Dosimetric Comparison Study Between Free Breathing and Breath Hold Techniques in Patients Treated by Liver-Directed Stereotactic Body Radiation Therapy

A systematic review of tumour position reproducibility and stability in breath-hold for radiation therapy of the upper abdomen

Background and purpose

Upper abdominal malignancies are relatively rare, and although surgery is considered the primary treatment option, radiation therapy has an emerging role in the management of liver, pancreas, kidney and adrenal gland tumours. Furthermore, stereotactic radiation therapy for the management of upper abdominal metastases is an expanding clinical indication. Breath-hold is one respiratory motion management strategy used in upper abdominal radiation therapy, and the reproducibility, and stability of breath-hold is critical for overall treatment accuracy.

Materials and methods

A systematic review of the literature was conducted in Medline, Embase and Cochrane databases with keyword and vocabulary terms related to radiation therapy, breath-hold and upper abdominal tumours.

Results

Following screening against the selection criteria, 41 studies were included. Breath-hold reproducibility was the most commonly reported outcome and exhale breath-hold was the most common type. Studies were either prospective or retrospective cohort studies, and the mean sample size was 19 participants. The risk of bias of each included study was assessed, and the mean quality assessment score for included studies was 90 % (77-100 %). Median exhale breath-hold cranio-caudal inter-fraction reproducibility was 0.6 mm, (IQR 0.3-1.6 mm), compared to inspiratory breath-hold 0.0 mm (IQR -0.6-2.97 mm). Stability measurements were ≤3 mm in 71 % of studies, irrespective of breath-hold type.

Discussion

Formulating institutional protocols for best clinical practice regarding breath-hold for upper abdominal tumours is challenging, given the significant variation in practices, interventions and definitions observed in the literature. Further investigation to individualise breath-hold strategies and safety margins is warranted.

Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma in Child-Pugh Class C As Bridge Therapy Before Liver Transplantation

Hepatocellular carcinoma (HCC) is a rising global health concern, frequently developing in patients with cirrhosis. Stereotactic body radiotherapy (SBRT) offers an effective treatment option for localized HCC, utilizing advanced imaging and planning technologies to accurately target tumors while sparing healthy tissues. It serves as an alternative when other locoregional therapies are contraindicated. We present the case of a 58-year-old male with HCC exceeding 5 cm and classified as Child-Pugh Class C. Following a failed attempt at transarterial chemoembolization (TACE) due to deteriorating liver function, SBRT was selected as an alternative bridging therapy. The patient received a total dose of 30 Gy in five fractions. Throughout the treatment, he experienced no significant toxicity, and post-SBRT imaging indicated gradual tumor regression. Seven months post-SBRT, the patient successfully underwent deceased-donor liver transplantation. Pathological examination of the explanted liver revealed necrotic nodules, indicating a positive response to SBRT.

Intrafractional Diaphragm Variations During Breath-Hold Stereotactic Body Radiotherapy for a Liver Tumor Based on Real-Time Registration Between Kilovoltage Projection Streaming and Digitally Reconstructed Radiograph Images: A Case Report

In liver stereotactic body radiotherapy (SBRT), precise image guidance is paramount, serving as the foundation of this treatment approach. The accuracy of SBRT in liver cancer treatment heavily relies on meticulous imaging techniques. The diaphragm, situated adjacent to the liver, is a crucial anatomical structure susceptible to positional and motion variations, which can potentially impact the accuracy of liver tumor targeting. This study explores the application of real-time kilovoltage projection streaming images (KVPSI) in comparison to digitally reconstructed radiography (DRR) for assessing diaphragm position deviations during breath-hold liver tumor SBRT. A 76-year-old male diagnosed with cholangiocarcinoma underwent breath-hold SBRT using split arc volumetric modulated arc therapy (VMAT), where a full arc was split into six sub-arcs, each spanning 60 degrees. The diaphragm dome positions were continuously monitored through KVPSI during treatment. The intrafractional position deviations of the diaphragm were calculated and analyzed for each split arc. The case report revealed a mean diaphragm dome deviation of 0.47 mm (standard deviation: 4.47 mm) in the entire arc. This pioneering study showcases the feasibility of intrafractional diaphragm position variation assessment using real-time KVPSI during the breath-hold liver tumor VMAT-SBRT. Integrating real-time imaging techniques enhances our comprehension of the intra-breath-hold variations, thereby guiding adaptive treatment strategies and potentially improving treatment outcomes. Clinical validation through further research is essential.