Parotid Gland Volume Research Articles

Does adaptive radiotherapy for head and neck cancer favorably impact dosimetric, clinical, and toxicity outcomes?: A review.

The current review aims to summarize the international experience of the impact of adaptive radiotherapy on dosimetry and clinical and toxicity outcomes. Additionally, it might trigger Radiation Oncologists to use ART and evaluate whether ART improves target volume coverage and/or normal tissue sparing and, consequently, therapeutic results. We conducted an electronic literature search of PubMed/MEDLINE and ScienceDirect from January 2007 to January 2023. The search adhered to the PRISMA guidelines and employed keywords such as ART, HNC, parotid gland, and target volume. Furthermore, we examined the reference lists for studies pertinent to the present review. This study included both retrospective and prospective studies that were considered for inclusion. ART replanning appears to be a sustainable strategy to minimize toxicity by improving normal tissue sparing. Furthermore, it can enhance target volume coverage by correctly determining the specific dose to be delivered to the tumor. In conclusion, this review confirmed that ART benefits dosimetric, clinical/therapeutic, and toxicity outcomes.

Evaluation of submandibular and parotid salivary glands by ultrasonography in patients with diabetes.

Microvascular complications of diabetes mellitus (DM) include oral manifestations and complications, including xerostomia, reduced salivary flow, susceptibility to infection, periodontal disease and salivary gland enlargement. The present study aims to evaluate B-mode ultrasonography (USG) parameters such as size, volume and echogenicity of the submandibular and parotid salivary glands on both sides, shear-wave elastography (SWE) value and colour Doppler properties in patients with DM and healthy control groups. In total, 160 right and left submandibular glands and 160 right and left parotid glands of 80 patients, 40 patients (20 type 1 DM, 20 type 2 DM) and 40 healthy control group, between the ages of 18-70 were examined by USG. Echogenicity, parenchyma internal structure, margin and dimensional measurements (antero-posterior length, supero-inferior length, medio-lateral length and volume) and colour Doppler with 'ML 6-15-D Matrix Array (4-15 MHz)' probe, shear-wave elastography '9L-D (2-8 MHz)' probe was investigated. Statistically significant difference was observed in echogenicity in the right submandibular gland, echogenicity in the right parotid gland, margin characteristics, parenchymal homogeneity and colour Doppler characteristics between the type 1 DM, type 2 DM and control groups (p < .05). It was observed that the size, volume and SWE values of both submandibular and parotid glands were higher in the DM patient group than in the control group. Higher values were observed in type 2 DM compared to type 1 DM in the patient group. USG is an effective imaging technique in investigating the effects of diabetes on the submandibular and parotid salivary glands.

3D radiotherapy in the parotid gland and its dosimetric relationship with salivary flow and quality of life in patients with head and neck cancer

Aim: Hyposalivation and dry mouth affect the quality of life in patients with Head and Neck Cancer, who did the treatment with radiotherapy. Thus this study has the objective to evaluate the dosimetric relationship between 3D radiotherapy and changes in salivary flow, xerostomia and quality of life in patients with head and neck cancer according to the volume of the irradiated parotid gland. Methods: 23 patients with cancer in the head and neck area and in need of 3D radiotherapy were followed up during radiotherapy treatment, and the parotid gland (PG) design was also performed in radiotherapy planning. Questionnaires were carried out to determine xerostomia and quality of life, while the salivary flow was determined through calculations regarding the collection and weighing of saliva. Such data were collected in three moments: before the beginning of the radiotherapy treatment (D0), in the middle of the treatment (D1) and at the end of it (D2). The numerical variables are represented by measures of central tendency and measures of dispersion. Results: when associating the salivary flow, the xerostomia questionnaire and the OHIP-14, a statistically significant difference was found (p-value &lt;0.001), as well as when comparing some volumes of irradiated PG with the OHIP-14. However, no relationship was found between dosimetric data, xerostomia and hyposalivation. Conclusion: patients undergoing 3D radiotherapy for malignant neoplasms in the head and neck region had decreased salivary flow, increased complaints of dry mouth and decreased quality of life. However, it was not possible to establish a statistically significant correlation between these findings and the volumes of irradiated parotids.

In silico study of the electronic portal imaging devices sensitivity to parotid glands shrinkage during radiotherapy for nasopharyngeal cases

This computational investigation examines the capability of electronic portal imaging devices (EPIDs) in detecting anatomical changes during radiation therapy. A photon beam for 6 MV was simulated using compliant phase-space files via BEAMnrc (an EGSnrc user code). Initially, the dose calculation was carried out using DOSXYZnrc, an EGSnrc user code, on a water-based calibration phantom made of water. Phantoms, constructed utilizing patient computed tomography data, were subsequently used to simulate clinically relevant parotid gland (PG) shrinkage through image deformation using ImSimQA software. Two EPID geometries were implemented; a simple water slab, and a comprehensive multi-layer representation of the EPID (referred to as the 17-slab model). Using a 1%/1 mm gamma index the 17-slab geometry was sensitive to volume reductions in the PG ≥ − 26% from its original volume, while the water slab detected volume reduction of ≥ − 28.5%. In a clinical setting, replanning of head and neck patients is initiated when a reduction of 24–30% in PG volume is detected through cone-beam computed tomography. The sensitivity index, indicative of the signal to error ratio between the reference and evaluated images, showed an increase as the gland volume decreased for both models. Notably, the 17-slab model consistently more sensitive than the water slab. This computational study highlights the prospective use of EPIDs in monitoring and detecting clinically significant volume changes in the PG during radiation treatment. Advances in knowledge: While EPIDs are frequently employed for patient setup and alignment, this computational work constructed a virtual EPID to assess its detection abilities for the anatomical changes in the PG due to radiation exposure in head and neck cancer cases.

Long-term outcomes of stimulated salivary flow and xerostomia after definitive intensity-modulated radiation therapy for patients with head and neck cancer†.

This retrospective study aimed to evaluate the time to recovery from xerostomia and analyze its predictors, along with long-term outcomes of stimulated salivary flow after intensity-modulated radiation therapy (IMRT) for head and neck cancer (HNC). We evaluated patients with HNC who had received IMRT with curative intent between 2012 and 2018 at our institution. The salivary recovery ratio (SRR) was defined as '(the stimulated salivary flow)/(pre-treatment salivary flow)'. The cutoff value of SRR in salivary recovery was estimated via the relationship between SRR and xerostomia grades. The salivary recovery time was defined as the time for SRR to exceed cutoff values from the end of radiotherapy. Fifty-seven patients were analyzed, with a 48-month median follow-up period of stimulated salivary flow. The cutoff value for SRR was 44.8%, and patients with a higher grade of xerostomia had a lower SRR (P < 0.001). The median salivary recovery time was 12months. The cumulative incidence rates of salivary recovery at two and four years were 84 (95% confidence interval [CI]: 53-79) and 92% (95% CI: 82-97), respectively, and these were significantly lower in patients with a higher mean parotid gland dose, mean oral cavity dose and stimulated salivary flow per parotid gland volume. Stimulated salivary flow and xerostomia recover over a long period after radiotherapy.

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.

Population Based Average Parotid Gland Volume and Prevalence of Incidental Tumors in T1-MRI.

Representative epidemiologic data on the average volume of the parotid gland in a large population-based MRI survey is non-existent. Within the Study of Health in Pomerania (SHIP), we examined the parotid gland in 1725 non-contrast MRI-scans in T1 weighted sequence of axial layers. Thus, a reliable standard operating procedure (Intraclass Correlation Coefficient &gt; 0.8) could be established. In this study, we found an average, single sided parotid gland volume of 27.82 cm3 (95% confidence interval (CI) 27.15 to 28.50) in male and 21.60 cm3 (95% CI 21.16 to 22.05) in female subjects. We observed positive associations for age, body mass index (BMI), as well as male sex with parotid gland size in a multivariate model. The prevalence of incidental tumors within the parotid gland regardless of dignity was 3.94% in the Northeast German population, slightly higher than assumed. Further epidemiologic investigations regarding primary salivary gland diseases are necessary.

Can Superficial Parotid Sparing Alone Reduce Xerostomia? A Retrospective Study Correlating Type of Tobacco Use, Chronic Xerostomia and Parotid Sparing

<h3>Purpose/Objective(s)</h3> Head and neck cancer is one of the most common cancers in India. Tobacco chewing is the most widespread form of tobacco consumption. Majority of the patients present in locally advanced stage and achieving parotid sparing with IMRT in these patients can be challenging. We aimed to correlate the incidence of chronic xerostomia with the type of tobacco use and parotid volumes. <h3>Materials/Methods</h3> Patients with squamous carcinomas of head and neck region treated with conventionally fractionated curative-intent radiotherapy (bilateral neck) to a dose of 60-70 Gy between June 2017 and March 2020 were included in the study. The superficial and deep lobes of parotid were contoured retrospectively and the dosimetric data along with physician-assessed Radiation Therapy Oncology Group (RTOG) xerostomia toxicity grades at one year were retrieved. The individual, superficial and deep lobe parotids were considered spared if the mean dose was less than 26Gy. Patients were divided into five groups: Group 1 constituted bilateral parotid-spared, Group 2 of contralateral parotid-spared, Group 3 of contralateral superficial parotid-spared, Group 4 of bilateral superficial parotid-spared, and Group 5 where no sparing could be achieved. The groups were compared using chi-square test. <h3>Results</h3> 174 patients were included in the study. The median age was 59 years (IRQ 20 - 89). Chewing (40%), followed by smoking (35%) were the most frequent forms of tobacco consumption. The most common subsite was oropharynx (30.5%) followed by hypopharynx (26.4%), and about 83% had locally advanced disease. The mean bilateral parotid volume was 55.9 cc (18-130 cc). Tobacco chewers had significantly smaller mean parotid (53cc vs 60cc, p=0.02) and submandibular gland volumes (6cc vs 14cc, p<0.001) as compared to smokers. Bilateral or contralateral parotid sparing was achieved in 62.7%, bilateral or contralateral superficial lobe in 27.6%, and no sparing in 9.8% of patients. At one year, grade 0/I xerostomia was reported by 89.5%, and ≥grade II xerostomia in 11.5%. The grade of xerostomia was similar in smokers and chewers (p=0.95). The ipsilateral (26.5 Gy vs 37.8 Gy, p <0.001) and contralateral (23.3 Gy vs 34.1 Gy, p <0.001) superficial parotid mean dose in patients with grade 0/I and ≥grade II xerostomia was significantly different. Patients with bilateral or contralateral superficial lobe sparing had lower rates of grade II/III xerostomia compared to no sparing group (p<0.001). <h3>Conclusion</h3> Tobacco chewers have smaller parotid and submandibular glands compared to smokers. This did not impact the sparing of glands or the severity of xerostomia. Contralateral or bilateral superficial parotid sparing translated into superior salivary gland function at 1 year.

Anatomy of parotid gland and its secretory ducts in sheep.

The parotid gland in sheep ends freely in front of the masseter muscle, and paracondylary section of occipital bone and extends deep until pterygoid extends of sphenoid bone and hyoid bone. The structure of salivary glands in mammals has been thoroughly studied using histological and sialographic method. This study aimed to reveal the detailed anatomic features and race-specific differences of the canal system of the parotid glands in Akkaraman sheep by using the corrosion cast technique. Thirteen sheep parotid glands from 7 Akkaraman sheep were used in this study. Parotid glands were removed from their places with ducts. Measurements were made with a calliper from back to front, top to bottom and inside to outside. After dissection of the parotid glands, their volumes were measured according to the 'Archimedes principle'. Also, 13 sheep parotid glands were examined using the polyester resin method. In the present study, our average metric results were: length of parotid duct was 10.92 ± 1.027 cm, length of parotid gland was 5.87 ± 1.04 cm, volume of parotid gland was 12.50 ± 2.48 cm³, thickness of parotid gland was 0.75 ± 0.36 cm and width of parotid gland was 4.07 ± 0.43 cm. The average weight of the parotid gland of Akkaraman sheep was identified as 25.3 g. Accessory parotid gland was not encountered in the current study. It was observed that polyester entered into the parotid duct and filled up until the acinus and made both acinus and secretory ducts well-examined in this study. It was also observed that the parotid gland consisted of lobes and lobules. The average number of lobes was 12. The number of lobules in a lobe varied between 3 and 16, each lobe consisted of an average of 9 lobules. It was found that each lobe has its own lobar duct.

Efficacy and Safety of Botulinum Toxin Type A in the Treatment of Benign Parotid Hypertrophy: A Prospective Study.

Benign parotid hypertrophy makes the earlobe area appear swollen and weakens the lateral facial contour and aesthetics. Efficacious treatment for benign parotid hypertrophy is not available. The authors evaluated the efficacy and safety of botulinum toxin type A for benign parotid hypertrophy treatment. Thirty-six participants with benign parotid hypertrophy were enrolled and treated with botulinum toxin type A injection. After 6 months of follow-up, changes in the thickness and length of the superficial lobe of the parotid gland were assessed. Analyses of patient subgroups and image analyses were also undertaken to assess improvement. Thirty-three participants completed this study. Superficial lobe of the parotid gland thickness was reduced significantly after botulinum toxin type A injection, but the longitudinal diameter of the parotid gland was not changed significantly ( p < 0.001 and p = 0.146, respectively). Subgroup analyses showed that the degree of parotid gland hypertrophy affected treatment efficacy and degree of improvement, but age and sex did not ( p < 0.001, p = 0.137, and p = 0.138, respectively). Image analyses showed improvement in the facial contour ( p < 0.05). Serious adverse reactions or complications were not observed. Botulinum toxin type A can be used to treat benign parotid hypertrophy, reduce parotid gland volume, and improve the facial contour. Therapeutic, IV.

3D RADIOTHERAPY IN THE PAROTID GLAND AND ITS DOSIMETRIC RELATIONSHIP WITH SALIVARY FLOW AND QUALITY OF LIFE

<h3>Objectives</h3> To evaluate the dosimetric relationship between 3D radiotherapy and changes in salivary flow, xerostomia, and quality of life in patients with head and neck cancer according to the volume of the irradiated parotid gland. <h3>Study Design</h3> Twenty-three patients with cancer in the head and neck area and in need of 3D radiotherapy were followed up during radiotherapy treatment, and the parotid gland (PG) design was also performed in radiotherapy planning. Questionnaires were carried out to determine xerostomia and quality of life, and salivary flow was determined through calculations involving the collection and weighing of saliva. The numerical variables were represented by measures of central tendency and measures of dispersion. <h3>Results</h3> When associating salivary flow, the xerostomia questionnaire, and quality of life, a statistically significant difference was found (<i>P</i> < .001). However, no relationship was found between dosimetry data, xerostomia, and hyposalivation. <h3>Conclusions</h3> Patients undergoing 3D radiotherapy for malignant neoplasms in the head and neck region had decreased salivary flow, increased complaints of dry mouth, and decreased quality of life; however, it was not possible to establish a statistically significant correlation between these findings and the volumes of irradiated parotids.

Criteria for Verification and Replanning Based on the Adaptive Radiotherapy Protocol "Best for Adaptive Radiotherapy" in Head and Neck Cancer.

No clear criteria have yet been established to guide decision-making for patient selection and the optimal timing of adaptive radiotherapy (ART) based on image-guided radiotherapy (IGRT). We have developed a novel protocol—the Best for Adaptive Radiotherapy (B-ART) protocol—to guide patient selection for ART. The aim of the present study is to describe this protocol, to evaluate its validity in patients with head and neck (HN) cancer, and to identify the anatomical and clinical predictors of the need for replanning. We retrospectively evaluated 82 patients with HN cancer who underwent helical tomotherapy (HT) and subsequently required replanning due to soft tissue changes upon daily MVCT. Under the proposed criteria, patients with anatomical changes >3 mm on three to four consecutive scans are candidates for ART. We compared the volumes on the initial CT scan (iCT) and the replanning CT (rCT) scan for the clinical target volumes (CTV1, referring to primary tumor or tumor bed and CTV2, metastatic lymph nodes) and for the parotid glands (PG) and body contour (B-body). The patients were stratified by primary tumor localization, clinical stage, and treatment scheme. The main reasons for replanning were: (1) a planning target volume (PTV) outside the body contour (n = 70; 85.4%), (2) PG shrinkage (n = 69; 84.1%), (3) B-body deviations (n = 69; 84.1%), and (4) setup deviations (n = 40; 48.8%). The replanning decision was made, on average, during the fourth week of treatment (n = 47; 57.3%). The mean reductions in the size of the right and left PG volumes were 6.31 cc (20.9%) and 5.98 cc (20.5%), respectively (p < 0.001). The reduction in PG volume was ≥30% in 30 patients (36.6%). The volume reduction in all of the anatomical structures was statistically significant. Four variables—advanced stage disease (T3–T4), chemoradiation, increased weight loss, and oropharyngeal localization—were significantly associated with the need for ART. The B-ART protocol provides clear criteria to eliminate random errors, and to allow for an early response to relevant changes in target volumes.

Evaluation of Conformity and Homogeneity Indices Consistency Throughout the Course of Head and Neck Cancer Treatment With and Without Using Adaptive Volumetric Modulated Arc Radiation Therapy

PurposeConformity indices (CI) and homogeneity indices (HI) are important tools for evaluating treatment plan quality. In this study, we evaluate the consistency of these indices with respect to anatomic changes undergone by patients. Methods and MaterialsFifty-five patients with advanced head and neck cancer were treated with simultaneous integrated boost volumetric modulated arc therapy. The initial plan (iplan) then was projected on the new computed tomographs (CT) and 2 adaptive plans (Aplans) for each patient were performed on the new CTs. A comparison of CI and HI between the iplan, hybrid plan (Hplan), and Aplan was performed. ResultsThere was a significant weight loss (P < .001) between CT1, CT2, and CT3, where the median weight at CT1 was 75.78 (68.95-83.42) kg, and 74.88 (68.35-82.2) kg at CT2 and 73.1 (67.6-80.7) kg at CT3. Also, gross tumor volume (GTV) showed significant decrease at CT1, CT2, and CT3. The initial GTV was 32.3 (21-58.6) cc and 28.24 (15.85-48.63) cc at CT2 and 25.12 (14.1-42.2) at CT3. In addition, there was a significant decrease in left parotid volume after 10 and 20 fractions; the median left parotid gland volume at CT1 was 31.04 (26.34-36.27) cc, then was 25.84 (19.19-28.59) cc after 10 fractions and 19.5 (13.53-22.25) cc after 20 fractions; the median right parotid volume at CT1 was 29.81 (24.6-38.75) cc and 22.38 (18.19-30.12) cc at CT2, then the volume fell to 17.74 (13.41-22.66) cc at CT3. Also, a significant increase in dose to organs at risk were noticed at Hplans, the median dose for brain stem at iplan was 5156 (4561-5324) cGy then increased to 5321 (4688-5545) cGy at Hplan1 then increased again to reach 5401 (4821-5812) cGy at Hplan2. The CI showed regression at Hplan1 and Hplan2 and then improvement at Aplan1 and Aplan2. The HI also showed regression in its value at the Hplans and then improved at the Aplans. ConclusionsBased on the results, we conclude that anatomic changes such as weight loss greatly affect the quality of plan, and with Aplans, we maintained the quality of plan by sustaining the values of CI and HI as in the iplan

MR-Guided Adaptive Radiotherapy for Head and Neck Cancer: Prospective Evaluation of Migration and Anatomical Changes of the Major Salivary Glands.

Simple SummaryDuring radiotherapy of head and neck cancer patients, the radiation dose for the major salivary glands (parotids and submandibular glands) should be kept as low as possible to reduce toxicity risks. Nevertheless, volume changes and positional shifts of salivary glands during treatment may result in an increased dose, so adapting the treatment plan is recommended. While previous studies primarily used one or two CTs or CBCTs for imaging during treatment, frequent MRI allows for improved soft tissue contrast and more exact contour adaptation without an additional imaging dose. In this study, twelve patients were treated with MRI-guided radiotherapy with weekly offline adaptations. Significant parotid- and submandibular gland shrinkage, as well as a medial shift of the parotids, were observed. These results support the rationale of MR-guided radiotherapy for head and neck cancer, emphasizing the relevance of future clinical evaluation of toxicity to optimize the benefits of MRI-guided radiotherapy.The aim of this study was to quantify anatomical changes of parotids and submandibular glands and evaluate potential dosimetric advantages during weekly adaptive MR-guided radiotherapy (MRgRT) for the definitive treatment of head and neck cancer (HNC). The data and plans of 12 patients treated with bilateral intensity-modulated radiotherapy for HNC using MR-linac, with weekly offline adaptations, were prospectively evaluated. The positional and volumetric changes of the salivary glands were analyzed by manual segmentation in weekly MRI images and the dosimetric impact of these anatomical changes on the adapted treatment plans was assessed. The mean volume change in parotid and submandibular gland volume was −31.9% (p < 0.0001) and −29.7% (p < 0.0001) after five weeks, respectively. The volume change was significantly correlated with the cumulative dose for the respective gland at the time of volume measurement. Inter-parotid distance changed by −5.4% (6.5 mm) on average after five weeks (p = 0.0005). The distance became significantly smaller only in the left-right direction. The inter-submandibular gland distance changed by 0.7 mm (p = 0.38). This study demonstrated significant changes in salivary gland volumes and position following daily MR guidance and weekly plan adaptation. Ongoing clinical trials will provide data on the clinical impact of these changes and novel MR-based adaptation strategies.

Proton Therapy Specific Salivary Gland Volume Changes After Head and Neck Radiotherapy

Salivary glands are exquisitely sensitive to radiotherapy. Patients treated with radiotherapy to the head and neck region commonly develop salivary gland volume loss and associated xerostomia. Salivary volume loss is associated with salivary function loss, making it a useful surrogate indicator of xerostomia. Previous studies have correlated the degree of salivary gland volume loss with mean radiation doses in patients undergoing photon head and neck radiation. However, change in salivary gland volume relative to radiation dose has not been evaluated in patients undergoing proton therapy. Currently, a constant value of 1.1 is used to relate physical dose (PD) to biological dose (BD) for proton therapy. However, specific tissues may respond differently and thus require a different PD to BD conversion. Herein, we evaluate changes in salivary gland volumes relative to radiation dose in head and neck cancer patients receiving proton therapy to examine the validity of current PD to BD conversions for head and neck salivary glands.Dosimetric data and pre-radiation parotid gland and submandibular gland (SMG) volumes were collected for 20 head and neck cancer patients that received proton therapy at our institution between 2018-2020. Pre-radiation volumes of the SMGs and parotids were collected from treatment planning scans. Post-treatment salivary gland volumes were contoured on 3-month post-treatment diagnostic scans. Mean doses to the glands were gathered from dose-volume histograms generated from treatment plans. Linear logistical regression was performed to measure the effect of dose on volume change.Volume changes of 27 parotids and 38 SMGs were evaluated. Mean doses were 10.0 Gy (standard deviation (SD) 13.2) and 25.2 Gy (SD 25.0) for parotids and SMGs, respectively. Mean dose was < 1 Gy, < 30 Gy, and < 50 Gy in 59.3%, 92.6%, and 100% of parotids compared to 39.5%, 55.3%, and 81.6% of SMGs, respectively. Mean ratios of gland volumes at 3 months post-treatment relative to pre-treatment were 0.962 (SD 0.210) and 1.106 (SD 0.273) for parotids and SMGs, respectively. Effect of mean dose on gland volume change was not statistically significant for either parotids or SMGs.The greater relative size reduction in parotids versus SMGs was consistent with previous photon data. The mean increase in SMG volume could represent post-treatment functional compensation in preserved glands, but this requires additional investigation. Also, determination of the effect of proton dose on salivary gland volume change requires further analysis. Currently, no conclusions can be drawn whether salivary glands are equally or differentially sensitive to proton therapy relative to photon therapy.

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.

Deformable image registration to assist clinical decision for radiotherapy treatment adaptation for head and neck cancer patients

Head and neck (H&N) cancer patients often present anatomical and geometrical changes in tumors and organs at risk (OARs) during radiotherapy treatment. These changes may result in the need to adapt the existing treatment planning, using an expert’s subjective opinion, for offline adaptive radiotherapy and a new treatment planning before each treatment, for online adaptive radiotherapy. In the present study, a fast methodology is proposed to assist in planning adaptation clinical decision using tumor and parotid glands percentage volume changes during treatment. The proposed approach was applied to 40 Η&Ν cases, with one planning Computed Tomography (pCT) image and CBCT scans for 6 weeks of treatment per case. Deformable registration was used for each patient’s pCT image alignment to its weekly CBCT. The calculated transformations were used to align each patient’s anatomical structures to the weekly anatomy. Clinical target volume (CTV) and parotid gland volume percentage changes were calculated in each case. The accuracy of the achieved image alignment was validated qualitatively and quantitatively. Furthermore, statistical analysis was performed to test if there is a statistically significant correlation between CTV and parotid glands volume percentage changes. Average MDA for CTV and parotid glands between corresponding structures defined by an expert in CBCTs and automatically calculated through registration was 1.4 ± 0.1 mm and 1.5 ± 0.1 mm, respectively. The mean registration time of the first CBCT image registration for 40 cases was lower than 3.4 min. Five patients show more than 20% tumor volume change. Six patients show more than 30% parotid glands volume change. Ten out of 40 patients proposed for planning adaptation. All the statistical tests performed showed no correlation between CTV/parotid glands percentage volume changes. The aim to assist in clinical decision making on a fast and automatic way was achieved using the proposed methodology, thereby reducing workload in clinical practice.

A Study to Assess the Dosimetric Impact of the Anatomical Changes Occurring in the Parotid Glands and Tumour Volume during Intensity Modulated Radiotherapy using Simultaneous Integrated Boost (IMRT-SIB) in Head and Neck Squamous Cell Cancers.

BackgroundAnatomical variations in head and neck cancer during IMRT leads to volume shrinkage, results in dosimetric variations in tumour and normal tissue including parotid glands, with a risk of radiation toxicities.Methods30 patients with a stage II–IV head and neck squamous cell carcinoma (HNSCC) were treated with definitive IMRT‐SIB and concomitant chemotherapy. Volumetric and dosimetric variations were evaluated during the period of IMRT by recalculating and obtaining dose‐volume histograms of re‐contoured target volumes and parotid glands on repeat CT scans taken multiple times during treatment (CT1, CT2, CT3 and CT4).ResultsResult showed significant (p < 0.001) mean decrease in both primary and nodal tumors volume with time whereas increase (p < 0.01 or p < 0.001) in respective V100 (%) and D2% (Gy). The mean parotid gland dose increased (p < 0.01 or p < 0.001) with time, whereas parotid gland volume and distance between plan isocenter and centre of mass of parotid glands decreased (p < 0.05 or p < 0.001) with time. Patient's mean weight and neck circumference both decrease (p < 0.001) with time whereas ECOG score increase (p < 0.001) with time. The mucosal toxicity increased significantly (p < 0.001) with time. The change in both weight and neck circumference showed significant (p < 0.001) and direct (positive correlation) association with change in parotid gland volume.ConclusionIf the PTV and normal anatomy are changing with time, adaptive IMRT would be beneficial radiation dose delivery where possible.

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

BackgroundXerostomia 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.MethodsWe 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).ResultsThe 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.ConclusionsThe 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.

The effects of residual parotid volume on symptom-specific quality of life and complications in patients undergoing parotid surgery.

To measure postoperative residual parotid volumes in parotidectomy patients and to measure the effect of residual parotid volumes on the symptom-specific quality of life (SSQOL) and complications. Between January 2010 and December 2016, 148 parotid gland surgeries were performed, and 74 patients were included in the study.Bilateral parotid gland volumes were measured by Magnetic Resonance Imaging (MRI). Parotidectomy Outcome Inventory-8 and aesthetic scale questionnaire were applied to the patients. The volumetric averages obtained were compared with the questions in the SSQOL scale, the aesthetic scale data, and complications. In the volumetric examination performed with MRI, the mean residual volumes of the operated parotid glands were 9.5 cm3, while the non-operated side was 28.8 cm3.The width of the surgery and the residual parotid tissue volume was inversely correlated.There was a statistically significant difference between the residual parotid gland volume and the pain related to the surgical area, depression in the surgical site, Frey's syndrome, incision scar, and numbness. As the residual parotid gland volumes decreased, the patients' cosmetic problems related to the surgical field increased significantly, and their SSQOL decreased. Postoperative residual parotid tissue volume could be an objective parameter to measure patients' SSQOL and complications. After parotidectomy, the maximum amount of disease-free tissue of the parotid gland should be left in place to increase patients' quality of life and minimize complications.