Procedures: Treatment Volume Localization (10%)

ARRT-T · 30 questions

• A patient with an oropharyngeal tumor needs six weeks of daily IMRT, has limited neck extension from arthritis, and cannot raise his arms above his head after shoulder surgery. Which immobilization setup best keeps his position reproducible from day to day?
• A patient with a large pendulous breast is booked for whole breast irradiation after lumpectomy. Shoulder stiffness makes a supine arms-overhead position uncomfortable, she cannot sustain a reliable breath hold, and the inframammary crease forms deep skin folds. At simulation, she can tolerate the supported arm position available on a prone breast board. Which treatment position and immobilization best meet her setup needs?
• A patient with painful bone metastases in the thoracic spine can lie only partially reclined; lying flat brings sharp pain within a minute. Ten palliative treatments are planned, and the same setup must be reproduced at each visit. Which positioning and immobilization approach best fits this treatment?
• A patient with a laryngeal tumor is simulated for an opposed lateral setup. The neck must stay extended so the mandible and cervical spine clear the target, the shoulders must stay below the field borders, and the head and neck must sit in the same place every day. Which positioning and immobilization arrangement best meets these localization requirements?
• A patient with a lower-lobe lung tumor is booked for simulation. The tumor moves noticeably with each breath, and the patient struggles to follow coached breath-hold instructions. CT simulation with breathing-motion imaging is available, while these machines cannot deliver respiratory gating. Which simulation, positioning and immobilization approach best accounts for the target's motion?
• A patient with laryngeal cancer is simulated for a matched midline neck field. The superior border reaches the skull base, and both shoulders must sit in a fixed, repeatable position clear of the lower border at every fraction. Which immobilization setup best reproduces this treatment position?
• A planning CT is being simulated for an abdominal target that sits against loops of small bowel, and the radiation oncologist wants the bowel lumen clearly visible on every slice for contouring. Which imaging preparation should be used before the scan to outline the bowel?
• At CT simulation, the therapist sees that small bowel loops sit directly against the pelvic target and are hard to separate from tumor. The physician orders an oral iodinated solution for the patient to drink one hour before the scan and asks for a simple explanation to give. Which purpose does the oral contrast serve on this planning CT?
• A patient drinks oral contrast before a pelvic CT simulation, and axial images show bright rounded structures low in the pelvis. The therapist must confirm these are bowel loops before the physician contours the target. Which sectional anatomy finding identifies them as bowel?
• A patient with a T2 glottic laryngeal cancer is simulated on a planning CT with IV contrast, so vessels enhance while the aerodigestive tract stays dark. On an axial slice at the level of the vocal cords you must identify the tube lying directly behind the tracheal air column before labeling the structures on the image. Which structure occupies that position, based on its relationship to the trachea?
• During a simulation CT of the upper abdomen, images are acquired with IV contrast in the portal venous phase. A 3 cm mass lies posterior to the peritoneal cavity, adjacent to the right kidney and psoas muscle, while nearby bowel loops lie anterior to it. Which localization of the mass best fits these anatomic relationships?
• During a pelvic simulation, the physician needs the loops of small bowel sitting above the bladder to stand out clearly on the axial CT slices so they can be separated from the target. The patient drinks comfortably and the department has cleared them for contrast. Which contrast approach best makes those bowel loops visible for contouring?
• A patient with a 3 cm tumor in the right lower lobe is simulated for stereotactic treatment, and fluoroscopy shows the lesion moving almost 2 cm with quiet breathing. The department can offer either a standard helical scan or a gated study, and the physicist needs the motion extent documented before contours are drawn. Which CT simulation acquisition best records the tumor's motion range for planning?
• A patient with a lung lesion that travels several centimeters with breathing is simulated for a stereotactic course; immobilization is set, the scanner can sort by respiratory phase, and the physician wants the motion characterized. Which CT acquisition approach best captures the target motion for planning?
• A patient with a lower-lobe lung tumor is simulated with a 4D CT for a motion-managed plan. On review, the breathing trace varies from cycle to cycle, and in several bins slices are missing across the tumor, which reaches the edge of the scanned volume at full inspiration. Which acquisition change best addresses both causes of incomplete respiratory bins on the repeat scan?
• A patient is simulated supine with both arms raised for a boost to a 1.4 cm supraclavicular target. The department's default planning CT uses 5 mm slices, and the radiation oncologist wants the target and its junction with the prior neck fields contoured on the same dataset. Which CT acquisition parameter should you adjust for this simulation?
• A patient with a right lower lobe lesion is being simulated for photon treatment, and the planning CT shows the lesion moving with quiet breathing. Immobilization and the scan range are already verified, and the physicist wants the full motion extent captured before contouring begins. Which CT acquisition approach will capture the full motion extent the physicist needs?
• A patient with a peripheral right lower lobe tumor is simulated for stereotactic lung treatment, and scout images show the mass moving several millimeters with each breath. The team must choose an acquisition that captures this motion for treatment planning. Which CT simulation acquisition best represents this respiratory motion for treatment planning?
• The bladder has been outlined on every axial slice of a pelvis CT taken at a fixed slice interval, with each outline's area stored on the workstation. The reported volume must account for every outline that was drawn. Which calculation gives the contoured bladder volume?
• During a CT simulation of a pelvis plan, the target is contoured on every axial slice, but the crosshair on the coronal reconstruction sits close to the superior edge of the volume. Which check confirms the isocenter before skin marks are made?
• A physician contours a lung lesion on the simulation CT, and the record must show each target volume as a separate structure for review. The plan has to cover microscopic spread beyond the visible lesion and absorb day-to-day setup variation. Which contour sequence correctly defines the volumes used for the dose plan?
• A pelvis planning CT was reconstructed at 5 mm spacing instead of the 3 mm spacing required by the simulation protocol, so the contoured target volume differs from the physician's estimate, and the isocenter sits at the center of the largest axial slice. Which corrections must be completed before the plan is calculated?
• During CT simulation for a pelvic plan, the radiation oncologist places a reference point in the middle of the target on the axial images. The patient will be set up daily with room lasers, and that point must be reproducible at every fraction. How should the therapist transfer the reference point and document it?
• After CT simulation of a pelvic target, the physician draws the target volume on the axial images and specifies that the isocenter should be at its center. Your workstation shows linked axial, sagittal, and coronal views with a movable crosshair. You must document the isocenter in the simulation note before the plan moves to dosimetry. How should you place and verify the isocenter relative to the contoured volume?
• After CT simulation for a head-and-neck case, department protocol requires four items in the record: verified skin marks, approved set-up photographs, written immobilization instructions, and a note on electronic device precautions. The planning team starts as soon as the therapist closes the session. Which documentation set most fully completes the simulation record?
• A head-and-neck patient finishes CT simulation in a thermoplastic mask with skin marks drawn and a set-up photograph taken, and the patient's wearable glucose monitor must be off at every visit. The record must let the next therapist confirm marks and photo, reproduce the position, and repeat the device step. Which record entry completes all three documentation requirements?
• Following a CT simulation, the therapist has saved two setup photographs, recorded skin marks, written set-up instructions, and a note describing how the patient's wearable electronic device was handled. A colleague will build the plan from this record tomorrow morning. Which verification confirms that the simulation documentation agrees with itself before planning begins?
• After CT simulation for an abdominal patient, a second therapist will run the daily treatments from the saved plan, and the scan plus setup photographs are already filed. Which detail must be written into the setup instructions to reproduce the position every day?
• Before a treatment plan is built, you check the simulation packet for a patient who has just finished her CT scan. The written setup sheet lists the immobilization device, her arms raised on the armrest, and the skin mark locations, but the setup photograph shows her with the device removed and her arms at her sides. The photograph is intended to document the treatment setup. Which documentation correction should be made before the packet is released for planning?
• After a CT simulation for a patient treated prone on a breast board, the record shows documented skin marks and four saved setup photographs, but the written setup note says only 'prone with the board in use.' Which update to the simulation documentation is needed before the plan is reviewed?