Importance of the Initial Volume of Parotid Glands in Xerostomia for Patients with Head and Neck Cancers Treated with IMRT

Potential predictive value of IVIM MR for xerostomia in nasopharyngeal carcinoma

BACKGROUND AND PURPOSE

Xerostomia, caused by radiation-induced parotid damage, is the most commonly reported radiotherapy (RT) complication for nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the value of intravoxel incoherent motion (IVIM) MR in monitoring radiation-induced parotid gland damage and predicting the risk of xerostomia.

METHODS

Fifty-four NPC patients were enrolled and underwent at least three IVIM MR scans: before (pre-RT), after 5 fractions of (5th-RT), halfway through (mid-RT), and after RT (post-RT). The degree of xerostomia patients was assessed before each MR examination. Furthermore, the time when patients first reported xerostomia symptoms was recorded. The changes in IVIM parameters throughout RT, as well as the relationships between IVIM parameters and xerostomia, were analysed.

RESULT

All IVIM parameters increased significantly from pre-RT to post-RT (p < 0.001). The rates of D, D* and f increase increased significantly from pre-RT to mid-RT (p < 0.001), indicating that cell necrosis mainly occurs in the first half of RT. In multivariate analysis, N3 (p = 0.014), pre-D (p = 0.007) and pre-D* (p = 0.003) were independent factors influencing xerostomia. D and f were significantly higher at 5th-RT than at pre-RT (both p < 0.05). IVIM detected parotid gland injury at 5th-RT at an average scanning time of 6.18 ± 1.07 days, earlier than the 11.94 ± 2.61 days when the patient first complained of xerostomia according to the RTOG scale (p < 0.001).

CONCLUSIONS

IVIM MR can dynamically monitor radiation-induced parotid gland damage and assess it earlier and more objectively than RTOG toxicity. Moreover, IVIM can screen people at risk of more severe xerostomia early.

The effects of mega-voltage CT scan parameters on offline adaptive radiation therapy

TomoTherapy involves image-guided radiation therapy (IGRT) using Mega-voltage CT (MVCT) for each treatment session. The acquired MVCT images can be utilized for the retrospective assessment of dose distribution. The TomoTherapy provides 18 distinct imaging conditions that can be selected based on a combination of algorithms, acquisition pitch, and slice interval. We investigated the accuracy of dose calculation and deformable image registration (DIR) depending on MVCT scan parameters and their effects on adaptive radiation therapy (ART). We acquired image values for density calibration tables (IVDTs) under 18 different MVCT conditions and compared them. The planning CT (pCT) was performed using a thoracic phantom, and an esophageal intensity-modulated radiation therapy (IMRT) plan was created. MVCT images of the thoracic phantom were acquired under each of the 18 conditions, and dose recalculation was performed. DIR was performed on the MVCT images acquired under each condition. The accuracy of DIR, depending on the MVCT scan parameters, was compared using the mean distance to agreement (MDA) and Dice similarity coefficient (DSC). The dose distribution calculated on the MVCT images was deformed using deformed vector fields (DVF). No significant differences were observed in the results of the 18 IVDTs. The esophageal IMRT plan also showed a small dose difference. Regarding verifying the DIR accuracy, the MDA increased, and the DSC decreased as the acquisition pitch and slice interval increased. The difference between the dose distributions after dose mapping was comparable to that before DIR. The MVCT scan parameters had little effect on ART.

Serial Changes in Parotid Gland Volume and Symptoms After Radiation Therapy in Oropharyngeal Cancer

Objective: To evaluate the serial changes in the volume of the parotid gland and clinical symptoms after a course of radiation therapy (RT) in patients with oropharyngeal cancer. Methods: A total of 33 patients who were diagnosed with oropharyngeal cancer and had been treated with RT or concurrent chemoradiation therapy were evaluated. Parotid gland volumes were measured serially by head and neck computed tomography with contrast-enhanced images before RT, and 6 months, 1 year, and 2 years after RT. Patients also filled out EORTC (European Organization for the Research and Treatment of Cancer) QLQ-C30 questionnaires on the quality of life (QOL) at the same time. This questionnaire included questions about salivary gland function: dry mouth, sticky saliva, and taste disorder. Higher scores on EORTC questionnaire translates to worse QOL. Results: All patients received more than 60 Gy irradiation in total. The mean volume of parotid gland decreased from 23.30 mL before RT to 15.80 mL, 15.93 mL, and 16.67 mL after 6 months, 1 year, and 2 years, respectively (P < 0.001 between pre-RT and all other 3 periods). The scores on the QOL questionnaire were higher (worsened QOL) at all 3 times after radiation than in the pre-RT period. The mean score of QOL increased from pre-RT to 2 years post-RT: "dry mouth" from 1.65 to 2.70, "sticky saliva" from 1.19 to 2.00, and "taste disorder" from 1.12 to 1.94. All 3 of these parameters were correlated with the volume of the parotid gland (P < 0.005 each). Conclusions: The volume of the parotid gland decreases significantly after RT for oropharyngeal cancer and does not recover significantly for at least 2 years. There was a significant correlation between decreased parotid volume and a lower QOL involving salivation.

Automated tracking of morphologic changes in weekly magnetic resonance imaging during head and neck radiotherapy

BACKGROUND AND PURPOSE

Anatomic changes during head and neck radiotherapy can impact dose delivery, necessitate adaptive replanning, and indicate patient-specific response to treatment. We have developed an automated system to track these changes through longitudinal MRI scans to aid identification and clinical intervention. The purpose of this article is to describe this tracking system and present results from an initial cohort of patients.

MATERIALS AND METHODS

The Automated Watchdog in Adaptive Radiotherapy Environment (AWARE) was developed to process longitudinal MRI data for radiotherapy patients. AWARE automatically identifies and collects weekly scans, propagates radiotherapy planning structures, computes structure changes over time, and reports important trends to the clinical team. AWARE also incorporates manual structure review and revision from clinical experts and dynamically updates tracking statistics when necessary. AWARE was applied to patients receiving weekly T2-weighted MRI scans during head and neck radiotherapy. Changes in nodal gross tumor volume (GTV) and parotid gland delineations were tracked over time to assess changes during treatment and identify early indicators of treatment response.

RESULTS

N = 91 patients were tracked and analyzed in this study. Nodal GTVs and parotids both shrunk considerably throughout treatment (-9.7 ± 7.7% and -3.7 ± 3.3% per week, respectively). Ipsilateral parotids shrunk significantly faster than contralateral (-4.3 ± 3.1% vs. -2.9 ± 3.3% per week, p = 0.005) and increased in distance from GTVs over time (+2.7 ± 7.2% per week, p < 1 × 10^-5 ). Automatic structure propagations agreed well with manual revisions (Dice = 0.88 ± 0.09 for parotids and 0.80 ± 0.15 for GTVs), but for GTVs the agreement degraded 4-5 weeks after the start of treatment. Changes in GTV volume observed by AWARE as early as one week into treatment were predictive of large changes later in the course (AUC = 0.79).

CONCLUSION

AWARE automatically identified longitudinal changes in GTV and parotid volumes during radiotherapy. Results suggest that this system may be useful for identifying rapidly responding patients as early as one week into treatment.

World Workshop on Oral Medicine VIII: Development of a Core Outcome Set for Dry Mouth: A Systematic Review of Outcome Domains for Xerostomia

OBJECTIVE

The purpose of this study was to identify all outcome domains used in clinical studies of xerostomia, that is, subjective sensation of dry mouth. This study is part of the extended project "World Workshop on Oral Medicine Outcomes Initiative for the Direction of Research" to develop a core outcome set for dry mouth.

STUDY DESIGN

A systematic review was performed on MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials databases. All clinical and observational studies that assessed xerostomia in human participants from 2001 to 2021 were included. Information on outcome domains was extracted and mapped to the Core Outcome Measures in Effectiveness Trials taxonomy. Corresponding outcome measures were summarized.

RESULTS

From a total of 34,922 records retrieved, 688 articles involving 122,151 persons with xerostomia were included. There were 16 unique outcome domains and 166 outcome measures extracted. None of these domains or measures were consistently used across all the studies. The severity of xerostomia and physical functioning were the 2 most frequently assessed domains.

CONCLUSION

There is considerable heterogeneity in outcome domains and measures reported in clinical studies of xerostomia. This highlights the need for harmonization of dry mouth assessment to enhance comparability across studies and facilitate the synthesis of robust evidence for managing patients with xerostomia.

Research Value of Intensity Modulated Radiation Therapy in Alleviating Parotid Gland Function Injury in Patients with Stage N0 Nasopharyngeal Carcinoma from Physical and Dosimetric Aspects

Objective

To study the feasibility of intensity modulated radiation therapy (IMRT) for stage N₀ nasopharyngeal carcinoma (NPC) and its parotid gland (PG) function preservation from physical and dosimetric aspects.

Methods

All the clinical data of 77 patients with pathologically confirmed T_1-4N₀M₀ NPC who received radiotherapy between July 2017 and October 2019 in the Radiotherapy Center of Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University were analyzed retrospectively. Three-dimensional conformal radiotherapy (3D-CRT) and IMRT were used in 35 and 42 cases, respectively. The treatment efficiency and the dosimetry differences of the PG in the intensity modulation plan were compared between groups. Quantitative monitoring of 99mTc radionuclide imaging of PG was performed before, at the end of, and 3, 6, and 12 months after radiotherapy. The degree of PG function injury and xerostomia was compared between groups at the end of radiotherapy and 12 months later.

Results

Higher minimal, maximal, and average irradiation doses of PG were determined in 3D-CRT-treated patients compared with IMRT-treated cases (P < 0.05). Compared with before radiotherapy, the PG uptake index (UI) and excretion index (EI) of both cohorts of patients decreased to varying degrees at the end of radiotherapy, with PG function injury and xerostomia symptoms observed in all cases but with no obvious difference between groups (P > 0.05). To a certain extent, the PG function recovered and the xerostomia symptoms relieved in both groups 12 months after radiotherapy, with better improvements in IMRT group versus 3D-CRT group.

Conclusion

IMRT has similar short-term efficacy to 3D-CRT in treating patients with stage N₀ NPC, but it can effectively reduce the dose of PG radiotherapy and protect the PG function on the premise of ensuring sufficient tumor coverage and dose, showing certain dosimetry advantages.

The Long-Term Recovery of Parotid Glands in Nasopharyngeal Carcinoma Treated by Intensity-Modulated Radiotherapy

Background

Xerostomia is one of the most common adverse events of radiotherapy in head and neck cancer patients. There have been many reports on functional changes of the parotid gland after radiation therapy, but there have been few reports on the volume of the parotid gland and its relationship with oral quality of life (QOL) and even fewer reports on longitudinal change of the parotid gland volume. The purpose of this study was to evaluate the long-term change of the parotid gland volume after intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma and the relationship between parotid irradiation dose and xerostomia symptoms.

Methods

We retrospectively analyzed 26 patients with nasopharyngeal cancer treated by IMRT. Longitudinal changes of parotid gland volumes after IMRT were evaluated on CT images. The parotid gland volumes in each period were converted to the ratio to parotid gland volumes before radiotherapy (relative parotid volume). Dunnett’s test was used to evaluate the longitudinal changes in relative parotid volumes at 0-6, 7-18, 19-30, 31-42, 43-54 and 55-66 months after IMRT. We assessed xerostomia 3 years or more after IMRT by measuring the degree of oral moisture using a moisture-checking device (Mucus, Life Co., Ltd.) and oral QOL evaluation by GOHAI (General Oral Health Assessment Index).

Results

The relative parotid volumes during radiotherapy and at 0-6, 7-18, 19-30, 31-42, 43-54 and 55-66 months after IMRT were 75.2 ± 14.3%, 67.2 ± 11.4%, 68.5 ± 15.9%, 72.4 ± 14.8%, 73.0 ± 13.8%, 76.2 ± 17.5%, and 77.1% ± 17.3%, respectively. The parotid volume had recovered significantly at 43-54 and 55-66 months after IMRT, especially in parotids receiving less than 40 Gy as the mean dose. The mean irradiated dose for bilateral parotids showed negative correlations with oral QOL score and oral moisture after a long period.

Conclusions

The parotid volume recovered gradually but had not reached a plateau even 3 years after radiotherapy, especially in parotids receiving less than 40 Gy as the mean dose.

Predictive dose accumulation for HN adaptive radiotherapy

During radiation therapy (RT) of head and neck (HN) cancer, the shape and volume of the parotid glands (PG) may change significantly, resulting in clinically relevant deviations of delivered dose from the planning dose. Early and accurate longitudinal prediction of PG anatomical changes during the RT can be valuable to inform decisions on plan adaptation. We developed a deep neural network for longitudinal predictions using the displacement fields (DFs) between the planning computed tomography (pCT) and weekly cone beam computed tomography (CBCT). Sixty-three HN patients treated with volumetric modulated arc were retrospectively studied. We calculated DFs between pCT and week 1-3 CBCT by B-spline and Demon deformable image registration (DIR). The resultant DFs were subsequently used as input to our novel network to predict the week 4 to 6 DFs for generating predicted weekly PG contours and weekly dose distributions. For evaluation, we measured dice similarity (DICE), and the uncertainty of accumulated dose. Moreover, we compared the detection accuracies of candidates for adaptive radiotherapy (ART) when the trigger criteria were mean dose difference more than 10%, 7.5%, and 5%, respectively. The DICE of ipsilateral/contralateral PG at week 4 to 6 using the prediction model trained with B-spline were 0.81 [Formula: see text] 0.07/0.81 [Formula: see text] 0.04 (week 4), 0.79 [Formula: see text] 0.06/0.81 [Formula: see text] 0.05 (week 5) and 0.78 [Formula: see text] 0.06/0.82 [Formula: see text] (week 6). The DICE with the Demons model were 0.78 [Formula: see text] 0.08/0.82 [Formula: see text] 0.03 (week 4), 0.77 [Formula: see text] 0.07/0.82 [Formula: see text] 0.04 (week 5) and 0.75 [Formula: see text] 0.07/0.82 [Formula: see text] 0.02 (week 6). The dose volume histogram (DVH) analysis with the predicted accumulated dose showed the feasibility of predicting dose uncertainty due to the PG anatomical changes. The AUC of ART candidate detection with our predictive model was over 0.90. In conclusion, the proposed network was able to predict future anatomical changes and dose uncertainty of PGs with clinically acceptable accuracy, and hence can be readily integrated into the ART workflow.

Does Dose Volume Histogram of Parotid Glands Correlate with Xerostomia Radiation Therapy Oncology Group Scores in Locoregionally Advanced Head and Neck Cancer Patients Treated with Intensity-Modulated Radiation Therapy?

Introduction Xerostomia is an imminent complication of head and neck radiotherapy best assessed subjectively. This study aimed to evaluate the effects of sparing parotid glands with intensity-modulated radiation therapy (IMRT) on subjective xerostomia scores in patients with locoregionally advanced head and neck cancer.

Subjects and Methods This is a prospective longitudinal study conducted in an outpatient department setting. A total of 43 patients with head and neck cancer were planned with IMRT as per the ICRU 62 (International Commission on Radiation Units and Measurement Report 62). The constraints to ipsilateral and contralateral parotid glands were 35 and 25 Gy, respectively. Treatment plan was assessed for doses to 100, 67, 50, and 33% volume of individual parotid glands. Patients were subjectively assessed using the Amosson’s Questionnaire and graded as per Eisbruch’s xerostomia Radiation Therapy Oncology Group scores. Dose volume histogram (DVH) was plotted and correlated with grades of xerostomia postradiation at 1, 3, 6, 9 and 12 months follow-ups. Statistical analysis was performed suing SPSS version 16, chi-square test, and one-way analysis of variance test.

Results No statistically significant correlation between mean dose of radiation, volume of the parotid glands, and grades of xerostomia was noted postradiation. A statistically significant improvement in grades of xerostomia between 3 and 6 months (p = 0.0), 3 and 9 months (p = 0.020), 6 and 9 months (p = 0.009), 6 and 12 months (p = 0.05), and 9 and 12 months (p = 0.00) was noted. Recovery in grades was noted at 9 months.

Conclusion There is no statistically significant direct correlation between DVH of the parotid glands and grades of xerostomia, although recovery in grades was statistically significant at 9 months.

Predictors for improvement of xerostomia in nasopharyngeal carcinoma patients receiving intensity-modulated radiotherapy

To identify predictors for improvement of xerostomia in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT).Patients diagnosed with stage I-IVb NPC (according to the 7th edition of the American Joint Committee on Cancer) between September 2015 and March 2016 were retrospectively analyzed. All the patients received IMRT. Predictors for improvement of xerostomia were analyzed using logistic regression analysis. Receiver operating characteristic curve analysis was used to identify the most appropriate cut-off values for predicting factors.This study included 195 patients: xerostomia improved in 109 patients and xerostomia remained unchanged in 86 patients. Volume of the parotid gland ≤52.2 cm was a risk factor for xerostomia improvement (odds ratio [OR] = 3.506, 95% confidence interval [CI]: 1.932-6.362, P = .001). The mean dose of <39 Gy to the ipsilateral parotid gland was a protective factor (OR = 0.417, 95% CI: 0.271-0.641, P = .001). V30 of the contralateral parotid gland ≤52% was a protective factor (OR = 0.593, 95% CI: 0.462-0.760, P = .001).Volume of the parotid gland, the mean dose of the ipsilateral parotid gland, and V30 of the contralateral parotid gland were independent predictors for improvement of xerostomia.

An evaluation of adaptive planning by assessing the dosimetric impact of weight loss throughout the course of radiotherapy in bilateral treatment of head and neck cancer patients

The purpose of this study was to investigate the dosimetric impact of weight loss in head and neck (H&N) patients and examine the effectiveness of adaptive planning. Data was collected from 22 H&N cancer patients who experienced weight loss during their course of radiotherapy. The robustness of Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) treatment plans were compared including the potential need for replanning. The dosimetric impact of weight loss was evaluated by calculating a verification plan for each patient on an assessment CT scan taken during the course of treatment. Using a regression analysis, significance was tested for the dosimetric change in target volumes and 10 specific organs at risk (OAR) using an anatomical separation difference in the H&N at corresponding levels. For both the IMRT and VMAT plans, a significant correlation was found for the dose to 5% of the high risk Planning Target Volume (PTV) (D₅), dose to 95% of the intermediate risk PTV and Clinical Target Volume (CTV) (D₉₅), and the percentage of the pharynx receiving 65 Gy. An independent t-test was also performed for each metric in the VMAT and IMRT plans showing the dose to 95% of the intermediate risk PTV as significant. No quantitative method for finding the threshold of anatomical separation difference requiring a replan was established. Based on the increase in dose to organs at risk and increased target coverage due to separation loss, it was concluded that adaptive radiotherapy may not always be necessary when alignment of bony anatomy and remaining soft tissue is within tolerance. Physician judgment and preference is needed in such situations.

Use of intensity-modulated radiation therapy for nasopharyngeal cancer in Japan: analysis using a national database

Background

Intensity-modulated radiation therapy (IMRT) yields better outcomes and fewer toxicities for radiation therapy (RT) of head and neck cancers (HNCs), including nasopharyngeal cancer (NPC). IMRT is the standard RT treatment and has been widely adopted in Western countries to treat HNCs. However, its uptake in clinical practice among NPC patients has never been studied.

Methods

We investigated the use of IMRT for NPC using data from a nationwide cancer registry to describe the use of IMRT among NPC patients in Japan. We analyzed the data of patients with HNC, including NPC, who underwent IMRT between 2012 and 2014, as recorded in the hospital-based cancer registries linked with insurance claims. We calculated the proportion of patients with NPC who underwent IMRT at each hospital. To evaluate the use of IMRT for NPC, the IMRT use for NPC was compared with the proportion of patients with prostate cancer who underwent IMRT.

Results

Among 508 patients with NPC who underwent RT at one of 87 hospitals, 348 (69%) underwent IMRT. This proportion gradually increased between 2012 and 2014 (62%, 64% and 77%). Meanwhile, 4790 patients with prostate cancer (90%) underwent IMRT. Although some hospitals where IMRT was performed treated many patients with NPC, the proportion of patients with NPC who were treated with IMRT was low.

Conclusions

IMRT has not been widely adopted in Japan for treating NPC. Barriers for adopting its use should be identified to close the gap between the standard and actual medical practice in Japan.

Prospective study of sequential volumetric changes of parotid gland in early oropharyngeal carcinoma patients treated by intensity-modulated radiation therapy: An institutional experience

Aims and Objectives:

During course of radiation therapy, anatomical variations occur risking overdose of parotid gland. We tried to quantify volume of parotid gland and mean dose to parotid gland after every 10 fractions (#).

Materials and Methods:

We conducted the prospective study from July 2016 to May 2017 in 25 patients of early-stage oropharyngeal carcinoma. Patients had Karnofsy Performance Score of 80–100, median age was 54 years, and 18 patients were males. Patients were planned with intensity-modulated radiation therapy planning with dose as 66 Gy/30# to planning target volume (PTV) including primary and 54 Gy/30# to PTV-nodal including elective neck irradiation. After each 10#, replanning was done, and variations in parotid volume were studied including D_mean (mean dose to parotids) and D₅₀ (the dose delivered to 50% of volume). Other tumor characteristic like PTV of primary was also assessed and minimum PTV volume covered by 95% isodose line was kept as 95%.

Results:

Average parotid volumes decreased by the mean value of 10% and 6% for the left and right parotids, respectively, and PTV of primary target decreased by mean of 13%. The difference in D_mean doses to parotid glands was 32% and 42% and difference in D₅₀ dose was 30% and 35% on the left and right side, respectively.

Conclusions:

The parotid volumes differ considerably during adaptive planning done after every ten fractions. These differences in parotid volumes and doses received to parotid glands play a significant role in the risk of xerostomia observed during later follow-up.

CT image biomarkers to improve patient-specific prediction of radiation-induced xerostomia and sticky saliva

BACKGROUND AND PURPOSE

Current models for the prediction of late patient-rated moderate-to-severe xerostomia (XER_12m) and sticky saliva (STIC_12m) after radiotherapy are based on dose-volume parameters and baseline xerostomia (XER_base) or sticky saliva (STIC_base) scores. The purpose is to improve prediction of XER_12m and STIC_12m with patient-specific characteristics, based on CT image biomarkers (IBMs).

METHODS

Planning CT-scans and patient-rated outcome measures were prospectively collected for 249 head and neck cancer patients treated with definitive radiotherapy with or without systemic treatment. The potential IBMs represent geometric, CT intensity and textural characteristics of the parotid and submandibular glands. Lasso regularisation was used to create multivariable logistic regression models, which were internally validated by bootstrapping.

RESULTS

The prediction of XER_12m could be improved significantly by adding the IBM "Short Run Emphasis" (SRE), which quantifies heterogeneity of parotid tissue, to a model with mean contra-lateral parotid gland dose and XER_base. For STIC_12m, the IBM maximum CT intensity of the submandibular gland was selected in addition to STIC_base and mean dose to submandibular glands.

CONCLUSION

Prediction of XER_12m and STIC_12m was improved by including IBMs representing heterogeneity and density of the salivary glands, respectively. These IBMs could guide additional research to the patient-specific response of healthy tissue to radiation dose.

Temporal Evolution of Parotid Volume and Parotid Apparent Diffusion Coefficient in Nasopharyngeal Carcinoma Patients Treated by Intensity-Modulated Radiotherapy Investigated by Magnetic Resonance Imaging: A Pilot Study

Purpose

To concurrently quantify the radiation-induced changes and temporal evolutions of parotid volume and parotid apparent diffusion coefficient (ADC) in nasopharyngeal carcinoma (NPC) patients treated by intensity-modulated radiotherapy by using magnetic resonance imaging (MRI).

Materials and Methods

A total of 11 NPC patients (9 men and 2 women; 48.7 ± 11.7 years, 22 parotid glands) were enrolled. Radiation dose, parotid sparing volume, severity of xerostomia, and radiation-to-MR interval (RMI) was recorded. MRI studies were acquired four times, including one before and three after radiotherapy. The parotid volume and the parotid ADC were measured. Statistical analysis was performed using SPSS and MedCalc. Bonferroni correction was applied for multiple comparisons. A P value less than 0.05 was considered as statistically significant.

Results

The parotid volume was 26.2 ± 8.0 cm³ before radiotherapy. The parotid ADC was 0.8 ± 0.15 × 10⁻³ mm²/sec before radiotherapy. The parotid glands received a radiation dose of 28.7 ± 4.1 Gy and a PSV of 44.1 ± 12.6%. The parotid volume was significantly smaller at MR stage 1 and stage 2 as compared to pre-RT stage (P < .005). The volume reduction ratio was 31.2 ± 13.0%, 26.1 ± 13.5%, and 17.1 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was significantly higher at all post-RT stages as compared to pre-RT stage reciprocally (P < .005 at stage 1 and 2, P < .05 at stage 3). The ADC increase ratio was 35.7 ± 17.4%, 27.0 ± 12.8%, and 20.2 ± 16.6% at stage 1, 2, and 3, respectively. The parotid ADC was negatively correlated to the parotid volume (R = -0.509; P < .001). The parotid ADC was positively associated with the radiation dose significantly (R² = 0.212; P = .0001) and was negatively associated with RMI significantly (R² = 0.203; P = .00096) significantly. Multiple regression analysis further showed that the post-RT parotid ADC was related to the radiation dose and RMI significantly (R² = 0.3580; P < .0001). At MR stage 3, the parotid volume was negatively associated with the dry mouth grade significantly (R² = 0.473; P < .0001), while the parotid ADC was positively associated with the dry mouth grade significantly (R² = 0.288; P = .015).

Conclusion

Our pilot study successfully demonstrates the concurrent changes and temporal evolution of parotid volume and parotid ADC quantitatively in NPC patients treated by IMRT. Our results suggest that the reduction of parotid volume and increase of parotid ADC are dominated by the effect of acinar loss rather than edema at early to intermediate phases and the following recovery of parotid volume and ADC toward the baseline values might reflect the acinar regeneration of parotid glands.

Evidence on effectiveness of intensity-modulated radiotherapy versus 2-dimensional radiotherapy in the treatment of nasopharyngeal carcinoma: Meta-analysis and a systematic review of the literature

BACKGROUND

Current management of nasopharyngeal carcinoma (NPC) uses radiotherapy (RT) as the curative treatment modality. Radiation delivery techniques for NPC can be achieved using 2D conventional RT or intensity-modulated radiotherapy (IMRT).

METHODS

A systematic review and meta-analysis of the literature was undertaken to assess the effectiveness of IMRT versus 2D conventional RT in primary treatment of NPC.

RESULTS

IMRT showed better results than 2D conventional RT in terms of local control, regional control, and overall survival, but when stratified, only in T4, N2, and stage III were the differences that were seen. Objective saliva measurements and physician-graded xerostomia were better in IMRT. However, patient-reported xerostomia showed minimal improvement only in IMRT. The evidence of superiority of IMRT over 2D conventional RT is not clear.

CONCLUSION

In the absence of more clinical data demonstrating the superiority of IMRT in the treatment of nasopharyngeal carcinoma, 2D conventional RT seems to be a reasonable treatment option, especially in limited resource settings. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2130-E2142, 2016.

Computed tomography number changes observed during computed tomography-guided radiation therapy for head and neck cancer

PURPOSE

To investigate CT number (CTN) changes in gross tumor volume (GTV) and organ at risk (OAR) according to daily diagnostic-quality CT acquired during CT-guided intensity modulated radiation therapy for head and neck cancer (HNC) patients.

METHODS AND MATERIALS

Computed tomography scans acquired using a CT-on-rails during daily CT-guided intensity modulated radiation therapy for 15 patients with stage II to IVa squamous cell carcinoma of the head and neck were analyzed. The GTV, parotid glands, spinal cord, and nonspecified tissue were generated on each selected daily CT. The changes in CTN distributions and the mean and mode values were collected. Pearson analysis was used to assess the correlation between the CTN change, organ volume reduction, and delivered radiation dose.

RESULTS

Volume and CTN changes for GTV and parotid glands can be observed during radiation therapy delivery for HNC. The mean (±SD) CTNs in GTV and ipsi- and contralateral parotid glands were reduced by 6 ± 10, 8 ± 7, and 11 ± 10 Hounsfield units, respectively, for all patients studied. The mean CTN changes in both spinal cord and nonspecified tissue were almost invisible (<2 Hounsfield units). For 2 patients studied, the absolute mean CTN changes in GTV and parotid glands were strongly correlated with the dose delivered (P<.001 and P<.05, respectively). For the correlation between CTN reductions and delivered isodose bins for parotid glands, the Pearson coefficient varied from -0.98 (P<.001) in regions with low-dose bins to 0.96 (P<.001) in high-dose bins and were patient specific.

CONCLUSIONS

The CTN can be reduced in tumor and parotid glands during the course of radiation therapy for HNC. There was a fair correlation between CTN reduction and radiation doses for a subset of patients, whereas the correlation between CTN reductions and volume reductions in GTV and parotid glands were weak. More studies are needed to understand the mechanism for the radiation-induced CTN changes.

Evaluation of deformable image registration methods for dose monitoring in head and neck radiotherapy

In the context of head and neck cancer (HNC) adaptive radiation therapy (ART), the two purposes of the study were to compare the performance of multiple deformable image registration (DIR) methods and to quantify their impact for dose accumulation, in healthy structures. Fifteen HNC patients had a planning computed tomography (CT0) and weekly CTs during the 7 weeks of intensity-modulated radiation therapy (IMRT). Ten DIR approaches using different registration methods (demons or B-spline free form deformation (FFD)), preprocessing, and similarity metrics were tested. Two observers identified 14 landmarks (LM) on each CT-scan to compute LM registration error. The cumulated doses estimated by each method were compared. The two most effective DIR methods were the demons and the FFD, with both the mutual information (MI) metric and the filtered CTs. The corresponding LM registration accuracy (precision) was 2.44 mm (1.30 mm) and 2.54 mm (1.33 mm), respectively. The corresponding LM estimated cumulated dose accuracy (dose precision) was 0.85 Gy (0.93 Gy) and 0.88 Gy (0.95 Gy), respectively. The mean uncertainty (difference between maximal and minimal dose considering all the 10 methods) to estimate the cumulated mean dose to the parotid gland (PG) was 4.03 Gy (SD = 2.27 Gy, range: 1.06-8.91 Gy).

Impact of head and neck cancer adaptive radiotherapy to spare the parotid glands and decrease the risk of xerostomia

BACKGROUND

Large anatomical variations occur during the course of intensity-modulated radiation therapy (IMRT) for locally advanced head and neck cancer (LAHNC). The risks are therefore a parotid glands (PG) overdose and a xerostomia increase. The purposes of the study were to estimate: - the PG overdose and the xerostomia risk increase during a "standard" IMRT (IMRTstd); - the benefits of an adaptive IMRT (ART) with weekly replanning to spare the PGs and limit the risk of xerostomia.

MATERIAL AND METHODS

Fifteen patients received radical IMRT (70 Gy) for LAHNC. Weekly CTs were used to estimate the dose distributions delivered during the treatment, corresponding either to the initial planning (IMRTstd) or to weekly replanning (ART). PGs dose were recalculated at the fraction, from the weekly CTs. PG cumulated doses were then estimated using deformable image registration. The following PG doses were compared: pre-treatment planned dose, per-treatment IMRTstd and ART. The corresponding estimated risks of xerostomia were also compared. Correlations between anatomical markers and dose differences were searched.

RESULTS

Compared to the initial planning, a PG overdose was observed during IMRTstd for 59% of the PGs, with an average increase of 3.7 Gy (10.0 Gy maximum) for the mean dose, and of 8.2% (23.9% maximum) for the risk of xerostomia. Compared to the initial planning, weekly replanning reduced the PG mean dose for all the patients (p<0.05). In the overirradiated PG group, weekly replanning reduced the mean dose by 5.1 Gy (12.2 Gy maximum) and the absolute risk of xerostomia by 11% (p<0.01) (30% maximum). The PG overdose and the dosimetric benefit of replanning increased with the tumor shrinkage and the neck thickness reduction (p<0.001).

CONCLUSION

During the course of LAHNC IMRT, around 60% of the PGs are overdosed of 4 Gy. Weekly replanning decreased the PG mean dose by 5 Gy, and therefore by 11% the xerostomia risk.

Volumetric and Dosimetric Assessment by Cone-Beam Computed Tomography Scans in Head and Neck Radiation Therapy: A Monitoring in Four Phases of Treatment

Due to the anatomical changes frequently occurring during the course of head and neck (H&N) cancer radiotherapy, the dose distribution, which was actually delivered to the patient, might significantly differ from that planned. The aim of this paper is to investigate these volumetric changes and the resulting dosimetric implications on organs at risk (OARs) and clinical target volumes (CTVs) by cone beam computed tomography (CBCT) scans throughout the treatment. Ten H&N patients, treated by Intensity Modulated Radiotherapy, were analyzed. CTVs and OARs were delineated on four CBCT, acquired at the 10th, 15th, 20th and 25th treatment session, and then compared with the ones at planning CT. The planned beams were applied to each CBCT to recalculate the dose distribution and the corresponding dose volume histograms were compared with those generated on planning CT. To evaluate the HU discrepancies between the conventional CT and CBCT images we used a Catphan® 504, observing a maximum discrepancy of about 30 HU. We evaluated the impact of this HU difference in dose calculation and a not clinically relevant error, within 2.8%, was estimated. No inhomogeneity correction was used. The results showed an increased CTV mean dose (Dmean) of about 3% was found, without significant reduction in volume. Due to the parotids' shrinkage (up to 42%), significant dosimetric increases were observed: ipsilateral gland at 15th CBCT (Dmean by 18%; V30 by 31%); controlateral gland at the 10th CBCT (Dmean by 12.2%; V30 by 18.7%). For the larynx, a significant increase of volume was found at the 20th (15.7%) and 25th CBCT (13.3%) but it complied with dose constraint. The differences observed for the spinal cord and mandible maximum doses were not clinically relevant. In conclusion, the dosimetric analysis on CBCT can help clinicians to monitor treatment progress and to evaluate whether and when a new plan is necessary. The main benefit of replanning could be to preserve the parotids and our data support the hypothesis that the 3rd week of radiotherapy should be a check point for parotids.

Head and neck intensity modulated radiotherapy parotid glands: time of re-planning

PURPOSE

To investigate the correct time point for re-planning by evaluating dosimetric changes in the parotid glands (PGs) during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients.

MATERIALS AND METHODS

Patients with head and neck cancer treated with IMRT were enrolled. During treatment all patients underwent cone-beam computed tomography (CBCT) scans to verify the set-up. CBCT scans at treatment days 10, 15, 20 and 25 were used to transfer the original plan (CBCTplan I, II, III, IV, respectively) using rigid registration between the two. The PGs were retrospectively contoured and evaluated with the dose-volume histogram. The mean dose, the dose to 50 % of volume, and the percentage of volume receiving 30 and 50 Gy were evaluated for each PG. The Wilcoxon sign ranked test was used to evaluate the effects of dosimetric variations and values <0.05 were taken to be significant.

RESULTS

From February to June 2011, ten patients were enrolled and five IMRT plans were evaluated for each patient. All the dosimetric parameters increased throughout the treatment course. However, this increase was statistically significant at treatment days 10 and 15 (CBCTplan I, II; p = 0.02, p = 0.03, respectively).

CONCLUSION

CBCT is a feasible method to assess the dosimetric changes in the PGs. Our data showed that checking the PG volume and dose could be indicated during the third week of treatment.

Analysis of factors influencing the development of xerostomia during intensity-modulated radiotherapy

OBJECTIVES

Factors influencing xerostomia during intensity-modulated radiation therapy (IMRT) were assessed.

METHODS

A 6-week study of 32 head and neck cancer (HNC) patients was performed. Subjects completed the Xerostomia Inventory (XI) and provided stimulated saliva (SS) at baseline, week 2 and at end of IMRT. Influence of SS flow rate (SSFR), calcium and mucin 5b (MUC5b) concentrations and radiation dose on xerostomia was determined.

RESULTS

HNC subjects experienced mean SSFR decline of 36% by visit 2 (N = 27; P = .012) and 57% by visit 3 (N = 20; P = .0004). Concentrations of calcium and MUC5b increased, but not significantly during IMRT (P > .05). Xerostomia correlated most with decreasing salivary flow rate as determined by Spearman correlations (P < .04) and linear mixed models (P < .0001).

CONCLUSIONS

Although IMRT is sparing to the parotid glands, it has an early effect on SSFR and the constituents in saliva in a manner that is associated with the perception of xerostomia.

Cone-beam computed tomography dose monitoring during intensity-modulated radiotherapy in head and neck cancer: parotid glands

PURPOSE

To evaluate the dosimetric changes of parotid glands (PG) during a course of intensity-modulated radiotherapy (IMRT) in head and neck (H&N) cancer patients.

METHODS

Ten patients with H&N cancer treated by IMRT were analyzed. The original treatment plan (CT(plan)) was transferred to cone-beam computed tomography (CBCT) acquired at the 15th and 20th treatment day (CBCT(plan) I and II, respectively). The PG mean dose (D(mean)), the dose to 50 % of the volume, and the percent of volume receiving 30 and 50 Gy were measured by the dose volume histogram.

RESULTS

30 IMRT plans were evaluated (3 plans/patient). All dosimetric end points increased significantly for both PG only when CT(plan) was compared to CBCT(plan) I. The D(mean) increased significantly only for ipsilateral PG (p = 0.02) at week 3.

CONCLUSION

During a course of IMRT, CBCT is a feasible method to check the PG dosimetric variations. Perhaps, the 3rd week of radiotherapy could be considered as the time-check-point.

Parotid gland volumetric changes during intensity-modulated radiotherapy in head and neck cancer

OBJECTIVE

To evaluate volumetric changes of parotid glands (PGs) during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients.

METHODS

During IMRT all patients underwent kilovolt cone-beam CT (CBCT) scans to verify the set-up positioning in a protocol study. On each CBCT scan, the PGs were retrospectively contoured and evaluated with a dose-volume histogram.

RESULTS

From February to June 2011, 10 patients were enrolled. 140 CBCT scans were registered (280 PGs): for each patient, a median of 14 CBCT scans were performed (range 14-16). At the start of radiation, the average volume for ipsilateral PGs (iPGs) was 18.77 ml (range 12.9-31.2 ml), whereas for contralateral PGs (cPGs) it was 16.63 ml (range 8.3-28.7 ml). At the last CBCT scan, the average volume loss was 43.5% and 44.0% for the iPG and cPG, respectively. When we analysed the percentage of volume loss, we observed that the volume decreased by linear regression (r(2)=0.92 for iPG; r(2)=0.91 for cPG), with an average volume loss rate of 1.5% per day for both PGs. During the third week of treatment the volume of both PGs reduced by 24-30%.

CONCLUSION

Our data show that, during IMRT, the shrinkage of PGs should be taken into account. A replan could be indicated in the third week of radiotherapy.

Xerostomia and salivary hypofunction in vulnerable elders: prevalence and etiology

OBJECTIVE

The goal of this article is to review existing research on the prevalence and etiology of dry mouth in the vulnerable elders and identify knowledge gaps.

STUDY DESIGN

Vulnerable elders (VE) are persons aged >65 years who have any or all of the following: limited mobility, limited resources, or complex health status. A systematic search was conducted of PubMed sources from 1989 to May 2010. Evidence was evaluated on the prevalence and etiology of xerostomia and salivary gland hypofunction (SGH) in VE.

RESULTS

The search identified 1,422 publications. The inclusion/exclusion criteria yielded 348 articles, 80 of which are cited herein.

CONCLUSIONS

Research has showed a high prevalence of xerostomia and SGH in VE. Common etiologies include medications, poor general health, female gender, and age. Gaps still exist in the evaluation of dry mouth in VE. Nonetheless, oral dryness will remain an important health issue as life expectancy increases.

Parotid gland-recovery after radiotherapy in the head and neck region--36 months follow-up of a prospective clinical study

Background

The aim of the present study was to evaluate the recovery potential of the parotid glands after using either 3D-conformal-radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) by sparing one single parotid gland.

Methods

Between 06/2002 and 10/2008, 117 patients with head and neck cancer were included in this prospective, non-randomised clinical study. All patients were treated with curative intent. Salivary gland function was assessed by measuring stimulated salivary flow at the beginning, during and at the end of radiotherapy as well as 1, 6, 12, 24, and 36 months after treatment. Measurements were converted to flow rates and normalized relative to rates before treatment. Mean doses (D_mean) were calculated from dose-volume histograms based on computed tomographies of the parotid glands.

Results

Patients were grouped according to the D_mean of the spared parotid gland having the lowest radiation exposure: Group I - D_mean < 26 Gy (n = 36), group II - D_mean 26-40 Gy (n = 45), and group III - D_mean > 40 Gy (n = 36). 15/117 (13%) patients received IMRT. By using IMRT as compared to 3D-CRT the D_mean of the spared parotid gland could be significantly reduced (D_mean IMRT vs. 3D-CRT: 21.7 vs. 34.4 Gy, p < 0.001). The relative salivary flow rates (RFSR) as a function of the mean parotid dose after 24 and 36 months was in group I 66% and 74%, in group II 56% and 49%, and in group III 31% and 24%, respectively. Multiple linear regression analyses revealed that the parotid gland dose and the tumor site were the independent determinants 12 and 36 months after the end of RT. Patients of group I and II parotid gland function did recover at 12, 24, and 36 months after the end of RT.

Conclusions

If a D_mean < 26 Gy for at least one parotid gland can be achieved then this is sufficient to reach complete recovery of pre-RT salivary flow rates. The radiation volume which depends on tumor site did significantly impact on the D_mean of the parotids, and thus on the saliva flow and recovery of parotid gland.

Assessment of post-radiotherapy salivary glands

Salivary glands are usually irradiated during radiotherapy for head and neck cancers, which can lead to radiation-induced damage. Radiation-induced xerostomia (oral dryness) is the most common post-radiotherapy complication for head and neck cancer patients and can reduce the patient's quality of life. Accurate and efficient salivary gland assessment methods provide a better understanding of the cause and degree of xerostomia, and may help in patient management. At present, there are different methods for the assessment of salivary gland hypofunction; however, none of them are considered to be standard procedure. This article reviews the value of common methods in the assessment of post-radiotherapy salivary glands.

A systematic review of salivary gland hypofunction and xerostomia induced by cancer therapies: management strategies and economic impact

PURPOSE

This systematic review aimed to assess the literature for management strategies and economic impact of salivary gland hypofunction and xerostomia induced by cancer therapies and to determine the quality of evidence-based management recommendations.

METHODS

The electronic databases of MEDLINE/PubMed and EMBASE were searched for articles published in English since the 1989 NIH Development Consensus Conference on the Oral Complications of Cancer Therapies until 2008 inclusive. For each article, two independent reviewers extracted information regarding study design, study population, interventions, outcome measures, results, and conclusions.

RESULTS

Seventy-two interventional studies met the inclusion criteria. In addition, 49 intensity-modulated radiation therapy (IMRT) studies were included as a management strategy aiming for less salivary gland damage. Management guideline recommendations were drawn up for IMRT, amifostine, muscarinic agonist stimulation, oral mucosal lubricants, acupuncture, and submandibular gland transfer.

CONCLUSIONS

There is evidence that salivary gland hypofunction and xerostomia induced by cancer therapies can be prevented or symptoms be minimized to some degree, depending on the type of cancer treatment. Management guideline recommendations are provided for IMRT, amifostine, muscarinic agonist stimulation, oral mucosal lubricants, acupuncture, and submandibular gland transfer. Fields of sparse literature identified included effects of gustatory and masticatory stimulation, specific oral mucosal lubricant formulas, submandibular gland transfer, acupuncture, hyperbaric oxygen treatment, management strategies in pediatric cancer populations, and the economic consequences of salivary gland hypofunction and xerostomia.

A systematic review of salivary gland hypofunction and xerostomia induced by cancer therapies: prevalence, severity and impact on quality of life

PURPOSE

This systematic review aimed to assess the literature for prevalence, severity, and impact on quality of life of salivary gland hypofunction and xerostomia induced by cancer therapies.

METHODS

The electronic databases of MEDLINE/PubMed and EMBASE were searched for articles published in English since the 1989 NIH Development Consensus Conference on the Oral Complications of Cancer Therapies until 2008 inclusive. Two independent reviewers extracted information regarding study design, study population, interventions, outcome measures, results and conclusions for each article.

RESULTS

The inclusion criteria were met by 184 articles covering salivary gland hypofunction and xerostomia induced by conventional, 3D conformal radiotherapy or intensity-modulated radiotherapy in head and neck cancer patients, cancer chemotherapy, total body irradiation/hematopoietic stem cell transplantation, radioactive iodine treatment, and immunotherapy.

CONCLUSIONS

Salivary gland hypofunction and xerostomia are induced by radiotherapy in the head and neck region depending on the cumulative radiation dose to the gland tissue. Treatment focus should be on optimized/new approaches to further reduce the dose to the parotids, and particularly submandibular and minor salivary glands, as these glands are major contributors to moistening of oral tissues. Other cancer treatments also induce salivary gland hypofunction, although to a lesser severity, and in the case of chemotherapy and immunotherapy, the adverse effect is temporary. Fields of sparse literature included pediatric cancer populations, cancer chemotherapy, radioactive iodine treatment, total body irradiation/hematopoietic stem cell transplantation, and immunotherapy.

Radiation-induced damage to microstructure of parotid gland: evaluation using high-resolution magnetic resonance imaging

PURPOSE

To elucidate the radiation-induced damage to the microstructure of the parotid gland using high-resolution magnetic resonance imaging.

METHODS AND MATERIALS

High-resolution magnetic resonance imaging of the parotid gland was performed before radiotherapy (RT) and during the RT period or < or =3 weeks after RT completion for 12 head-and-neck cancer patients using a 1.5-T scanner with a microscopy coil. The maximal cross-sectional area of the gland was evaluated, and changes in the internal architecture of the gland were assessed both visually and quantitatively.

RESULTS

Magnetic resonance images were obtained at a median parotid gland dose of 36 Gy (range, 11-64). According to the quantitative analysis, the maximal cross-sectional area of the gland was reduced, the width of the main duct was narrowed, and the intensity ratio of the main duct lumen to background was significantly decreased after RT (p <.0001). According to the visual assessment, the width of the main duct tended to narrow and the contrast of the duct lumen tended to be decreased, but no significant differences were noted. The visibility of the duct branches was unclear in 10 patients (p = .039), and the septum became dense in 11 patients (p = .006) after RT.

CONCLUSION

High-resolution magnetic resonance imaging is a noninvasive method of evaluating radiation-induced changes to the internal architecture of the parotid gland. Morphologic changes in the irradiated parotid gland were demonstrated during the RT course even when a relatively small dose was delivered to the gland.

Assessment of xerostomia and its impact on quality of life in head and neck cancer patients undergoing radiotherapy, and validation of the Taiwanese version of the xerostomia questionnaire

The purposes of this study were to (a) explore the impact of xerostomia and saliva flow on quality of life and (b) validate the Taiwanese version of the Xerostomia Questionnaire (XQ) for patients undergoing radiotherapy (RT) for head and neck cancer in Taiwan. This was a prospective longitudinal study. Instruments consisted of the Xerostomia Questionnaire-Taiwan version (XQ-T) and the Medical Outcomes Study Short Form-36 Taiwan Version. Salivary output was measured by collecting unstimulated whole saliva. The questionnaires and measurements of salivary output were completed before RT was initiated and at two, four, six, and eight weeks after RT had started. Changes in xerostomia scores, quality of life, saliva flow, and predictors of quality of life over time were examined by using general estimating equations. The XQ-T is the first xerostomia measurement instrument developed for use with Taiwanese cancer patients and demonstrated excellent reliability and validity. Saliva flow was significantly correlated with XQ-T scores at two, four, six, and eight weeks after RT had started, but not before RT had begun. Saliva flow and quality-of-life scores significantly diminished and xerostomia scores significantly increased over the eight-week period. Saliva flow and XQ-T scores significantly predicted quality of life, after adjusting for the maturation effect. The results of this study show that the XQ-T is the first xerostomia measurement instrument to be developed for Taiwanese cancer patients and demonstrates excellent reliability and validity.

Parotid-gland-sparing 3D conformal radiotherapy in patients with bilateral radiotherapy of the head and neck region--results in clinical practice

The aim was to improve the prediction rate of hyposalivation after using a modern 3D-conformal-radiotherapy-technique (3D-CRT) by sparing of the contralateral parotid gland. Between June 2002 and October 2006, 107 patients (90 male, 17 female, average age: 58 years) with squamous cell carcinoma of the head and neck were included in a prospective, non-randomized study. All patients were treated using 3D-CRT. Parotid function was assessed by measuring stimulated salivary flow before, during and at the end of radiotherapy, as well as 1, 6 and 12 months after radiotherapy. Measurements were converted to flow rates and normalized relative to that before treatment. Mean doses (D(mean)) were calculated from dose-volume histograms (DVHs) based on computed tomographies (CTs) for the left and right parotid gland separately. Patients were grouped according to the D(mean) of the lowest irradiated parotid gland. Group I included all patients who received a D(mean)<26Gy (n=23), group II D(mean) 26-40Gy (n=38) and group III D(mean)>40Gy (n=46). By the time of 6 months after irradiation, salivary flow rates decreased continuously during the therapy. In group I the flow rate decreased to 59%, in group II to 40% and in group III to 14%, p<0.05. One year after irradiation a recovery effect could be measured in all groups. A sufficient saliva flow rate can be proven if one parotid gland is spared with a D(mean) dose <26Gy. Approximately, one quarter of the participants showed a significant improvement.

Grading xerostomia by physicians or by patients after intensity-modulated radiotherapy of head-and-neck cancer

PURPOSE

To assess observer-based vs. patient self-reported scoring of xerostomia after intensity-modulated radiotherapy (IMRT) of head-and-neck (HN) cancer.

METHODS

A total of 38 patients who had received IMRT for HN cancer underwent xerostomia evaluations 6 to 24 months after completion of therapy using three methods each time: (1) Grading by 3 observers according to the Radiotherapy Oncology Group/European Organization for Research and Therapy of Cancer (RTOG/EORTC) system; (2) patient self-reported validated xerostomia questionnaire (XQ); and (3) major salivary gland flow measurements.

RESULTS

The interobserver agreement regarding the RTOG/EORTC grades was moderate: kappa-coefficient 0.54 (95% CI=0.31-0.76). The correlations between the average RTOG/EORTC grades and the salivary flow rates were not statistically significant. A trend for significant correlation was observed between these grades and the percent (relative to the pretherapy) nonstimulated salivary flow rates (p=0.07), but not with the percent stimulated flow rates. Better correlations were found between grading made more than the median time (15 min) after the last liquid sipping and the nonstimulated (but not the stimulated) flows compared with grading made shortly after sipping. In contrast, significant correlations were found between the XQ scores and the nonstimulated (p<0.005) and the stimulated (p<0.005) salivary flow rates, as well as with the percentages of the corresponding pretherapy values (p=0.002 and 0.038, respectively). No significant correlation was found between the RTOG/EORTC grades and the XQ scores. The observer-based grades underestimated the severity of xerostomia compared with the patient self-reported scores.

CONCLUSIONS

Patient self-reported, rather than physician-assessed scores, should be the main end points in evaluating xerostomia.

Analysis of interfractional set-up errors and intrafractional organ motions during IMRT for head and neck tumors to define an appropriate planning target volume (PTV)- and planning organs at risk volume (PRV)-margins

BACKGROUND AND PURPOSE

To analyze the interfractional set-up errors and intrafractional organ motions and to define appropriate planning target volume (PTV)- and planning organs at risk volume (PRV)-margins in intensity-modulated radiotherapy (IMRT) for head and neck tumors.

PATIENTS AND METHODS

Twenty-two patients with head and neck or brain tumors who were treated with IMRT were enrolled. The set-up errors were defined as the displacements of the coordinates of bony landmarks on the beam films from those on the simulation films. The organ motions were determined as the displacements of the coordinates of the landmarks on the images recorded every 3 min for 15 min on the X-ray simulator from those on the initial image.

RESULTS

The standard deviations (SDs) of the systematic set-up errors (Sigma-INTER) and organ motions (Sigma-intra) distributed with a range of 0.7-1.3 and 0.2-0.8 mm, respectively. The average of the SDs of the random set-up errors (sigma-INTER) and organ motions (sigma-intra) ranged from 0.7 to 1.6 mm and from 0.3 to 0.6 mm, respectively. Appropriate PTV-margins and PRV-margins for all the landmarks ranged from 2.0 to 3.6 mm and from 1.8 to 2.4 mm, respectively.

CONCLUSIONS

We have adopted a PTV-margin of 5mm and a PRV-margin of 3mm for head and neck IMRT at our department.