Brianne Loritz BS., R.T.(T)



Clinical Oncology AssignmentDirections: Please choose a treatment plan that includes one of the anatomic regions below:Breast/chest wall with lymph nodesFind a case in your clinic that you have worked on, or are working on, to research and answer the corresponding questions regarding the overall treatment plan. (Note: this can be a case that your clinical instructor is planning or planned but you observed/participated). Please include any references and helpful screenshots to describe your rationale and to explain the treatment plan design and process.Questions: How was this patient positioned for simulation? What positioning devices/accessories were used, how and why? (5 points)A: For this treatment the patient was positioned supine in a large voc loc bag supporting the upper body, especially the arms, head & neck, and thorax region. Her arms are above her head and therefore out of the treatment field. Her head is turned away from the affected side to avoid treatment to the spinal cord and esophagus when treating the nodal region. Underneath the vac loc bag is a neutral F solid head rest and wingboard that is indexed to the table. The index bar helps ensure the patient is sitting correctly in the vac loc bag especially superior to inferiorly. The wingboard plus vac loc help build up the patient to compensate for the slant of the chest and make the lung parallel with the chest wall.1 In scenarios when the breast tissue is large the slant can also avoid the breast from falling toward patient face/chin. An angles cushion is under the patient knees for back comfort. Discuss the target dose as defined by your physician and the rationale behind the total dose and fractionation regimen. Include any references or current research to help answer the question. (5 points) A: The target dose defined is the entire right chestwall region (plus expanders), supraclavicular nodes, and levels 1-3 axillary nodes. The total dose prescribed is 5000 cGy in 25 fractions. Plus a 1000 cGy boost to the chestwall scar for 5 fractions. The treatment will be delivered with a 1 cm bolus on the lateral and medical tangent every other day. This fractionation and dose the MD chose comes from the NCCN guidelines, Breast Cancer Version 1.2017.2 What specific avoidance structures were contoured? Include a screen shot of your contoured target and organs at risk. Create and embed a table of OAR tolerance doses based on your physician prescription and include any associated QUANTEC values. List the contraindications if tolerance doses were to be exceeded. (20 points)A: The table below list the structure that were contoured. Figure 1. includes an image of these structures as well as the axillary lymph node levels 1, 2, 3, and supraclavicular nodes that were also contoured. Organ at RiskMD Tolerance DoseQUANTEC valueContraindicationsBronchial TreeMAX 80 GyMax Dose 80 GyPneumonitis EsophagusV45<33% (RTOG-0920)Mean Dose <34 GyV60<33%V50<32%EsophagitisSpinal CordMax 45GyMax Dose 50 Gy MyelopathyRT lungV20<15%V20 <=30% Symptomatic pneumonitisRT ThyroidALARA does not have constraint per MDV26 <20% (*John Hopkins Hospital)HypothyroidismBrachial PlexusMax 60-66 GyMax Dose 66 GyV60 <5% (*RTOG 0619)Brachial plexopathyLiverMean dose <32 GyMean Dose <32 GyRILD in normal liver functionTable 1. Information recorded from MD verbally and QUANTEC data.3 Colors coordinate with Figure 1 below.Figure 1. screen shot of your contoured targets and organs at risk.Identify any involved lymph nodes in your treatment region. Embed a screen shot of the nodal regions with corresponding labels. (15 points)A: Lymph nodes involved include Axillary lymph node levels 1, 2, and 3 and supraclavicular nodes. Figure 2. Lymph nodes included in the treatment volume.Use your IMAIOS Subscription:? and other anatomy references to describe the anatomical “boundaries” (physical limits) of the area treated. Embed a diagram and/or screen shot of your CT data to point out the boundaries. (20 points)A: For this set up you must consider the tangential beams, supraclavicular beam, and axillary beam. Tangent BordersMedially: Midline (wire placed in sim)Laterally: Mid-axially line (2cm beyond breast tissue) Plans measure ~2.16 cmSuperiorly: 1st costal interspace. Below humeral headInferiorly: ~1.5- 2 cm below inframammary fold. Plan measures ~2.06 cmFigure 3. Beams eye view of RT medial tangent beam. Notice Y2 Jaw=0, beam is half beam blocked. Lateral beam is opposed.Figure 4. Beams eye view of RT medial tangent beam with MLC blocking to midline wire to block lung and contralateral reconstructed breast.Supraclavicular BordersMedially: to the right edge of the spinal cordLaterally: splitting the humeral headSuperiorly: to include supraclavicular spaceInferiorly: abutting with tangent field at 1st costal interspaceFigure 5. Beams eye view of supraclavicular beam. Note Y1 jaw=0, beam is half beam blocked.Figure 6. Beams eye view of supraclavicular beam with MLC blocking spinal cord, esophagus, and humeral head. Posterior Axillary BorderMedially: splitting the sternal-clavicular articulation to cover axially nodesLaterally: splitting the humeral headSuperiorly: to about coracoid processInferiorly: abutting with tangent field at 1st costal interspaceFigure 7. Beams eye view of posterior axillary boost (PAB). Note Y1 jaw=0, beam is half beam blocked.Figure 8. Beams eye view of PAB with MLC blocking.Describe, in detail, the radiation treatment technique used to treat this anatomical region. (20 points)Examples: Technique type (VMAT, IMRT, Conformal), VMAT-Number of arcs, their direction, collimator rotations, number of degrees. Beam angles, couch rotations, field design, wedges, use of split fields, etc. Include all specific setup information to describe your process. Include any screen shots to help describe your plan design. A: The radiation treatment technique used in this case was 3D conformal with a single isocenter and half beam blocking The tangential beams, 180 degrees apart, were angled to avoid treatment to healthy lung tissue and contralateral reconstructed breast. The collimator was kept at 0 degrees. (Note had this been a left sided treatment, the collimator may have been angled slightly to use the jaws to block primary beam from the heart and lung.) The superior border of the tangent beam matches with the inferior border of the supraclavicular and axillary fields, around the 1st intercostal rib, below the humeral head. MLCs were used to block out as much of the right lung as possible without compromising treatment to the chestwall. Field in field technique on the 18 MV right medial oblique. This was used to help carve out hot spots that accumulated around the anterior portion of the breast. This makes sense seeing the tissue at this portion is much thinner compared to that closer to the chestwall. The patients separation was large, measuring around 28 cm from entrance beam to exit beam. Therefore mixed beam energies of 6MV and 18MV photons were used for the plan. The field weighting favored the medial beams with about 60% of the beam coming from the medial. This makes sense because the medial beam does not have as much tissue to penetrate through initially so when the beams started as equally weighted majority of the dose was being absorbed in the lateral portion of the chestwall/spacer. The plan was normalized to a reference point chosen in the breast. Another note to make is that there will be a 1 cm bolus placed on the tangent beams every other day. This is to help bring dose to the surface of the tangent and assure good dose to the skin. Bolus was chosen because this patient is a reconstructed breast therefore treatment to the skin is important for any left over disease. The implant underneath will still be receiving the full dose. The figure below is a visual of the bolus covering the entire medial tangent beam. Note the bolus should be removed for the supraclavicular and axillary beams.Figure 9. Shows 1 cm bolus covering tangent beam. The supraclavicular field is angled 10 degrees to get better coverage of the supraclavicular nodes without treatment to the spinal cord, chin, airway, or esophagus. During set up it is important for the therapists to verify patients chin is up and turned as far to the left as possible. The MLCs are used to block out the humeral head, spinal cord, esophagus, and part of the right thyroid gland. The technique used is known as half beam blocking. This is where the Y2 jaw of the tangent beam is 0 cm and the Y1 jaw of the supraclav and axillary beam is 0 cm, here is the matchline between the two beams. At CSM having a single isocenter that is halfbeam blocked allows the therapists to keep the table in the same position for the tangential and supraclav/axiallary treatment, therefore NOT having to adjust the table between fields. The matchline can be seen below in Figure 10 showing the dose colorwash. You can see where the supraclavicular field and tangential fields abut. -762002286000Figure 10. The dose colorwash showing the matchline between the supraclavicular field and tangent fields.The posterior axillary boost field is at 180 degrees to help give dose to the axillary nodes. It is also half beam blocked so its Y1 jaw is 0 cm. The PAB is only contributing 475cGy to the total prescribed nodal dose of 5000cGy. This is because the supraclavicular beam was not able to adequately deposit the prescribed dose to the nodes because of thickness of the patient, and therefore the axillary “boost” is necessary. See figure 11 below. -63817520891500Figure 11. Total dose contribution from PAB is 475 cGy at 19 cGy/fx. The last 5 fractions will be a 200 cGy daily boost to the scar using a cerrobend block in a 15X15 cone. Using 6 MeV electrons, 100 SSD.Figure 12. Showing the electron cut out for patients scar boost.Include a final DVH of your treatment plan with appropriate labels and discuss your ability to meet the target and OAR tolerance guidelines. (15 Points)A: As seen in Table 2 and Figure 9 below all MD constraints were met for this plan. As for QUANTEC guidelines the Thyroid did not meet the V26<26%.3 QUANTEC is given as guidelines therefore in this situation the MD was ok with the dose getting to the right thyroid because she knew it was more important to get the appropriate dose to the supraclavicular nodes. The MLCs were used to limit dose to the thyroid as much as possible but the dosimetrists knew it would not be feasible to block the entire thyroid without missing nodal coverage. Organ at RiskSpinal CordMAX DOSE = 7.7 GyEsophagusV45= 0%LiverMEAN DOSE = 1 GyRT LungV20 = 9.7%RT ThyroidV26 <20% **per MD okay with the RT thyroid V26 at 26% because it is necessary for nodal coverage. Also patient has no left thyroid issues.**Bronchial TreeMAX DOSE = 32.2 GyBrachial PlexusMAX DOSE = 54.4 GyTable2. Recorded outcomes for OARs.-628650-14287500Figure 9. Final DVH including OAR and target volumes.Lenards N, Vann A. Breast Cancer. [Softchalk]; La Crosse, WI:UW-L Medical Dosimetry program; 2018.Gradishar W, Anderson B, Balassanian R, et al. NCCN Guidelines Insights Breast Cancer, Version 1.2017 Featured Updates to the NCCN Guidelines. Journal of the National Comprehensive Cancer Network. 2017;15(4):433-451. Appendix: Normal Tissue Constraint Guidelines. QUANTEC. 2010. . Accessed February 12, 2018. ................
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