Application of active breathing control in 3-dimensional conformal radiation therapy for hepatocellular carcinoma: the feasibility and benefit

Advances in gross tumor target volume determination in radiotherapy for patients with hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is one of the most common malignant neoplasms. With the advancement of technology, the precision of radiotherapy (RT) for HCC has considerably increased, and it is an indispensable modality in the comprehensive management of HCC. Some RT techniques increase the radiation dose to HCC, which decreases the radiation dose delivered to the surrounding normal liver tissue. This approach significantly improves the efficacy of HCC treatment and reduces the incidence of Radiation-induced Liver Disease (RILD). Clear imaging and precise determination of the Gross Target Volume (GTV) are prerequisites of precise RT of HCC. The main hindrances in determining the HCC GTV include indistinct tumor boundaries on imaging and the impact on respiratory motion. The integration of multimodal imaging, four-dimensional imaging, and artificial intelligence (AI) techniques can help overcome challenges for HCC GTV. In this article, the advancements in medical imaging and precise determination for HCC GTV have been reviewed, providing a framework for the precise RT of HCC.

Liver stereotactic body radiation therapy without fiducial or retained ethiodized oil guidance warrants greater than 5 mm planning target volumes

INTRODUCTION

For liver stereotactic body radiation therapy (SBRT), the placement of fiducial markers or retained ethiodized oil by transarterial chemoembolisation (TACE) provides a landmark for consistent target localisation. TACE and fiducial markers are invasive procedures that harbour additional risks. We hypothesise that liver SBRT can be accurately delivered without the use of these invasive surrogate markers.

METHODS

We retrospectively identified 50 consecutive patients who underwent liver SBRT with respiratory motion management to a single lesion which exhibited retained ethiodized oil per prior TACE delivery. For each SBRT fraction, two manual rigid image registrations were performed by the treating physician. One using the liver contour as a surrogate for the target and second aligning only to the radio-opaque retained ethiodized oil of the treated lesion. The magnitude of the displacement vector between the two registration methods was used to assess the accuracy of target localisation if ethiodized oil was not present.

RESULTS

For the 50 patients, a total of 244 analysable cone-beam CTs (CBCTs) were included (six CBCTs excluded due to poor ethiodized oil visualisation). Respiratory motion management techniques consisted of active breathing control for 13 and abdominal compression for 37 patients. Forty-two patients had peripheral lesions and eight had central lesions (<2 cm from left and right portal veins). The average target localisation offset between the two registration methods (i.e. liver contour vs. retained ethiodized oil alignment) for patients with a single peripheral or central liver lesion was 5.8 and 5.3 mm, respectively.

CONCLUSIONS

Across all patients, the average change in target position exceeded 5 mm for image registration methods based on the liver contour alone versus the retained ethiodized oil region. This suggests that margins greater than 5 mm may be required for respiratory motion-managed liver SBRT treatments in patients who do not undergo prior TACE or fiducial placement.

Online verification of breath-hold reproducibility using kV-triggered imaging for liver stereotactic body radiation therapy

PURPOSE

To introduce a new technique for online breath-hold verification for liver stereotactic body radiation therapy (SBRT) based on kilovoltage-triggered imaging and liver dome positions.

MATERIAL AND METHODS

Twenty-five liver SBRT patients treated with deep inspiration breath-hold were included in this IRB-approved study. To verify the breath-hold reproducibility during treatment, a KV-triggered image was acquired at the beginning of each breath-hold. The liver dome position was visually compared with the expected upper/lower liver boundaries created by expanding/contracting the liver contour 5 mm in the superior-inferior direction. If the liver dome was within the boundaries, delivery continued; otherwise, beam was held manually, and the patient was instructed to take another breath-hold until the liver dome fell within boundaries. The liver dome was delineated on each triggered image. The mean distance between the delineated liver dome to the projected planning liver contour was defined as liver dome position error edome . The mean and maximum edome of each patient were compared between no breath-hold verification (all triggered images) and with online breath-hold verification (triggered images without beam-hold).

RESULTS

Seven hundred thirteen breath-hold triggered images from 92 fractions were analyzed. For each patient, an average of 1.5 breath-holds (range 0-7 for all patients) resulted in beam-hold, accounting for 5% (0-18%) of all breath-holds; online breath-hold verification reduced the mean edome from 3.1 mm (1.3-6.1 mm) to 2.7 mm (1.2-5.2 mm) and the maximum edome from 8.6 mm (3.0-18.0 mm) to 6.7 mm (3.0-9.0 mm). The percentage of breath-holds with edome >5 mm was reduced from 15% (0-42%) without breath-hold verification to 11% (0-35%) with online breath-hold verification. online breath-hold verification eliminated breath-holds with edome >10 mm, which happened in 3% (0-17%) of all breath-holds.

CONCLUSION

It is clinically feasible to monitor the reproducibility of each breath-hold during liver SBRT treatment using triggered images and liver dome. Online breath-hold verification improves the treatment accuracy for liver SBRT.

Institutional experience of using active breathing control for paediatric and teenage patients receiving thoraco-abdominal radiotherapy

Introduction

Active Breathing Control (ABC) is a motion management strategy that facilitates reproducible breath-hold for thoracic radiotherapy (RT), which may reduce radiation dose to organs at risk (OARs). Reduction of radiation-induced toxicity is of high importance in younger patients. However, there is little published literature on the feasibility of ABC in this group. The purpose of this study was to report our experience of using ABC for paediatric and teenage patients.

Methods

Patients ≤18 years referred for thoracic RT using ABC at our centre from 2013-2021 were identified. Electronic records were retrospectively reviewed to obtain information on diagnosis, RT dose and technique, OAR dosimetry, tolerability of ABC, post-treatment imaging and early toxicity rates.

Results

12 patients completed RT and were able to comply with ABC during planning and for the duration of RT. Median age was 15.5 years (10-18 years). Diagnoses were: Hodgkin lymphoma (n = 5), mediastinal B-cell lymphoma (n = 1), Ewing sarcoma (n = 5) and rhabdomyosarcoma (n = 1). For mediastinal RT cases (n = 6), median dose delivered was 30.6Gy(19.8-40Gy), median mean heart dose was 11.4Gy(4.8-19.4Gy), median mean lung dose was 9.9Gy(5.7-14.5Gy) and mean lung V20 was 10.9%. For ipsilateral RT cases, (n = 6), median hemithorax and total doses to primary tumour were 18Gy(15-20Gy) and 52.2Gy(36-60Gy) respectively. Median mean heart dose was 19.5Gy(10.6-33.2Gy) and median mean lung dose was 17.7Gy(16.3-30.5Gy). Mean bilateral lung V20 was 39.6%. Median mean contralateral lung dose was 5.2Gy(3.5-11.6Gy) and mean contralateral lung V20 was 1.5%. At a median follow-up of 36 months, only 1 patient had symptomatic radiation pneumonitis having received further thoracic RT following relapse.

Conclusions

ABC is feasible and well tolerated in younger patients receiving RT. Children as young as 10 years are able to comply. Use of ABC results in OAR dosimetry which is comparable to similar data in adults and can facilitate RT for extensive thoracic sarcoma.

Recurrence of hepatocellular carcinoma after radiofrequency ablation in a poor-risk patient with chronic renal failure and other complications successfully treated with stereotactic body radiotherapy

The patient was an 85-year-old man with hepatitis C-related liver cirrhosis and chronic renal failure caused by diabetes mellitus under maintenance hemodialysis (HD) who developed hepatocellular carcinoma (HCC) after achieving a sustained viral response with direct acting antiviral therapy 1 year and 3 months previously. HCC located near the right hepatic vein was treated by radiofrequency ablation (RFA) but recurrent disease accompanied by hepatic vein invasion was detected 3 months after RFA. The recurrent HCC was curatively treated with stereotactic body radiotherapy (SBRT). The patient had additional complications, including grade III AV block controlled by a pacemaker, colonic adenoma resected by endoscopic mucosal resection, and a small cerebral aneurysm, which was untreated. At 2 years after SBRT, there had been no recurrence of HCC. In this old HCC patient with various complications including HD with polypharmacy, multidisciplinary treatment, including SBRT, enabled the patient to achieve complete remission and maintain a good quality of life.

A prospective trial demonstrating the benefit of personalized selection of breath-hold technique for upper-abdominal radiotherapy using the Active Breathing Co-ordinator (ABC)

BACKGROUND

For upper abdominal (UA) tumors, our institutional-standard motion reduction method is Expiration Breath Hold (EBH), using Active Breathing Coordinator (ABC)^TM. However, an individual patient's breath-hold (BH) reproducibility (R_BH) may be improved in Deep Inspiration or Inspiration Breath-Hold (DIBH or IBH). This trial compared the tumor position R_BH, stability (S_BH), and breath-hold time (T_BH) of three BH methods, using ABC, to personalize the selection of technique, by employing a pre-planning screening assessment.

METHODS

Patients planned for UA radiotherapy (kidney, pancreas, liver, or adrenal gland), were invited to participate in this prospective trial. Active Breathing Coordinator (ABC)^TM education was conducted, then participants attempted EBH, DIBH and IBH, in randomized order. During five consecutive BH's for each method, kV fluoroscopy images of the diaphragm were acquired. The BH technique selection was personalized according to a decision matrix. The EBH and the personalized technique cohort mean R_BH and S_BH of were analyzed.

RESULTS

Between May 2019 and March 2020, 19 participants were recruited. Median age of participants was 68 years (range 32-81). Tumor sites included kidney (n=1), adrenal gland (n=5) and liver (n=14). One participant was excluded due to poor BH compliance, leaving 270 images from 18 participants for analysis. Mean T_BH was 22.1, 23.9 & 24.2 seconds for EBH, DIBH and IBH respectively. Screening selected EBH for 44% (n=8), IBH for 39% (n=7) and DIBH for 17% (n=3) of participants. The mean R_BH was superior at 0.92mm (0.79mm SD) for the personalized technique, compared to EBH of 1.79mm (1.49mm SD) (p=0.016). Pre-planned subset analysis of participants whose personalized technique was not EBH showed improved mean R_BH of 0.63mm (0.29mm SD) compared to their EBH R_BH of 2.2mm (1.7mm SD) (p=0.011).

CONCLUSIONS

In 56% of participants, DIBH or IBH demonstrated superior R_BH compared to EBH Personalized BH screening can inform selection of an ABC BH method which provides optimal R_BH with improved T_BH for an individual's planning and treatment course.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR): XXX (withheld - blinded manuscript).

Impact of breath-hold level on positional error aligned by stent/Lipiodol in Hepatobiliary radiotherapy with breath-hold respiratory control

Background

Respiratory motion management with breath hold for patients with hepatobiliary cancers remain a challenge in the precise positioning for radiotherapy. We compared different image-guided alignment markers for estimating positional errors, and investigated the factors associated with positional errors under breath-hold control.

Methods

Spirometric motion management system (SDX) for breath holds was used in 44 patients with hepatobiliary tumor. Among them, 28 patients had a stent or embolized materials (lipiodol) as alignment markers. Cone-beam computed tomography (CBCT) and kV-orthogonal images were compared for accuracy between different alignment references. Breath-hold level (BHL) was practiced, and BHL variation (ΔBHL) was defined as the standard deviation in differences between actual BHLs and baseline BHL. Mean BHL, ΔBHL, and body-related factors were analyzed for the association with positional errors.

Results

Using the reference CBCT, the correlations of positional errors were significantly higher in those with stent/lipiodol than when the vertebral bone was used for alignment in three dimensions. Patients with mean BHL > 1.4 L were significantly taller (167.6 cm vs. 161.6 cm, p = 0.03) and heavier (67.1 kg vs. 57.4 kg, p = 0.02), and had different positional error in the craniocaudal direction (− 0.26 cm [caudally] vs. + 0.09 cm [cranially], p = 0.01) than those with mean BHL < 1.4 L. Positional errors were similar for patients with ΔBHL< 0.03 L and > 0.03 L.

Conclusion

Under rigorous breath-hold respiratory control, BHL correlated with body weight and height. With more accurate alignment reference by stent/lipiodol, actual BHL but not breath-hold variation was associated with craniocaudal positional errors.

Protocol of a study investigating breath-hold techniques for upper-abdominal radiation therapy (BURDIE): addressing the challenge of a moving target

BACKGROUND

Radiation therapy to upper abdominal sites is technically challenging due to motion of tumors and surrounding organs resulting from normal respiration. Breath-hold, using an Active Breathing Coordinator is one strategy used to reduce motion in these tumor sites. Though widely used, no studies have prospectively compared the different breath-hold techniques (inspiration, deep-inspiration and expiration) using ABC in the same patient cohort.

METHODS

Patients planned for radiation therapy to upper abdominal tumors are invited to participate in this prospective study. Participants attempt three breath hold techniques: inspiration, deep-inspiration and expiration breath-hold, in random order. kV fluoroscopy images of the dome of diaphragm are taken of five consecutive breath-holds in each technique. Reproducibility and stability of tumour position are measured, and used to select the technique with which to proceed to planning and treatment. Reproducibility at planning and each treatment fraction is measured, along with breath hold time, treatment efficiency and patient experience.

DISCUSSION

The screening method was validated after the first three participants. This screening process may be able to select the best breath-hold technique for an individual, which may lead to improved reproducibility. The screening process is being piloted as a prospective clinical trial.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR): 12618001691235. Registered 12th October 2018. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376109&isReview=true .

Dosimetric study of three-dimensional static and dynamic SBRT radiotherapy for hepatocellular carcinoma based on 4DCT image deformable registration

The purpose of this work was to determine the actual dose received by normal tissues during four‐dimensional radiation therapy (4DRT) composed of ten phases of four‐dimensional computer tomography (4DCT) images. The analysis was performed by tracking the hepatocellular carcinoma SBRT. Data were acquired from the tracking of each phase with the beam aperture for 28 hepatocellular carcinoma patients, and the data were used to generate a cumulative plan, which was compared to a three‐dimensional (3D) plan formed from a merged target volume based on 4DCT images in a radiation treatment planning system (TPS). The change in normal tissue dose was evaluated in the plan using the parameters V5, V10, V15, V20, V25, V30, V35, and V40 (volumes receiving 5, 10, 15, 20, 25, 30, 35, and 40 Gy, respectively) in the dose‐volume histogram for the liver; the mean dose was analyzed for the following tissues: liver, left kidney, and right kidney. The maximum dose was analyzed for the following tissues: bowel, duodenum, esophagus, stomach, and heart. There was a significant difference in the dose between the 4D planning target volume (PTV) (average 115.71 cm³) and ITV (169.86 cm³). The planning objective was for 95% of the volume of the PTV to be covered by the prescription dose, but the mean dose for the liver, left kidney and right kidney had an average decrease of 23.13%, 49.51%, and 54.38%, respectively. The maximum dose for the bowel, duodenum, esophagus, stomach, and heart had an average decrease of 16.77%, 28.07%, 24.28%, 4.89%, and 4.45%, respectively. Compared to 3D RT, the radiation volume for the liver V5, V10, V15, V20, V25, V30, V35, and V40 using the 4D plans had a significant decrease (P ﹤ 0.05). The 4D method creates plans that permit sparing of the normal tissues more than the commonly used ITV method, which delivers the same dosimetric effects to the target.

The role of external beam radiotherapy for hepatocellular carcinoma patients with lymph node metastasis: a meta-analysis of observational studies

Purpose

Lymph node metastasis of hepatocellular carcinoma is categorized as advanced in Barcelona Clinic of Liver Cancer staging, and sorafenib is a sole treatment recommended. However, appliance of local treatment including external beam radiotherapy (EBRT) has not been uncommon. We performed a meta-analysis and systemically reviewed current literature to evaluate the efficacy and safety of EBRT.

Methods

PubMed, Medline, Cochrane library, and Embase were systemically searched until December 17, 2017. The primary endpoint of analyses was response rate (RR), and 1-year overall survival and complication rates of grade ≥3 were secondary endpoints. Complications were primarily assessed descriptively.

Results

A total of 8 studies comprising 521 patients were included. The pooled RR was 73.1% (95% confidence interval [CI]: 63.6–80.9), and high-dose EBRT groups had better RR than the low-dose group (82.2% [95% CI: 74.4–88.1] vs 51.1% [95% CI: 40.3–61.7]; P=0.001]. The pooled 1-year overall survival rate was 41.0% (95% CI: 32.9–49.6). Six studies assessed the survival benefit according to RR, and 5 (83.3%) of these 6 studies reported statistically significant survival benefit. The most common grade ≥3 toxicities were thrombocytopenia and gastrointestinal complication, with pooled rates of 3.4% (95% CI: 1.2–9.5) and 3.5% (95% CI:1.7–7.2), respectively.

Conclusion

EBRT showed a pooled RR of 73.1% and was safely performed. EBRT might palliate symptoms through tumor reductions and improve survival. Use of sorafenib combined or sequentially with EBRT can be recommended rather than monotherapy.

Intra- and inter-fractional liver and lung tumor motions treated with SBRT under active breathing control

Purpose

To assess intra‐ and inter‐fractional motions of liver and lung tumors using active breathing control (ABC).

Methods and Materials

Nineteen patients with liver cancer and 15 patients with lung cancer treated with stereotactic body radiotherapy (SBRT) were included in this retrospective study. All patients received a series of three CTs at simulation to test breath‐hold reproducibility. The centroids of the whole livers and of the lung tumors from the three CTs were compared to assess intra‐fraction variability. For 15 patients (8 liver, 7 lung), ABC‐gated kilovoltage cone‐beam CTs (kV‐CBCTs) were acquired prior to each treatment, and the centroids of the whole livers and of the lung tumors were also compared to those in the planning CTs to assess inter‐fraction variability.

Results

Liver intra‐fractional systematic/random errors were 0.75/0.39 mm, 1.36/0.97 mm, and 1.55/1.41 mm at medial‐lateral (ML), anterior‐posterior (AP), and superior‐inferior (SI) directions, respectively. Lung intra‐fractional systematic/random errors were 0.71/0.54 mm (ML), 1.45/1.10 mm (AP), and 3.95/1.93 mm (SI), respectively. Substantial intra‐fraction motions (>3 mm) were observed in 26.3% of liver cancer patients and in 46.7% of lung cancer patients. For both liver and lung tumors, most inter‐fractional systematic and random errors were larger than the corresponding intra‐fractional errors. However, these inter‐fractional errors were mostly corrected by the treatment team prior to each treatment based on kV CBCT‐guided soft tissue alignment, thereby eliminating their effects on the treatment planning margins.

Conclusions

Intra‐fractional motion is the key to determine the planning margins since inter‐fractional motion can be compensated based on daily gated soft tissue imaging guidance of CBCT. Patient‐specific treatment planning margins instead of recipe‐based margins were suggested, which can benefit mostly for the patients with small intra‐fractional motions.

Magnitude and influencing factors of respiration-induced liver motion during abdominal compression in patients with intrahepatic tumors

PURPOSE

The purpose of this study was to use 4-dimensional-computed tomography (4D-CT) to evaluate respiration-induced liver motion magnitude and influencing factors in patients with intrahepatic tumors undergoing abdominal compression.

METHODS

From January 2012 to April 2016, 99 patients with intrahepatic tumors were included in this study. They all underwent 4D-CT to assess respiratory liver motion. This was performed during abdominal compression in 53 patients and during free-breathing (no abdominal compression) in 46 patients. We defined abdominal compression as being effective in managing the breath amplitude if respiration-induced liver motion in the cranial-caudal (CC) direction during compression was ≤5 mm and as being ineffective if >5 mm of motion was observed. Gender, age, body mass index (BMI), transarterial chemoembolization history, liver resection history, tumor area, tumor number, and tumor size (diameter) were determined. Multivariate logistic regression analysis was used to analyze influencing factors associated with a breath amplitude ≤5 mm in the CC direction.

RESULTS

The mean respiration-induced liver motion during abdominal compression in the left-right (LR), CC, anterior-posterior (AP), and 3-dimensional vector directions was 2.9 ± 1.2 mm, 5.3 ± 2.2 mm, 2.3 ± 1.1 mm and 6.7 ± 2.1 mm, respectively. Univariate analysis indicated that gender and BMI significantly affected abdominal compression effectiveness (both p < 0.05). Multivariate analysis confirmed these two factors as significant predictors of effective abdominal compression: gender (p = 0.030) and BMI (p = 0.006). There was a strong correlation between gender and compression effectiveness (odds ratio [OR] = 7.450) and an even stronger correlation between BMI and compression effectiveness (OR = 10.842).

CONCLUSIONS

The magnitude of respiration-induced liver motion of patients with intrahepatic carcinoma undergoing abdominal compression is affected by gender and BMI, with abdominal compression being less effective in men and overweight patients.

Investigation of the optimum location of external markers for patient setup accuracy enhancement at external beam radiotherapy

In external beam radiotherapy, one of the most common and reliable methods for patient geometrical setup and/or predicting the tumor location is use of external markers. In this study, the main challenging issue is increasing the accuracy of patient setup by investigating external markers location. Since the location of each external marker may yield different patient setup accuracy, it is important to assess different locations of external markers using appropriate selective algorithms. To do this, two commercially available algorithms entitled a) canonical correlation analysis (CCA) and b) principal component analysis (PCA) were proposed as input selection algorithms. They work on the basis of maximum correlation coefficient and minimum variance between given datasets. The proposed input selection algorithms work in combination with an adaptive neuro-fuzzy inference system (ANFIS) as a correlation model to give patient positioning information as output. Our proposed algorithms provide input file of ANFIS correlation model accurately. The required dataset for this study was prepared by means of a NURBS-based 4D XCAT anthropomorphic phantom that can model the shape and structure of complex organs in human body along with motion information of dynamic organs. Moreover, a database of four real patients undergoing radiation therapy for lung cancers was utilized in this study for validation of proposed strategy. Final analyzed results demonstrate that input selection algorithms can reasonably select specific external markers from those areas of the thorax region where root mean square error (RMSE) of ANFIS model has minimum values at that given area. It is also found that the selected marker locations lie closely in those areas where surface point motion has a large amplitude and a high correlation.

A Feasibility Study on Ribs as Anatomical Landmarks for Motion Tracking of Lung and Liver Tumors at External Beam Radiotherapy

At external beam radiotherapy for some tumors located at thorax region due to lack of information in gray scale fluoroscopic images tumor position determination is problematic. One of the clinical strategies is to implant clip as internal fiducial marker inside or near tumor to represent tumor position while the contrast of implanted clip is highly observable rather than tumor. As alternative, using natural anatomical landmarks located at thorax region of patient body is proposed to extract tumor position information without implanting clips that is invasive method with possible side effect. Among natural landmarks, ribs of rib-cage structure that result proper visualization at X-ray images may be optimal as representative for tumor motion. In this study, we investigated the existence of possible correlation between ribs as natural anatomical landmarks and various lung and liver tumors located at different sites as challenging issue. A simulation study was performed using data extracted from 4-dimensional extended cardiac-torso anthropomorphic phantom that is able to simulate motion effect of dynamic organs, as well. Several tumor sites with predefined distances originated from chosen ribs at anterior-posterior direction were simulated at 3 upper, middle, and lower parts of chest. Correlation coefficient between ribs and tumors was calculated to investigate the robustness of ribs as anatomical landmarks for tumor motion tracking. Moreover, a consistent correlation model was taken into account to track tumor motion with a rib as best candidate among selected ribs. Final results represent availability of using rib cage as anatomical landmark to track lung and liver tumors in a noninvasive way. Observations of our calculations showed a proper correlation between tumors and ribs while the degree of this correlation is changing depends on tumor site while lung tumors are more varied and complex with less correlation with ribs motion against liver tumors.

Optimum location of external markers using feature selection algorithms for real-time tumor tracking in external-beam radiotherapy: a virtual phantom study

In external-beam radiotherapy, using external markers is one of the most reliable tools to predict tumor position, in clinical applications. The main challenge in this approach is tumor motion tracking with highest accuracy that depends heavily on external markers location, and this issue is the objective of this study. Four commercially available feature selection algorithms entitled 1) Correlation-based Feature Selection, 2) Classifier, 3) Principal Components, and 4) Relief were proposed to find optimum location of external markers in combination with two "Genetic" and "Ranker" searching procedures. The performance of these algorithms has been evaluated using four-dimensional extended cardiac-torso anthropomorphic phantom. Six tumors in lung, three tumors in liver, and 49 points on the thorax surface were taken into account to simulate internal and external motions, respectively. The root mean square error of an adaptive neuro-fuzzy inference system (ANFIS) as prediction model was considered as metric for quantitatively evaluating the performance of proposed feature selection algorithms. To do this, the thorax surface region was divided into nine smaller segments and predefined tumors motion was predicted by ANFIS using external motion data of given markers at each small segment, separately. Our comparative results showed that all feature selection algorithms can reasonably select specific external markers from those segments where the root mean square error of the ANFIS model is minimum. Moreover, the performance accuracy of proposed feature selection algorithms was compared, separately. For this, each tumor motion was predicted using motion data of those external markers selected by each feature selection algorithm. Duncan statistical test, followed by F-test, on final results reflected that all proposed feature selection algorithms have the same performance accuracy for lung tumors. But for liver tumors, a correlation-based feature selection algorithm, in combination with a genetic search algorithm, proved to yield best performance accuracy for selecting optimum markers.

Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

PURPOSE

Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy.

METHODS

Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registered to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma.

RESULTS

In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast.

CONCLUSIONS

Based on the authors' animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT.

Performance evaluations of demons and free form deformation algorithms for the liver region

We investigated the influence of breathing motion on radiation therapy according to four- dimensional computed tomography (4D-CT) technology and indicated the registration of 4D-CT images was significant. The demons algorithm in two interpolation modes was compared to the FFD model algorithm to register the different phase images of 4D-CT in tumor tracking, using iodipin as verification. Linear interpolation was used in both mode 1 and mode 2. Mode 1 set outside pixels to nearest pixel, while mode 2 set outside pixels to zero. We used normalized mutual information (NMI), sum of squared differences, modified Hausdorff-distance, and registration speed to evaluate the performance of each algorithm. The average NMI after demons registration method in mode 1 improved 1.76% and 4.75% when compared to mode 2 and FFD model algorithm, respectively. Further, the modified Hausdorff-distance was no different between demons modes 1 and 2, but mode 1 was 15.2% lower than FFD. Finally, demons algorithm has the absolute advantage in registration speed. The demons algorithm in mode 1 was therefore found to be much more suitable for the registration of 4D-CT images. The subtractions of floating images and reference image before and after registration by demons further verified that influence of breathing motion cannot be ignored and the demons registration method is feasible.

New progress of non-surgical treatments for hepatocellular carcinoma

Many non-surgical treatments of hepatocellular carcinoma (HCC) have significantly improved in the last few decades and have shown survival benefits for selected patients with HCC. Today ablation can improve survival in individuals diagnosed in early HCC and even offer a curative treatment in selected candidates. Patients with intermediate-stage HCC benefit from transarterial chemoembolization (TACE). Drug-eluting bead transarterial chemoembolization (DEB-TACE) has shown a better combined ischemic and cytotoxic effect locally and less system toxicity when compared with conventional TACE. Those diagnosed at advanced stage benefit from sorafenib. In addition to TACE and sorafenib which could improve survival for selected patients, three-dimensional conformal radiotherapy treatment (3-DCRT), selection internal radiation therapy and systemic chemotherapy have also shown anti-tumor activity in the treatment of advanced HCC, but their survival benefit have not been proven. The limited effects of single therapy suggested that the combination would enhance the overall treatment effect. Other potential non-surgical therapies like gene therapy and immunotherapy are still in testing phases, except for some small-scale clinical trials which have been reported to show some beneficial effect. Here, we review the current non-surgical treatments in HCC and the new advances in this field.

Dosimetric differences among volumetric modulated arc radiotherapy (RapidArc) plans based on different target volumes in radiotherapy of hepatocellular carcinoma

We investigated the dosimetric differences among volumetric-modulated arc radiotherapy (RapidArc, RA) plans designed for various target volumes in hepatocellular carcinoma (HCC). Ten HCC patients underwent 3D-CT scanning at free breathing (FB), 3D-CT at end inspiration hold (EIH) assisted by an Active Breathing Coordinator (ABC), and 4D-CT scanning. Gross tumor volumes (GTVs) were manually contoured on CT images. The individualized internal gross target volume (IGTV(1)) was obtained from 10 GTVs from 4D-CT images. Tumor individual margins were measured from GTV(FB) to IGTV(1). The IGTV(2) was obtained from GTV(FB) by applying individual margins. Four planning target volumes (PTV(1-4)) were obtained from IGTV(1), IGTV(2), GTV(FB), and GTV(EIH), respectively. An RA plan was designed for each of the PTVs (RA(1-4)). One 358° arc was used for PTVs(1-3), while three 135° arcs were used for PTV(4). It was found that PTV(2) and PTV(3) were larger than PTV(1) and PTV(4). The mean values of PTV(3)/PTV(1) and PTV(3)/PTV(4) were 2.5 and 1.9, respectively. The individual margins in the X, Y and Z axial directions varied greatly among these patients. There were no significant differences in the conformal index or homogeneity index among the four RA plans. RA(1) and RA(4) significantly reduced the radiation dose of normal liver tissue compared with RA(2) and RA(3) (P < 0.01). There were no significant differences between the radiation doses of the stomach and duodenum. RapidArc combined with 4D-CT or ABC technology is a promising method in radiotherapy of HCC, and accurately targeted the tumor volume while sparing more normal liver tissue.

RapidArc combined with the active breathing coordinator provides an effective and accurate approach for the radiotherapy of hepatocellular carcinoma

PURPOSE

The goal of this research was to investigate the feasibility of volumetric modulated arc therapy, RapidArc (RA), in association with the active breathing coordinator (ABC) for the treatment of hepatocellular carcinoma (HCC) with radiotherapy.

PATIENTS AND MATERIALS

A total of 12 patients with HCC, after receiving transcatheter arterial chemoembolization (TACE) treatment, underwent three-dimensional computer tomography (3D-CT) scanning associated with ABC using end inspiration hold (EIH), end expiration hold (EEH), and free breathing (FB) techniques. The three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and RA plans (three 135° arcs) were designed on different CT images, respectively. The liver volume, gross tumor volume (GTV), and planning target volume (PTV) of the three breath status and the dosimetric differences of the different plans were compared.

RESULTS

There were no significant differences in the volumes of live and GTV between the three breathing techniques (p > 0.05); the PTV in FB was greater than in the EEH and EIH (p < 0.05). The overall conformality index (CI) and homogeneity index (HI) for RA (CI 0.92, HI 0.90) were better than IMRT (CI 0.90, HI 0.89) and 3D-CRT (CI 0.70, HI 0.84) for the three breathing techniques (p< 0.05). The RA and IMRT significantly reduced the mean dose, V(20), V(30), and V(40) of normal liver compared to 3D-CRT, while the V(5) and V(10) in RA were higher than in IMRT. The mean values in mean dose, V(10), V(20), V(30), and V(40) of the normal liver were reduced from 13.12 Gy, 46%, 24%, 13%, and 8% in RA(FB) to 10.23 Gy, 35%, 16%, 8%, and 5% in RA(EEH) and 9.23 Gy, 32%, 16%, 8%, and 5% in RA(EIH ), respectively. In addition, the treatment time of RA was equal to 3D-CRT, which was significantly shorter than IMRT.

CONCLUSION

RA in conjunction with ABC for the treatment of HCC with radiotherapy can achieve better dose delivery and ensure the accuracy of the target volume, which spares more organs at risk, uses fewer monitor units, and shortens treatment time.

Clinical study of transarterial chemoembolization combined with 3-dimensional conformal radiotherapy for hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Monotherapy is not very effective for intermediate or advanced stage HCC. Efficacy of combined therapy using transarterial chemoembolization (TACE) with three-dimensional conformal radiotherapy (3-DCRT) for advanced HCC should be evaluated.

METHODS

HCC patients were selected from our patient database. The sequence of treatments that patients underwent was several courses of TACE followed in 2-4 weeks by 3-DCRT. The median tumor irradiation dose was 44Gy. Toxicity, tumor response, and overall survival rate were analyzed.

RESULTS

140 HCC patients were followed up by the last follow-up time. Among these patients, hepatic toxicities due to treatment were notable in 15 cases. Gastrointestinal bleeding after the overall treatment occurred in 3 cases. Leukopenia of grade III was detected in 1 case. Radiation-induced liver disease (RILD) was observed in 3 patients. Among 140 patients, 27, 97, and 16 cases achieved partial response, stable disease, and progressive disease, respectively. The overall survival rates of 1-year, 3-years, and 5-years were 66%, 29%, and 13%, respectively, with a median survival time of 18 months. Both Child-Pugh grade and radiation dose were determined to be independent predictors for overall survival from multivariate analysis.

CONCLUSION

The combined modality of TACE and 3-DCRT is a promising treatment for unresectable HCC. A large-scale, prospective randomized trial should be performed to confirm the utility of this combined therapy.

Comparison of efficacy and toxicity of short-course carbon ion radiotherapy for hepatocellular carcinoma depending on their proximity to the porta hepatis

BACKGROUND AND PURPOSE

To compare the efficacy and toxicity of short-course carbon ion radiotherapy (C-ion RT) for patients with hepatocellular carcinoma (HCC) in terms of tumor location: adjacent to the porta hepatis or not.

MATERIALS AND METHODS

The study consisted of 64 patients undergoing C-ion RT of 52.8 GyE in four fractions between April 2000 and March 2003. Of these patients, 18 had HCC located within 2 cm of the main portal vein (porta hepatis group) and 46 patients had HCC far from the porta hepatis (non-porta hepatis group). We compared local control, survival, and adverse events between the two groups.

RESULTS

The 5-year overall survival and local control rates were 22.2% and 87.8% in the porta hepatis group and 34.8% and 95.7% in the non-porta hepatis group, respectively. There were no significant differences (P=0.252, P=0.306, respectively). Further, there were no significant differences in toxicities. Biliary stricture associated with C-ion RT did not occur.

CONCLUSIONS

Excellent local control was obtained independent of tumor location. The short-course C-ion RT of 52.8 GyE in four fractions appears to be an effective and safe treatment modality in the porta hepatis group just as in the non-porta hepatis group.

Three-dimensional conformal radiation therapy and intensity-modulated radiation therapy combined with transcatheter arterial chemoembolization for locally advanced hepatocellular carcinoma: an irradiation dose escalation study

PURPOSE

To determine the maximum tolerated dose (MTD) of three-dimensional conformal radiation therapy (3DCRT)/intensity-modulated radiation therapy (IMRT) combined with transcatheter arterial chemoembolization for locally advanced hepatocellular carcinoma.

METHODS AND MATERIALS

Patients were assigned to two subgroups based on tumor diameter: Group 1 had tumors <10 cm; Group II had tumors ≥10 cm. Escalation was achieved by increments of 4.0 Gy for each cohort in both groups. Dose-limiting toxicity (DLT) was defined as a grade of ≥3 acute liver or gastrointestinal toxicity or any grade 5 acute toxicity in other organs at risk or radiation-induced liver disease. The dose escalation would be terminated when ≥2 of 8 patients in a cohort experienced DLT.

RESULTS

From April 2005 to May 2008, 40 patients were enrolled. In Group I, 11 patients had grade ≤2 acute treatment-related toxicities, and no patient experienced DLT; and in Group II, 10 patients had grade ≤2 acute toxicity, and 1 patient in the group receiving 52 Gy developed radiation-induced liver disease. MTD was 62 Gy for Group I and 52 Gy for Group II. In-field progression-free and local progression-free rates were 100% and 69% at 1 year, and 93% and 44% at 2 years, respectively. Distant metastasis rates were 6% at 1 year and 15% at 2 years. Overall survival rates for 1-year and 2-years were 72% and 62%, respectively.

CONCLUSIONS

The irradiation dose was safely escalated in hepatocellular carcinoma patients by using 3DCRT/IMRT with an active breathing coordinator. MTD was 62 Gy and 52 Gy for patients with tumor diameters of <10 cm and ≥10 cm, respectively.

Compensatory enlargement of the liver after treatment of hepatocellular carcinoma with carbon ion radiotherapy - relation to prognosis and liver function

BACKGROUND AND PURPOSE

To examine whether liver volume changes affect prognosis and hepatic function in patients treated with carbon ion radiotherapy (CIRT) for hepatocellular carcinoma (HCC).

MATERIAL AND METHODS

Between April 1995 and March 2003, among the cases treated with CIRT, 43 patients with HCC limited to the right hepatic lobe were considered eligible for the study. The left lateral segment was defined as the non-irradiated region. Liver volume was measured using contrast CT at 0, 3, 6, and 12 months after CIRT. We examined serum albumin, prothrombin activity, and total bilirubin level as hepatic functional reserve.

RESULTS

After CIRT, the non-irradiated region showed significant enlargement, and enlarged volume of this region 3 months after CIRT 50 cm(3) was a prognostic factor. The 5-year overall survival rates were 48.9% in the larger enlargement group (enlarged volume of non-irradiated region 3 months after CIRT > or =50 cm(3)) and 29.4% in the smaller enlargement group (as above, <50 cm(3)). The larger enlargement group showed better hepatic functional reserve than the smaller enlargement group 12 months after CIRT.

CONCLUSIONS

This study suggests that compensatory enlargement in the non-irradiated liver after CIRT contributes to the improvement of prognosis.

Maintenance of Sorafenib following combined therapy of three-dimensional conformal radiation therapy/intensity-modulated radiation therapy and transcatheter arterial chemoembolization in patients with locally advanced hepatocellular carcinoma: a phase I/II study

BACKGROUND

Three-dimensional conformal radiation therapy (3DCRT)/intensity-modulated radiation therapy (IMRT) combined with or without transcatheter arterial chemoembolization (TACE) for locally advanced hepatocellular carcinoma (HCC) has shown favorable outcomes in local control and survival of locally advanced HCC. However, intra-hepatic spreading and metastasis are still the predominant treatment failure patterns. Sorafenib is a multikinase inhibitor with effects against tumor proliferation and angiogenesis. Maintenance Sorafenib would probably prevent or delay the intrahepatic and extrahepatic spread of HCC after radiotherapy, which provides the rationale for the combination of these treatment modalities.

METHODS AND DESIGN

Patients with solitary lesion (bigger than 5 cm in diameter) histologically or cytologically confirmed HCC receive TACE (1-3 cycles) plus 3DCRT/IMRT 4-6 weeks later. Maintenance Sorafenib will be administered only for the patients with non-progression disease 4 to 6 weeks after the completion of radiotherapy. The dose will be 400 mg, p.o., twice a day. Sorafenib will be continuously given for 12 months unless intolerable toxicities and/or tumor progression. If no more than 3 patients discontinue Sorafenib treatment who experience dose-limiting toxicity after necessary dose modification and delay and/or radiation-induced liver disease in the first 15 enrolled patients, the study will recruit second fifteen patients for further evaluating safety and efficacy of treatment. Hypothesis of the current study is that Sorafenib as a maintenance therapy after combined therapy of 3DCRT/IMRT and TACE is safe and superior to radiotherapy combined with TACE alone in terms of time to progression (TTP), progression-free survival (PFS) and overall survival (OS) in comparison to historical data.

DISCUSSION

A recent meta-analysis showed TACE in combination with radiotherapy, improved the survival and the tumor response of patients, and was thus more therapeutically beneficial. In this study, local therapy for HCC is the combination of TACE and radiotherapy. Radiation exposure as a kind of stress might induce the compensatory activations of multiple intracellular signaling pathway mediators, such as PI3K, MAPK, JNK and NF-kB. Vascular endothelial growth factor (VEGF) was identified as one factor that was increased in a time- and dose-dependent manner after sublethal irradiation of HCC cells in vitro, translating to enhanced intratumor angiogenesis in vivo. Therefore, Sorafenib-mediated blockade of the Raf/MAPK and VEGFR pathways might enhance the efficacy of radiation, when Sorafenib is followed sequentially as a maintenance modality. (ClinicalTrials.gov number, NCT00999843.).

Progress in non-surgical treatment of primary hepatic carcinoma

At present, surgery-based comprehensive therapy plays a dominant role in the treatment of primary hepatic carcinoma. But the majority of patients had lost their opportunities of surgical treatment when diagnosis was confirmed. Moreover, only 15% patients may benefit from surgical excision. Therefore, non-surgical approaches still hold an important position in primary hepatic carcinoma treatment. The purpose of this article is to review the progress in non-surgical treatments of primary hepatic carcinoma such as micro-invasive therapy, radiotherapy, chemotherapy and biotherapy.

Radiotherapy of primary hepatocellular carcinoma

Primary hepatocellular carcinoma (PHC) is one of the common tumors in China, and its predominant pathologic type is hepatocellular carcinoma (HCC). Radiotherapy is now an common and effective treatment method. In this article, the radiosensitization and development of radiotherapeutic technology are reviewed. Recent progress in reducing the radiation-induced hepatic injury is also summarized.