long field.
- 53. From Dr. AnLiu Total Marrow Irradiation Using Tomotherapy
- 54.
- 55. Stereotactic • “Stereo” (Greek:“solid” or “3-dimensional”) “tact” (Latin: “to touch” ) • Thus the literal meaning: “3-dimensional arrangement to touch”
- 56. Stereotactic Irradiation • Stereotacticirradiation is a highly precise form of radiation therapy initially developed to treat small brain tumors and functional abnormalities of the brain. • However, attempts are under way to extend the technique to other parts of the body (stereotactic body radiotherapy) (SBRT).
- 57. Stereotactic Irradiation • Stereotacticirradiation gives radiotherapy from many different angles around the body. The beams meet at the tumor. • This means that the tumor receives a high dose of radiation and the tissues around it receive a much lower dose. • This lowers the risk of side effects.
- 58. Types of StereotacticIrradiation Stereotactic Irradiation Stereotactic Radiosurgery Stereotactic radiotherapy
- 59. ❖ Stereotactic Radiotherapy Thedelivery of multiple fractionated doses of radiation to a definitive target volume sparing normal structure (both intra as well as extracranial) ❖ Stereotactic Radiosurgery The delivery of a single, high dose of irradiation to a small and critically located intracranial volume, sparing normal structure Types of Stereotactic Irradiation
- 60. The aim isto encompass the target volume in the high dose area and, by means of a steep dose gradient, to spare the surrounding normal tissue Aim of Stereotactic Irradiation
- 61. Characteristics of StereotacticIrradiation The main characteristics of stereotactic irradiation are: • The total prescribed doses are of the order of 10 Gy - 50 Gy. • The planning targets are small, with typical volumes ranging from 1 cm3 to 35 cm3. • The requirements for positional and numerical accuracy in dose delivery are ±1 mm and ± 5%, respectively. • Essentially any radiation beam that has been found useful for external beam radiotherapy has also found use in radiosurgery (cobalt-60 gamma rays, megavoltage x rays, proton and heavy charged particle beams, neutron beams).
- 62. Equipment of StereotacticIrradiation Stereotactic Irradiation Gamma Knife CyberKnife NovalisTX Linac Tomotherapy Proton Beam Stereotactic Radiosurgery Stereotactic Radiotherapy All machines can be used in both SRT and SRS except GammaKnife can only be used in SRS
- 63. Radiosurgical Techniques Gamma Knife(Gamma unit) • Gamma Knife (Gamma unit) is a radiosurgical device that has been associated with, and dedicated to, radiosurgery for the past four decades.
- 64. Gamma Knife • Gammaunit incorporates 201 cobalt-60 sources, each source with an activity of 1.1 TBq (30 Ci). • Sources produce 201 circular gamma ray beams directed to a single focal spot at an SAD of 40 cm.
- 65. Gamma Knife • Collimatoraims the radiation emitted by the Co-60 sources to a common focal point.
- 66. Gamma Knife • Thisis analogous to focusing the radiant energy of the sun with a magnifying glass to a hot focus. • Near the glass there is not much heat, but the energy is intense at the focal point. • Optical lenses can not focus gamma rays, rather individual beams are allowed to summate by overlapping at the focal point of the collimator, achieving the same effect. Collimator allows the beam focus size to be adjusted from 4 to 18 mm in size.
- 67. CyberKnife Miniature linac ona robotic arm (CyberKnife): • This radiosurgical technique uses: • A miniatute 6 MV linac instead of a conventional isocentric linac. The miniature linac operates in the X band and is mounted on an industrial robotic manipulator. • Non-invasive image guided target localization, instead of the conventional frame based stereotaxy. • Image-guided frameless radiosurgery system achieves the same level of targeting precision as the frame-based radiosurgery.
- 68. Treatment couch Linear accelerator Manipulator Image detectors X-ray sources Synchrony™ camera TargetingSystem Robotic Delivery System Cyberknife
- 69. NovalisTX The Novalis Tx platform incorporatestwo complementary imaging systems that work together to enhance treatment precision by enabling doctors to target areas being treated.
- 70. NovalisTX • The ETX™(ExacTrac®) room-basedX-ray imaging system provides real-time imaging and fine-tuning of a robotic couch that moves in six dimensions to ensure that the targeted lesion is aligned with the treatment beam during treatment.
- 71. Tomotherapy rapidly rotates thebeam around the patient (and inside the housing of the unit), thus allowing the beam to enter the patient from many different angles in succession. So it can be used in SBRT Tomotherapy
- 72. The chiefadvantage of charged proton radiosurgery is that the beams stop at a depth related to the beam's energy. The lack of an exit dose and the sharp beam profile of protons allow target irradiation with lower integral doses than are delivered with photon irradiation. Proton Radiosurgery
- 73. LINAC • The LinearAccelerator is used to focus high energy Xray onto the tumor site, disrupting its DNA. • High energy x-rays will be directed to the patient’s tumor and shaped as they exit the machine to conform to the shape of the patient’s tumor.
- 74. Modifications to StandardIsocentric Linacs for Radiosurgery Modifications are relatively simple and consist of: • Supplementary collimation • Either in the form of a set of collimators to define small diameter beams • Or with a miniature MLC to define small area irregular fields • Remotely controlled motorized table or treatment chair rotation. • Table brackets or a floor stand for immobilizing the stereotactic frame during treatment. • Special brakes to immobilize the vertical, longitudinal and lateral table motions during treatment. • Interlocked readouts for angular and height position of the couch.
- 75. Multiple Non-coplanar ConvergingArcs Technique • Target dose is delivered through a series of gantry arcs, each arc with a different stationary position of the treatment couch or chair. • Arc angles are usually smaller than 180o to avoid parallel-opposed beams in the plane of the arc. • Typical number of arcs used ranges from 4 to 11.
- 76. Beam Entry TracesFor Various Linac- Based Techniques
- 77. Stereotactic Frame ImmobilizationIn Linac-based Radiosurgery • Immobilization of the stereotactic frame during the treatment is achieved with special brackets which attach the frame to the linac couch, chair, or a special floor stand. • Direct couch mounting of the stereotactic frame is less expensive, safer for the patient, and more practical than mounting onto a floor stand.
- 78.
- 79. Stereotactic Collimators Thestereotactic radiation is characterized bya very steep dose fall-off on the margin of the target volume. The steep dose gradient is achieved by the use of appropriate collimators and a multitude of radiation directions.
- 80. Collimation For Linac-Based Radiosurgery •Most linac based radiosurgical techniques use circular radiation beams which are produced by special collimators attached to the tray holder in the head of the linac. • Circular beams are usually between 10 and 40 mm in diameter at the linac isocentre and are produced by 10 cm thick lead cylinders with appropriate circular holes drilled along their axes. • Use of the original rectangular linac collimators for defining the small radiosurgical beams is not recommended.
- 81. Example Of CircularCollimator Attached To The Linac Head
- 82.
- 83. Intraoperative radiotherapy • Intraoperativeradiotherapy (IORT) is a special radiotherapeutic technique that delivers in a single session a radiation dose of the order of 10 - 20 Gy to a surgically exposed internal organ, tumor or tumor bed. • IORT combines two conventional modalities of cancer treatment: surgery and radiotherapy. • Usually used to “clean up” a surgical bed
- 84. Beam Modalities forIORT Three beam modalities are used for IORT: • Megavoltage electrons • Orthovoltage X rays • High dose rate brachytherapy with iridium-192 source.
- 85. Electron Beam forIORT • The enengy of the electron beams used is usually between 9-16 Mev.
- 86. Original Hard DockingCox Ll Standard Linear Accelerator
- 87. Mobile Beam IORTSystem-Mobetron 4-12 MeV
- 88.
- 89.
- 90.
- 91. Control Workstation Arm stand with x-raysource X-ray source IORT with kV X-Ray
- 92. Solid Applicator AndBalloon
- 93. Solid applicator sizeavailable: 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 cm in diameter, labeled by A, B, C, D, E, F, G, and H for the part number. Reusable 100 times. Balloon size available: 3.0, 3.5, 4.0, 4.5, 5.0 cm in diameter. Single use. Applicator on the x-ray source Solid Applicator And Balloon
- 94. Spatial Distribution OfX-ray Beam 0 +1.5 mm -1.5 mm 7 6 5 4 3 2 1 Gy/min 50 kV, 40 µA
- 95. Carl Zeiss IORTIntraBeam System in OR A solid applicator with X-ray source ready to insert Radiation from a mini-x-ray source of 50kV Drape Applicator Lead Shield
- 96. Step 1: Thelumpectomy, immediately following tumor removal. Step 2: After the surgeon has removed the tumor, the radiation oncologist positions the INTRABEAM applicator in the area of the breast where the tumor was located. Step 3: Low energy radiation is delivered locally to the targeted tissue in the tumor bed, minimizing healthy tissue exposure to radiation. Step 4: After 20-30 minutes of radiotherapy, the applicator is removed and the surgeon then closes the incision. IORT Procedure with Solid Applicator
- 97. Electrons Vs. LowEnergy X Rays Electrons 12 MeV applicator 60 mm X ray 50 KV applicator 25 mm
- 98. Interstitial multi- catheter MammoSite IntraoperativeBrachytherapy Contura SAVI
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- 100. MammoSite – Single Entry/SingleCatheter
- 101.
- 102. SAVI Applicator – SingleEntry/Multi-Catheter
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- 105. Modified breast HAM (MickRadionuclear Instruments) Tungsten shield 2-cm total thickness
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- 107.
- 108. The Bragg peak •The Bragg peak is a pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation during its travel through matter. • For protons and other ion rays, the peak occurs immediately before the particles come to rest. • This is called Bragg peak • Proton beam is accelerated by Cyclotron.
- 109. Spread Out BraggPeak (SOBP) • In a typical treatment plan for proton therapy, the Spread Out Bragg Peak (SOBP, dashed blue line), is the therapeutic radiation distribution. • The SOBP is the sum of several individual Bragg peaks (thin blue lines) at staggered depths. The depth-dose plot of an x-ray beam (red line) is provided for comparison.
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- 111.
- 112. Conventional Radiotherapy And ProtonTherapy ROI Beam intensity Profile PatientTumor Beam intensity Profile ROI Tumour Beam intensity Profile Beam intensity Profile Beam intensity Profile Beam intensity Profile
- 113. Fast Neutron BeamTherapy
- 114. Neutron Radiotherapy Fast NeutronTherapy Beams Boron Neutron Capture Therapy
- 115. Fast Neutrons MethodsOf Production • Neutrons can be produced in a cyclotron by accelerating deuterons or protons and impinging them on a beryllium target. • Protons or deuterons must be accelerated to ≥50 MeV to produce neutron beams with penetration comparable to megavoltage x-rays.
- 116. P+ n Fast Neutrons FromDeuteron Bombardment Of Be •Stripping Process – • Proton is stripped from the deuteron. • Recoil neutron retains some of the incident kinetic energy of the accelerated deuteron. • For each neutron produced, one atom of Be is converted to B. 9 Be4 n + 10 B5
- 117. • Knock-out Process •Protons impinge target of beryllium, where they knock-out neutrons. • For each neutron “knocked-out”, one atom of Be is converted to B. 99 Be4 nP+ + 5 B Fast Neutrons From Proton Bombardment Of Be
- 118. Fast Neutrons MethodsOf Production
- 119. ❖ Large radioresistanttumors are not well controlled by photon (or proton) therapy ❖ Resting cells are radioresistant ❖ Hypoxic (low oxygen) cells are radioresistant ❖ Neutron therapy is less affected by cell cycle or oxygen content Why are Neutrons Needed?
- 120.
- 121. About Flash Therapy •Flash radiotherapy is a novel external non-invasive radiotherapy technique that consists of delivering a high dose of radiation at an ultra-high dose rate. • When compared to radiotherapy delivered at conventional dose rates (1 – 7 cGy/sec), the Flash phenomenon seems to appear when irradiation is delivered with a dose superior to 8 Gy and at a dose rate above 33 Gy/sec in a very short time (less than a second).
- 122. About Flash Therapy ❖Researcherstheorize that irradiation at very high dose rate causes oxygen depletion in tissues which renders healthy tissue radioresistant, enabling dose escalation to levels that destroy tumor tissues even in high hypoxia. ❖In other words, healthy tissue seems to withstand this novel method of irradiation better, while the tumor has the same level of sensitivity to Flash irradiation as to conventional treatment.
- 123. Advantages of FlashRadiotherapy • Why is radiotherapy with ultra- high dose-rate (Flash) of interest? • Possible increase in differential response between normal tissue and tumors. • Short treatment times (<1s) • Motion management, i.e. remove intra-fraction motion • Patient comfort • Improved treatment efficiency
- 124.
- 125. IGRT • Image-guided radiationtherapy (IGRT) is the use of x-ray images taken immediately before, during or after your radiation therapy treatment session to improve the accuracy and precision of treatment.
- 126. Treatment Planning inRadiotherapy position in the ct scan position in the treatment In the treatment the prostate position changes with respect to the reference position. Determines the reference position of the prostate throughout the treatment.
- 127. Why May TheTarget Be Elsewhere? • Mispositioning (interfraction) • Organ motion (intrafraction) • Shape change (interfraction) Sources of uncertainties May result in absorbed dose in the volumes of interest and organs at risk that do not correspond to the theoretical dose planned.
- 128. Immobilization Systems In manycases it is not enough. Personalized cushions Vacuum cushions
- 129. What is IGRT? IGRTmeans several things; • Use of images for online setup correction, before treatment begins • IGRT also may mean adaptive radiation therapy
- 130. What is IGRT? •With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Original treatment plan and anatomy Original treatment plan and new anatomy with tumor shrinkage due to radiation Adapted treatment plan Critical structure Target Prescription isodose
- 131. Will IGRT replaceIMRT? •No, the two are complementary. • IMRT allows the dose to conform tightly to the PTV. • IGRT allows the PTV to shrink to the CTV. • IG-IMRT then allows simultaneously margin-reduction and dose conformation. Conventional RT IMRT IG-IMRT CTV PTV Organ at risk High dose isodose
- 132. Imaging Techniques ForIGRT Planar Imaging IGRT Electronic Portal Imaging Devices (EPID Cyberknife Novalis Real-Time Tumor Tracking (RTRT) Gantry-Mounted Systems
- 133. Types of EPID ❖Liquid Matrix Ion Chamber ❖ Camera based devices ❖ Amorphous silicon flat panel detectors ❖ Amorphous selenium flat panel detectors
- 134. Real-Time Tumor Tracking (RTRT)CyberKnife ImagingTechniques for IGRT
- 135. On Board Imaging Intensifier KVXray Room Mounted OBI Gantry mounted OBI
- 136. Imaging Techniques forIGRT Volumetric X-ray imaging ❖ Kilovoltage fan-beam CT (kV CT) ❖ Kilovoltage cone-beam CT (kV CBCT) ❖ Megavoltage cone-beam CT (MV CBCT) ❖ Megavoltage fan-beam CT (MV CT)
- 137. Respiratory gating • RPMGating System • Infrared camera • External marker block • Gating workstation
- 138.
- 139. Brachytherapy • Brachytherapy =dose delivered from sealed radioactive sources implanted in the patient close to the target (brachys = Greek for short distance)
- 140. Brachytherapy the placement ofthe radiation sources in the target treatment area the rate or ‘intensity’ of the irradiation dose delivered to the tumour the duration of dose delivery Different types of brachytherapy can be defined according to:
- 141. Source Placement The twomain types of brachytherapy treatment in terms of the placement of the radioactive source are; Interstitial implant brachytherapy and Contact brachytherapy.
- 142. Interstitial Brachytherapy • Inthe case of interstitial brachytherapy, the sources are placed directly in the target tissue of the affected site, such as the prostate or breast Interstitial implant for breast radiotherapy
- 143. Contact Brachytherapy • Contactbrachytherapy involves placement of the radiation source in a space next to the target tissue. This space may be; • A body cavity (intracavitary brachytherapy) such as the cervix, uterus or vagina; • A body lumen (intraluminal brachytherapy) such as the trachea or oesophagus; • A radiation source can also be placed in blood vessels (intravascular brachytherapy) for the treatment of coronary in- stent restenosis.
- 144.
- 145. Dose rate • Thedose rate of brachytherapy refers to the level or ‘intensity’ with which the radiation is delivered to the surrounding medium and is expressed in Grays per hour (Gy/h). Low-dose rate(LDR) Medium-dose rate (MDR) High-dose rate (HDR) Pulsed-dose rate (PDR)
- 146. Low-Dose Rate(LDR) • LDRbrachytherapy involves implanting radiation sources that emit radiation at a rate of up to 2 Gy/h. LDR brachytherapy is commonly used for cancers of the oral cavity, oropharynx, sarcomas and prostate cancer.
- 147. Medium-dose rate (MDR) •MDR brachytherapy is characterized by a medium rate of dose delivery, ranging between 2 Gy/h to 12 Gy/h.
- 148. High-Dose Rate (HDR) •HDR brachytherapy is when the rate of dose delivery exceeds 12 Gy/h.The most common applications of HDR brachytherapy are in tumours of the cervix, esophagus, lungs, breasts and prostate. • Most HDR treatments are performed on an outpatient basis, but this is dependent on the treatment site.
- 149. Example for HDRBrachytherapy A tongue implant treated using a Nucletron High Dose Rate (HDR) remote afterloading unit
- 150. Pulsed-Dose Rate (PDR) •PDR brachytherapy involves short pulses of radiation, typically once an hour, to simulate the overall rate and effectiveness of LDR treatment. Typical tumour sites treated by PDR brachytherapy are gynaecological and head and neck cancers.
- 151. Radiation Sources Half-lifeEnergyTypeRadionuclide 30.17 years0.662MeVγ-rayCaesium-137 (137Cs) 5.26 years 1.17, 1.33 MeV γ-raysCobalt-60 (60Co) 73.8 days 0.38 MeV (mean) γ-raysIridium-192 (192Ir) 59.6 days 27.4, 31.4 and 35.5 keV γ-raysIodine-125 (125I) 17.0 days21 keV (mean)γ-ray Palladium-103 (103Pd) 1.02 years3.54 MeV β-- particles Ruthenium-106 (106Ru)
- 152. Duration of DoseDelivery The placement of radiation sources in the target area can be: temporary permanent
- 153. Temporary Brachytherapy • Temporarybrachytherapy involves placement of radiation sources for a set duration (usually a number of minutes or hours) before being withdrawn.
- 154. Permanent Brachytherapy • Permanentbrachytherapy, also known as seed implantation, involves placing small LDR radioactive seeds or pellets (about the size of a grain of rice) in the tumour or treatment site and leaving them there permanently to gradually decay. • Over a period of weeks or months, the level of radiation emitted by the sources will decline to almost zero. • The inactive seeds then remain in the treatment site with no lasting effect. • Permanent brachytherapy is most commonly used in the treatment of prostate cancer.
- 155. Permanent Brachytherapy "seeds" usedfor brachytherapy of prostate cancer
- 156. Electronic Brachytherapy Customized Ballon Applicator KVXray Tube AXXENT X ray Source Assembly
- 157.
- 158. Radiology • Radiology isthe medical discipline that uses medical imaging to diagnose and treat diseases within the bodies of both humans and animals.
- 159.
- 160. X-Ray Radiography • X-raymachine provide a static image on radiograph.
- 161. Fluoroscopy ❖ Fluoroscopy isbased on x-rays. ❖ X-ray tube is installed ❖ The radiation dose is higher than Radiography. ❖ Provide both static and dynamic images.
- 162. Computerized Tomography (CT) •A computerized tomography (CT) scan combines a series of X-ray images taken from different angles and uses computer processing to create cross- sectional images, or slices, of the bones, blood vessels and soft tissues inside your body.
- 163. Magnetic Resonance Imaging(MRI) • Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body.
- 164. Ultrasound • Ultrasound isa type of imaging. It uses high- frequency sound waves to look at organs and structures inside the body.
- 165.
- 166. What is NuclearMedicine • Nuclear medicine is a medical specialty that uses radioactive tracers (radiopharmaceuticals) to assess bodily functions and to diagnose and treat disease.
- 167. Nuclear Medicine Nuclear Medicine Diagnostic NM Therapeutic N M
- 168. Therapeutic Nuclear Medicine •Therapy using unsealed radioactive sources includes treatment of the thyroid (hyperthyroidism and thyroid cancer) using radioactive iodine, pain palliation of bone metastasis using radioactive bone seeking agents and others.
- 169. Diagnostic Nuclear Medicine Diagnostic NuclearMedicine Gamma Camera PET Scan
- 170.
- 171. Gamma Camera Gamma Camera SingleHead Gamma Camera Double Head Gamma Camera Trible Head Gamma Camera
- 172. Single Head GammaCamera
- 173. Double Head GammaCamera
- 174. Trible Head GammaCamera
- 175.
- 176. Static • Single imageof a particular structure • Demonstrates radiopharmaceutical distribution • Ex: lung scans, spot bone scans images, thyroid images • Obtained in various orientations, anterior, posterior, and oblique • Low activity levels • Generally 30 seconds to five minutes
- 177. Whole Body • Entirebody or a large section of body • Primarily used for • Bone scans • Tumor scans • Abscess imaging • Clinical and research applications
- 178. Dynamic • Timed recordof distribution of radiopharmaceutical • Commonly used for • Cardiac studies • Hepatobiliary studies • Gastric emptying studies Dynamic Renogram
- 179. 179 SPECT • SPECT meansSingle Photon Emission Computed Tomography • Images similar to CT & MRI • thin slices through a particular organ • 360 degree rotatator heads allows for: • Coronal, planar and 3D imaging • Ex: cardiac perfusion, brain, liver and bone studies
- 180. 180 SPECT and CTCombination • Merges SPECT functional testing with CT anatomic landmark images • Statistics show • 25-30% change of treatment options from what would have been done with SPECT alone
- 181.
- 182. Positron Emission Tomography(PET) • Positron Emission Tomography (PET) is a nuclear imaging technique that produces a 3-D image of functional processes in the body by detecting the radiation emitted by photons . • The system detects pairs of gamma rays emitted indirectly by positron emitting radionuclide (tracer), which was previously injected in body on a biologically active molecule, • 3-D images of tracer concentration within the body are then constructed by computer analysis.
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- 185. PET-CT Scanner Flat couchtop insert CT Scanner PET scanner ❖Allows hardware based registration as the patient is scanned in the treatment position ❖CT images can be used to provide attenuation correction factors for the PET scan image reducing scanning time by upto 40% 60cm
- 186. PET-CT CT only PETonly PET/ CT
- 187.
- 188.
- 189.
- 190. Blood Products Irradiation •Irradiation of blood components for the prevention of transfusion- associated graft versus host disease (TA-GvHD) in immunosuppressed or otherwise at-risk patients is a long- established practice. • Blood and blood components may be treated with gamma rays from 137Cs or 60Co sources