Energy‐dependent <scp>OAR</scp> sparing and dose conformity for total marrow irradiation of obese patients

Cherpak, Amanda; Monajemi, Thalat; Chytyk-Praznik, Krista; Mulroy, Liam

doi:10.1002/acm2.12413

Cited by 14 publications

(17 citation statements)

References 35 publications

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“…The target delineation for both TMI and TMLI has been varied in literature. Exclusion of mandible, maxilla, bones in the forearm, small bones of the hands and feet from the target has been diverse [1][2][3][4][5]. We have included the entire skeletal system excluding mandible, hyoid, laryngeal cartilage and patella.…”

Section: Discussionmentioning

confidence: 99%

“…However, this modality does not spare organs-at-risk (OAR) except lungs and results in large heterogeneities in radiation dosage across the body. Total marrow irradiation (TMI) targets the entire skeleton and lymphoid tissues while sparing the organs at risk such as parotids, oral cavity, lens, thyroid, lungs, heart, bowel, kidneys, liver, breast, etc., and is emerging as an alternative to TBI as it has shown reasonable safety and efficacy in phase I/II trials [1][2][3][4][5][6]. Addition of lymphoid irradiation to TMI which amounts to total marrow and lymphoid irradiation (TMLI) has the potential to reduce the rejection against the lymphocytes in donor marrow.…”

Section: Introductionmentioning

confidence: 99%

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Total marrow and lymphoid irradiation with helical tomotherapy: a practical implementation report

et al. 2020

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To standardize the technique; evaluate resources requirements and analyze our early experience of total marrow and lymphoid irradiation (TMLI) as part of the conditioning regimen before allogenic bone marrow transplantation using helical tomotherapy. Materials and Methods: Computed tomography (CT) scanning and treatment were performed in head first supine (HFS) and feet first supine (FFS) orientations with an overlap at mid-thigh. Patients along with the immobilization device were manually rotated by 180° to change the orientation after the delivery of HFS plan. The dose at the junction was contributed by a complementary dose gradient from each of the plans. Plan was to deliver 95% of 12 Gy to 98% of clinical target volume with dose heterogeneity <10% and pre-specified organs-at-risk dose constraints. Megavoltage-CT was used for position verification before each fraction. Patient specific quality assurance and in vivo film dosimetry to verify junction dose were performed in all patients. Results: Treatment was delivered in two daily fractions of 2 Gy each for 3 days with at least 8-hour gap between each fraction. The target coverage goals were met in all the patients. The average person-hours per patient were 16.5, 21.5, and 25.75 for radiation oncologist, radiation therapist, and medical physicist, respectively. Average in-room time per patient was 9.25 hours with an average beam-on time of 3.32 hours for all the 6 fractions. Conclusion: This report comprehensively describes technique and resource requirements for TMLI and would serve as a practical guide for departments keen to start this service. Despite being time and labor intensive, it can be implemented safely and robustly.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Total marrow and lymphoid irradiation with helical tomotherapy: a practical implementation report

et al. 2020

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“…The target delineation for both TMI and TMLI has been varied in literature. Exclusion of mandible, maxilla, bones in the forearm, small bones of the hands and feet from the target has been diverse [1][2][3][4][5][6]. We have included the entire skeletal system excluding mandible, hyoid, laryngeal cartilage and patella.…”

Section: Discussionmentioning

confidence: 99%

“…Total marrow irradiation (TMI) is emerging as an alternative to TBI as it has shown reasonable safety and efficacy in phase I/II trials [1][2][3][4][5][6]. Addition of lymphoidal irradiation to TMI (TMLI) has the potential to reduce the rejection against the lymphocytes in donor marrow.…”

Section: Introductionmentioning

confidence: 99%

Total marrow and lymphoid irradiation with helical tomotherapy: A practical implementation report

Chilukuri

Sundar

Thiyagarajan

et al. 2020

Preprint

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Objective To standardize the technique and resources for total marrow and lymphoid irradiation (TMLI) as part of the conditioning regimen before allogenic bone marrow transplantation (ABMT) using helical tomotherapy.Methods We used this technique in our first 5 patients requiring TMLI. Patients were immobilized using a mask and a whole-body vacuum cushion. CT scanning was performed in head first supine (HFS) and feet first supine (FFS) orientations with an overlap at mid-thigh. Target consisted of the entire skeleton, spleen, sanctuary sites and major lymphatics whereas lungs, kidneys, aero-digestive tract, bowel, parotids, heart and liver were defined as organs at risk (OAR). Treatment was performed in two parts based on 2 different plans generated in HFS and FFS orientations with an overlap at the mid thigh. Patients along with the immobilization device were manually rotated by 180° to change the orientation after the delivery of HFS plan. The dose at the junction was contributed by a complementary dose gradient from each of the plans. Plan was to deliver 95% of 12Gy to 98% of CTV with dose heterogeneity < 10% and pre-specified OAR doe constraints. Megavoltage-CT was used for position verification before each fraction. Patient specific quality assurance and an in-vivo film dosimetry to verify junction dose were performed in all patients.Results Treatment was delivered in two daily fractions of 2Gy each for 3 days with at least 8-hours gap between each fraction. The target coverage goals were met in all the patients. The average person-hours per patient were 16.5, 21.5 and 25.75 for radiation oncologist, radiation therapist and medical physicist respectively. Average in-room time per patient was 9.25 hours with an average beam-on time of 3.32 hours for all the six fractions. Conclusion This report comprehensively describes technique and resource requirements for TMLI and would serve as a practical guide for departments keen to start this service. Despite being time and labor intensive, it can be implemented safely and robustly. We will be using this methodology in a prospective phase II trial to study safety and feasibility of dose escalated TMLI as part of conditioning regimen before ABMT.

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“…With conventional TBI treatment, high-energy beams (10–18 MV) have historically been used, particularly for patients for which the thickness is greater than 35 cm, and therefore considered to be homogenous. However, when high-energy photon beams of more than 10 MV were used, the photoneutrons can lead to an increase in the undesired dose to the patient [23]. TMI techniques using 10 and 15 MV offer no advantages in consideration of the higher integral dose, larger penumbra and similar beam-on time and dose rate.…”

Section: Discussionmentioning

confidence: 99%

Effect of changes in monitor unit rate and energy on dose rate of total marrow irradiation based on Linac volumetric arc therapy

et al. 2019

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Background This study set out to evaluate the effect of dose rate on normal tissues (the lung, in particular) and the variation in the treatment efficiency as determined by the monitor unit (MU) and energy applied in Linac-based volumetric arc therapy (VMAT) total marrow irradiation (TMI). Methods Linac-based VMAT plans were generated for the TMI for six patients. The planning target volume (PTV) was divided into six sub-volumes, each of which had their own isocenter. To examine the effect of the dose rate and energy, a range of MU rates (40, 60, 80, 100, 300, and 600 MU/min) were selected for 6, 10, and 15 MV. All the plans were verified by portal dosimetry. Results The dosimetric parameters for the target and normal tissue were consistent in terms of the energy and MU rate. The beam-on time was changed from 59.6 to 6 min for 40 and 600 MU/min. When 40 MU/min was set for the lung, the dose rate delivered to the lung was less than 6 cGy/min (that is, 90%), while the beam-on time was approximately 10 min. The percentage volume of the lung receiving 20 cGy/min was 1.47, 3.94, and 6.22% at 6, 10, and 15 MV, respectively. However, for 600 MU/min, the total lung volume received over 6 cGy/min regardless of the energy, and over 20 cGy/min for 10 and 15 MV (i.e., 54.4% for 6 MV). Conclusions In TMI treatment, reducing the dose rate administered to the lung can decrease the incidence of pulmonary toxicity. To reduce the probability of normal tissue complications, the selection of the lowest MU rate is recommended for fields including the lung. To minimize the total treatment time, the maximum MU rate can be applied to other fields. Electronic supplementary material The online version of this article (10.1186/s13014-019-1296-y) contains supplementary material, which is available to authorized users.

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Energy‐dependent OAR sparing and dose conformity for total marrow irradiation of obese patients

Cited by 14 publications

References 35 publications

Total marrow and lymphoid irradiation with helical tomotherapy: a practical implementation report

Total marrow and lymphoid irradiation with helical tomotherapy: a practical implementation report

Total marrow and lymphoid irradiation with helical tomotherapy: A practical implementation report

Effect of changes in monitor unit rate and energy on dose rate of total marrow irradiation based on Linac volumetric arc therapy

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