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

Area of Science:

• Radiation Oncology
• Medical Physics
• Hematology

Background:

• Allogeneic bone marrow transplantation requires effective conditioning regimens.
• Total marrow and lymphoid irradiation (TMLI) is an advanced radiotherapy technique.
• Helical tomotherapy offers precise dose delivery for complex treatment fields.

Purpose of the Study:

• To standardize the technique for total marrow and lymphoid irradiation (TMLI).
• To evaluate the resource requirements for implementing TMLI.
• To analyze early clinical experience with TMLI before allogeneic bone marrow transplantation.

Main Methods:

• Computed tomography (CT) scanning and treatment in dual orientations (head-first/feet-first supine).
• Manual patient rotation for junctional dose integration.
• Dose delivery of 12 Gy in 6 fractions with stringent target coverage and organs-at-risk constraints.
• Megavoltage-CT for verification and in vivo dosimetry for quality assurance.

Main Results:

• Successful target coverage (95% of 12 Gy to 98% of CTV) was achieved in all patients.
• Significant resource allocation required: 16.5 hrs (radiation oncologist), 21.5 hrs (radiation therapist), 25.75 hrs (medical physicist) per patient.
• Total in-room time averaged 9.25 hours with 3.32 hours of beam-on time per patient.

Conclusions:

• TMLI using helical tomotherapy can be implemented safely and robustly.
• The technique is time and labor-intensive, requiring careful planning and resource management.
• This study provides a practical guide for departments adopting TMLI services.