Introduction to Radiation Therapy Planning with PET/CT Online Training

Continue Continue Continue Continue Untitled Scene Master Template HILS2218 | Effective Date: 29-Jul-2021 ? Introduction to Radiation Therapy Planning with PET/CT Online Training This course will discuss the fundamentals of radiation therapy, treatment techniques, tumor grading and staging, and simulation and radiation therapy workflows. It will also review the advantages of using PET/CT in radiation therapy planning. Describe the fundamentals of radiation therapy Describe the processes of simulation and radiation therapy delivery List the criteria for tumor grading and cancer staging Describe the different treatment techniques used in radiation therapy 1 4 3 2 5 State how PET/CT imaging assists with radiation therapy planning and treatment monitoring Welcome Welcome to the Introduction to Radiation Therapy Planning with PET/CT Online Training, discussing the fundamentals of radiation therapy, treatment techniques, tumor grading and staging, and simulation and radiation therapy workflows. It will also review the advantages of using PET/CT in radiation therapy planning. This course will cover the following five learning objectives. For navigation help, select the question mark button located in the lower right corner of each slide. ? Fundamentals of Radiation Therapy Radiation therapy is one of three established cancer treatments. Used to treat: Metastatic disease Proliferation of benign disease Stop recurrence Treat symptoms of advanced cancer Linear Accelerators Radioactive Sources Routinely combined with surgery and/or chemotherapy to improve therapeutic results. Fundamentals of Radiation Therapy Fundamentals: Radiation therapy is one of three established cancer treatments available today. It is used to treat most types of solid tumors as well as some selected hematologic malignancies. It is mostly used to treat metastatic disease, but it also can play a small role in preventing proliferation of benign disease, stop cancer from recurring elsewhere, and treat symptoms of advanced cancer. To improve therapeutic results, radiation is routinely combined with surgery, chemotherapy, or both. It is often used with surgery to destroy microscopic regions of tumor extension; and with chemotherapy to destroy the primary tumor more effectively. During radiation therapy, the radiation must be generated in a manner that it can be directed at the targeted tissues. Radiation for cancer therapy is predominantly generated through two means: linear accelerators and radioactive sources. Select the tab arrows to learn more about the two means. Linear Accelerators: External beam radiation therapy is the most commonly used form of therapy today, using a Linear Accelerator, or LINAC. This device accelerates charged particles, or electrons, to velocities near the speed of light, using oscillating electronic fields to push electrons through a series of accelerating cavities. The electrons are accelerated to energies between 4 to 18 mega electron volts. The electrons strike thin metal targets and are converted to photons using the bremsstrahlung process and a photon beam is produced. The dose from the photon beam is related to its intensity, defined as the number of photons per unit area. Linear Accelerators can also be configured to produce therapeutic electron beams by removing a photon generating target and replacing it with a thinner electron scattering foil. Radioactive Sources: Unstable isotopes can spontaneously decay to lower energy states, releasing energy in the process. This process releases therapeutically useful photons, electrons, or other decay products. Therapy isotopes vary in half-life and energies. The higher the energy of the isotopes, the deeper into the tissues the therapies penetrate. Lower energy isotopes must be placed closer to the lesion. Sources are usually formed into small-sealed seeds, typically 1 to 5 millimeters in size as a temporary or permanent placement. Radioactive Sources Radioisotopes in Radiation Therapy: Unstable isotopes can spontaneously decay to lower energy states, releasing therapeutically useful photons/electrons/other decay products. The HIGHER the energy of the isotope, the DEEPER into the tissues the therapies penetrate Lower energy isotopes have to be placed closer to the lesion Sources are formed into small sealed seeds (1-5 mm) Data Courtesy of From Cox JD, Ang KK, editors. Radiation oncology: rationale, technique, results. 8th ed. St Louis: Mosby; 2003. keV, Kiloelectron volt Linear Accelerators (LINAC) Electron Production Mode Photon Production Mode Images Courtesy of Basics of Radiation Therapy: Zeman, Schriber, and Tapper ? Delivery of Therapeutic Radiation Linear Accelerator Brachytherapy Both Require: A precise location of the lesion within the patient anatomy Customization of the treatment plan for the individual patient Reliable and reproducible positioning of the patient relative to the radiation sources Images Courtesy of Varian Delivery of Therapeutic Radiation For externally delivered radiation, LINACs are usually mounted on gantries that rotate around the patient during delivery. The area that is being treated is at the center of the rotation and receives the majority of the dose as opposed to the healthy areas around the lesion. For treatment based on implanted radioactive sources, or brachytherapy, proper dose delivery consists of designing and delivering a three dimensional distribution of the radiation within the area to be treated. This will deliver a high dose region that decreases rapidly beyond the treatment volume. Both of these treatment options require: a precise location of the lesion within the patient anatomy; customization of the treatment plan for the individual patient; and reliable and reproducible positioning of the patient relative to the radiation sources, so that the intended radiation pattern can be precisely delivered. Treatment Techniques in Radiation Therapy Intro to Radiation Therapy Planning with PET/CT Treatment Techniques in Radiation Therapy In this section, we will discuss some history of Radiation therapy along with past and present treatment techniques. ? History of Radiation Therapy Treatment 1895 Wilhelm Conrad Roentgen discovers x-rays, coins term 1903 Henri Becquerel, Pierre Curie, Marie Curie awarded Nobel Peace Prize in Physics for discovery of spontaneous radio-activity Discovery Era 1911 Marie Curie awarded Nobel Peace Prize in Chemistry for discovery of radium and polonium 1920s Brachytherapy widely used to treat accessible tumors with radium needles or tubes 1928 International Commission of Radiological Protection (ICRP) is founded 1953 Linear accelerators deliver high-energy photons for deep-seated tumors & electrons for superficial lesions 1913 Wilhelm Conrad Roentgen invents heated cathode X-ray tube, enables external beam radiotherapy 1925 Philips introduces 50 kV equipment to treat superficial tumors 1948 Radiotherapy with synthetic radioactive cobalt (telecobalt therapy) eliminated the skin barrier tolerance 1970s 2D simulators improve radiotherapy delivery using 2D projections Kilovoltage Era Megavoltage Era Thariat, J., Hannoun-Levi, JM., Sun Myint, A. et al. Past, present, and future of radiotherapy for the benefit of patients. Nat Rev Clin Oncol 10, 52–60 (2013). History of Radiation Therapy Treatment This timeline shows a history of radiation therapy, beginning in 1895 when Wilhelm Conrad Roentgen discovered x-rays. The Discovery era went up until around 1911. The Kilovoltage era, began around 1913, and continued until the 1940’s, and the Megavoltage era, from the 1940’s until the 1970’s. ? History of Radiation Therapy Treatment 3D Era 1990s Multileaf collimator, driven by computerized treatment planning system, transforms 2D external-beam radiotherapy to 3D conformal radiotherapy 1996 Fluency is optimized with intensity-modulated radiation therapy using multileaf collimators, enabling inverse dose planning and dose-sculpting around concave volumes; sparing the parotids reduces xerostomia after head-and-neck irradiation Late 1990s Dose-volume histograms become increasingly used for decision making in 3D conformal radiotherapy planning 2000s Particle beam radiotherapy (protons or carbon ions) yields improved tumour coverage and spares normal tissues 2000s Whole-body stereotactic radiotherapy is used for mobile tumour targeting enabling robotic image-guided technology to track targets in real time 2005 Volumated dynamic arctherapy futher improves intensity-modulated radiation therapy techniques High-precision Modern Radiotherapy Era Thariat, J., Hannoun-Levi, JM., Sun Myint, A. et al. Past, present, and future of radiotherapy for the benefit of patients. Nat Rev Clin Oncol 10, 52–60 (2013). History of Radiation Therapy Treatment The modern advances in radiation therapy began in the 1990’s with the 3D era. Currently, we are in the high precision modern radiotherapy era. ? External Beam Treatment Techniques 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 Select the numbered steps to learn more about the various external beam treatment techniques. External Beam Treatment Techniques → usually mounted on gantries that rotate around the patient during delivery Image Courtesy of Varian External Beam Treatment Techniques External Beam Treatment Techniques: Now we will discuss 8 different types of External Beam Treatment Techniques for radiation. Select the numbered steps to learn more about the various external beam treatment techniques. 2D RT: In the 1970’s, it became possible to target tumors more accurately using 2D bony radiographic projections with the use of dedicated 2D simulators in well-individualized radiotherapy departments. There are 2 ways to deliver 2D radiation therapy. The first is using opposing fields for delivery. The second is using a 4 field box technique which delivers the dose from 4 different angles. 3D CRT: In the 1980s, CT scanners started moving into clinical practice. With the use of the computers in radiotherapy planning, radiation delivery gradually shifted from 2D to 3D planning. CT based simulation and planning allowed better radiation dose distributions. The introduction of multi leaf collimators, driven by algorithms and therapy planning systems, shape irregular fields and provide protection to normal tissue around the tumor volume. Planning with 3D CRT takes the 3D shape of the lesion into account, and any nearby vital body structures. It requires irregular shaping of beams and limited intensity modulation, or wedges. IMRT: Radiation oncology has seen dramatic advancements in radiation treatment technology that have increased the accuracy of treatment avoiding irradiation of surrounding healthy tissue. Such developments such as intensity modulated radiation therapyhave allowed radiation oncologist to more accurately sculpt dose around the tumor while sparing healthy tissue. IMRT improves on the 3D CRT technology. With 3D CRT, the beams contour the lesion, and the area that is exposed is not contoured. Organs at risk are also included in the treatment area, and healthy tissue is irradiated with as much intensity as the lesion. With IMRT, the dose is modulated so that the area being treated is more contoured, eliminating the organs at risk and healthy tissue from the highest doses. This is particularly useful in the treatment of patients with head and neck cancers, and is used to sculpt isodoses around the parotids. IGRT: Image guided radiation therapy uses on-board imaging on the linear accelerator during course of radiation treatment that takes pictures of the tumor immediately before or during the time radiation is being delivered. Specialized computer software compares the images used to establish the treatment plan, then necessary adjustments can be made to target radiation more precisely at the lesion, and avoid the surrounding healthy tissue. Gated delivery techniques using triggering devices allow for greater precision of radiation delivery while the tumor is in motion. There are two methods of IGRT. One is a 2D imaging method that uses an orthogonal beam pair to localize the lesion. This is a less precise method than the 3D imaging, which uses a CT scanner at the LINAC. VMAT: Volume modulated arc therapy is a type of radiation therapy technique that relies on using an arc or rotation to deliver the radiation dose. The delivery of the radiation is performed using a continuous rotation of the radiation source and allows the patient to be treated from a full 360 degree beam angle. This technology is essentially an alternative to IMRT. One major advantage of this technique is it’s efficiency and a reduction in the treatment delivery time. SRS & SRT: Both stereotactic surgery and stereotactic radiotherapy are techniques that deliver a high dose using hypofractionation. Hyprofactionation is a radiation therapy treatment in which the total dose of radiation is divided into large doses and given once a day, or less often, to a small area of the body. The treatment is given over a shorter period of time than the standard radiation therapy. There are three types of technology that deliver radiation during stereotactic radiosurgery. The LINAC uses x-rays to deliver treatments. These machines can perform SRS in a single session or over 3 to 5 sessions for larger tumors. The Gamma Knife uses 192 or 201 small beams of gamma rays to target and treat brain lesions and abnormalities. The individual beams are too weak to hurt the brain tissue as they travel through on the way to the target. The radiation is most powerful when the beams intersect. This technique is used for small to medium tumors in the brain. Proton Beam is a charged particle radiosurgery machine. It uses protons as a particle that is directed at the tumor. Protons ionize the atoms in the lesion, causing destruction of the tissue. Because cancer cells are less able to repair the damage than non-cancerous cells, they die off quicker. It is used to treat brain cancers in a single session or body tumors over several sessions. Tomotherapy: TomoTherapy, or helical therapy, combines an advanced form of IMRT, with the accuracy of CT scanning technology, all in one machine. This advanced therapy technology sculpts the therapy beam to direct powerful and precise radiation to tumors that are hard to reach. It employs built in CT imaging to confirm the shape and position of the tumor before each treatment, and reduces radiation exposure to healthy tissues and organs. Tomotherapy machines differ from LINACs in a number of ways. The main difference is that Tomotherapy delivers an intensity modulated pencil beam during the gantry rotation while the patient is moved through the bore simultaneously. They are better at targeting treatment sites throughout the body without having to pause for patient re-positioning. IORT: Intraoperative Radiation Therapy delivers a concentrated dose of radiation to a tumor while it’s exposed during surgery. This technology is useful in treating microscopic disease, reducing radiation treatment time, and providing an added radiation boost to the therapy. Typically, standard radiation therapy involves five days of treatment per week, for a total of 5-6 weeks. Using IORT, radiation can be delivered with similar dosage in a single session, while also preserving more healthy tissue. This helps to reduce side effects and time spent for the patient and your facility. Intraoperative Radiation Therapy (IORT) Advantages Treats microscopic disease Reduction of radiation treatment time Added radiation therapy boost IORT v. Standard Radiation Similar dose in a single session Preserves more healthy tissue Reduces side effects and time 8 Delivers a concentrated dose of radiation while tumor is exposed during surgery TomoTherapy Combines advanced form of IMRT with accuracy of CT scanning technology Precise radiation to hard to reach tumors Uses CT imaging to confirm shape/position of tumor Reduces radiation exposure to healthy tissues TomoTherapy v. LINAC Delivers intensity modulated pencil beam Gantry rotates while patient moves through bore Better at targeting treatment sites without pausing to move/adjust patient 7 CT guided IMRT Stereotactic Radiosurgery (SRS) & Stereotactic Radiotherapy (SRT) 6 Uses x-rays to deliver treatments Uses 192 to 201 small beams of gamma rays for brain lesions Uses protons as a particle that is directed at the tumor LINAC Gamma Knife Proton Beam Used to treat functional abnormalities and small tumors in the brain 1Image Courtesy of Varian, 2Image Courtesy of the Mayo Clinic, 3Image Courtesy of the National Association for Proton Tx Volume-Modulated Arc Therapy (VMAT) Delivery of radiation is performed using continuous rotation of the radiation source Allows patient to be treated from a full 360˚ beam angle 5 Alternative to IMRT Reduces treatment delivery time Image Courtesy of Varian Image Guided Radiation Therapy (IGRT) 4 On-board imaging takes pictures of tumor before or during radiation delivery. Specialized software uses images to establish a treatment plan. Gated delivery systems use triggering devices to allow for greater precision. Necessary adjustments can be made to the patient’s position and/or radiation beams to more precisely target lesion. 2D Imaging 3D Imaging Images Courtesy of Varian Intensity Modulated Radiation Therapy (IMRT) 3 Organ at Risk High Dose Area Tumor Organ at Risk High Dose Area Tumor Beam 3 Gantry 240˚ Beam 1 Gantry 0˚ Beam 2 Gantry 120˚ 3D CRT IMRT Allows more accurate “sculpting” around the tumor 3D Conformal Radiation Therapy (3D-CRT) 2 Takes into account the 3D shape of the lesion and nearby vital body structures Organ at Risk High Dose Area Tumor Beam 3 Gantry 240˚ Beam 1 Gantry 0˚ Beam 2 Gantry 120˚ External Beam Radiation Therapy (2D RT) 1 Opposing Fields 4 Field Box Uses 2D bony radiographic projections to accurately target tumors Beam 1 Gantry 0˚ Beam 2 Gantry 180˚ Beam 1 Gantry 0˚ Beam 3 Gantry 180˚ Beam 2 Gantry 90˚ Beam 4 Gantry 270˚ Image Courtesy of Siemens Healthineers ? Brachytherapy Techniques Brachytherapy is highly individualized for each patient, and performed as an inpatient procedure. Patient requirements: Localized cancer Small tumor size Patient must be able to tolerate the procedure Occasionally pre-irradiated with external beam prior to brachytherapy, or in conjunction with 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 Select the numbered steps to learn more about the various brachytherapy treatment techniques. Sealed radioactive source is placed in or very near the tumor Cancerous tumor Image Courtesy of the Saint Luke’s Health System Brachytherapy Techniques Brachytherapy Techniques: Brachytherapy is one of the earliest forms of radiotherapy. After discovery of radium by Marie Curie, it was used for brachytherapy in the late 19th century. Today, there are many different techniques and a large variety of equipment for delivery of the dose, and is highly individualized for each patient. Less than 10% of radiotherapy patients receive brachytherapy. The type of patient that usually is chosen for brachytherapy is a patient that has a localized cancer. The tumor must be relatively small, and the patient must be able to tolerate the procedure. Occasionally the patient is pre-irradiated with external beam prior to receiving brachytherapy and many times it’s used in conjunction with external beam therapy. Brachytherapy is performed by placing a sealed radioactive source in or very near the cancerous tumor. The sealed implant contains a small amount of radioactive material. Treatment success depends greatly on the source position along with the operator skill and experience. It’s typically performed as an inpatient procedure as opposed to external beam radiotherapy, which is usually administered in an outpatient setting. Low Dose Rate: Brachytherapy primarily uses three different techniques. Low Dose Rate uses a lower strength radioactive source and is associated with longer treatment times for a one time treatment. The most common LDR treatment site is the prostate, which involves permanent placement of tiny radioactive seeds in the tissue. Historically, LDR has been used in the treatment of other sites, such as gynecologic and head and neck cancers where low activity sources are temporarily placed for several days. High Dose Rate: High Dose Rate uses a higher strength source, for a shorter period of time. The patient must take some precautions around other people during this treatment. The implants are inserted once a day for several minutes and may either be removed or stay in place. This treatment can be performed as either an inpatient or outpatient procedure. Pulsed Dose Rate: Pulsed Dose Rate treatment is a brachytherapy technique that combines physical advantages of HDR technology with radiobiological advantages of LDR brachytherapy. Pulsed brachytherapy uses a stronger radiation source than that employed in LDR brachytherapy and provides a series of short 10 to 30 minutes long exposures every hour amounting to approximately the same total dose as that administered in the LDR. The advantages of PDR include: full radiation protection, all treatment types are feasible with one machine, optimization of the dose rate distribution, only one source to replace every three months, no source inventory, and finally, no source preparation. The disadvantages include: the maximum number of needles that can be implanted is limited by the number of after loading channels; only one person per day can be treated; the presence of connecting tubes between the machine and the needles may cause some discomfort for the patient, and the multiple source transfers may result in treatment irregularities due to source blockages. Surface Molds: There are basically three types of implants used in brachytherapy. The first is a treatment for superficial lesions of the skin. It consists of a mold for the area of concern, with a radioactive source close to the skin. The source distance from the skin determines the incident dose, the dose decrease because of fall off, and the dose homogeneity. Dose fall off decreases when sources are further away from the skin because of the inverse square law, and the further the source is from the skin, the more homogenous the dose distribution is. Some of the advantages of surface molds include: the fast dose fall off when it comes to body tissues, as well as they can conform to any surface. Intercavitary Implants: Another type of implant is the intercavitary implant, which is the introduction of radioactivity into a body cavity using an applicator. There a many different types of cancers that are treated using this method, including gynecological, bronchial, esophageal and rectal cancers. The most common use of this type of brachytherapy application is cervical cancer. It employs the use of many different types of applicators and is either used as a monotherapy or in addition to external beam therapy. Interstitial Implants: Interstitial implants consist of needles or flexible catheters inserted directly in the targeted area via surgery, which can be major, at times. Some of the cancers that use this type of therapy are breast, head and neck, sarcomas, and prostate cancers. These types of implants can be temporary, where the implant is removed before the patient is discharged from the hospital, or permanent, where the patient is discharged with the implant in place. Permanent implants consist of sealed sources, which are typically seeds, into the target organ. Temporary implants are rarely used today. Types of Sources/Implants Interstitial Implants Needles or flexible catheters inserted directly in the targeted area Types of cancers treated: Breast Head/Neck Sarcomas Prostate Surgery needed for insertion 6 Table with 2 columns and 2 rows Permanent Temporary Patient is discharged with implant in place Implant is removed before patient is discharged Types of Sources/Implants Intercavitary Implants Introduction of radioactivity into a body cavity via an applicator Types of cancers treated: Gynecological Bronchial Esophageal Rectal Most common application: cervical cancer 5 Image Courtesy of Varian Types of Sources/Implants Surface Molds Treats superficial layers of the skin Mold with a radioactive source Source distance from the skin determines: Incident dose Decrease of dose because of fall off Dose homogeneity 4 Image Courtesy of Varian Table with 1 columns and 3 rows Advantages Fast dose fall off when it comes to body tissues Can conform to any surface Dosing Techniques Pulsed Dose Rate (PDR) Combines physical advantages of HDR with radiobiological advantages of LDR Stronger radiation than HDR Series of 10-30 min exposures every hour 3 Table with 2 columns and 7 rows Advantages Disadvantages Full radiation protection Max # of needles implanted are limited All brachytherapy feasible with one machine Only 1 person per day can be treated Optimized dose rate distribution Discomfort due to weight of connecting tubes on the needles Only 1 source to replace every 3 months Multiple source irregularities No source inventory No source preparation Dosing Techniques High Dose Rate (HDR) Higher strength radioactive source Implants in the body for shorter period of time Implants inserted once a day for several minutes Can be removed or stay in place Inpatient & outpatient 2 Image Courtesy of Varian Patient must be cautious around other people Dosing Techniques Low Dose Rate (LDR) Lower strength radioactive source Longer treatment times for one treatment Most common treatment site: prostate → permanently placed source Other sites include: gynecologic, head, and neck cancers → low activity sources placed temporarily (several days) 1 Image Courtesy of Varian Tumor Grading & Staging Intro to Radiation Therapy Planning with PET/CT Tumor Grading and Staging Intro The next topic is how tumors are graded and staged before therapy. ? Tumor Grading and Staging Tumor grade describes a tumor based on the abnormality of the tumor cells under a microscope, and indicates how quickly a tumor is likely to grow/spread. Tumor Staging Tumor Staging Tumor Grading Tumor Grading Tumor Grading Table with 3 columns and 6 rows Grade Description GX undetermined Grade cannot be assessed G1 low Well differentiated G2 intermediate Moderately differentiated G3 high Poorly differentiated G4 high Undifferentiated G2 G1 G4 G3 Tumor Grading and Staging Tumor Grading: Tumor grade is the description of a tumor based on how abnormal the tumor cells and tumor tissue look under a microscope. It is an indicator of how quickly a tumor is likely to grow and spread. Grading systems differ, depending on the type of cancer. In general, tumors are graded as 1, 2, 3 or 4 depending on the amount of abnormality. In grade 1 tumors, the tumor cells and the organization of the tumor tissue appear close to normal. The following table is a list of grades that can be assigned to a tumor. Tumor Staging: Tumor staging uses the TNM system. The T refers to the size and extent of the primary tumor. The N refers to the amount of spread to nearby lymph nodes. The M refers to the presence of distant metastasis. A number is added to each letter to indicate the size and/or extent of the primary tumor and the degree of cancer spread. The x indicates that it can not be evaluated. Tumor staging uses the TNM System. Tumor Staging Size and extent of the primary tumor TX: Cannot be evaluated T0: No evidence of primary tumor Tis: Abnormal cells are present, but not spreading T1, T2, T3, T4: Size and extent Amount spread to nearby lymph nodes NX: Cannot be evaluated N0: No regional lymph node involvement N1, N2, N3: Degree of regional lymph node involvement Presence of distant metastasis MX: Cannot be evaluated M0: No distant metastasis M1: Indicated distant metastasis T N M Simulation and Radiation Therapy Workflows Intro to Radiation Therapy Planning with PET/CT Simulation and Radiation Therapy Workflows In this section, let’s discuss the workflows involved in simulation and radiation therapy. 1. Position Patient Must be exactly reproduced at the LINAC for treatment 2. Find Origin/Reference Establishes a coordinate system to identify isocenter of the tumor 3. Define Isocenter Point of interest where radiation beam is aimed for treatment 4. Mark Patient Mark or tattoo patients skin or mask where radiation should be aimed 5. Transfer Images Transfer images to treatment planning system ? Simulation 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 Process for determining the proper selection and orientation of beams, so that they properly overlap a target 1Image Courtesy of Varian Simulation Simulation Layer: The first step in designing and delivering radiation therapy to a patient is called simulation. Simulation is a process for determining the proper selection and orientation of beams so that they properly overlap a target. Simulation requires the determination of the patient’s dimensions for dose calculation as well as the determination and/or creation of identifiable reference points, to ensure the beams are being aimed correctly. Traditionally, CT has been the imaging modality of choice for radiation therapy simulation, but many hospitals and outpatient oncology centers around the world are using combined PET/CT systems in their radiation treatment planning process. The combined modalities provides additional information to more precisely target the radiation upon the diseased tissue, and to protect sensitive healthy tissue, such as heart, brain, spinal cord, esophagus, rectum, etc. A common simulation workflow mainly consists of 5 steps. Select the numbered steps below to walk through the simulation workflow. Patient Positioning: The first and very important step, is patient positioning, since treatment success or failure can be traced back to patient positioning and immobilization. This step is crucial because the patient position must be exactly reproduced at the linear accelerator for treatment. The simulation or treatment planning scan varies for each patient depending upon their unique condition, as well as type and extent of disease, but for all patients, it must be set up in a reproducible, accurate and precise manner. It is imperative that the treatment planning images be acquired in the exact, precise position that will be used in the treatment process. The following techniques should be utilized during positioning. First, the scanner should be equipped with an external laser system with 3-4 sources. An RTP pallet is used for the scan, and an identical one is used during the radiation treatment process. In addition, positioning and immobilization devices should be used during the scan to help keep the patient still. These same devices will also be used during treatment to duplicate positioning. The patient’s physical and emotional comfort can aid in reducing movement during the procedure. The major positioning elements include the lok-bar, patient positioning device, and the RTP flat pallet with an indexing system. Select the markers for more detail. Indexing requires the RTP flat pallet to be affixed to the patient handling table. The pallet features an array of indexing points running down its sides. The user attaches a lok-bar to any of the indexing points to index where they would like the patient positioning device to be located, then set the patient positioning device on the lok-bar which holds it in place. Select the arrow to learn about other common positioning devices. Common Positioning Devices: There are 2 main types of head and neck positioning devices. For conventional radiation therapy treatments the typical head and neck thermoplastic masks can be used. They are reliable and comfortable for the patient to have during both the simulation and treatment process. For advanced treatments such as IMRT, IGRT and 360 degree arc treatments a more sturdy head and neck patient positioning device may be required, that holds not only the head and neck but also the super clavicle region of the patient. Other common positioning devices are breast boards and vacuum bags or cushions. There are two types of breast boards available – supine and prone positioning. The selection of a supine versus prone will largely depend on the ability of the patient to tolerate the position during imaging and treatment. The breast board is a good immobilization solution not only for breast but also for lung and liver patients. The vacuum bags or cushions are very popular for hip and pelvis positioning because of patient comfort and setup reproducibility. They form a customized mold of the patient’s anatomical contours and can hold their shape throughout the entire treatment period, and are easy to clean and are reusable. Determine Origin/Scan Reference: After the patient has been properly positioned with the appropriate immobilization devices, the next step is to determine the origin or scan reference, which is establishing a coordinate system to which the isocenter of the tumor will be identified. 3 radio-opaque markers are placed at 3 different locations. The radio-opaque markers center on the virtual simulation software will be defined as the origin or scan reference. This is done while the patient is lying on the table. Define the Planning Isocenter: Once the origin is determined, the Radiation Oncologist will help determine the planning isocenter. The planning isocenter is a point of interest in the detected target volume at which the radiation beam is aimed for treatment. Mark the Patient: Once the planning isocenter is determined, the external positioning lasers move from the origin or scan reference point to the desired treatment isocenter. The patient then either receives a tattoo or their mask is marked. Marking tools may include India ink or radio-opaque BB’s. Markings determined during the simulation process are used to align the patient at the linear accelerator during the treatment process. Transfer Images: Finally, the images are transferred to the treatment planning system. The region of interest is generated on lesions using CT or PET/CT fused images and exported as RT structure sets to RT planning systems. The combined metabolic and anatomical information of PET/CT provides accurate delineation of the gross tumor volume and planning target volume, over CT imaging alone. Combined PET/CT imaging also improves the ability to delineate necrotic areas and modify the radiation treatment field, and results in more efficient radiation therapy planning, over CT alone. Common Positioning Devices Select to return to Patient Positioning. Head & Neck Conventional: Thermoplastic Reliable and comfortable patient fixation Advanced: Head/neck/supraclavicular devices ensure reproducibility Can be used for IMRT, IGRT & 360 arc treatments on the LINAC Breast Boards Supine or prone Selection depends on patient Used for breast, lung, and liver treatments Vacuum Bags/Cushions Forms customized mold of patient’s anatomical contours Used for hip & pelvis positioning Transfer Images Exporting PET based structures to RT planning systems: Region of interest (ROI) generated using CT or PET/CT fused images are exported as DICOM RT structure sets to the RT planning system Accurate GTV and PTV based on combined metabolic and anatomical imaging Delineation of necrotic areas for modification of the PTV 5 Image Source: Source: Imaging Live, Volume 7. Noora al Hammadi, MD, Dept of Radiation Oncology, Hamad Medical Corporation, Doha, Qatar. Mark the Patient with the Planning Isocenter External positioning lasers move from the origin/scan reference to the desired planning isocenter The patient receives a tattoo or their mask is marked: India ink or radio-opaque BB’s Markings are used to align patient at the linear accelerator during treatment 4 Define the Planning Isocenter 3 Origin/scan reference from radio-opaque markers Planning isocenter is a point of interest in the detected target volume, at which the radiation beam is aimed for treatment Isocenter Image Courtesy of Siemens Healthineers Determine Origin/Scan Reference 2 Place 3 radio-opaque markers at 3 different locations The center point will be defined as the origin or scan reference Image Courtesy of Siemens Healthineers Patient Positioning 1 RTP Flat Pallet Features an array of indexing points running down the sides Patient Positioning Device Set patient positioning device on lok-bar Lok-Bar Users attach a lok-bar to any of the indexing points to index a product Common Positioning Devices Requirements: Images must be acquired in exact, precise, reproducible position External laser system with 3-4 sources RTP Pallet Positioning and immobilization devices used in planning & treatment ? Radiation Therapy Planning 1 2 Definition of Planning Target Volume and Organs at Risk Selection of therapy techniques and beam parameters Determine dose prescription and fractionation Calculation of dose distribution 3 4 Learn More Learn More Radiation Therapy Planning Radiation Therapy Planning: The next step in the process is the therapy planning. This step includes the definition of the planning target volume and the organs at risk. This step also includes the selection of the therapy technique and beam parameters. Then the dose prescription and fractionation is determined as well as the calculation of the dose distribution. Select the Learn More tabs. Definition of PTV and OAR: Radiotherapy is a localized treatment. The definition of tumor and target volumes for radiotherapy is vital to its successful execution. This requires the best possible characterization of the location and extent of tumor. There are three main volumes in radiotherapy planning. The first is the position and extent of gross tumor, that is what can be seen, palpated or imaged, which is known as the gross tumor volume (GTV). The second volume contains the GTV, plus a margin for sub-clinical disease spread which therefore cannot be fully imaged, which is known as the clinical target volume (CTV). It is the most difficult because it cannot be accurately defined for an individual patient. Future developments in imaging, especially towards the molecular level, should allow more specific delineation of the CTV. The CTV is important because this volume must be adequately treated to achieve cure. The third volume, the planning target volume (PTV), allows for uncertainties in planning or treatment delivery. It is a geometric concept designed to ensure that the radiotherapy dose is actually delivered to the CTV. When planning external beam radiation therapy, there will always be healthy organs or tissues that will be in the path of the beam. In the planning stage, the organs have to be defined so that the risk of damage is minimized. This can be performed using either a 2D or a 3D anatomical model. Selection of Beam Parameters and Treatment Techniques: Once the contours have been defined and the organs at risk identified, the next step is to select the beam parameters and treatment techniques. Estimation of the expected dose requires extensive computer calculations on a volumetric grid and then the results are evaluated. Treatment planning is often an extensive process for the dosimetrist, who makes changes to the beam design to improve the resulting dose distribution. Even though there are vast improvements in software to help with this process, there is still a human factor that has to take into account all the information to figure out what is best for the patient. Selection of Beam Parameters and Treatment Techniques Dose estimation requires extensive computer calculations on a volumetric grid Dosimetrist makes changes to the beam design to improve the resulting dose distribution Definition of PTV and OAR Organs at Risk Define healthy organs or tissues in the path of the beam to minimize damage Tumor and Target Volumes 3D Anatomical Imaging Gross Tumor Volume (GTV) Outlines the position and extent of the gross tumor (what can be seen, palpated, or imaged) Clinical Target Volume (CTV) Contains the GTV plus a margin for sub-clinical disease spread which cannot be imaged Planning Target Volume (PTV) Allows for uncertainties in planning or treatment delivery 2D Anatomical Imaging Top – Image Courtesy of Siemens Healthineers, bottom – Image Courtesy of Varian ? Treatment Delivery Treatment plan is approved and sent to the LINAC May require quality assurance steps, treatment sent to test phantom with dose measurement devices Measured data is analyzed: Compared to dose estimations from RTP system Comparison approved prior to treatment Patient is positioned on the treatment table Use same immobilization devices as during simulation Patient moved to approximate treatment position using laser guided adjustments Orthogonal portal images, diagnostic x-rays, or cone beam CT volumes taken to adjust patient position Gantry is moved to starting beam angle then proceeds through succeeding beams Treatment times: 5–30+ mins Delivery in fractions Factors that affect treatment quality: Geometric errors Respiratory & cardiac motion Weight loss and shrinking Images Courtesy of Varian Treatment Delivery Let’s now discuss the delivery of the treatment. Once a treatment plan is approved, then the next steps in the process require that the data be transferred from the treatment planning system to the LINAC. In some cases where new or particularly complicated treatments are being proposed, it is necessary to interject quality assurance steps where the treatment plan is delivered to a test phantom with dose measurement devices. The measured data then needs to be analyzed, compared to dose estimations from the treatment planning system, and the comparison approved prior to treatment. The patient is then placed on the treatment table using the same immobilization device created during the simulation. The patient is moved to the approximate treatment position using laser guided adjustments. Typically orthogonal portal images, diagnostic x-rays or cone-beam CT volumes are taken to assess the patient position against a computer generated version using the planning CT or PET/CT volumes. Generally small adjustments to the patient position are made automatically. Alternatively, small markers implanted directly in the tumor can be used to provide more direct positioning information. The actual treatments then involve moving the treatment machine, or gantry, to the starting beam angle and then proceeding through the succeeding beams usually without manual interruption. Typical treatment times range from 5-10 minutes for simple cases to over 30 minutes for more complex treatments. Typically radiation treatments are delivered in fractions, which is one complete delivery of all beams, and fractions are repeated for 30 or more days, usually 5-6 times per week. Because of the repeated treatment sessions, there are a number of factors which affect the quality of the treatment. Because the patient’s setup is repeated for each fraction, there are unavoidable geometrical errors. These are usually inconsequential since the targeted PTV accounts for this possibility. Normal respiratory and cardiac motions also affect the actual dose delivered. For some patients, respiratory gating is used to reduce these effects. While these issues can generally be managed, the patient can lose weight over the weeks of treatment, their tumor may progress or shrink, and any number of other changes may affect the treatment given. In these circumstances, the patient’s situation needs to be reassessed, and planning processes repeated. ? Final Consultation The Radiation Oncologist will: Review the treatment course Review status of the patient Schedule a follow up to monitor conditions Final Consultation When all of the treatment has been delivered, it will be time for the final consultation with the patient. In this consultation, the radiation oncologist will review the treatment course and the status of the patient. At this time, a follow up schedule will be arranged to check on the success of the treatment and a follow up schedule to monitor the patient’s condition. Advantages of Using PET/CT in Radiation Therapy Planning Intro to Radiation Therapy Planning with PET/CT Advantages of Using PET/CT in Radiation Therapy Planning For the final part of the training, we will discuss the advantages of using PET/CT when performing radiation therapy planning. PET/CT useful in monitoring and evaluation of early treatment PET/CT useful in monitoring and evaluation of early treatment ? Advantages Precise metabolic imaging Precise metabolic imaging PET/CT assists with staging accuracy PET/CT assists with staging accuracy Exact tumor imaging for accurate/reproducible treatment planning Exact tumor imaging for accurate/reproducible treatment planning PET/CT can assist with functional characterization of tumors PET/CT can assist with functional characterization of tumors Incomplete disease visualization in conventional anatomical imaging Incomplete disease visualization in conventional anatomical imaging Incomplete disease visualization in conventional anatomical imaging CT Only – Primary Oral Cancer PET/CT Imaging – Metastases Select each advantage to learn more. Image Courtesy of University of Tennessee, Knoxville, TN, USA Advantages Tab 1: Conventional anatomical imaging such as CT has been the traditional imaging modality used for radiation therapy treatment planning. Anatomical imaging is dependent on the change in size and appearance of the tumor requiring structural or morphological change to occur. Subtle changes in the tumor, such as necrotic areas of the tumor, are therefore difficult to asses. Here is a clinical case that illustrates the benefits of PET/CT vs CT only imaging. In this oral cancer case, the primary tumor is seen on CT as well as on the PET/CT, which is indicated by the red arrow. A small neck node metastases is seen only on the PET/CT, indicated by the green arrow, which would greatly impact the RT plan. Anatomic modalities may not visualize the entire disease. Tab 2: Here is the impact of precise metabolic imaging on radiation therapy planning on tumor and planning volumes. For anatomy-based planning, with CT for example, large margins are added to the clinical target volume and uniform dose delivery for the entire tumor independent of metabolic activity. PET-based planning allows for personalized planning decrease of normal tissue dose with tighter margins for reduced side effects from radiation therapy. Tab 3: PET/CT helps in providing a more exact tumor staging process so radiation therapy treatment is more individualized. The images here show a PET/CT study that assisted with tumor staging post thyroid surgery prior to therapy. The lesions could not be seen on the CT and the location of the lesions were very hard to detect on the PET alone. The fused image created accurate staging prior to therapy. Tab 4: One of the challenges in the radiation oncology routine is that there is some significant variability in tumor contouring to define the GTV. The inaccuracy in the interpretation of the finding may result in over or under treatment of the lymph nodes, radiating of healthy tissues, and under-treatment of the tumor regions. The use of PET/CT results in high constancy of the GTV definition in RT planning. Some of the areas that are at particular advantage because of PET/CT imaging are the hilus area, the heart and pericardium, large vessels and the mediastinum. The use of PET/CT helps to reduce the time it takes for tumor contouring. Tab 5: PET/CT appears to be useful for early detection of pathological treatment response. In this example we have two separate rectal cancer studies. PET/CT appears to be useful in the early prediction of pathological treatment response to chemo and radiation therapy treatment. The first case shows a favorable response to chemo and radiation therapy. The tumor shows progressive reduction. The second case exhibits poor tumor response after chemo and radiation therapy. Tab 6: One of the limiting factors for the efficiency of radiotherapy is tumor hypoxia. The negative impact of hypoxic tumor cells are that they are resistant to radiation and chemo therapies. It also tends to induce the cell to change to a more aggressive tumor phenotype. Lastly, it can increase the relapse rate and development of metastases. One of the challenges for imaging and therapy of hypoxic tumors are the precise and reproducible localization of hypoxic regions within a tumor. Another challenge is translating the imaging information into a therapeutic concept, for example, how the dose should be tailored for the hypoxic regions within the tumor. PET/CT can assist with characterizing the functional aspects of a tumor that will be undergoing radiation therapy. PET/CT can assist with functional characterization of tumors Negative Impact of Hypoxic Tumor Cells: Resistance to radiation and chemo therapies Induces the cell to change into a more aggressive tumor phenotype Increases relapse rate and development of metastases Challenges for Imaging and Therapy of Hypoxic Tumor Cells: Precise and Reproducible localization within the tumor Translation of imaging information into a therapeutic concept PET/CT useful in monitoring and evaluation of early treatment Favorable Response Unfavorable Response Before Tx Day 8 Day 15 Post Tx Image Courtesy of Siemens Healthineers Exact tumor imaging for accurate/reproducible treatment planning Problem: Significant variability in tumor contouring to define GTV. Inaccuracy may result in: Over/under treatment of lymph nodes Radiating healthy tissue Under treatment of tumor regions Solution: PET/CT results in high constancy of the GTV definition in RT planning, and reduces tumor contouring time. Areas of particular advantage: Hilus area Heart and pericardium Large vessels of mediastinum Image Courtesy of Siemens Healthineers PET/CT assists with staging accuracy CT PET Image Courtesy of Siemens Healthineers Precise metabolic imaging Anatomy-Based Planning Large margins added to the CTV Uniform dose delivery for entire tumor independent of metabolic activity PET-Based Planning Personalized planning descrease of normal tissue dose with tighter margins Reduced side effects from radiation therapy ? Course Review Congratulations. You have completed the Introduction to Radiation Therapy Planning with PET/CT course. Select the numbered buttons below to review the material. List the criteria for tumor grading and cancer staging Describe the different treatment techniques used in radiation therapy State the fundamentals of radiation therapy 1 1 1 3 3 3 2 2 2 4 4 4 5 5 5 Describe the processes of simulation and radiation therapy delivery State how PET/CT imaging assists with radiation therapy planning and treatment monitoring Course Review State how PET/CT imaging assists with radiation therapy planning and treatment monitoring Advantages: Incomplete disease visualization in conventional anatomical imaging Precise metabolic imaging PET/CT assists with staging accuracy Exact tumor imaging for accurate/reproducible treatment planning PET/CT in monitoring and evaluation of early treatment PET/CT can assist with functional characterization of tumors Describe the processes of simulation and radiation therapy delivery Simulation Position the Patient Find the Origin/Scan Reference Define the Isocenter Mark the Patient Transfer the Images Radiation Therapy Planning Define Planning Target Volume and Organs at Risk Select therapy techniques and beam parameters Determine dose prescription and fractionation Calculate dose distribution Treatment Delivery Treatment plan is approved and sent to the LINAC Patient is positioned on the treatment table Gantry is moved to starting beam angle then proceeds through succeeding beams Final Consultation List the criteria for tumor grading and cancer staging Tumor staging uses the TNM System. T = Size and extent of the primary tumor N = Amount spread to nearby lymph nodes M = Presence of distant metastasis Tumor Grading Table with 3 columns and 6 rows Grade Description GX undetermined Grade cannot be assessed G1 low Well differentiated G2 intermediate Moderately differentiated G3 high Poorly differentiated G4 high Undifferentiated Describe the different treatment techniques used in radiation therapy External Beam Treatment Techniques: External Beam Radiation Therapy (2D RT) 3D Conformal Radiation Therapy (3D-CRT) Intensity Modulated Radiation Therapy (IMRT) Image Guided Radiation Therapy (IGRT) Volume-Modulated Arc Therapy (VMAT) Stereotactic Radiosurgery (SRS) & Stereotactic Radiotherapy (SRT) TomoTherapy Intraoperative Radiation Therapy (IORT) Brachytherapy Treatment Techniques Dosing Techniques Low Dose Rate (LDR) High Dose Rate (HDR) Pulsed Dose Rate (PDR) Types of Sources/Implants Surface Molds Intercavitary Implants Interstitial Implants State the fundamentals of radiation therapy Radiation therapy is one of three established cancer treatments. Used to treat: Metastatic disease Proliferation of benign disease Stop recurrence Treat symptoms of advanced cancer 2 types of Radiation Therapy: LINAC Brachytherapy Disclaimer Please note that the learning material is for training purposes only. For the proper use of the software or hardware, please always use the Operator Manual or Instructions for Use (hereinafter collectively “Operator Manual”) issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of the software and hardware available at the time of the training. The Operator Manual shall be used as your main reference, in particular for relevant safety information like warnings and cautions. Please note: Some functions shown in this material are optional and might not be part of your system. Certain products, product related claims or functionalities (hereinafter collectively “Functionality”) may not (yet) be commercially available in your country. Due to regulatory requirements, the future availability of said Functionalities in any specific country is not guaranteed. Please contact your local Siemens Healthineers sales representative for the most current information. The reproduction, transmission or distribution of this training or its contents is not permitted without express written authority. Offenders will be liable for damages. All names and data of patients, parameters and configuration dependent designations are fictional and examples only. All rights, including rights created by patent grant or registration of a utility model or design, are reserved. © Siemens Healthcare GmbH 2022 Siemens Healthineers Headquarters\Siemens Healthcare GmbH\Henkestr. 127\ 91052 Erlangen, Germany\Telephone: +49 9131 84-0\siemens-healthineers.com ? Disclaimer Exit To access your Certificate of Completion, select the Launch button drop down on the course overview page. You can also access the certificate from your PEPconnect transcript. ? You have completed the Introduction to Radiation Therapy Planning with PET/CT Online Training. Completion Navigation Help Select the icon above to open the table of contents. Click Next to continue. Next Welcome Slide The timeline displays the slide progression. Slide the orange bar backwards to rewind the timeline. Click Next to continue. Next Tmeline Select the CC icon to display closed captioning (subtitles). Click Next to continue. Next Caption Icon Select the buttons to learn more about a topic. Be sure to review all topics before navigating to the next slide. Click Next to continue. Next Tab Arrow Slide Select the X to close the pop-up. Click Next to continue. Next Layer Slide Some images may have a magnifier icon. Select the image to see an enlarged view. 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Assessment Slide Question Bank 1 HOOD05162003306881 | Effective Date: 19-Dec-2022 1.1 Welcome 1.2 Fundamentals of Radiation Therapy 1.3 Delivery of Therapeutic Radiation 1.4 Treatment Techniques in Radiation Therapy 1.5 History of Radiation Therapy Treatment 1.7 External Beam Treatment Techniques 1.8 Brachytherapy Techniques 1.9 Tumor Grading and Staging Intro 1.10 Tumor Grading and Staging 1.11 Simulation and Radiation Therapy Workflows 1.12 Simulation 1.13 Radiation Therapy Planning 1.14 Treatment Delivery 1.15 Final Consultation 1.16 Advantages of Using PET/CT in Radiation Therapy Planning 1.17 Advantages 1.18 Course Review 1.19 Disclaimer 1.20 Completion