Authors: M. Rejab, M.Med.Phys. ^{a , c , d}, N.F. Khairuman, M.Sc. ^a, S. Jagabattuni, M.Med.Phys. ^b, D.A. Hizam, M.Med.Sc. ^a, N. Mohd Shariff, M.Med., FRCR ^c, D.D.W. Lee, FRCR ^{a , c}, N.M. Ung, Ph.D. ^{a , c}, Z. Jamalludin, Ph.D. ^{a , c}, A.H. Ng, Ph.D. ^{a , c , ∗}

a Department of Clinical Oncology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, 50603, Malaysia
b Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, 50603, Malaysia
c Department of Clinical Oncology, Universiti Malaya Medical Centre, Kuala Lumpur, 59100, Malaysia
d Medical Physics Department, Universiti Malaya Medical Centre, Kuala Lumpur, 59100, Malaysia

Leukemia is the sixth most common cancer in Malaysia, with 4273 cases reported between 2012 and 2016. Among pediatric patients under 15 years-old, Acute Lymphoblastic Leukemia (ALL) predominates, with an incidence of 77.4 per million population. 1 Total Body Irradiation (TBI) is a critical component in conditioning regimens for pediatric ALL patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Peters C. et al. 2 reported a randomized controlled trial that demonstrated significantly higher event-free survival (EFS) with a TBI-based regimen compared to a chemotherapy-based regimen. The findings were coherent with the For Omitting Radiation Under Majority age (FO- RUM) study which supported TBI-based regimens as being superior in improving overall survival (OS), reducing relapse, and lowering treatment-related mortality (TRM), despite concerns about late toxicities. 3 TBI remains an important conditioning regimen for treating high-risk pediatric ALL patients, offering higher survival benefits outweighing the risks of long-term adverse effects.

TBI has traditionally been delivered using large parallel-opposed fields at extended source-to-surface distances (eSSD), with patients positioned laterally or standing. Despite achieving adequate whole-body dose coverage, the technique has several drawbacks, including prolonged treatment times, patient discomfort and limited sparing of OARs, which can lead to both acute and late toxicities. 3-5 Dose uncertainties of up to ±10% have been reported with opposed radiotherapy fields. The limitations of conventional techniques for TBI have driven a breakthrough of modern techniques such as Helical Tomotherapy (HT) and volumetric modulated arc therapy (VMAT). 6 VMAT-based TBI offers pivotal advantages over conventional methods in improving dose homogeneity, OAR sparing and reduced monitor unit (MU) during treatment delivery. Patients are treated in a comfortable supine position without complex setups or custom shielding. Challenges were addressed related to large target volumes and the limitations of CT simulator and linear accelerator, which necessitates the acquisition of 2 image sets requiring patient repositioning. Extensive contouring, optimal plan optimization and quality assurance processes may further prolong treatment preparation. 7 Some treatment centres have adopted rotational TBI platforms, to enable seamless headfirst supine (HFS)-feet first supine (FFS) transitions without patient repositioning. Moreover, planning script automation has further improved planning efficiency.

Tas et al. demonstrated VMAT-TBI’s feasibility in delivering superior dose homogeneity with reduced OAR exposure, and reliable treatment verification using cone-beam CT and surface-guided systems. However, implementing VMAT-TBI requires advanced technology, meticulous planning, and robust quality control to ensure safe and effective delivery. The adoption of VMAT-TBI at the University Malaya Medical Centre (UMMC) is limited by bunker size and the absence of a dedicated TBI-specific linear accelerator. While VMAT is routinely used for other treatment sites, its application for TBI is still emerging. This study assesses the clinical feasibility of VMAT-TBI using a morphological phantom, in overcoming conventional TBI limitations such as dose heterogeneity and normal tissue sparing. Precision in beam delivery with efficient workflow aims to improve patient outcomes, particularly for pediatric cases, to enable safe and scalable implementation in resource-limited settings through rigorous phantom-based validation.

As of January 1, 2022, ARRT requires CE Credits for Directed Journal Readings to be based on the word count for each article. So, the number of CE Credits for each DJR article will vary for ARRT. 

ARRT CQR Credit Distribution
Radiation Therapy 2022       
   Procedures    
   Prescription and Dose Calculation = 0.5
   Treatments = 0.25
Radiation Therapy 2017     
   Procedures    
   Prescription and Dose Calculation = 0.5
   Treatments = 0.25